Publications

TitleAbstractYear(sorted descending)
Filter
PMID
Filter
heterologous expression of lactobacillus casei reco improved the multiple-stress tolerance and lactic acid production in lactococcus lactis nz9000 during salt stress.the aim of this study was to investigate the effect of nisin-inducible reco expression on the stress tolerance of lactococcus lactis nz9000. reco protein from lactobacillus casei zhang was introduced into lactococcus lactis nz9000 by using a nisin-inducible expression system. the recombinant strain (nz-reco) exhibited higher growth performances and survival rate compared with the control strain (nz-vector) under stress conditions. in addition, the nz-reco strain exhibited 1.37-, 1.41-, and 1.42- ...201323796607
stable integration and expression of heterologous genes in several lactobacilli using an integration vector constructed from the integrase and attp sequences of phage φat3 isolated from lactobacillus casei atcc 393.an integration vector capable of stably integrating and maintaining in the chromosomes of several lactobacilli over hundreds of generations has been constructed. the major integration machinery used is based on the φat3 integrase (int) and attp sequences determined previously. a novel core sequence located at the 3' end of the trna(leu) gene is identified in lactobacillus fermentum atcc 14931 as the integration target by the integration vector though most of such sequences found in other lactoba ...201323064454
effect of drying methods of microencapsulated lactobacillus acidophilus and lactococcus lactis ssp. cremoris on secondary protein structure and glass transition temperature as studied by fourier transform infrared and differential scanning calorimetry.protective mechanisms of casein-based microcapsules containing mannitol on lactobacillus acidophilus and lactococcus lactis ssp. cremoris, changes in their secondary protein structures, and glass transition of the microcapsules were studied after spray- or freeze-drying and after 10 wk of storage in aluminum foil pouches containing different desiccants (naoh, licl, or silica gel) at 25°c. an in situ fourier transform infrared analysis was carried out to recognize any changes in fatty acids (fa) ...201323357021
construction and application of a food-grade expression system for lactococcus lactis.a food-grade host/vector expression system for lactococcus lactis was constructed using alanine racemase gene (alr) as the complementation marker. we obtained an alanine racemase auxotrophic mutant l. lactis nz9000δalr by double-crossover recombination using temperature-sensitive integration plasmid pg(+)host9 and a food-grade vector palr with entirely lactococcal dna elements, including lactococcal replicon, nisin-inducible promoter pnisa and the alr gene from lactobacillus casei bl23 as a comp ...201322674186
microbiology of cheddar cheese made with different fat contents using a lactococcus lactis single-strain starter.flavor development in low-fat cheddar cheese is typified by delayed or muted evolution of desirable flavor and aroma, and a propensity to acquire undesirable meaty-brothy or burnt-brothy off-flavor notes early in ripening. the biochemical basis for these flavor deficiencies is unclear, but flavor production in bacterial-ripened cheese is known to rely on microorganisms and enzymes present in the cheese matrix. lipid removal fundamentally alters cheese composition, which can modify the cheese mic ...201323684037
microbial ecology dynamics during rye and wheat sourdough preparation.the bacterial ecology during rye and wheat sourdough preparation was described by 16s rrna gene pyrosequencing. viable plate counts of presumptive lactic acid bacteria, the ratio between lactic acid bacteria and yeasts, the rate of acidification, a permutation analysis based on biochemical and microbial features, the number of operational taxonomic units (otus), and diversity indices all together demonstrated the maturity of the sourdoughs during 5 to 7 days of propagation. flours were mainly co ...201324096427
an extracellular serine/threonine-rich protein from lactobacillus plantarum ncimb 8826 is a novel aggregation-promoting factor with affinity to mucin.autoaggregation in lactic acid bacteria is directly related to the production of certain extracellular proteins, notably, aggregation-promoting factors (apfs). production of aggregation-promoting factors confers beneficial traits to probiotic-producing strains, contributing to their fitness for the intestinal environment. furthermore, coaggregation with pathogens has been proposed to be a beneficial mechanism in probiotic lactic acid bacteria. this mechanism would limit attachment of the pathoge ...201323892754
o-glycosylation as a novel control mechanism of peptidoglycan hydrolase activity.acm2, the major autolysin of lactobacillus plantarum, is a tripartite protein. its catalytic domain is surrounded by an o-glycosylated n-terminal region rich in ala, ser, and thr (ast domain), which is of low complexity and unknown function, and a c-terminal region composed of five sh3b peptidoglycan (pg) binding domains. here, we investigate the contribution of these two accessory domains and of o-glycosylation to acm2 functionality. we demonstrate that acm2 is an n-acetylglucosaminidase and id ...201323760506
utilization of lactic acid bacterial genes in synechocystis sp. pcc 6803 in the production of lactic acid.metabolic pathway engineering of cyanobacteria for the production of industrially important chemicals from atmospheric co2 has generated interest recently. here, we engineered synechocystis sp. pcc 6803 to produce lactic acid using a lactate dehydrogenase (ldh) gene from various lactic acid-producing bacteria, lactococcus lactis (ldhb and ldhx), lactobacillus plantarum (ldhl and ldh), and lactobacillus rhamnosus (ldhl). the lactic acid was secreted outside the cell using a transporter (lldp) gen ...201323649263
bioluminescence imaging study of spatial and temporal persistence of lactobacillus plantarum and lactococcus lactis in living mice.lactic acid bacteria, especially lactobacilli, are common inhabitants of the gastrointestinal tract of mammals, for which they have received considerable attention due to their putative health-promoting properties. in this study, we describe the development and application of luciferase-expressing lactobacillus plantarum and lactococcus lactis strains for noninvasive in vivo monitoring in the digestive tract of mice. we report for the first time the functional in vitro expression in lactobacillu ...201323204409
high-salt brines compromise autoinducer-mediated bacteriocinogenic lactobacillus plantarum survival in spanish-style green olive fermentations.the effect of nacl on plantaricin production by five lactobacillus plantarum strains was investigated. plantaricin production in these strains was found to be regulated by three-component regulatory systems ruled by two different autoinducer peptides (aips), either plnc8if or plantaricin a. bacteriocin activity exhibited by these strains came to a halt in liquid medium containing nacl concentrations of or above 2%. in contrast, bacteriocin activity was still observed when the producing strains w ...201323122506
using recombinant lactococci as an approach to dissect the immunomodulating capacity of surface piliation in probiotic lactobacillus rhamnosus gg.primarily arising from their well understood beneficial health effects, many lactobacilli strains are considered good candidates for use as probiotics in humans and animals. lactobacillar probiosis can itself be best typified by the lactobacillus rhamnosus gg strain, which, with its well-documented clinical benefits, has emerged as one of the most widely used probiotics in the food and health-supplement industries. even so, many facets of its molecular mechanisms and limitations as a beneficial ...201323691212
interaction of campylobacter spp. and human probiotics in chicken intestinal mucus.campylobacter is the most common cause of bacterial food-borne diarrhoeal disease throughout the world. the principal risk of human contamination is handling and consumption of contaminated poultry meat. to colonize poultry, campylobacter adheres to and persists in the mucus layer that covers the intestinal epithelium. inhibiting adhesion to the mucus could prevent colonization of the intestine. the aim of this study was to investigate in vitro the protective effect of defined commercial human p ...201322672405
cloning, production, and functional expression of the bacteriocin sakacin a (saka) and two saka-derived chimeras in lactic acid bacteria (lab) and the yeasts pichia pastoris and kluyveromyces lactis.mature sakacin a (saka, encoded by sapa) and its cognate immunity protein (saki, encoded by sapia), and two saka-derived chimeras mimicking the n-terminal end of mature enterocin p (entp/saka) and mature enterocin a (enta/saka) together with saki, were fused to different signal peptides (sp) and cloned into the protein expression vectors pnz8048 and pmg36c for evaluation of their production and functional expression by different lactic acid bacteria. the amount, antimicrobial activity, and speci ...201323794087
microbial succession and metabolite changes during long-term storage of kimchi.kimchi is often stored for a long period of time for a diet during the winter season because it is an essential side dish for korean meals. in this study ph, abundance of bacteria and yeasts, bacterial communities, and metabolites were monitored periodically to investigate the fermentation process of kimchi for 120 d. bacterial abundance increased quickly with a ph decrease after an initial ph increase during the early fermentation period. after 20 d, ph values became relatively stable and free ...201323550842
lactococcus garvieae: where is it from? a first approach to explore the evolutionary history of this emerging pathogen.the population structure and diversity of lactococcus garvieae, an emerging pathogen of increasing clinical significance, was determined at both gene and genome level. selected lactococcal isolates of various origins were analyzed by a multi locus sequence typing (mlst). this gene-based analysis was compared to genomic characteristics, estimated through the complete genome sequences available in database. the mlst identified two branches containing the majority of the strains and two branches be ...201324391975
lactococcus lactis bfe920 activates the innate immune system of olive flounder (paralichthys olivaceus), resulting in protection against streptococcus iniae infection and enhancing feed efficiency and weight gain in large-scale field studies.the protective effect of a food-grade lactic acid bacterium lactococcus lactis bfe920 against disease of olive flounder (paralichthys olivaceus) cultivated on a large scale was studied. initially, antimicrobial activity of l. lactis against several fish pathogens was evaluated in vitro; the probiotic showed strong antibacterial activity against streptococcus iniae, streptococcus parauberis and enterococcus viikkiensis, and moderate activity against lactococcus garviae. when olive flounders were ...201324041843
development of a 16s-23s rrna intergenic spacer-based quantitative pcr assay for improved detection and enumeration of lactococcus garvieae.lactococcus garvieae is an important foodborne pathogen causing lactococcosis associated with hemorrhagic septicemia in fish worldwide. a real-time quantitative polymerase chain reaction (qpcr) protocol targeting the 16s-23s rrna intergenic spacer (its) region was developed for the detection and enum-eration of l. garvieae. the specificity was evaluated using genomic dnas extracted from 66 cocci strains. fourteen l. garvieae strains tested were positive, whereas 52 other strains including lactoc ...201323106479
basic residues r260 and k357 affect the conformational dynamics of the major facilitator superfamily multidrug transporter lmrp.secondary-active multidrug transporters can confer resistance on cells to pharmaceuticals by mediating their extrusion away from intracellular targets via substrate/h(+)(na(+)) antiport. while the interactions of catalytic carboxylates in these transporters with coupling ions and substrates (drugs) have been studied in some detail, the functional importance of basic residues has received much less attention. the only two basic residues r260 and k357 in transmembrane helices in the major facilita ...201222761697
metabolic profiling of lactococcus lactis under different culture conditions.gas chromatography mass spectrometry (gc-ms) and headspace gas chromatography mass spectrometry (hs/gc-ms) were used to study metabolites produced by lactococcus lactis subsp. cremoris mg1363 grown at a temperature of 30 °c with and without agitation at 150 rpm, and at 37 °c without agitation. it was observed that l. lactis produced more organic acids under agitation. primary alcohols, aldehydes, ketones and polyols were identified as the corresponding trimethylsilyl (tms) derivatives, whereas a ...201222759915
pneumococcal neuraminidase a: an essential upper airway colonization factor for streptococcus pneumoniae.streptococcus pneumoniae colonizes the upper respiratory tract from where the organisms may disseminate systemically to cause life threatening infections. the mechanisms by which pneumococci colonize epithelia are not understood, but neuraminidase a (nana) has a major role in promoting growth and survival in the upper respiratory tract. in this article we show that mutants of s. pneumoniae d39 deficient in nana or neuraminidase b (nanb) are abrogated in adherence to three epithelial cell lines, ...201222759312
pepper: a webserver for prediction of prokaryote promoter elements and regulons.accurate prediction of dna motifs that are targets of rna polymerases, sigma factors and transcription factors (tfs) in prokaryotes is a difficult mission mainly due to as yet undiscovered features in dna sequences or structures in promoter regions. improved prediction and comparison algorithms are currently available for identifying transcription factor binding sites (tfbss) and their accompanying tfs and regulon members.201222747501
increase of stress resistance in lactococcus lactis via a novel food-grade vector expressing a shsp gene from streptococcus thermophilus.the effects of the expression of a small heat shock protein (shsp) gene from streptococcus thermophilus on stress resistance in lactococcus lactis under different environmental stresses were investigated in this study. pmg36e-shsp, an expression vector, was first constructed by inserting a shsp open reading frame (orf) cloned from s. thermophilus strain st-qc into pmg36e. then, a food-grade expression vector, pmg-shsp, was generated by deleting the erythromycin resistance gene from pmg36e-shsp. ...201224031940
the multidrug transporter lmrp protein mediates selective calcium efflux.lmrp is a major facilitator superfamily multidrug transporter from lactococcus lactis that mediates the efflux of cationic amphiphilic substrates from the cell in a proton-motive force-dependent fashion. interestingly, motif searches and docking studies suggested the presence of a putative ca(2+)-binding site close to the interface between the two halves of inward facing lmrp. binding experiments with radioactive (45)ca(2+) demonstrated the presence of a high affinity ca(2+)-binding site in puri ...201222730320
novel conjugative plasmids from the natural isolate lactococcus lactis subspecies cremoris dpc3758: a repository of genes for the potential improvement of dairy starters.a collection of 17 natural lactococcal isolates from raw milk cheeses were studied in terms of their plasmid distribution, content, and diversity. all strains in the collection harbored an abundance of plasmids, including lactococcus lactis ssp. cremoris dpc3758, whose 8-plasmid complement was selected for sequencing. the complete sequences of paf22 (22,388 kb), paf14 (14,419 kb), paf12 (12,067 kb), paf07 (7,435 kb), and paf04 (3,801 kb) were obtained, whereas gene functions of technological int ...201222720917
monitoring lysin motif-ligand interactions via tryptophan analog fluorescence spectroscopy.the lysin motif (lysm) is a peptidoglycan binding protein domain found in a wide range of prokaryotes and eukaryotes. various techniques have been used to study the lysm-ligand interaction, but a sensitive spectroscopic method to directly monitor this interaction has not been reported. here a tryptophan analog fluorescence spectroscopy approach is presented to monitor the lysm-ligand interaction using the lysm of the n-acetylglucosaminidase enzyme of lactococcus lactis. a three-dimensional model ...201222713342
evidence of two functionally distinct ornithine decarboxylation systems in lactic acid bacteria.biogenic amines are low-molecular-weight organic bases whose presence in food can result in health problems. the biosynthesis of biogenic amines in fermented foods mostly proceeds through amino acid decarboxylation carried out by lactic acid bacteria (lab), but not all systems leading to biogenic amine production by lab have been thoroughly characterized. here, putative ornithine decarboxylation pathways consisting of a putative ornithine decarboxylase and an amino acid transporter were identifi ...201222247134
theoretical investigation of the enzymatic phosphoryl transfer of β-phosphoglucomutase: revisiting both steps of the catalytic cycle.enzyme catalyzed phosphate transfer is a part of almost all metabolic processes. such reactions are of central importance for the energy balance in all organisms and play important roles in cellular control at all levels. mutases transfer a phosphoryl group while nucleases cleave the phosphodiester linkages between two nucleotides. the subject of our present study is the lactococcus lactis β-phosphoglucomutase (β-pgm), which effectively catalyzes the interconversion of β-d-glucose-1-phosphate (β ...201222238068
from meadows to milk to mucosa - adaptation of streptococcus and lactococcus species to their nutritional environments.lactic acid bacteria (lab) are indigenous to food-related habitats as well as associated with the mucosal surfaces of animals. the lab family streptococcaceae consists of the genera lactococcus and streptococcus. members of the family include the industrially important species lactococcus lactis, which has a long history safe use in the fermentative food industry, and the disease-causing streptococci streptococcus pneumoniae and streptococcus pyogenes. the central metabolic pathways of the strep ...201222212109
characterization of llaki, a new metal ion-independent restriction endonuclease from lactococcus lactis klds4.requirement of divalent cations for dna cleavage is a general feature of type ii restriction enzymes with the exception of few members of this group. a new type ii restriction endonuclease has been partially purified from lactococcus lactis klds4. the enzyme was denoted as llaki and showed to recognize and cleave the same site as foki. the enzyme displayed a denatured molecular weight of 50 kda and behaved as a dimer in solution as evidenced by the size exclusion chromatography. to investigate t ...201225969755
oral intake of heat-killed cells of lactococcus lactis strain h61 promotes skin health in women.we conducted a double-blind, placebo-controlled trial to evaluate the effect of heat-killed cells of lactococcus lactis strain h61 on various skin properties of japanese women. volunteers (age 31-62 years) were randomly assigned to receive test food with or without 60 mg of heat-killed strain h61 (fifteen women in each group; h61 and control groups, respectively) daily for 8 weeks. results were analysed for three age categories (30s, 40s and 50-60s). compared with that at week 0, skin hydration ...201225191547
the maltose abc transporter in lactococcus lactis facilitates high-level sensitivity to the circular bacteriocin garvicin ml.we generated and characterized a series of spontaneous mutants of lactococcus lactis il1403 with average 6- to 11-fold-lowered sensitivities to the circular bacteriocin garvicin ml (garml). carbohydrate fermentation assays highlighted changes in carbohydrate metabolism, specifically loss of the ability to metabolize starch and maltose, in these mutants. pcr and sequencing showed that a 13.5-kb chromosomal deletion encompassing 12 open reading frames, mainly involved in starch and maltose utiliza ...201222411612
functional expression of an orchid fragrance gene in lactococcus lactis.vanda mimi palmer (vmp), an orchid hybrid of vanda tesselata and vanda tan chay yan is a highly scented tropical orchid which blooms all year round. previous studies revealed that vmp produces a variety of isoprenoid volatiles during daylight. isoprenoids are well known to contribute significantly to the scent of most fragrant plants. they are a large group of secondary metabolites which may possess valuable characteristics such as flavor, fragrance and toxicity and are produced via two pathways ...201222408409
lactococcus lactis expressing food-grade β-galactosidase alleviates lactose intolerance symptoms in post-weaning balb/c mice.the endogenous β-galactosidase expressed in intestinal microbes is demonstrated to help humans in lactose usage, and treatment associated with the promotion of beneficial microorganism in the gut is correlated with lactose tolerance. from this point, a kind of recombinant live β-galactosidase delivery system using food-grade protein expression techniques and selected probiotics as vehicle was promoted by us for the purpose of application in lactose intolerance subjects. previously, a recombinant ...201222395907
genetic engineering of lactococcus lactis to produce an amylase inhibitor for development of an anti-diabetes biodrug.diabetes is known as a multifactorial disease. the treatment of diabetes is complicated due to its inherent pathophysiological factors related to the disease. one of the complications of diabetes is postprandial hyperglycemia. glucosidase inhibitors, particularly ?-amylase inhibitors can help manage postprandial hyperglycemia. the low molecular weight inhibitor of ? -amylases called pami (peptide amylase inhibitor) inhibits the ? -amylase. in this study we cloned this amylase blocker pami in lac ...201222378551
transcription analysis of hyaluronan biosynthesis genes in streptococcus zooepidemicus and metabolically engineered lactococcus lactis.the has operon genes in the hyaluronan (ha) producer, streptococcus zooepidemicus, encode for some of the critical enzymes in the ha biosynthetic pathway. heterologous expression of different combinations of multiple has genes has resulted in increasing ha production to varying degrees in different recombinant strains. in this work, a recombinant lactococcus lactis strain (sjr6) was constructed, with insertion of three has operon genes (hasabd) from s. zooepidemicus. the sjr6 strain was found to ...201222367612
diacetyl levels and volatile profiles of commercial starter distillates and selected dairy foods.starter distillates (sdl) are used as ingredients in the formulation of many food products such as cottage cheese, margarine, vegetable oil spreads, processed cheese, and sour cream to increase the levels of naturally occurring buttery aroma associated with fermentation. this buttery aroma results, in part, from the presence of the vicinal dicarbonyl, diacetyl, which imparts a high level of buttery flavor notes and is a key component of sdl. diacetyl (2,3-butanedione) is a volatile product of ci ...201222365196
population genomics and phylogeography of an australian dairy factory derived lytic bacteriophage.in this study, we present the full genomic sequences and evolutionary analyses of a serially sampled population of 28 lactococcus lactis-infecting phage belonging to the 936-like group in australia. genome sizes were consistent with previously available genomes ranging in length from 30.9 to 32.1 kbp and consisted of 55-65 open reading frames. we analyzed their genetic diversity and found that regions of high diversity are correlated with high recombination rate regions (p value = 0.01). phyloge ...201222355195
improved acid stress survival of lactococcus lactis expressing the histidine decarboxylation pathway of streptococcus thermophilus chcc1524.degradative amino acid decarboxylation pathways in bacteria generate secondary metabolic energy and provide resistance against acid stress. the histidine decarboxylation pathway of streptococcus thermophilus chcc1524 was functionally expressed in the heterologous host lactococcus lactis nz9000, and the benefits of the newly acquired pathway for the host were analyzed. during growth in m17 medium in the ph range of 5-6.5, a small positive effect was observed on the biomass yield in batch culture, ...201222351775
bacterium-like particles as multi-epitope delivery platform for plasmodium berghei circumsporozoite protein induce complete protection against malaria in mice.virus-like particles have been regularly used as an antigen delivery system for a number of plasmodium peptides or proteins. the present study reports the immunogenicity and protective efficacy of bacterium-like particles (blps) generated from lactococcus lactis and loaded with plasmodium berghei circumsporozoite protein (pbcsp) peptides.201222348325
immunization against leishmania major infection using lack- and il-12-expressing lactococcus lactis induces delay in footpad swelling.leishmania is a mammalian parasite affecting over 12 million individuals worldwide. current treatments are expensive, cause severe side effects, and emerging drug resistance has been reported. vaccination is the most cost-effective means to control infectious disease but currently there is no vaccine available against leishmaniasis. lactococcus lactis is a non-pathogenic, non-colonizing gram-positive lactic acid bacterium commonly used in the dairy industry. recently, l. lactis was used to expre ...201222348031
lytic activity of lysh5 endolysin secreted by lactococcus lactis using the secretion signal sequence of bacteriocin lcn972.bacteriophage endolysins have an interesting potential as antimicrobials. the endolysin lysh5, encoded by staphylococcus aureus phage vb_saus-phi-ipla88, was expressed and secreted in lactococcus lactis using the signal peptide of bacteriocin lactococcin 972 and lactococcal constitutive and inducible promoters. up to 80 u/mg of extracellular active endolysin was detected in culture supernatants, but most of the protein (up to 323 u/mg) remained in the cell extracts.201222344638
functional expression of mouse insulin-like growth factor-i with food-grade vector in lactococcus lactis nz9000.to functionally express the recombinant mouse insulin-like growth factor-i (rtmigf-i) in lactococcus lactis nz9000 with a food-grade vector.201222332956
lantibiotics: how do producers become self-protected?lantibiotics are small peptides produced by gram-positive bacteria, which are ribosomally synthesized as a prepeptide. their genes are highly organized in operons containing all the genes required for maturation, transport, immunity and synthesis. the best-characterized lantibiotic is nisin from lactococcus lactis. nisin is active against other gram-positive bacteria via various modes of actions. to prevent activity against its producer strain, an autoimmunity system has developed consisting of ...201222329892
complete genome sequence of lactococcus lactis subsp. cremoris a76.we report the complete genome sequence of lactococcus lactis subsp. cremoris a76, a dairy strain isolated from a cheese production outfit. genome analysis detected two contiguous islands fitting to the l. lactis subsp. lactis rather than to the l. lactis subsp. cremoris lineage. this indicates the existence of genetic exchange between the diverse subspecies, presumably related to the technological process.201222328746
the branched-chain amino acid aminotransferase encoded by ilve is involved in acid tolerance in streptococcus mutans.the ability of streptococcus mutans to produce and tolerate organic acids from carbohydrate metabolism represents a major virulence factor responsible for the formation of carious lesions. pyruvate is a key metabolic intermediate that, when rerouted to other metabolic pathways such as amino acid biosynthesis, results in the alleviation of acid stress by reducing acid end products and aiding in maintenance of intracellular ph. amino acid biosynthetic genes such as ilvc and ilve were identified as ...201222328677
role of phosphate in the central metabolism of two lactic acid bacteria--a comparative systems biology approach.lactic acid-producing bacteria survive in distinct environments, but show common metabolic characteristics. here we studied the dynamic interactions of the central metabolism in lactococcus lactis, extensively used as a starter culture in the dairy industry, and streptococcus pyogenes, a human pathogen. glucose-pulse experiments and enzymatic measurements were performed to parameterize kinetic models of glycolysis. significant improvements were made to existing kinetic models for l. lactis, whic ...201222325620
engineering of self-sustaining systems: substituting the yeast glucose transporter plus hexokinase for the lactococcus lactis phosphotransferase system in a lactococcus lactis network in silico.the success rate of introducing new functions into a living species is still rather unsatisfactory. much of this is due to the very essence of the living state, i.e. its robustness towards perturbations. living cells are bound to notice that metabolic engineering is being effected, through changes in metabolite concentrations. in this study, we asked whether one could engage in such engineering without changing metabolite concentrations. we have illustrated that, in silico, one can do so in prin ...201222700394
lacticin lc14, a new bacteriocin produced by lactococcus lactis bmg6.14: isolation, purification and partial characterization.a new bacteriocin, lacticin lc14, produced by lactococcus lactis bmg6.14, was isolated and characterized. it was purified to homogeneity from overnight broth culture by ammonium sulfate precipitation, sep-pak chromatography, and two steps of reversed-phase hplc. lacticin lc14 showed bactericidal-type antimicrobial activity against several lactic acid bacteria and pathogenic strains including listeria monocytogenes. it was inactivated by proteinase k and pronase e, but was resistant to papain, ly ...201222697129
the purr regulon in lactococcus lactis - transcriptional regulation of the purine nucleotide metabolism and translational machinery.purine nucleotides are either synthesized de novo from 5-phosphoribosyl-1-pyrophosphate (prpp) or salvaged from the environment. in lactococcus lactis, transcription of the de novo synthesis operons, purcsqlf and purdek, has genetically been shown to be activated by the purr protein when bound to a conserved purbox motif present on the dna at a fixed distance from the promoter -10 element. purr contains a prpp-binding site, and activation occurs when the intracellular prpp pool is high as a cons ...201222679106
tuning the drug efflux activity of an abc transporter in vivo by in vitro selected darpin binders.abc transporters use the energy from binding and hydrolysis of atp to import or extrude substrates across the membrane. using ribosome display, we raised designed ankyrin repeat proteins (darpins) against detergent solubilized lmrcd, a heterodimeric multidrug abc exporter from lactococcus lactis. several target-specific darpin binders were identified that bind to at least three distinct, partially overlapping epitopes on lmrd in detergent solution as well as in native membranes. remarkably, func ...201222675494
a specific mutation in the promoter region of the silent cel cluster accounts for the appearance of lactose-utilizing lactococcus lactis mg1363.the lactococcus lactis laboratory strain mg1363 has been described to be unable to utilize lactose. however, in a rich medium supplemented with lactose as the sole carbon source, it starts to grow after prolonged incubation periods. transcriptome analyses showed that l. lactis mg1363 lac(+) cells expressed celb, encoding a putative cellobiose-specific phosphotransferase system (pts) iic component, which is normally silent in mg1363 lac(-) cells. nucleotide sequence analysis of the cel cluster of ...201222660716
functional characterization of amphipathic α-helix in the osmoregulatory abc transporter opua.the atp-binding-cassette transporter opua from lactococcus lactis is composed of two atpase subunits (opuaa) and two subunits (opuabc) with the transmembrane domain fused to an extracellular substrate-binding protein. of the almost 1900 homologues of opua known to date, a subset has an amino-terminal amphipathic helix (plus extra transmembrane segment) fused to the core of the transmembrane domain of the opuabc subunit. fret measurements indicate that the amphipathic α-helix is located close to ...201222656643
identification and functional expression of the mitochondrial pyruvate carrier.the transport of pyruvate, the end product of glycolysis, into mitochondria is an essential process that provides the organelle with a major oxidative fuel. although the existence of a specific mitochondrial pyruvate carrier (mpc) has been anticipated, its molecular identity remained unknown. we report that mpc is a heterocomplex formed by two members of a family of previously uncharacterized membrane proteins that are conserved from yeast to mammals. members of the mpc family were found in the ...201222628554
proteomic analysis of spontaneous mutants of lactococcus lactis: involvement of gapdh and arginine deiminase pathway in h2o2 resistance.lactococcus lactis, one of the most commonly used dairy starters, is often subjected to oxidative stress in cheese manufacturing. a comparative proteomic analysis was performed to identify the molecular modifications responsible for the robustness of three spontaneous h(2)o(2)-resistant (spox) strains. in the parental strain, glyceraldehyde-3-phosphate deshydrogenase (gapdh) activity is ensured by gapb and the second gapdh gapa is not produced in standard growth conditions. we showed that gapa w ...201222623348
cytoplasmic and extracellular expression of pharmaceutical-grade mycobacterial 65-kda heat shock protein in lactococcus lactis.lactic acid bacteria (lab) are an attractive and safe alternative for the expression of heterologous proteins, as they are nonpathogenic and endotoxin-free organisms. lactococcus lactis, the lab model organism, has been extensively employed in the biotechnology field for large-scale production of heterologous proteins, and its use as a "cell factory" has been widely studied. we have been particularly interested in the use of l. lactis for production of heat shock proteins (hsps), which reportedl ...201222614283
a derivative of lactococcus lactis strain h61 with less interleukin-12 induction has a different cell wall.lactococcus lactis h61 can increase the cellular immune responses of aged (14-mo-old) senescence-accelerated mice. the aim of this study was to investigate the factors contributing to il-12 induction by strain h61 by analyzing strains derived from it. strain h61 derivative no. 13 was obtained by growing the parent strain at 37°c. this derivative induced significantly lower production of il-12 from j774.1 macrophage cells than did the parent strain h61. the 2 strains differed in the resistance of ...201222612923
therapeutic live vaccines as a potential anticancer strategy.the design of efficient cancer treatments is one of the major challenges of medical science. therapeutic vaccines of cancer have been emerged as an attractive approach for their capacity of breaking the immune tolerance and invoking long-term immune response targeting cancer cells without autoimmunity. an efficient antigen delivery system is the key issue of developing an effective cancer vaccine. in this regard, live vaccination strategies including various live bacterial and viral vectors have ...201222610886
real-time investigation of the muco-adhesive properties of lactococcus lactis using a quartz crystal microbalance with dissipation monitoring.this work was devoted to probe, at the entire population level, interactions between mucins and lactococcus lactis, using qcm-d. real-time monitoring of adsorption on polystyrene of pgm (pig gastric mucin) and subsequent adhesion of l. lactis was performed for ibb477 and mg1820 strains. measuring simultaneously shifts in resonance frequency and dissipation on the polystyrene-coated crystal demonstrated a two-phase process for pgm adsorption. xps analysis confirmed the presence of adsorbed mucin. ...201222594395
substrate specificity of the citrate transporter citp of lactococcus lactis.the citrate transporter citp of lactic acid bacteria catalyzes electrogenic precursor-product exchange of citrate versus l-lactate during citrate-glucose cometabolism. in the absence of sugar, l-lactate is replaced by the metabolic intermediates/end products pyruvate, α-acetolactate, and acetate. in this study, the binding and translocation properties of citp were analyzed systematically for a wide variety of mono- and dicarboxylates of the form x-cr(2)-coo(-), where x represents oh (2-hydroxy a ...201222563050
fine tuning of the lactate and diacetyl production through promoter engineering in lactococcus lactis.lactococcus lactis is a well-studied bacterium widely used in dairy fermentation and capable of producing metabolites with organoleptic and nutritional characteristics. for fine tuning of the distribution of glycolytic flux at the pyruvate branch from lactate to diacetyl and balancing the production of the two metabolites under aerobic conditions, a constitutive promoter library was constructed by randomizing the promoter sequence of the h(2)o-forming nadh oxidase gene in l. lactis. the library ...201222558426
antilisterial activity of nisin-like bacteriocin-producing lactococcus lactis subsp. lactis isolated from traditional sardinian dairy products.with the aim of selecting lab strains with antilisterial activity to be used as protective cultures to enhance the safety of dairy products, the antimicrobial properties of 117 lactococcus lactis subsp. lactis isolated from artisanal sardinian dairy products were evaluated, and six strains were found to produce bacteriocin-like substances. the capacity of these strains to antagonize listeria monocytogenes during cocultivation in skimmed milk was evaluated, showing a reduction of l. monocytogenes ...201222536018
multilocus sequence typing scheme for the characterization of 936-like phages infecting lactococcus lactis.lactococcus lactis phage infections are costly for the dairy industry because they can slow down the fermentation process and adversely impact product safety and quality. although many strategies have been developed to better control phage populations, new virulent phages continue to emerge. thus, it is beneficial to develop an efficient method for the routine identification of new phages within a dairy plant to rapidly adapt antiphage tactics. here, we present a multilocus sequence typing (mlst ...201222522686
protective effects of cathelicidin-encoding lactococcus lactis in murine ulcerative colitis.intrarectal administration of mouse cathelin-related antimicrobial peptide (mcramp) reduced intestinal inflammation in mice. in the current study, we examined whether mcramp-transformed lactococcus lactis given orally attained similar protective effects.201222507188
spherical lactic acid bacteria activate plasmacytoid dendritic cells immunomodulatory function via tlr9-dependent crosstalk with myeloid dendritic cells.plasmacytoid dendritic cells (pdc) are a specialized sensor of viral and bacterial nucleic acids and a major producer of ifn-α that promotes host defense by priming both innate and acquired immune responses. although synthetic toll-like receptor (tlr) ligands, pathogenic bacteria and viruses activate pdc, there is limited investigation of non-pathogenic microbiota that are in wide industrial dietary use, such as lactic acid bacteria (lab). in this study, we screened for lab strains, which induce ...201222505996
isolation of lactococcus lactis mutants simultaneously resistant to the cell wall-active bacteriocin lcn972, lysozyme, nisin, and bacteriophage c2.lactococcin 972 (lcn972) is a nonlantibiotic bacteriocin that inhibits cell wall biosynthesis by binding to lipid ii. in this work, two mutants resistant to lcn972, lactococcus lactis d1 and d1-20, with high (>320 arbitrary units [au]/ml) and low (80 au/ml) susceptibilities, respectively, have been isolated. resistance to lcn972 did not impose a burden to growth under laboratory conditions, nor did it substantially alter the physicochemical properties of the cell surface. however, the peptidogly ...201222504807
reversal of autoimmune diabetes by restoration of antigen-specific tolerance using genetically modified lactococcus lactis in mice.current interventions for arresting autoimmune diabetes have yet to strike the balance between sufficient efficacy, minimal side effects, and lack of generalized immunosuppression. introduction of antigen via the gut represents an appealing method for induction of antigen-specific tolerance. here, we developed a strategy for tolerance restoration using mucosal delivery in mice of biologically contained lactococcus lactis genetically modified to secrete the whole proinsulin autoantigen along with ...201222484814
complete genome sequence of lactococcus lactis io-1, a lactic acid bacterium that utilizes xylose and produces high levels of l-lactic acid.we report the complete genome sequence of lactococcus lactis io-1 (= jcm7638). it is a nondairy lactic acid bacterium, produces nisin z, ferments xylose, and produces predominantly l-lactic acid at high xylose concentrations. from ortholog analysis with other five l. lactis strains, io-1 was identified as l. lactis subsp. lactis.201222461545
interaction between lactococcus lactis and lactococcus raffinolactis during growth in milk: development of a new starter culture.many milk fermentations use mixed cultures of lactic acid bacteria. to select a new mixed starter culture, 100 acid-producing bacterial strains were isolated from raw cow milk. of these, 13 strains identified as belonging to the genera lactococcus, lactobacillus, leuconostoc, or weissella (based on phenotypic and genotypic tests) were assessed for a symbiotic effect between pairs of isolated strains during growth in milk. among the strains tested, a mixed culture of lactococcus lactis ssp. lacti ...201222459863
ppia, a surface ppiase of the cyclophilin family in lactococcus lactis.protein folding in the envelope is a crucial limiting step of protein export and secretion. in order to better understand this process in lactococcus lactis, a lactic acid bacterium, genes encoding putative exported folding factors like peptidyl prolyl isomerases (ppiases) were searched for in lactococcal genomes.201222442694
expression of a biologically active gfp-α(s1)-casein fusion protein in lactococcus lactis.in this study, we successfully developed a recombinant strain of lactococcus lactis nz9000 (nz9000) that produced green fluorescent protein fused to α(s1)-casein (gfp-α(s1)cas). a modified lactic acid bacterial vector (pnz8148#2) was constructed by inserting genes for gfp and α(s1)-casein, a major cow's milk allergen, and the resulting vector, pnz8148#2-gfp-α(s1)cas, was applied to the expression of recombinant gfp-α(s1)cas protein (rgfp-α(s1)cas) in nz9000. after inducing expression with nisin, ...201222437853
oral vaccination with lactococcus lactis expressing the vibrio cholerae wzm protein to enhance mucosal and systemic immunity.a gene associated with lipopolysaccharide (lps) transport was cloned from a local clinical vibrio cholerae o1 strain of the ogawa serotype by using the lactococcus lactis nisin-controlled expression (nice) system. the v. cholerae wzm gene, which codes for an integral membrane transporter protein, was expressed and targeted to the cytoplasmic membrane, and was crudely isolated through simple centrifugation and sds solubilization. to examine seroreactivity of this construct, rabbits were orally fe ...201222426330
bioluminescence-based identification of nisin producers - a rapid and simple screening method for nisinogenic bacteria in food samples.we present a simple and rapid method for screening nisin producers that directly identifies nisinogenic bacteria by induction of bioluminescence within the lactococcus lactis nz9800lux biosensor strain (immonen and karp, 2007, biosensors and bioelectronics 22, 1982-7). an overlay of putative nisinogenic colonies with the biosensor strain gives identification results within 1h. functionality and specificity of the method were verified by screening nisin producers among 144 raw milk colonies and a ...201222831816
involvement of the major capsid protein and two early-expressed phage genes in the activity of the lactococcal abortive infection mechanism abit.the dairy industry uses the mesophilic, gram-positive, lactic acid bacterium (lab) lactococcus lactis to produce an array of fermented milk products. milk fermentation processes are susceptible to contamination by virulent phages, but a plethora of phage control strategies are available. one of the most efficient is to use lab strains carrying phage resistance systems such as abortive infection (abi) mechanisms. yet, the mode of action of most abi systems remains poorly documented. here, we shed ...201222820334
oral immunization using live lactococcus lactis co-expressing lack and il-12 protects balb/c mice against leishmania major infection.leishmaniasis is a parasitic disease affecting over 12 million individuals worldwide. current treatments are laborious, expensive, cause severe side effects, and emerging drug resistance has been reported. while vaccination is the most cost-effective means to control infectious diseases there is no human vaccine currently available against leishmania infections. lactococcus lactis is a non-pathogenic, non-colonizing gram-positive lactic acid bacterium commonly used in the dairy industry. recentl ...201222814408
purification and partial characterization of bacteriocin produced by lactococcus lactis ssp. lactis ll171.lactic acid bacteria (lab) are possessing ability to synthesize antimicrobial compounds (like bacteriocin) during their growth. in this regard, novel bacteriocin compound secreting capability of lab isolated from tulum cheese in turkey was demonstrated. the synthesized bacteriocin was purified by ammonium sulphate precipitation, dialysis and gel filtration. the molecular weight (≈3.4 kda) of obtained bacteriocin was confirmed by sds-page, which revealed single peptide band. molecular identificat ...201222805947
rerouting citrate metabolism in lactococcus lactis to citrate-driven transamination.oxaloacetate is an intermediate of the citrate fermentation pathway that accumulates in the cytoplasm of lactococcus lactis ilcitm(pfl3) at a high concentration due to the inactivation of oxaloacetate decarboxylase. an excess of toxic oxaloacetate is excreted into the medium in exchange for citrate by the citrate transporter citp (a. m. pudlik and j. s. lolkema, j. bacteriol. 193:4049-4056, 2011). in this study, transamination of amino acids with oxaloacetate as the keto donor is described as an ...201222798354
structural basis for the transcriptional regulation of heme homeostasis in lactococcus lactis.although heme is a crucial element for many biological processes including respiration, heme homeostasis should be regulated strictly due to the cytotoxicity of free heme molecules. numerous lactic acid bacteria, including lactococcus lactis, acquire heme molecules exogenously to establish an aerobic respiratory chain. a heme efflux system plays an important role for heme homeostasis to avoid cytotoxicity of acquired free heme, but its regulatory mechanism is not clear. here, we report that the ...201222798069
bacterial translational regulations: high diversity between all mrnas and major role in gene expression.in bacteria, the weak correlations at the genome scale between mrna and protein levels suggest that not all mrnas are translated with the same efficiency. to experimentally explore mrna translational level regulation at the systemic level, the detailed translational status (translatome) of all mrnas was measured in the model bacterium lactococcus lactis in exponential phase growth.201223036066
production of fibronectin binding protein a at the surface of lactococcus lactis increases plasmid transfer in vitro and in vivo.lactococci are noninvasive lactic acid bacteria frequently used as protein delivery vectors and, more recently, as dna delivery vehicles. we previously showed that lactococcus lactis (ll) expressing the fibronectin-binding protein a of staphylococcus aureus (ll-fnbpa+) showed higher internalization rates in vitro in caco-2 cells than the native (wt) lactococci and were able to deliver a eukaryotic green fluorescent protein (gfp) expression plasmid in 1% of human caco-2 cells. here, using the bov ...201223028664
molecular characterization and structural instability of the industrially important composite metabolic plasmid plp712.the widely used plasmid-free lactococcus lactis strain mg1363 was derived from the industrial dairy starter strain ncdo712. this strain carries a 55.39 kb plasmid encoding genes for lactose catabolism and a serine proteinase involved in casein degradation. we report the dna sequencing and annotation of plp712, which revealed additional metabolic genes, including peptidase f, d-lactate dehydrogenase and α-keto acid dehydrogenase (e3 complex). comparison of plp712 with other large lactococcal lact ...201223023974
lactococcus lactis subsp. cremoris fc triggers ifn-γ production from nk and t cells via il-12 and il-18.lactic acid bacteria (lab) benefit health as probiotics in a strain-dependent way. in this study, we investigated the immunomodulatory effects of lactococcus lactis subsp. cremoris fc (lcfc) on dendritic cells (dcs), natural killer (nk) cells and t cells. lcfc induced the production of cytokines such as il-10, il-12, il-6 and tnf-α from murine bone marrow dcs (bmdcs) via myd88-dependent pathway. in comparison with the type strain l. lactis subsp. cremoris atcc 19257, lcfc induced particularly hi ...201223102661
phages of lactic acid bacteria: the role of genetics in understanding phage-host interactions and their co-evolutionary processes.dairy fermentations are among the oldest food processing applications, aimed at preservation and shelf-life extension through the use of lactic acid bacteria (lab) starter cultures, in particular strains of lactococcus lactis, streptococcus thermophilus, lactobacillus spp. and leuconostoc spp. traditionally this was performed by continuous passaging of undefined cultures from a finished fermentation to initiate the next fermentation. more recently, consumer demands on consistent and desired flav ...201223089252
toward pectin fermentation by saccharomyces cerevisiae: expression of the first two steps of a bacterial pathway for d-galacturonate metabolism.saccharomyces cerevisiae cannot metabolize d-galacturonate, an important monomer of pectin. use of s. cerevisiae for production of ethanol or other compounds of interest from pectin-rich feedstocks therefore requires introduction of a heterologous pathway for d-galacturonate metabolism. bacterial d-galacturonate pathways involve d-galacturonate isomerase, d-tagaturonate reductase and three additional enzymes. this study focuses on functional expression of bacterial d-galacturonate isomerases in ...201223079077
expression in lactococcus lactis of functional genes related to amino acid catabolism and cheese aroma formation is influenced by branched chain amino acids.formation of cheese aroma compounds by lactococcus lactis from amino acid catabolism depends on a complex network of reactions, which involve enzymes such as aminotransferases, dehydrogenases, lyases, and decarboxylases, among others. based on the ability of some l. lactis strains to grow with low requirements of amino acids, we have studied in l. lactis ifpl730 the effect of the branched chain amino acid (bcaa) content on the expression of functional genes related to amino acid catabolism and a ...201223107499
identification of the genes involved in the secretion and self-immunity of lacticin q, an unmodified leaderless bacteriocin from lactococcus lactis qu 5.lacticin q (lnqq) produced by lactococcus lactis qu 5 is an unmodified linear bacteriocin, which is synthesized without an n-terminal leader peptide. in vitro synthesis and in vivo expression of lnqq have revealed the intracellular toxicity of this leaderless peptide, as well as the necessity of a dedicated secretion and self-immunity system of producer cells. further dna sequencing and analysis have discovered 11 putative orf genes at the lnqq locus. none of the orf genes showed similarities to ...201223103973
efficient production of l-lactic acid from hydrolysate of jerusalem artichoke with immobilized cells of lactococcus lactis in fibrous bed bioreactors.hydrolysate of jerusalem artichoke was applied for the production of l-lactic acid by immobilized lactococcus lactis cells in a fibrous bed bioreactor system. preliminary experiments had indicated that the high quality hydrolysate, which was derived from the 40 min acid treatment at 95 °c and ph 1.8, was sufficient to support the cell growth and synthesis of l-lactic acid. with the addition of 5 g/l yeast extract, the fermentative performance of free cell system was evidently improved. after the ...201222975123
structure-guided engineering of lactococcus lactis alcohol dehydrogenase lladha for improved conversion of isobutyraldehyde to isobutanol.we have determined the x-ray crystal structures of the nadh-dependent alcohol dehydrogenase lladha from lactococcus lactis and its laboratory-evolved variant lladha(re1) at 1.9å and 2.5å resolution, respectively. lladha(re1), which contains three amino acid mutations (y50f, i212t, and l264v), was engineered to increase the microbial production of isobutanol (2-methylpropan-1-ol) from isobutyraldehyde (2-methylpropanal). structural comparison of lladha and lladha(re1) indicates that the enhanced ...201222974724
different roles for lactococcal aggregation factor and mucin binding protein in adhesion to gastrointestinal mucosa.adhesion of bacteria to mucosal surfaces and epithelial cells is one of the key features for the selection of probiotics. in this study, we assessed the adhesion property of lactococcus lactis subsp. lactis bgkp1 based on its strong autoaggregation phenotype and the presence of the mucin binding protein (mbpl). genes involved in aggregation (aggl) and possible interaction with mucin (mbpl), present on the same plasmid pkp1, were previously separately cloned in the plasmid pazil. in vivo and in v ...201222961901
hallmarks of processivity in glycoside hydrolases from crystallographic and computational studies of the serratia marcescens chitinases.degradation of recalcitrant polysaccharides in nature is typically accomplished by mixtures of processive and nonprocessive glycoside hydrolases (ghs), which exhibit synergistic activity wherein nonprocessive enzymes provide new sites for productive attachment of processive enzymes. gh processivity is typically attributed to active site geometry, but previous work has demonstrated that processivity can be tuned by point mutations or removal of single loops. to gain additional insights into the d ...201222952223
production and crystallization of α-phosphoglucomutase from lactococcus lactis.α-phosphoglucomutase (α-pgm) is an enzyme that is essential for the growth of lactococcus lactis. the enzyme links bacterial anabolism with sugar utilization through glycolysis by catalyzing the reversible interconversion of glucose 6-phosphate and α-glucose 1-phosphate. the gene encoding α-pgm was cloned and overexpressed in l. lactis. the purified protein was functionally active and was crystallized with ammonium sulfate as a precipitant using vapour-diffusion and seeding techniques. optimized ...201222949208
the structure of the extracellular teichoic acids from the allergy-protective bacterium lactococcus lactis g121.the gram-positive bacterium lactococcus lactis g121 is a farm isolate that protects mice from ovalbumin-induced asthma. to understand the molecular mechanisms of such allergy-protective properties, the isolation and characterization of cell envelope constituents is crucial. here, structural analyses of the extracellular teichoic acid (ec ta) from l. lactis g121 are presented. extraction with 0.9% saline afforded a crude ta fraction. consecutive size exclusion chromatography on biogel p60 and p10 ...201222944677
exopolysaccharides modify functional properties of whey protein concentrate.the objective of this research was to produce whey protein concentrate (wpc) with modified functionality using exopolysaccharide- (eps) producing cultures. two different eps-producing cultures, lactococcus lactis ssp. cremoris jfr and streptococcus thermophilus, producing eps1 and eps2 respectively, were used in this study. one eps-nonproducing commercial cheese culture (dvs 850; chr. hansen, milwaukee, wi) was used as the control. reconstituted sweet whey powder was used in this study to elimin ...201222939784
heat resistance and salt hypersensitivity in lactococcus lactis due to spontaneous mutation of llmg_1816 (gdpp) induced by high-temperature growth.during construction of several gene deletion mutants in lactococcus lactis mg1363 which involved a high-temperature (37.5°c) incubation step, additional spontaneous mutations were observed which resulted in stable heat resistance and in some cases salt-hypersensitive phenotypes. whole-genome sequencing of one strain which was both heat resistant and salt hypersensitive, followed by pcr and sequencing of four other mutants which shared these phenotypes, revealed independent mutations in llmg_1816 ...201222923415
effects of temperature and trehalose on foam separation of nisin from the culture broth produced by lactococcus lactis subspecies lactis w28.nisin is an antimicrobial peptide, an important biopreservative, and it is produced by certain strains of lactococcus lactis ssp. lactis. in this paper, a foam separation technique was used for the separation of nisin from its culture broth, and the effects of temperature and trehalose on the performance of foam separation of nisin were studied to increase the enrichment ratio and recovery percentage of nisin and decrease the inactivity percentage of nisin. the results showed that temperature an ...201222901486
novel angiotensin i-converting enzyme inhibitory peptides produced in fermented milk by specific wild lactococcus lactis strains.the ability of specific wild lactococcus lactis strains to hydrolyze milk proteins to release angiotensin i-converting enzyme (ace) inhibitory peptides was evaluated. the peptide profiles were obtained from the <3 kda water-soluble extract and subsequently fractionated by reversed-phase hplc. the fractions with the lowest half-maximal inhibitory concentration estimated values (peptide concentration necessary to inhibit ace activity by 50%) were lc. lactis nrrl b-50571 fraction (f)1 (0.034 ± 0.00 ...201222901481
structural divergence of paralogous s components from ecf-type abc transporters.energy coupling factor (ecf) proteins are atp-binding cassette transporters involved in the import of micronutrients in prokaryotes. they consist of two nucleotide-binding subunits and the integral membrane subunit ecft, which together form the ecf module and a second integral membrane subunit that captures the substrate (the s component). different s components, unrelated in sequence and specific for different ligands, can interact with the same ecf module. here, we present a high-resolution cr ...201222891302
the putative lactococcal extracytoplasmic function anti-sigma factor llmg2447 determines resistance to the cell wall-active bacteriocin lcn972.lactococcin 972 (lcn972) is a cell wall-active bacteriocin that inhibits cell wall biosynthesis in lactococcus lactis. in this work, the transcriptomes of the lcn972-resistant (lcn(r)) mutant l. lactis d1 and its parent strain were compared to identify factors involved in lcn972 resistance. upregulated genes included members of the cell envelope stress (cessr) regulon, the penicillin-binding protein pbpx gene and gene llmg2447, which may encode a putative extracytoplasmic function (ecf) anti-sig ...201222890757
plasminogen activation by lactic acid bacteria.plasminogen was incubated with lactic acid bacteria and the plasmin activity in the mixture was measured. three of 15 strains tested revealed significant plasminogen activation ability. lactococcus lactis subsp. lactis biovar diacetylactis niai c59 showed the highest activity. the strain activated not only human plasminogen but also bovine plasminogen. the activity demonstrated a high level of thermal stability within a range of ph 3.0-9.0. the plasminogen activator activity in strain c59 increa ...201222878187
isolation and characterization of functional tripartite group ii introns using a tn5-based genetic screen.group ii introns are rna enzymes that splice themselves from pre-mrna transcripts. most bacterial group ii introns harbour an open reading frame (orf), coding for a protein with reverse transcriptase, maturase and occasionally dna binding and endonuclease activities. some orf-containing group ii introns were shown to be mobile retroelements that invade new dna target sites. from an evolutionary perspective, group ii introns are hypothesized to be the ancestors of the spliceosome-dependent nuclea ...201222876289
Refresh
firstprev
...11121314151617181920...
nextlast
Displaying items 1001 - 1100 of 5589