Publications

TitleAbstractYear(sorted ascending)
Filter
PMID
Filter
molecular pharmacological characterization of two multidrug transporters in lactococcus lactis.the active extrusion of cytotoxic compounds from the cell by multidrug transporters is one of the major causes of failure of chemotherapeutic treatment of tumor cells and of infections by pathogenic microorganisms. a multidrug transporter in lactococcus lactis, lmra, is a member of the atp-binding cassette superfamily and a bacterial homolog of the human multidrug resistance p-glycoprotein. another multidrug transporter in lactococcus lactis, lmrp, belongs to the major facilitator superfamily, a ...200010739879
a food-grade cloning system for industrial strains of lactococcus lactis.we have previously reported the construction of a food-grade cloning vector for lactococcus using the ochre suppressor, supb, as the selective marker. this vector, pfg1, causes only a slight growth inhibition in the laboratory strain mg1363 but is unstable in the industrial strains tested. as supb suppresses both amber and ochre stop codons, which are present in 82% of all known lactococcal genes, this undesirable finding may result from the accumulation of elongated mistranslated polypeptides. ...200010742196
expression of a heterologous glutamate dehydrogenase gene in lactococcus lactis highly improves the conversion of amino acids to aroma compounds.the first step of amino acid degradation in lactococci is a transamination, which requires an alpha-keto acid as the amino group acceptor. we have previously shown that the level of available alpha-keto acid in semihard cheese is the first limiting factor for conversion of amino acids to aroma compounds, since aroma formation is greatly enhanced by adding alpha-ketoglutarate to cheese curd. in this study we introduced a heterologous catabolic glutamate dehydrogenase (gdh) gene into lactococcus l ...200010742211
cloning, characterization, controlled overexpression, and inactivation of the major tributyrin esterase gene of lactococcus lactis.the gene encoding the major intracellular tributyrin esterase of lactococcus lactis was cloned using degenerate dna probes based on 19 known n-terminal amino acid residues of the purified enzyme. the gene, named esta, was sequenced and found to encode a protein of 258 amino acid residues. the transcription start site was mapped 233 nucleotides upstream of the start codon, and a canonical promoter sequence was identified. the deduced amino acid sequence of the esta product contained the typical g ...200010742212
sensitivity of nisin-resistant listeria monocytogenes to heat and the synergistic action of heat and nisin.nisin, a bacteriocin produced by some strains of lactococcus lactis, acts against foodborne pathogen listeria monocytogenes. a single exposure of cells to nisin can generate nisin-resistant (nisr) mutants, which may compromise the use of nisin in the food industry. the objective of this research was to compare the heat resistance of nisr and wild type (wt) listeria monocytogenes. the synergistic effect of heat-treatment (55 degrees c) and nisin (500 iu ml-1) on the nisr cells and the wt l. monoc ...200010747260
allosteric regulation of the class iii anaerobic ribonucleotide reductase from bacteriophage t4.ribonucleotide reductase (rnr) is an essential enzyme in all organisms. it provides precursors for dna synthesis by reducing all four ribonucleotides to deoxyribonucleotides. the overall activity and the substrate specificity of rnr are allosterically regulated by deoxyribonucleoside triphosphates and atp, thereby providing balanced dntp pools. we have characterized the allosteric regulation of the class iii rnr from bacteriophage t4. our results show that the t4 enzyme has a single type of allo ...200010748029
secondary and tertiary structure changes of reconstituted lmra induced by nucleotide binding or hydrolysis. a fourier transform attenuated total reflection infrared spectroscopy and tryptophan fluorescence quenching analysis.lmra, a membrane protein of lactococcus lactis, extrudes amphiphilic compounds from the inner leaflet of the cytoplasmic membrane, using energy derived from atp hydrolysis. a combination of total reflection fourier transform infrared spectroscopy, (2)h/h exchange, and fluorescence quenching experiments was used to investigate the effect of nucleotide binding and/or hydrolysis on the structure of lmra reconstituted into proteoliposomes. these measurements allowed us to describe secondary structur ...200010753896
characterization of the lactococcus lactis transcription factor flpa and demonstration of an in vitro switch.the commercially important bacterium lactococcus lactis contains two fnr-like proteins (flpa and flpb) which have a high degree of identity to each other and to the flp of lactobacillus casei. flpa was isolated from a gst-flpa fusion protein produced in escherichia coli. like flp, isolated flpa is a homodimeric protein containing both zn and cu. however, the properties of flpa were more like those of the e. coli oxygen-responsive transcription factor fnr than the flp of l. casei. as prepared flp ...200010760139
genome plasticity among related ++lactococcus strains: identification of genetic events associated with macrorestriction polymorphisms.the genomic diversity of nine strains of the lactococcus lactis subsp. cremoris (ncdo712, ncdo505, ncdo2031, ncdo763, mms36, c2, lm0230, lm2301, and mg1363) was studied by macrorestriction enzyme analysis using pulsed-field gel electrophoresis. these strains were considered adequate for the investigation of genomic plasticity because they have been described as belonging to the same genetic lineage. comparison of apai and smai genome fingerprints of each strain revealed the presence of several m ...200010762249
kinetics and substrate specificity of membrane-reconstituted peptide transporter dtpt of lactococcus lactis.the peptide transport protein dtpt of lactococcus lactis was purified and reconstituted into detergent-destabilized liposomes. the kinetics and substrate specificity of the transporter in the proteoliposomal system were determined, using pro-[(14)c]ala as a reporter peptide in the presence of various peptides or peptide mimetics. the dtpt protein appears to be specific for di- and tripeptides, with the highest affinities for peptides with at least one hydrophobic residue. the effect of the hydro ...200010762255
influence of different substrate limitations on the yield, composition and molecular mass of exopolysaccharides produced by lactococcus lactis subsp. cremoris in continuous cultures.the type of substrate limitation had a remarkable influence on the molecular mass of exopolysaccharides (eps) produced by lactococcus lactis subsp. cremoris nizo b40 and nizo b891. under glucose/energy limitation, the molecular mass was much smaller than under leucine or phosphate limitation, resulting in a marked decrease of the intrinsic viscosity of this eps. the sugar composition of eps produced by both strains, and the phosphate content of eps produced by nizo b40, were not affected by the ...200010945787
effects of lactobacillus strains on the ripening and organoleptic characteristics of arzúa-ulloa cheese.seven batches of arzúa-ulloa, a short-ripened soft cow's milk cheese produced in galicia (nw spain), were prepared from pasteurized milk. two control batches of cheese (cb) were made with an acid-aromatic starter containing lactococcus lactis subsp. lactis and lactococcus lactis subsp. lactis var. diacetylactis, isolated from raw-milk arzúa-ulloa cheeses. five batches of cheese (lb) were made with the acid-aromatic starter plus one of five strains of mesophilic homofermentative lactobacillus spp ...200010946837
dihydroorotate dehydrogenase from clostridium oroticum is a class 1b enzyme and utilizes a concerted mechanism of catalysis.dihydroorotate dehydrogenase from clostridium oroticum was purified to apparent homogeneity and found to be a heterotetramer consisting of two alpha (32 kda) and two beta (28 kda) polypeptides. this subunit composition, coupled with known cofactor requirements and the ability to transfer electrons from l-dihydroorotate to nad(+), defines the c. oroticum enzyme as a family 1b dihydroorotate dehydrogenase. the results of steady-state kinetic analyses and isotope exchange studies suggest that this ...200010956027
treatment of murine colitis by lactococcus lactis secreting interleukin-10.the cytokine interleukin-10 (il-10) has shown promise in clinical trials for treatment of inflammatory bowel disease (ibd). using two mouse models, we show that the therapeutic dose of il-10 can be reduced by localized delivery of a bacterium genetically engineered to secrete the cytokine. intragastric administration of il-10-secreting lactococcus lactis caused a 50% reduction in colitis in mice treated with dextran sulfate sodium and prevented the onset of colitis in il-10(-/-) mice. this appro ...200010958782
cholate resistance in lactococcus lactis is mediated by an atp-dependent multispecific organic anion transporter.the cholate-resistant lactococcus lactis strain c41-2, derived from wild-type l. lactis mg1363 through selection for growth on cholate-containing medium, displayed a reduced accumulation of cholate due to an enhanced active efflux. however, l. lactis c41-2 was not cross resistant to deoxycholate or cationic drugs, such as ethidium and rhodamine 6g, which are typical substrates of the multidrug transporters lmrp and lmra in l. lactis mg1363. the cholate efflux activity in l. lactis c41-2 was not ...200010960105
lantibiotic biosynthesis: interactions between prelacticin 481 and its putative modification enzyme, lctm.class aii and aiii lantibiotics and mersacidin are antibacterial peptides containing unusual residues obtained by posttranslational modifications of prepeptides, presumably catalyzed by lanm. lctm, the lanm for lacticin 481, is essential for the production of this class aii lantibiotic. using the yeast two-hybrid system, we showed direct contact between the prelacticin 481 and lctm, supporting the proposed lctm function. sixteen domains are conserved between the 10 known lanm proteins, whereas t ...200010960114
improved vectors for nisin-controlled expression in gram-positive bacteria.a set of shuttle vectors, able to replicate in escherichia coli and in gram-positive bacteria, containing a nisin-inducible promoter (pnisa) and genes encoding nisr and nisk, the two-component signaling mechanism for activating transcription from pnisa in the presence of nisin, was constructed. to test these vectors, enterococcus faecalis pcf10 plasmid genes prgx, prgy, and prgz, which respectively encode cytosolic, integral membrane, and cell surface proteins, were cloned downstream of pnisa. i ...200010964628
characterization of a novel plasmid-encoded hsds subunit, s.llaw12i, from lactococcus lactis w12.a novel type i restriction-modification specificity subunit, s. llaw12i, has been identified on the naturally occurring 8.0-kb plasmid paw122 in the lactic acid bacterium lactococcus lactis subsp. cremoris w12. presence of the hsds protein together with a complete type i restriction-modification system conferred increased phage restriction to the host, indicating exchange of specificity subunits. sequence analysis showed that the s.llaw12i subunit is most probably of type ic. presumably, the hsd ...200010964630
changes in glycolytic activity of lactococcus lactis induced by low temperature.the effects of low-temperature stress on the glycolytic activity of the lactic acid bacterium lactococcus lactis were studied. the maximal glycolytic activity measured at 30 degrees c increased approximately 2.5-fold following a shift from 30 to 10 degrees c for 4 h in a process that required protein synthesis. analysis of cold adaptation of strains with genes involved in sugar metabolism disrupted showed that both the phosphoenolpyruvate-dependent sugar phosphotransferase system (pts) subunit h ...200010966377
physiological and regulatory effects of controlled overproduction of five cold shock proteins of lactococcus lactis mg1363.the physiological and regulatory effects of overproduction of five cold shock proteins (csps) of lactococcus lactis were studied. cspb, cspd, and cspe could be overproduced at high levels (up to 19% of the total protein), whereas for cspa and cspc limited overproduction (0.3 to 0.5% of the total protein) was obtained. northern blot analysis revealed low abundance of the cspc transcript, indicating that the stability of cspc mrna is low. the limited overproduction of cspa is likely to be caused b ...200010966387
production of angiotensin-i-converting-enzyme-inhibitory peptides in fermented milks started by lactobacillus delbrueckii subsp. bulgaricus ss1 and lactococcus lactis subsp. cremoris ft4.two fermented milks containing angiotensin-i-converting-enzyme (ace)-inhibitory peptides were produced by using selected lactobacillus delbrueckii subsp. bulgaricus ss1 and l. lactis subsp. cremoris ft4. the ph 4.6-soluble nitrogen fraction of the two fermented milks was fractionated by reversed-phase fast-protein liquid chromatography. the fractions which showed the highest ace-inhibitory indexes were further purified, and the related peptides were sequenced by tandem fast atom bombardment-mass ...200010966406
dissolution of xylose metabolism in lactococcus lactis.xylose metabolism, a variable phenotype in strains of lactococcus lactis, was studied and evidence was obtained for the accumulation of mutations that inactivate the xyl operon. the xylose metabolism operon (xylrab) was sequenced from three strains of lactococci. fragments of 4.2, 4.2, and 5.4 kb that included the xyl locus were sequenced from l. lactis subsp. lactis b-4449 (formerly lactobacillus xylosus), l. lactis subsp. lactis io-1, and l. lactis subsp. lactis 210, respectively. the two envi ...200010966417
lactococcus lactis as a cell factory for high-level diacetyl production.we report the engineering of lactococcus lactis for the efficient conversion of sugar into diacetyl by combining nadh-oxidase overproduction and alpha-acetolactate decarboxylase inactivation. eighty percent of the carbon flux was found to be rerouted via alpha-acetolactate to the production of diacetyl by preloading the cells with nadh-oxidase before their use as a cell factory.200010966436
modulation of humoral immune response through probiotic intake.thirty healthy volunteers were randomised into three different treatment groups and consumed lactobacillus gg, lactococcus lactis or placebo (ethyl cellulose) for 7 days. on days 1, 3 and 5, an attenuated salmonella typhi ty21a oral vaccine was given to all subjects to mimic an enteropathogenic infection. all subjects responded well to the vaccine, but no significant differences were observed in numbers of iga-, igg- and igm-secreting cells among the different groups. there was a trend towards a ...200010967260
genotypic and phenotypic heterogeneity among lactococci isolated from traditional pecorino sardo cheese.twenty-nine lactococcus lactis isolates from one traditional 24 h-old pecorino sardo cheese were characterized phenotypically, technologically and genotypically in order to assess the biodiversity within this wild microbial population. two dna-based techniques, plasmid profiling and pfge, were used for the genetic typing of the isolates. all 29 isolates were characterized at strain level and eight different genotypes were recognized. in addition, by combining the results from plasmid profile ana ...200010971750
biological and molecular characterization of a two-peptide lantibiotic produced by lactococcus lactis ifpl105.the lactic acid bacterium lactococcus lactis ifpl105 secretes a broad spectrum bacteriocin produced from the 46 kb plasmid pbac105. the bacteriocin was purified to homogeneity by ionic and hydrophobic exchange and reverse-phase chromatography. bacteriocin activity required the complementary action of two distinct peptides (alpha and beta) with average molecular masses of 3322 and 2848 da, respectively. the genes encoding the two peptides were cloned and sequenced and were found to be identical t ...200010971756
solvent extraction of bacteriocins from liquid cultures.a solvent extraction method was developed to concentrate lacidin from the culture of lactobacillus acidophilus osu133. the new method concentrates the bacteriocin at the interface between chloroform and the aqueous culture of the producing bacterium. compared with other extraction procedures, the new method effectively recovers higher bacteriocin yield and results in relatively clean preparations. recovery of lacidin by the chloroform extraction procedure, compared with ammonium sulphate precipi ...200010972727
regulation of growth inhibition at high temperature, autolysis, transformation and adherence in streptococcus pneumoniae by clpc.the clpc atpase is a subfamily of hsp100/clp molecular chaperones-regulators of proteolysis. by screening a library of loss of function mutants for the ability to survive treatment with penicillin, we identified the gene clpc. the corresponding protein was identified as a clpc atpase, sharing strong peptide sequence identity with clpc of bacillus subtilis, listeria monocytogenes and lactococcus lactis. northern blot experiments showed that expression of clpc was induced in response to high tempe ...200010972795
each peptide of the two-component lantibiotic lacticin 3147 requires a separate modification enzyme for activity.the genetic determinants for production and immunity to the two-component lantibiotic lacticin 3147 are encoded by a 12.6 kb region of the plasmid pmrc01. this region contains ten genes arranged in two divergent clusters; these include the structural genes and a number of genes whose products show significant similarity to proteins involved in the biosynthesis of other lantibiotics. using a strategy of deletion and mutational analysis, the effect of disruption of a number of these genes was inve ...200010974102
immunology. therapeutic manipulation of gut flora.in developed countries as many as two individuals in every thousand suffer from inflammatory bowel disease (ulcerative colitis and crohn's disease). in his perspective, shanahan discusses a new therapeutic approach to treating these conditions in which bacteria normally found in the gut are engineered to produce the anti-inflammatory cytokine interleukin-10 and then are fed as probiotics to mice with these disorders (steidler et al.).200010979858
efficacy of nisin-coated polymer films to inactivate salmonella typhimurium on fresh broiler skin.nisin is an antimicrobial peptide produced by the food-grade microorganism lactococcus lactis subsp. lactis. this peptide inhibits many gram-positive bacteria, and when combined with chelating agents it inhibits gram-negative bacteria such as salmonella sp. the efficacy of packaging films treated with nisin-containing formulations to reduce salmonella contamination of fresh broiler drumstick skin and increase the refrigerated shelf life was investigated. three films (5.1 cm2) of varying hydropho ...200010983791
transcriptional and translational regulation of alpha-acetolactate decarboxylase of lactococcus lactis subsp. lactis.the alpha-acetolactate decarboxylase (aldc) gene, aldb, is the penultimate gene of the leu-ilv-ald operon, which encodes the three branched-chain amino acid (bcaa) biosynthesis genes in lactococcus lactis. its product plays a dual role in the cell: (i) it catalyzes the second step of the acetoin pathway, and (ii) it controls the pool of alpha-acetolactate during leucine and valine synthesis. it can be transcribed from the two promoters present upstream of the leu and ilv genes (p1 and p2) or ind ...200010986242
is1675, a novel lactococcal insertion element, forms a transposon-like structure including the lacticin 481 lantibiotic operon.two copies of is1675, a novel lactococcal insertion element from the is4 family, are present on a 70-kb plasmid, where they frame the lantibiotic lacticin 481 operon. the whole structure could be a composite transposon designated tn5721. this study shows that the lacticin 481 operon does not include any regulatory gene and provides a new example of a transposon-associated bacteriocin determinant. we identified five other is1675 copies not associated with the lacticin 481 operon. the conservation ...200010986268
structural characterisation and enzymic modification of the exopolysaccharide produced by lactococcus lactis subsp. cremoris b891.lactococcus lactis subsp. cremoris b891 grown on whey permeate produced an exopolysaccharide containing d-gal and d-glc in a molar ratio of 2:3. the polysaccharide was partially o-acetylated. by means of hf solvolysis, o-deacetylation, enzymic modification, sugar linkage analysis and id/2d nmr studies the exopolysaccharide was shown to be composed of repeating units with the following structure: [structure: see text].200010990026
comparative genomics of the late gene cluster from lactobacillus phages.three prophage sequences were identified in the lactobacillus johnsoni strain ncc533. prophage lj965 predicted a gene map very similar to those of pac-site streptococcus thermophilus phages over its dna packaging and head and tail morphogenesis modules. sequence similarity linked the putative dna packaging and head morphogenesis genes at the protein level. prophage lj965/s. thermophilus phage sfi11/lactococcus lactis phage tp901-1 on one hand and lactobacillus delbrueckii phage ll-h/lactobacillu ...200010998330
viability of probiotic (bifidobacterium, lactobacillus acidophilus and lactobacillus casei) and nonprobiotic microflora in argentinian fresco cheese.we evaluated the suitability of argentinian fresco cheese as a food carrier of probiotic cultures. we used cultures of bifidobacterium bifidum (two strains), bifidobacterium longum (two strains), bifidobacterium sp. (one strain), lactobacillus acidophilus (two strains), and lactobacillus casei (two strains) in different combinations, as probiotic adjuncts. probiotic, lactic starter (lactococcus lactis and streptococcus thermophilus), and contaminant (coliforms, yeasts, and molds) organisms were ...200011003217
identification of a gene cluster encoding krebs cycle oxidative enzymes linked to the pyruvate carboxylase gene in lactococcus lactis ssp. lactis c2.we identified a 14-kb pyruvate carboxylase gene-containing fragment from a lactococcal c2-lambda phage genomic library. downstream of the pyruvate carboxylase gene-containing fragment, a gene cluster coding for open reading frames displaying extensive homology to citrate synthase, aconitase, and a truncated isocitrate dehydrogenase was identified. however, the truncation was shown to have occurred during the cloning by two noncontiguous sau3ai fragments ligating together. the lactococcal citrate ...200011003218
protection against staphylococcus aureus mastitis in dairy cows using a bismuth-based teat seal containing the bacteriocin, lacticin 3147.we assessed the effectiveness of a novel dry cow treatment containing lacticin 3147 using deliberate challenge studies in lactating cows. infection-free quarters of lactating cows were infused with teat seal (cross vetpharm group, ltd., dublin, ireland) combined with the food-grade bacteriocin, lacticin 3147. natural infection of the teat was simulated by deliberately introducing staphylococcus aureus into the teat duct and teat sinus. relative to control quarters, teat seal plus lacticin 3147 r ...200011003227
cloning, sequence analysis, and expression of lactobacillus casei phage pl-1 lysis genes.the genes encoding the host cell wall-lytic proteins were searched in the genome dna of phage pl-1 active against lactobacillus casei atcc 27092 by comparing the amino acid sequences with those of others using a computer software of the ddbj data base. the gene regions found were cloned into e. coli by inserting pcr-amplified dna fragments into the ecori site of puc 19, and the nucleotide sequences were determined. one of the orfs (hol) consisted of 270 bp encoding 90 amino acids. the hol produc ...200011003466
the n-terminal region of the oenococcus oeni bacteriophage fog44 lysin behaves as a bona fide signal peptide in escherichia coli and as a cis-inhibitory element, preventing lytic activity on oenococcal cells.the function of the n-terminal region of the oenococcus oeni phage fog44 lysin (lys44) as an export signal was investigated. we observed that when induced in escherichia coli, lys44 was cleaved between residues 27 and 28 in a seca-dependent manner. lys44 processing could be blocked by a specific signal peptidase inhibitor and was severely reduced by modification of the cleavage site. the lethal effect of lys44 expression observed in e. coli was ascribed to the presence of its n-terminal 27-resid ...200011004183
adaptation of the nisin-controlled expression system in lactobacillus plantarum: a tool to study in vivo biological effects.the potential of lactic acid bacteria as live vehicles for the production and delivery of therapeutic molecules is being actively investigated today. for future applications it is essential to be able to establish dose-response curves for the targeted biological effect and thus to control the production of a heterologous biopeptide by a live lactobacillus. we therefore implemented in lactobacillus plantarum ncimb8826 the powerful nisin-controlled expression (nice) system based on the autoregulat ...200011010894
development of bioactive food packaging materials using immobilised bacteriocins lacticin 3147 and nisaplin.immobilisation of the bacteriocins nisin and lacticin 3147 to packaging materials was investigated. stability of both cellulose-based bioactive inserts and anti-microbial polyethylene/polyamide pouches was examined over time. anti-microbial activity against the indicator strain lactococcus lactis subsp. lactis hp, in addition to listeria innocua dpc 1770 and staphylococcus aureus mmpr3 was observed for all bacteriocin-adsorbed materials. activity retention of the inserts showed an initial decrea ...200011016613
a simple and sensitive method to extract bacterial, yeast and fungal dna from blood culture material.this study investigated the various commercially available kits and 'in-house' methods to extract dna from gram-negative and gram-positive bacteria, yeast and fungal agents in commonly employed blood culture material. the main methods investigated were as follows; qiagen qiamp blood kit, roche high pcr template preparation kit, puregene dna extraction kit, boiling, glass beads/sonication and wash/alkali/heat lysis. the results indicated that a simple wash/alkali/heat lysis method was the most se ...200011018270
an evaluation of chelex-based dna purification protocols for the typing of lactic acid bacteria.an easy and rapid protocol to extract dna to be used as template for polymerase chain reaction (pcr) fingerprinting experiments from cultivable lactic acid bacteria (lab) is proposed. different procedures for rapid extraction of dna by chelex (iminodiacetid acid) ionic resin were compared. factors affecting the quality and reproducibility of pcr fingerprinting profiles were also investigated. two out of three chelex-based protocols allowed to obtain dna samples which, after pcr amplification, pr ...200011018274
effects of mixed starter composition on nisin z production by lactococcus lactis subsp. lactis biovar. diacetylactis ul 719 during production and ripening of gouda cheese.a starter culture system that produced both acid and nisin at acceptable rates in milk for manufacture of gouda cheese was developed using nisin z-producing l. lactis subsp. lactis biovar. diacetylactis ul 719 (ul 719) and a commercial flora danica (fd) starter culture. different compositions of mixed cultures (0, 0.2, 0.4, 0.6 or 0.8% ul 719 with 1.4% fd) were tested for acidification and nisin z production in milk after 12 h incubation at 30 degrees c. the 0.6/1.4% combination, selected as the ...200011020036
novel sucrose transposons from plant strains of lactococcus lactis.lactococcus lactis strains isolated from vegetable products transferred the ability to ferment sucrose in conjugation experiments with the recipient strain l. lactis mg1614. nisin production and sucrose fermentation were transferred together from two strains, but transfer also occurred from several other strains which did not produce nisin. pulsed-field gel electrophoresis analysis showed that all transconjugants had acquired large chromosomal insertions at two main sites. nisin sucrose transcon ...200011034285
phylogenetic analysis of gram-positive bacteria based on grpe, encoded by the dnak operon.the dnak operon in gram-positive bacteria includes grpe, dnaj and, in some members, hrca as well. both dnak and dnaj have been utilized for constructing phylogenetic relationships among various organisms. multiple copies exist for dnak and dnaj genes in some bacterial genera, as opposed to a single gene copy for grpe and for hrca, according to the currently available data. here, we present a partial protein-based phylogenetic tree for gram-positive bacteria, derived by using the amino acid seque ...200011034484
in-vitro activity and killing effect of polycationic peptides on methicillin-resistant staphylococcus aureus and interactions with clinically used antibiotics.the in-vitro activity of nisin, a 34-residue peptide produced by several lactococcus lactis strains, and ranalexin, a 20-residue peptide isolated from the skin of the bullfrog rana catesbeiana, alone and in combination with amoxycillin, amoxycillin-clavulanate, imipenem, clarithromycin, ciprofloxacin, rifampin and vancomycin was investigated against 40 nosocomial isolates of methicillin-resistant staphylococcus aureus (mrsa). all isolates were inhibited at concentrations of 1 to 32 microg/ml. sy ...200011035243
mutational analysis of two structural genes of the temperate lactococcal bacteriophage tp901-1 involved in tail length determination and baseplate assembly.two putative structural genes, orf tmp (tape measure protein) and orf bpp (baseplate protein), of the temperate lactococcal phage tp901-1 were examined by introduction of specific mutations in the prophage strain lactococcus lactic ssp. cremoris 901-1. the adsorption efficiencies of the mutated phages to the indicator strain l. lactic ssp. cremoris 3107 were determined and electron micrographs were obtained. specific mutations in orf tmp resulted in the production of mostly phage head structures ...200011040123
zinc uptake, oxidative stress and the fnr-like proteins of lactococcus lactis.lactococcus lactis ssp. cremoris mg1363 contains two fnr homologues, flpa and flpb, encoded by the distal genes of two paralogous operons (orfx(a/b)-orfy(a/b)-flpa/b). an flpa flpb double mutant strain is hypersensitive to hydrogen peroxide and has a depleted intracellular zn(ii) pool. the phenotypes of the flp mutant strains suggest that flpa and flpb control the expression of high and low affinity atp-dependent zn(ii) uptake systems, respectively. plate tests revealed that expression from a or ...200011040433
the life cycles of the temperate lactococcal bacteriophage philc3 monitored by a quantitative pcr method.we present here a new and general approach for monitoring the life cycles of temperate bacteriophages which establish lysogeny by inserting their genomes site-specifically into the bacterial host chromosome. the method is based on quantitative amplification of specific dna sites involved in various cut-and-join events during the life cycles of the phages (i.e. the cos, attp, attb, attl and attr sites) with the use of sequence-specific primers. by comparing the amounts of these specific dna sites ...200011040439
the conserved c-terminus of the citrate (citp) and malate (mlep) transporters of lactic acid bacteria is involved in substrate recognition.the membrane potential-generating transporters citp of leuconostoc mesenteroides and mlep of lactococcus lactis are homologous proteins with 48% identical residues that catalyze citrate-lactate and malate-lactate exchange, respectively. the two transporters are highly specific for substrates containing a 2-hydroxycarboxylate motif (ho-cr(2)-coo(-)) in which substitutions of the r groups are tolerated well. differences in substrate specificity between mlep and citp are based on subtle changes in ...200011041872
multiple homing pathways used by yeast mitochondrial group ii introns.the yeast mitochondrial dna group ii introns ai1 and ai2 are retroelements that insert site specifically into intronless alleles by a process called homing. here, we used patterns of flanking marker coconversion in crosses with wild-type and mutant ai2 introns to distinguish three coexisting homing pathways: two that were reverse transcriptase (rt) dependent (retrohoming) and one that was rt independent. all three pathways are initiated by cleavage of the recipient dna target site by the intron- ...200011046140
combinatorial peptide libraries reveal the ligand-binding mechanism of the oligopeptide receptor oppa of lactococcus lactis.the oligopeptide transport system (opp) of lactococcus lactis has the unique capacity to mediate the transport of peptides from 4 up to at least 18 residues. the substrate specificity of this binding protein-dependent atp-binding cassette transporter is determined mainly by the receptor protein oppa. to study the specificity and ligand-binding mechanism of oppa, the following strategy was used: (i) oppa was purified and anchored via the lipid moiety to the surface of liposomes; (ii) the proteoli ...200011050157
continuous production of lacticin 3147 and nisin using cells immobilized in calcium alginate.bacteriocinogenic strains, lactococcus lactis subsp. lactis dpc 3147 and l. lactis dpc 496, producing lacticin 3147 and nisin, respectively, were immobilized in double-layered calcium alginate beads. these beads were inoculated into mrs broth at a ratio of 1:4 and continuously fermented for 180 h. free cells were used to compare the effect of immobilization on bacteriocin production. after equilibrium was reached, a flow rate of 580 ml h(-1) was used in the immobilized cell (ic), and 240 ml h(-1 ...200011054159
[the production of antihypertensive peptides in beta-casein proteolysis].antihypertensive peptides were obtained after the proteolysis of beta-casein by starter cells lactococcus lactis ssp. lactis and lactococci with pepsin or fromase. the peptides have shown the effect as inhibitors of angiotensin-converting enzyme. the strongest action the peptide obtained after the proteolysis of beta-casein by synergic action of lactococci with pepsin has shown. it demonstrates a capability of formation of such peptides directly in milk products during their making and maturatio ...200011059391
identification of enterococcus species and phenotypically similar lactococcus and vagococcus species by reverse checkerboard hybridization to chaperonin 60 gene sequences.data from four recent studies (s. h. goh et al., j. clin. microbiol. 36:2164-2166, 1998; s. h. goh et al., j. clin. microbiol. 34:818-823, 1996; s. h. goh et al., j. clin. microbiol. 35:3116-3121, 1997; a. y. c. kwok et al., int. j. syst. bacteriol. 49:1181-1192, 1999) suggest that an approximately 600-bp region of the chaperonin 60 (cpn60) gene, amplified by pcr with a single pair of degenerate primers, has utility as a potentially universal target for bacterial identification (id). this cpn60 ...200011060051
molecular analysis of mutated lactobacillus acidophilus promoter-like sequence p15.the promoter-like sequence p15 that was previously cloned from the chromosome of lactobacillus acidophilus atcc 4356 is active in lactobacillus reuteri, lactobacillus plantarum, lactobacillus acidophilus, and escherichia coli, but not in lactococcus lactis. n-methyl-n-nitroso-n-guanidine (mnng) mutagenesis of p15 was used to select for a promoter active in l. lactis mg1363. molecular analysis of the mutated promoter (designated p16) revealed a 90 bp deletion and a t-->a transversion. this deleti ...200011068681
conditions for conjugative transposon transfer in lactococcus lactis.three different techniques for bacterial mating were applied to wild type and culture collection strains of lactococcus lactis harbouring transposons: direct plate conjugation, filter mating and mating on milk agar. efficiencies and frequencies of transfer were compared. transconjugants were characterized by marker properties and molecular assays. transposon-coded suc+ nis+ phenotype as well as suc+ bac+ nis- phenotype were transferred with frequencies ranging between 10-9 and 10-6. milk agar pl ...200011069634
germ therapy with il-10 to treat inflammatory bowel diseases. 200011074364
nucleotide sequence and analysis of pbl1, a bacteriocin-producing plasmid from lactococcus lactis ipla 972.the complete sequence of the 10.9-kbp bacteriocinogenic plasmid pbl1 from lactococcus lactis subsp. lactis ipla 972 has been determined. thirteen orfs were encountered, of which 5 were incomplete. pbl1 proved to be a narrow-host-range plasmid which replicates neither in bacilus subtilis nor in lactobacillus spp. the structural organization of the pbl1 replication region was highly similar to other well-known theta-replicating plasmids of lactococci, at both the untranslated (the replication orig ...200011078650
formation of biogenic amines in raw milk hispánico cheese manufactured with proteinases and different levels of starter culture.two proteinases, a neutral proteinase from bacillus subtilis and a cysteine proteinase from micrococcus sp., were used to accelerate the ripening process of raw cow's milk hispánico cheese, a semihard variety. two levels (0.1% and 1%) of a commercial starter culture containing lactococcus lactis subsp. lactis and l. lactis subsp. cremoris were added for cheese manufacture. the influence of both factors, proteinase addition and level of starter culture, on the growth of amino acid-decarboxylating ...200011079699
heterologously expressed staphylococcus aureus fibronectin-binding proteins are sufficient for invasion of host cells.staphylococcus aureus invasion of mammalian cells, including epithelial, endothelial, and fibroblastic cells, critically depends on fibronectin bridging between s. aureus fibronectin-binding proteins (fnbps) and the host fibronectin receptor integrin alpha(5)beta(1) (b. sinha et al., cell. microbiol. 1:101-117, 1999). however, it is unknown whether this mechanism is sufficient for s. aureus invasion. to address this question, various s. aureus adhesins (fnbpa, fnbpb, and clumping factor [clfa]) ...200011083807
fbpabc gene cluster in neisseria meningitidis is transcribed as an operon.the neisserial fbpabc locus has been proposed to constitute a single transcriptional unit. to confirm this operonic arrangement, transcription assays using reverse transcriptase pcr amplification were conducted with neisseria meningitidis. the presence of fbpab and fbpbc transcripts obtained by priming cdna synthesis with an fbpc-sequence-specific oligonucleotide indicates that fbpabc is organized as a single expression unit. the ratio of fbpa to fbpabc mrna was approximately between 10- to 20-f ...200011083849
inducible expression of enterococcus faecalis aggregation substance surface protein facilitates bacterial internalization by cultured enterocytes.aggregation substance (as) is an enterococcus faecalis surface protein that may contribute to virulence. using a recently described system for controlled expression of as in e. faecalis and the heterologous host lactococcus lactis, experiments were designed to assess the effect of as on bacterial internalization by ht-29 and caco-2 enterocytes. as expression was associated with increased internalization of e. faecalis by ht-29 enterocytes and of l. lactis by ht-29 and caco-2 enterocytes. compare ...200011083854
purification and characterisation of a beta-galactosidase from aspergillus aculeatus with activity towards (modified) exopolysaccharides from lactococcus lactis subsp. cremoris b39 and b891.beta-galactosidase from aspergillus aculeatus was purified from a commercial source for its hydrolytic activity towards (modified) exopolysaccharides (epss) produced by lactococcus lactis subsp. cremoris b39 and b891. the enzyme had a molecular mass of approximately 120 kda, a pi between 5.3 and 5.7 and was optimally active at ph 5.4 and 55-60 degrees c. based on the n-terminal amino acid sequence, the enzyme probably belongs to family 35 of the glycosyl hydrolases. the catalytic mechanism was s ...200011086688
lldi, a plasmid-encoded type i restriction and modification system in lactococcus lactis.a plasmid-encoded type i restriction and modification (r-m) system, designated lldi, was identified in lactococcus lactis biovar diacetylactis ld10-1. lldi consists of three genes encoding endonuclease, methylase and specificity subunits, respectively. rt-pcr analysis revealed that the three genes are co-transcribed as a polycistronic mrna in l. lactis. the specificity subunit of lldi differs significantly in the target recognition domains from those of other type i r-m systems, suggesting that ...200011092734
evidence for horizontal gene transfer in evolution of elongation factor tu in enterococci.the elongation factor tu, encoded by tuf genes, is a gtp binding protein that plays a central role in protein synthesis. one to three tuf genes per genome are present, depending on the bacterial species. most low-g+c-content gram-positive bacteria carry only one tuf gene. we have designed degenerate pcr primers derived from consensus sequences of the tuf gene to amplify partial tuf sequences from 17 enterococcal species and other phylogenetically related species. the amplified dna fragments were ...200011092850
branched-chain amino acid biosynthesis is essential for optimal growth of streptococcus thermophilus in milk.lactic acid bacteria are nutritionally demanding bacteria which need, among other things, amino acids for optimal growth. we identified the branched-chain amino acid (bcaa) biosynthesis pathway as an essential pathway for optimal growth of streptococcus thermophilus in milk. through random insertional mutagenesis, we isolated and characterized two mutants for which growth in milk is affected as a consequence of ilvb and ilvc gene interruptions. this situation demonstrates that the bcaa biosynthe ...200011097879
the autoproteolysis of lactococcus lactis lactocepin iii affects its specificity towards beta-casein.the effect of autoproteolysis of lactococcus lactis lactocepin iii on its specificity towards beta-casein was investigated. beta-casein degradation was performed by using either an autolysin-defective derivative of l. lactis mg1363 carrying the proteinase genes of l. lactis sk11, which was unable to transport oligopeptides, or autoproteolyzed enzyme purified from l. lactis sk11. comparison of the peptide pools by high-performance liquid chromatography analysis revealed significant differences. t ...200011097880
diacetyl and alpha-acetolactate overproduction by lactococcus lactis subsp. lactis biovar diacetylactis mutants that are deficient in alpha-acetolactate decarboxylase and have a low lactate dehydrogenase activity.lactococcus lactis subsp. lactis biovar diacetylactis strains are utilized in several industrial processes for producing the flavoring compound diacetyl or its precursor alpha-acetolactate. using random mutagenesis with nitrosoguanidine, we selected mutants that were deficient in alpha-acetolactate decarboxylase and had low lactate dehydrogenase activity. the mutants produced large amounts of alpha-acetolactate in anaerobic milk cultures but not in aerobic cultures, except when the medium was su ...200011097941
gene transfer to clostridium cellulolyticum atcc 35319.although much is known about the bacterial cellulosome and its various protein components, their contributions to bacterial growth on cellulose and the process of cellulolysis in vivo cannot currently be assessed. to remedy this, the authors have developed gene transfer techniques for clostridium cellulolyticum atcc 35319. firstly, transfer of tn1545 has been obtained using an enterococcus faecalis donor. secondly, incp-mediated conjugative mobilization of plasmids from escherichia coli donors h ...200011101665
efficient insertional mutagenesis in streptococcus thermophilus.bacteria have always been considered ideal organisms for genetic analysis. while this is true for some model organisms, like escherichia coli, bacillus subtilis and, more recently, lactococcus lactis, genetic analysis of other organisms is often prevented by lack of valuable tools, like vectors, transposons and methods for transformation, gene inactivation and random insertional mutagenesis. this is the case of the moderately thermophilic bacterium streptococcus thermophilus, an organism that, i ...200011111038
acid- and multistress-resistant mutants of lactococcus lactis : identification of intracellular stress signals.lactococcus lactis growth is accompanied by lactic acid production, which results in acidification of the medium and arrest of cell multiplication. despite growth limitation at low ph, there is evidence that lactococci do have inducible responses to an acid ph. in order to characterize the genes involved in acid tolerance responses, we selected acid-resistant insertional mutants of the l. lactis strain mg1363. twenty-one independent characterized mutants were affected in 18 different loci, some ...200010672175
gut mucosal immunostimulation by lactic acid bacteria.the beneficial properties of lactic acid bacteria (lab) on human health have been frequently demonstrated. the interaction of lab with the lymphoid cells associated to the gut to activate the mucosal immune system and the mechanisms by which they can exert an adjuvant effect is still unclear, as well as if this property is common for all the lab. we studied the influence of the oral administration of different geneous of lab such as lactobacillus casei, l. acidophilus, l. rhamnosus, l. delbrueck ...200011201658
characterization by molecular cloning and sequencing of the gene encoding an aminopeptidase from listeria monocytogenes.the pepc gene of listeria monocytogenes encodes aminopeptidase c that is predicted to share 72% amino acid sequence similarity and 53% sequence identity with the cysteine aminopeptidase pepc from lactococcus lactis. the gene product also shows strong similarity to aminopeptidase c from streptococcus thermophilus and lactobacillus helveticus, and to a cysteine proteinase/bleomycin hydrolase from saccharomyces cerevisiae. the enzyme from l. monocytogenes displayed broad n-terminal hydrolytic activ ...200011204766
lactic acid bacteria as live vaccines.mucosal routes for vaccine delivery offer several advantages over systemic inoculation from both immunological and practical points of view. the development of efficient mucosal vaccines therefore represents a top prority in modern vaccinology. one way to deliver protective antigens at the mucosal surfaces is to use live bacterial vectors. until recently most of these were derived from attenuated pathogenic microorganisms. as an alternative to this strategy, non-pathogenic food grade bacteria su ...200011464916
viscoelastic properties of an exocellular polysaccharide produced by a lactococcus lactis.the viscoelastic properties of a well-characterized exocellular polysaccharide (eps) produced by the lactic acid bacterium lactococcus lactis subsp. cremoris strain b40 were investigated. dynamic rheological measurements were made as a function of frequency and eps concentration. the bead-spring model of rouse could reasonably describe the dynamic properties. concentrated eps solutions have a significant elasticity (g' > g") at high frequencies. the relatively high g' values at high concentratio ...200011710103
[a new strategy of gene therapy for hyperphenylalaninemia rats].to construct a recombinant vector which expresses active phenylalanine-amonia-lyase (pal) in lactococcus lactis (l. l.), and to convert phe into cinnamic acid in small intestine by the engineering l. l. to decrease the phe level in the peripheral blood, and to cure hyperphenylalaninemia rats.200011798804
the production of mixed cultures containing strains of lactococcus lactis, leuconostoc cremoris and lactobacillus rhamnosus, on commercial starter media.mixed starters containing lactococcus lactis, leuconostoc cremoris and lactobacillus rhamnosus strains were produced on commercial starter media (mb complete, thermolac, marlac), as well as on milk. with the exception of marlac, the starters were cultured under ph control. the effect of media and incubation temperature (22 or 32 degrees c) on population ratios, on specific acidifying activities (saa) of the cultures as well as on their ability to produce aroma compounds in milk was studied. the ...200011320415
an abc-type multidrug transporter of lactococcus lactis possesses an exceptionally broad substrate specificity.lmra is a 590-amino acid membrane protein which confers multidrug resistance on lactococcus lactis cells by extruding amphiphilic compounds from the inner leaflet of the cytoplasmic membrane at the expense of atp hydrolysis. its structural and functional characteristics place it in the p-glycoprotein cluster of the atp-binding cassette transporter superfamily, making it the first prokaryotic multidrug transporter of this cluster. the number of compounds recognized and transported by lmra is rema ...200011498401
gene cloning, sequencing, and inactivation of the branched-chain aminotransferase of lactococcus lactis lm0230.a branched-chain aminotransferase gene (ilve) from lactococcus lactis lm0230 was identified on a 9-kb chromosomal insert by complementation in escherichia coli dl39. sequencing of a 2.0-kbp fragment resulted in the identification of a 1,023-bp open reading frame that could encode a 340-amino-acid protein. sequence analysis of the deduced amino acid sequence revealed 62% identity to ilve of haemophilus influenzae and high similarity to ilves from a variety of organisms found in genbank classified ...200010831406
dynamic changes of intracellular ph in individual lactic acid bacterium cells in response to a rapid drop in extracellular ph.we describe the dynamics of changes in the intracellular ph (ph(i)) values of a number of lactic acid bacteria in response to a rapid drop in the extracellular ph (ph(ex)). strains of lactobacillus delbrueckii subsp. bulgaricus, streptococcus thermophilus, and lactococcus lactis were investigated. listeria innocua, a gram-positive, non-lactic acid bacterium, was included for comparison. the method which we used was based on fluorescence ratio imaging of single cells, and it was therefore possibl ...200010831407
surface of lactic acid bacteria: relationships between chemical composition and physicochemical properties.the surface chemical composition and physicochemical properties (hydrophobicity and zeta potential) of two lactic acid bacteria, lactococcus lactis subsp. lactis bv. diacetilactis and lactobacillus helveticus, have been investigated using cells harvested in exponential or stationary growth phase. the surface composition determined by x-ray photoelectron spectroscopy (xps) was converted into a molecular composition in terms of proteins, polysaccharides, and hydrocarbonlike compounds. the concentr ...200010831437
characterization of abir, a novel multicomponent abortive infection mechanism encoded by plasmid pkr223 of lactococcus lactis subsp. lactis kr2.the native lactococcal plasmid pkr223 encodes two distinct phage resistance mechanisms, a restriction and modification (r/m) system designated llakr2i and an abortive infection mechanism (abi) which affects prolate-headed-phage proliferation. the nucleotide sequence of a 16,174-bp segment of pkr223 encompassing both the r/m and abi determinants has been determined, and sequence analysis has validated the novelty of the abi system, which has now been designated abir. analysis of deletion and inse ...200010831451
the homodimeric atp-binding cassette transporter lmra mediates multidrug transport by an alternating two-site (two-cylinder engine) mechanism.the bacterial lmra protein and the mammalian multidrug resistance p-glycoprotein are closely related atp-binding cassette (abc) transporters that confer multidrug resistance on cells by mediating the extrusion of drugs at the expense of atp hydrolysis. the mechanisms by which transport is mediated, and by which atp hydrolysis is coupled to drug transport, are not known. based on equilibrium binding experiments, photoaffinity labeling and drug transport assays, we conclude that homodimeric lmra m ...200010835349
accumulation of casein-derived peptides during growth of proteinase-positive strains of lactococcus lactis in milk: their contribution to subsequent bacterial growth is impaired by their internal transport.to explain the limited nutritional value of milk cultured with proteinase-positive (prt+) strains of lactococcus lactis for the subsequent growth of dairy lactococci, we investigated further the time courses of modifications in the free amino acid and peptide contents of cultured milk. when growing in milk for up to 24 h, prt+ strains of lc. lactis progressively accumulated amino acids and casein-derived peptides. the growth of proteinase-negative (prt-) wild-type strains and peptide transport m ...200010840677
novel type i restriction specificities through domain shuffling of hsds subunits in lactococcus lactis.this study identifies a natural system in lactococcus lactis, in which a restriction modification specificity subunit resident on a 6159 bp plasmid (pah33) alters the specificity of a functional r/m mechanism encoded by a 20.3 kb plasmid, pah82. the new specificity was identified after phenotypic and molecular analysis of a 26.5 kb co-integrate plasmid (pah90), which was detected after bacteriophage challenge of the parent strain. analysis of the regions involved in the co-integration revealed t ...200010844674
ctsr of lactococcus lactis encodes a negative regulator of clp gene expression.bacteria undergo a complex programme of differential gene expression in response to stress. in bacillus subtilis, it was recently shown that ctsr, a negative transcriptional regulator, mediates stress-induced expression of components of the clp protease complex. in this study, a gene was identified in the gram-positive bacterium lactococcus lactis that encodes a 17 kda product with 38% identity to the ctsr protein of b. subtilis. by northern analyses it was found that in a l. lactis strain carry ...200010846223
pharmacokinetics of lactobacillus plantarum ncimb 8826, lactobacillus fermentum kld, and lactococcus lactis mg 1363 in the human gastrointestinal tract.genetically modified lactic acid bacteria may be a way to deliver vaccinal epitopes in the gastrointestinal tract.200010848668
metabolic characterization of lactococcus lactis deficient in lactate dehydrogenase using in vivo 13c-nmr.the metabolism of glucose by nongrowing cells of lactococcus lactis strain fi7851, constructed from the wild-type l. lactis strain mg1363 by disruption of the lactate dehydrogenase (ldh) gene [gasson, m.j., benson, k., swindel, s. & griffin, h. (1996) lait 76, 33-40] was studied in a noninvasive manner by 13c-nmr. the kinetics of the build-up and consumption of the pools of intracellular intermediates mannitol 1-phosphate, fructose 1,6-bisphosphate, 3-phosphoglycerate, and phosphoenolpyruvate as ...200010849005
the neprilysin family in health and disease.the mammalian neprilysin (nep) family comprises at least seven members: nep itself, kell blood group antigen (kell), the endothelin-converting enzymes (ece-1 and ece-2), the enzyme pex, associated with x-linked hypophosphataemia, "x-converting enzyme" (xce) a cns-expressed orphan peptidase and a soluble, secreted endopeptidase (sep). these zinc metallopeptidases are all type ii integral membrane proteins. where identified, these enzymes have roles in the processing or metabolism of regulatory pe ...200010849750
effect of carbon dioxide under high pressure on the survival of cheese starter cultures.a new processing method that rapidly forms curds and whey from milk has the potential to improve cheesemaking procedures if cheese starter cultures can tolerate the processing conditions. the survival of lactobacillus delbrueckii ssp. bulgaricus, lactococcus lactis ssp. lactis, or streptococcus thermophilus through this new process was evaluated. inoculated milk containing 0, 1, or 3.25% fat or lactobacillus mrs broth or tryptone yeast lactose broth (depending on microorganism used) was sparged ...200010852570
abc transporters in lipid transport.since it was found that the p-glycoproteins encoded by the mdr3 (mdr2) gene in humans and the mdr2 gene in mice are primarily phosphatidylcholine translocators, there has been increasing interest in the possibility that other atp binding cassette (abc) transporters are involved in lipid transport. the evidence reviewed here shows that the mdr1 p-glycoprotein and the multidrug resistance (-associated) transporter 1 (mrp1) are able to transport lipid analogues, but probably not major natural membr ...200010856718
genetic locus for streptolysin s production by group a streptococcus.group a streptococcus (gas) is an important human pathogen that causes pharyngitis and invasive infections, including necrotizing fasciitis. streptolysin s (sls) is the cytolytic factor that creates the zone of beta-hemolysis surrounding gas colonies grown on blood agar. we recently reported the discovery of a potential genetic determinant involved in sls production, saga, encoding a small peptide of 53 amino acids (s. d. betschel, s. m. borgia, n. l. barg, d. e. low, and j. c. de azavedo, infec ...200010858242
osmoregulated abc-transport system of lactococcus lactis senses water stress via changes in the physical state of the membrane.an osmoregulated abc transporter (opua) with novel structural features has been identified that responds to water stress. this glycine betaine transport system consists of an atp-binding/hydrolyzing subunit (opuaa) and a protein (opuabc) that contains both the translocator and the substrate-binding domain. the components of opua have been overexpressed, purified, and functionally incorporated into liposomes with an atp-regenerating system in the vesicle lumen. a transmembrane osmotic gradient (o ...200010860977
solution properties of viilian, the exopolysaccharide from lactococcus lactis subsp. cremoris sbt 0495.the exopolysaccharide (eps) "viilian" was isolated from a large-batch fermentation of lactococcus lactis subsp. cremoris sbt 0495. after applying a newly developed purification procedure, pure viilian with a weight-averaged molar mass of 2.64 x 10(3) kg/mol was obtained in a yield of 0.6 g/l culture broth. the native eps, as well as lower molar mass fractions obtained by sonication of the native polymer, were studied by capillary viscometry and size-exclusion chromatography (sec) coupled to mult ...200010861375
isothiocyanates in myrosinase treated herb extract of cleome chrysantha decne. and their antimicrobial activities.gc/ms analysis of the volatiles produced by the action of endogenous myrosinase in cleome chrysantha decne. herb, showed three major components, 1-isocyano-4-methyl benzene, gamma-muurolene and (cis) nerolidole (21.72%, 12.15% and 10.39%, respectively). 1-isocyano-4-methyl benzene is not produced from myrosinase treated seeds of cleome chrysantha decne., while muurolene and nerolidole were found at higher concentrations 16.1% and 13.67%, respectively. some other isothiocyanates identified in the ...200010861975
lactic acid bacteria as a cell factory: rerouting of carbon metabolism in lactococcus lactis by metabolic engineering.lactic acid bacteria display a relatively simple metabolism wherein the sugar is converted mainly to lactic acid. the extensive knowledge of metabolic pathways and the increasing information of the genes involved allows for the rerouting of natural metabolic pathways by genetic and physiological engineering. we discuss several examples of metabolic engineering of lactococcus lactis for the production of important compounds, including diacetyl, alanine and exopolysaccharides.200010862894
transcriptional control of the citrate-inducible citmcdefgrp operon, encoding genes involved in citrate fermentation in leuconostoc paramesenteroides.in this study we describe the expression pattern of the leuconostoc paramesenteroides citmcdefgrp operon in response to the addition of citrate to the growth medium. an 8.8-kb polycistronic transcript, which includes the citmcdefgrp genes, was identified; its synthesis was dramatically induced upon addition of citrate to the growth medium. we also found that expression of the cit operon is subjected to posttranscriptional regulation, since processing sites included in four complex secondary stru ...200010869065
Refresh
firstprev
...11121314151617181920...
nextlast
Displaying items 1901 - 2000 of 5589