Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| lactococcal bacteriocins: mode of action and immunity. | bacteriocins are antimicrobial peptides produced by bacteria. some of those synthesized by lactococcus lactis have been characterized in great detail recently. the lactococcal bacteriocins are hydrophobic cationic peptides, which form pores in the cytoplasmic membrane of sensitive cells. | 1995 | 8528613 |
| nucleotide sequence of a plasmid pcl2.1 from lactococcus lactis ssp. lactis ml8. | the nucleotide sequence of a small cryptic plasmid, pcl2.1, from lactococcus lactis ssp. lactis ml8 was determined. sequence analysis of the pcl2.1 revealed that it contained 2112 bp, 33.9% gc, and two open reading frames that encoded polypeptides of 26 and 14 kda. in vitro transcription-translation of the pcl2.1 confirmed the existence of two polypeptides. based on sequence homology, it is deduced that the orf2 product functions in plasmid replication by a rolling circle mechanism. | 1995 | 8825377 |
| progress in the development of lactococcus lactis as a recombinant mucosal vaccine delivery system. | the non-pathogenic, non-colonising gram-positive organism lactobacillus lactis is beeing developed as an antigen delivery system for mucosal vaccination. a high level expression system has been developed which allows loading of the bacterium with high levels of a heterologous antigen (ttfc) prior to inoculation. mucosal inoculation of one such recombinant strain results in a protective serum antibody response and production of ttfc-specific iga at mucosal sites. | 1995 | 8919927 |
| bactericidal properties of hydrogen peroxide and copper or iron-containing complex ions in relation to leukocyte function. | various combinations of hydrogen peroxide, reductant (ascorbic acid and superoxide ion), and copper or iron salts and their coordination complexes were examined to determine their cytotoxicity toward several bacteria with diverse metabolic capabilities and cell envelope structures. four sets of bactericidal conditions were identified, comprising: (1) high concentration levels (5-100 mm) of h2o2 in the absence of exogenous metal ions and reductant; (2) ferrous or ferric coordination complexes plu ... | 1995 | 9101234 |
| attachment of lactic acid bacteria to beef-muscle surfaces. | the effect of immersion time and cell concentration in the attachment of several lactic acid bacteria with antibacterial activity to beef-muscle surface was studied. the number of firmly attached bacteria increased with immersion time in the case of pediococcus acidilacti, lactobacillus sake, lactococcus cremoris (two strains) and pediococcus acidilacti. pediococcus pentosaceus, lactococcus lactis and lactobacillus curvatus reached maximum adhesion after 15-30 min. the highest strength of attach ... | 1996 | 9131790 |
| induction of ifn-gamma and il-1 alpha production in macrophages stimulated with phosphopolysaccharide produced by lactococcus lactis ssp. cremoris. | the induction of interferon (ifn) and interleukin-1 (il-1) production in murine macrophages by a phosphopolysaccharide, produced by a dairy lactic acid bacteria, lactococcus lactis ssp. cremoris, was investigated. when the phosphopolysaccharide was added into macrophage cultures at concentrations from 1 to 200 micrograms/ml, substantial ifn titers (6.2-79.2 iu/ml) were detected. using the reverse transcription-polymerase chain reaction (rt-pcr), the expression of mrna encoding ifn-gamma was veri ... | 1996 | 8880300 |
| production of antifungal substance by lactococcus lactis subsp. lactis chd-28.3. | six of the 2100 colonies of lactic acid bacteria isolated from 4 month old cheddar cheese and raw buffalo milk showed antifungal activity against aspergillus flavus iari when tested by the well agar diffusion assay on potato dextrose agar containing 0.1% triton x-100. out of these, the most promising isolate having a broad spectrum of antifungal activity including aspergillus flavus iari, a. flavus ncim 555, a. parasiticus ncim 898 and fusarium spp. was identified as lactococcus lactis subsp. la ... | 1996 | 8880325 |
| mutational analysis and chemical modification of cys24 of lactococcin b, a bacteriocin produced by lactococcus lactis. | using site-directed mutagenesis the single cysteine residue at position 24 of lactococcin b was replaced by all other possible amino acids. most of these mutant molecules retained bacteriocin activity, with the exception of those in which cysteine was replaced by a positively charged amino acid. this would seem to be in agreement with the authors' earlier observation that treatment of the wild-type molecule with hgcl2 resulted in its inactivation. the factor that causes inactivation of lactococc ... | 1996 | 8885398 |
| main microbial flora present as natural starters in cebreiro raw cow's-milk cheese (northwest spain). | thirty samples of cebreiro, a fresh or short-time-ripened raw cow's-milk cheese produced in northwest spain, were analyzed for the presence of aerobic mesophilic bacteria, (amc) lactic acid bacteria (lab), enterococci and micrococcaceae. mean amc and lab counts exceeding 10(9)/g were higher than those reported for other fresh or short-time-ripened cheeses, although micrococcaceae occurred in lower numbers (< 10(5)/g) than reported for other raw-milk cheeses. out of a total of 126 lab representat ... | 1996 | 8930715 |
| inducible gene expression and environmentally regulated genes in lactic acid bacteria. | relatively recently, a number of genes and operons have been identified in lactic acid bacteria that are inducible and respond to environmental factors. some of these genes/operons had been isolated and analysed because of their importance in the fermentation industry and, consequently, their transcription was studied and found to be regulatable. examples are the lactose operon, the operon for nisin production, and genes in the proteolytic pathway of lactococcus lactis, as well as xylose metabol ... | 1996 | 8879404 |
| lytic systems in lactic acid bacteria and their bacteriophages. | lytic systems of lactic acid bacteria and their bacteriophages are reviewed with an emphasis on molecular characterization. details of enzyme biochemistry and the cloning and analysis of lytic genes are presented, with coverage of lactococcal prolate headed bacteriophages, lactococcal isometric bacteriophages, lactobacillus bacteriophages and lactococcal autolysins. some comments on the importance of autolysis in cheese ripening are included and the biotechnological exploitation of cloned and ch ... | 1996 | 8879405 |
| genomic organization of lactic acid bacteria. | current knowledge of the genomes of the lactic acid bacteria, lactococcus lactis and streptococcus thermophilus, and members of the genera lactobacillus, leuconostoc, pediococcus and carnobacterium, is reviewed. the genomes contain a chromosome within the size range of 1.8 to 3.4 mbp. plasmids are common in lactococcus lactis (most strains carry 4-7 different plasmids), some of the lactobacilli and pediococci, but they are not frequently present in s. thermophilus, lactobacillus delbrueckii subs ... | 1996 | 8879406 |
| presence of non-functional nisin genes in lactococcus lactis subsp. lactis isolated from natural starters. | sixty-four lactococcal strains isolated from natural whey starters were screened for the presence of the nisin structural gene by polymerase chain reaction. seven of them showed a specific pcr product of 320 bp; only two produced antagonistic activity and were resistant to nisin. southern blots of smai-digested dna from pcr-positive strains hybridized with a nisa probe displayed a location of the gene on different smai fragments. among pcr-positive strains, nisin producers showed specific transc ... | 1996 | 8931323 |
| tween 80 effect on bacteriocin synthesis by lactococcus lactis subsp. cremoris j46. | sorbitan polyoxyethylene monooleate (tween 80) suppressed bacteriocin cell adhesion. within the range 0-1% (v/v), there was an increase in bacteriocin production in regulated (ph 5.5 or 6.0) batch cultures with increasing tween 80 concentration. for example, at ph 5.5 and in the presence of 1% tween 80, bacteriocin production was about fourfold higher than in its absence. however, further increase in tween 80 concentration did not result in a significant modification of the bacteriocin titre. it ... | 1996 | 8934792 |
| lactococcus lactis and stress. | it is now generally recognized that cell growth conditions in nature are often suboptimal compared to controlled conditions provided in the laboratory. natural stresses like starvation and acidity are generated by cell growth itself. other stresses like temperature or osmotic shock, or oxygen, are imposed by the environment. it is now clear that defense mechanisms to withstand different stresses must be present in all organisms. the exploration of stress responses in lactic acid bacteria has jus ... | 1996 | 8879409 |
| a general system for generating unlabelled gene replacements in bacterial chromosomes. | a general system is described that facilitates gene replacements such that the recombinant strains are not labelled with antibiotic resistance genes. the method is based on the conditional replication of derivatives of the lactococcal plasmid pwv01, which lacks the repa gene encoding the replication initiation protein. replacement vectors can be constructed in and isolated from gram-positive and gram-negative helper strains that provide repa in trans. cointegrate formation of the integration vec ... | 1996 | 9003306 |
| a new, broad-substrate-specificity aminopeptidase from the dairy organism lactobacillus helveticus sbt 2171. | an aminopeptidase with a very broad substrate specificity was purified to homogeneity from lactobacillus helveticus sbt 2171 by fplc. the enzyme was purified 144-fold from a cell-free extract with a yield of 16%. the purified enzyme appeared as a single band on an sds-page gel. it had a molecular mass of 95 kda and an isoelectric point of 4.9. the enzyme hydrolysed a large range of naphthylamide- and nitroanilide-substituted amino acids, as well as several di-, tri- and oligopeptides. it also ex ... | 1996 | 8936307 |
| identification and characterization of a mobilizing plasmid, pnd300, in lactococcus lactis m189 and its encoded nisin resistance determinant. | a 60 kb conjugative plasmid, pnd300, which encodes nisin resistance, was identified in lactococcus lactis ssp. lactis (l. lactis) m189. pnd300 was found to mobilize the transfer of some other plasmids as indicated by the mobilization of plasmids encoding lactose utilization. the nisin resistance determinant from pnd300 was initially subcloned on a 12 kb dna fragment and subsequently reduced to 10.4 kb. restriction analysis, pcr, southern hybridization and sequencing illustrated that the nisin re ... | 1996 | 8939027 |
| exploitation of a chromosomally integrated lactose operon for controlled gene expression in lactococcus lactis. | lactococcus lactis mg5267 is a plasmid-free strain in which the lactose operon is integrated in the bacterial chromosome. the chromosomal lacg gene which encodes phospho-beta-galactosidase was inactivated by a double cross-over integration event. unexpectedly, the resultant mutant was shown to retain a lac-positive phenotype. the lysin gene from listeria monocytogenes bacteriophage lm-4 was subsequently integrated into the chromosome of this strain such that expression of the heterologous gene w ... | 1996 | 8919450 |
| genetic organization of the mle locus and identification of a mler-like gene from leuconostoc oenos. | characterization of the mle locus harboring the malolactic enzyme gene mlea and malate permease gene mlep from leuconostoc oenos was completed in this study by mrna analysis. northern (rna) blot experiments revealed a 2.6-kb transcript, suggesting an operon structure harboring mlea and mlep genes. primer extension analysis showed that the mle operon has a single transcription start site located 17 nucleotides upstream of the atg translation start site for the mlea gene. we found sequences, ttgac ... | 1996 | 8953720 |
| molecular analysis of the replication origin of the lactococcus lactis plasmid pcj305. | the replication origin region, ori, of the lactococcus lactis subsp. lactis plasmid pci305 contains three-and-one-half directly repeated 22-bp sequences and two inverted repeat sequences, ir1 and ir2. these inverted repeat sequences overlap the promoter of the repb gene, which encodes a protein (repb) essential for plasmid replication. gel retardation assays, using lactococcal crude cell extracts in which repb was overproduced, were used to demonstrate that the replication protein interacts with ... | 1996 | 8954884 |
| sequencing, expression, and genetic characterization of the helicobacter pylori ftsh gene encoding a protein homologous to members of a novel putative atpase family. | in this study, we isolated and sequenced a helicobacter pylori gene, designated ftsh, coding for a 632-amino-acid protein which displayed striking similarity throughout its full length to ftsh proteins identified in escherichia coli, lactococcus lactis, and bacillus subtilis. h. pylori ftsh also possessed approximately 200-amino-acid region containing a putative atpase module which is conserved among members of the aaa protein family (aaa, atpase associated with diverse cellular activities). the ... | 1996 | 8892813 |
| food-grade cloning and expression system for lactococcus lactis. | a versatile set of cloning and expression vectors has been developed for application in self-cloning and other genetic modifications of lactococcus lactis. the expression vectors were equipped with the controlled and strong laca promoter of the lactococcal lactose operon. in addition, the transcriptional terminator of the aminopeptidase n gene, pepn, was inserted, which in some cases increased the genetic stabilities of the vectors and the cloned dna. the small, 0.3-kb lacf gene encoding the sol ... | 1996 | 8975595 |
| proinflammatory effect of pediococcus pentosaceus, a bacterium used as hay preservative. | bacterial cultures, such as pediococcus pentosaceus, are used to treat hay with the objective of preventing hay heating and moulding, and thus, the development of the microbial growth which causes farmer's lung. the aim of this study was to investigate whether such bacterial cultures have the potential to induce a pulmonary inflammatory response. mice were instilled 3 days week-1 for 3 weeks with either saline or nonviable preparations of p. pentosaceus, saccharopolyspora rectivirgula, lactococc ... | 1996 | 8980961 |
| expression of the pip/gcdfp-15 gene and survival in breast cancer. | expression of the pip/gcdfp-15 gene was determined by measuring pip/gcdfp-15-mrna in breast carcinomas of 91 patients. the patients were followed-up for an average of 47 months after initial diagnosis and treatment of the disease. there were no deaths in the group of 14 patients with tumours of high pip/gcdfp-15-mrna levels, while 16 of 77 patients of the group with low pip/gcdfp-15-mrna tumour levels died. a similar advantage for high pip/gcdfp-mrna expression was observed with regard to diseas ... | 1996 | 8982381 |
| the effect of cations on the hydrolysis of lactose and the transferase reactions catalysed by beta-galactosidase from six strains of lactic acid bacteria. | beta-galactosidases from lactobacillus delbruekii subsp. bulgaricus 20056, lb. casei 20094, lactococcus lactis subsp. lactis 7962, streptococcus thermophilus ts2, pediococcus pentosaceus pe39 and bifidobacterium bifidum 1901 were partially purified. the rate of hydrolysis of lactose given by the predominant beta-galactosidase activity from each of the bacteria studied was in all cases enhanced by mg2+, while the effect of k+ and na+ differed from strain to strain. the beta-galactosidases from al ... | 1996 | 8987531 |
| regulation of carbohydrate transport in lactococcus and lactobacillus. | 1996 | 9084765 | |
| genetics of subtilin and nisin biosyntheses: biosynthesis of lantibiotics. | several peptide antibiotics have been described as potent inhibitors of bacterial growth. with respect to their biosynthesis, they can be divided into two classes: (i) those that are synthesized by a non-ribosomal mechanism, and (ii) those that are ribosomally synthesized. subtilin and nisin belong to the ribosomally synthesized peptide antibiotics. they contain the rare amino acids dehydroalanine, dehydrobutyrine, meso-lanthionine, and 3-methyllanthionine. they are derived from prepeptides whic ... | 1996 | 8775971 |
| splicing of a group ii intron in a functional transfer gene of lactococcus lactis. | a chromosomally located sex factor that controls conjugation in lactococcus lactis 712 has been cloned and sequenced, leading to the discovery of an open reading frame with homology to the maturases of group ii self-splicing introns. reverse transcriptase polymerase chain reaction amplification was used to demonstrate that the intron was spliced out of mrna in vivo, and sequence analysis revealed the site of splicing. the intron was inserted within a sex-factor gene which encodes a protein with ... | 1996 | 8843433 |
| imbalance of leucine flux in lactococcus lactis and its use for the isolation of diacetyl-overproducing strains. | diacetyl is a by-product of pyruvate metabolism in lactococcus lactis, where pyruvate is first converted to alpha-acetolactate, which is slowly decarboxylated to diacetyl in the presence of oxygen. l. lactis usually converts alpha-acetolactate to acetoin enzymatically, by alpha-acetolactate decarboxylase encoded by the aldb gene. we took advantage of the fact that this enzyme also has a central role in the regulation of branched-chain amino acids, to select spontaneous aldb mutants in an unbalan ... | 1996 | 8779600 |
| genetic manipulation of the pathway for diacetyl metabolism in lactococcus lactis. | diacetyl is an important food flavor compound produced by certain strains of citrate-metabolizing lactic acid bacteria. citrate is converted to pyruvate, from which diacetyl is produced via intermediate alpha-acetolactate. this paper reports the cloning and analysis of the gene (aldb) encoding alpha-acetolactate decarboxylase from lactococcus lactis mg1363. deletion of the mg1363 chromosomal aldb gene was achieved by double crossover homologous recombination. the mutant strain was found to produ ... | 1996 | 8779601 |
| the proteolytic system of lactobacillus sanfrancisco cb1: purification and characterization of a proteinase, a dipeptidase, and an aminopeptidase. | a cell envelope 57-kda proteinase, a cytoplasmic 65-kda dipeptidase, and a 75-kda aminopeptidase were purified from lactobacillus sanfrancisco cb1 sourdough lactic acid bacterium by sequential fast protein liquid chromatography steps. all of the enzymes are monomers. the proteinase was most active at ph 7.0 and 40 degrees c, while aminopeptidase and dipeptidase had optima at ph 7.5 and 30 to 35 degrees c. relatively high activities were observed at the ph and temperature of the sourdough ferment ... | 1996 | 8795211 |
| multiple-peptidase mutants of lactococcus lactis are severely impaired in their ability to grow in milk. | to examine the contribution of peptidases to the growth of lactococcus lactis in milk, 16 single- and multiple-deletion mutants were constructed. in successive rounds of chromosomal gene replacement mutagenesis, up to all five of the following peptidase genes were inactivated (fivefold mutant): pepx, pepo, pept, pepc, and pepn. multiple mutations led to slower growth rates in milk, the general trend being that growth rates decreased when more peptidases were inactivated. the fivefold mutant grew ... | 1996 | 8631666 |
| cloning and analysis of the restriction-modification system llabi, a bacteriophage resistance system from lactococcus lactis subsp. cremoris w56. | the genes coding for the type ii restriction-modification (r/m) system llabi, which recognized the sequence 5'-c decreases tryag-3', have been cloned from a plasmid in lactococcus lactis subsp. cremoris w56 and sequenced. the dna sequence predicts an endonuclease of 299 amino acids (33 kda) and a methylase of 580 amino acids (65 kda). a 4.0-kb hindiii fragment in psa3 was able to restrict bacteriophages, showing that the cloned r/m system can function as a phage defense mechanism in l. lactis. | 1996 | 8795244 |
| modelling and engineering of enzyme/substrate interactions in subtilisin-like enzymes of unknown 3-dimensional structure. | homology modelling was used to predict enzyme-substrate interactions in three entirely different subtilisin-like enzymes of unknown three-dimensional structure. i.e. (a) cell-envelope proteinase of lactococcus lactis, (b) putative leader peptidase for pre-nisin from l. lactis, and (c) human furin. models were based on known three-dimensional structures of subtilisins and thermitase in complex with inhibitors. detailed analysis of interactions of the p1-p4 residues of model substrates with the s1 ... | 1996 | 8796311 |
| energetics and mechanism of drug transport mediated by the lactococcal multidrug transporter lmrp. | the gene encoding the secondary multidrug transporter lmrp of lactococcus lactis was heterologously expressed in escherichia coli. the energetics and mechanism of drug extrusion mediated by lmrp were studied in membrane vesicles of e. coli. lmrp-mediated extrusion of tetraphenyl phosphonium (tpp+) from right-side-out membrane vesicles and uptake of the fluorescent membrane probe 1-[4-(trimethylamino)phenyl]-6-phenylhexa-1,3,5-triene (tma-dph) into inside-out membrane vesicles are driven by the m ... | 1996 | 8798651 |
| heterologous expression and characterization of recombinant lactococcus lactis neutral endopeptidase (neprilysin). | a neutral endopeptidase (nep) from lactococcus lactis has recently been cloned and shown to contain high sequence homology with the human neutral endopeptidase, endopeptidase 24.11 (i. mierau et al., j. bacteriol. 175, 2087-2096, 1993). the gene for the neutral endopeptidase from l. lactis was cloned into the pqe expression vector, resulting in the fusion of a hexahistidine at the n-terminus. the recombinant enzyme was expressed to high levels in escherichia coli (approximately 10 mg/liter of cu ... | 1996 | 8806762 |
| multidrug resistance mediated by a bacterial homolog of the human multidrug transporter mdr1. | resistance of lactococcus lactis to cytotoxic compounds shares features with the multidrug resistance phenotype of mammalian tumor cells. here, we report the gene cloning and functional characterization in escherichia coli of lmra, a lactococcal structural and functional homolog of the human multidrug resistance p-glycoprotein mdr1. lmra is a 590-aa polypeptide that has a putative topology of six alpha-helical transmembrane segments in the n-terminal hydrophobic domain, followed by a hydrophilic ... | 1996 | 8855237 |
| loss of plasmid-mediated oligopeptide transport system in lactococci: another reason for slow milk coagulation. | fast milk-coagulating (fmc+) strains of lactococci are known to segregate slow milk-coagulating (fmc-) variants, which has been attributed to loss of proteinase (prt) activity encoded by plasmid dna. it was found that the fmc- phenotype could also be due to loss of a plasmid encoding an oligopeptide permease (opp) system. in lactococcus lactis subsp. lactis (l. lactis) c2o, lactose metabolism (lac) and prt were linked to pjk550 and the opp system to pjk430. in lactococcus lactis subsp. cremoris ... | 1996 | 8812781 |
| cloning and expression of the zymomonas mobilis "production of ethanol" genes in lactobacillus casei. | this study describes the expression of the zymomonas mobilis genes coding for pyruvate decarboxylase (pdc) and alcohol dehydrogenase (adh) in lactobacillus casei 686. to promote transcription, the promoter and ribosome binding site (rbs) from the lactococcus lactis subsp. lactis-derived vector, pmge36e, were inserted upstream of the pdc gene. the former sequences were positioned such that translation of pdc was coupled to translation of an 81-base pair open reading frame terminating within the p ... | 1996 | 8824172 |
| application of direct-fed microbial bacteria and fructooligosaccharides for salmonella control in broilers during feed withdrawal. | providing direct-fed-microbial (dfm) bacteria and fructooligosaccharides (fos) for the control of potential escalation of salmonella colonization during simulated feed withdrawal and confinement was assessed. eight hundred and eighty broilers (16 pens; 55 chicks per pen) were reared to 6 wk of age. chicks were sprayed with a solution containing 10(6) nalidixic-acid resistant salmonella typhimuriumnr cells per milliliter on the 2nd d after hatching. because this first challenge did not yield a hi ... | 1996 | 8833368 |
| controlled gene expression systems for lactococcus lactis with the food-grade inducer nisin. | the kinetics, control, and efficiency of nisin-induced expression directed by the nisa promoter region were studied in lactococcus lactis with transcriptional and translational fusions to the gusa reporter genes. in the nisin-producing l. lactis strain nz9700, the specific beta-glucuronidase activity increased very rapidly after mid-exponential growth until the maximum level at the start of the stationary phase was reached. expression of the gusa gene was also studied in l. lactis nz9800, an nz9 ... | 1996 | 8837421 |
| an origin of dna replication from lactococcus lactis bacteriophage c2. | an origin of dna relication was identified in the intergenic region between the early and late gene regions of prolate lactococcal phage c2. a dna fragment containing this origin, designated ori, was shown to direct dna replication in lactococcus lactis but not in escherichia coli. a comparison of ori with the corresponding regions of other prolate phages revealed strict conservation of the nucleotide sequence in one half of this intergenic region. this conserved region alone would not support d ... | 1996 | 8919811 |
| multidrug resistance in lactococcus lactis: evidence for atp-dependent drug extrusion from the inner leaflet of the cytoplasmic membrane. | lactococcus lactis possesses an atp-dependent drug extrusion system which shares functional properties with the mammalian multidrug resistance (mdr) transporter p-glycoprotein. one of the intriguing aspects of both transporters is their ability to interact with a broad range of structurally unrelated amphiphilic compounds. it has been suggested that p-glycoprotein removes drugs directly from the membrane. evidence is presented that this model is correct for the lactococcal multidrug transporter ... | 1996 | 8861952 |
| dna sequence analysis, expression, distribution, and physiological role of the xaa-prolyldipeptidyl aminopeptidase gene from lactobacillus helveticus cnrz32. | lactobacillus helveticus cnrz32 possesses an xaa-prolyldipeptidyl aminopeptidase (pepx), which releases amino-terminal dipeptides from peptides containing proline residues in the penultimate position. the pepx gene, designated pepx, from lb. helveticus cnrz32 was sequenced. analysis of the sequence identified a putative 2379-bp pepx open-reading frame, which encodes a polypeptide of 793 amino acid residues with a deduced molecular mass of 88,111 da. the gene shows significant sequence identity w ... | 1996 | 8867635 |
| evidence for a role of nist in transport of the lantibiotic nisin produced by lactococcus lactis n8. | the biosynthesis, immunity and regulation of nisin, a lanthionine-containing antimicrobial peptide produced by lactococcus lactis, is encoded by two gene clusters, nisa/zbtciprk and nisfeg. the mutant strain lac46 with a deletion in the translocator gene nist could not secrete nisin but nisin activity was detected from cell lysates. the nist mutation was complemented by a nist-expression plasmid resulting in restored capacity to secrete nisin. these results demonstrate that nist is the transport ... | 1996 | 8870256 |
| [probable nature of rickettsia prowazekii virulence]. | a 29.5 kda outer membrane protein (ompb) of r. prowazekii virulent breinl strain is known to differ from its counterpart in attenuated madrid e strain, while ompb of this latter one and of its virulent variant evir coincide in mobility. the infectivity of these strains for macrophages was previously shown to be different as well, and to correlate with their virulence. previously cloned r. prowazekii breinl strain, 1.644-bp insert from lambda gtll recombinant expressing as ompb in inducer-indepen ... | 1996 | 8927063 |
| cloning and characterization of the genes encoding the malolactic enzyme and the malate permease of leuconostoc oenos. | using degenerated primers from conserved regions of the protein sequences of malic enzymes, we amplified a 324-bp dna fragment by pcr from leuconostoc oenos and used this fragment as a probe for screening a leuconostoc oenos genomic bank. of the 2,990 clones in the genomic bank examined, 7 with overlapping fragments were isolated by performing colony hybridization experiments. sequencing 3,453 bp from overlapping fragments revealed two open reading frames that were 1,623 and 942 nucleotides long ... | 1996 | 8919788 |
| identification and sequence analysis of is1297, an iss1-like insertion sequence in a leuconostoc strain. | the insertion sequence (is) iss1 from lactococcus lactis was amplified from lactococcal genomic dna using a primer to the 18-bp inverted repeat sequence. the amplified product hybridized to a single ecori fragment in a total genomic dna digest of leuconostoc mesenteroides ssp. dextranicum nzdri 2218. the dna sequence of this iss1-like element (is1297) and the le. mesenteroides sequences flanking the is were determined and compared with other iso-iss1 elements. no direct repeats were found immedi ... | 1996 | 8890744 |
| gene organization and transcription of a late-expressed region of a lactococcus lactis phage. | the lactococcal phage bil41 belongs to the small isometric-headed phages of the 936 quasi-species and is resistant to the abortive infection determined by abib. a 10.2-kb segment from this phage, in which late transcription is initiated, has been sequenced. thirteen open reading frames (orfs) organized in one transcriptional unit have been identified. the location of two of them and the structural features of the proteins they code for are evocative of terminase subunits. five other orfs specify ... | 1996 | 8892814 |
| malolactic fermentation by engineered saccharomyces cerevisiae as compared with engineered schizosaccharomyces pombe. | the ability of yeast strains to perform both alcoholic and malolactic fermentation in winemaking was studied with a view to achieving a better control of malolactic fermentation in enology. the malolactic gene of lactococcus lactis (mles) was expressed in saccharomyces cerevisiae and schizosaccharomyces pombe. the heterologous protein is expressed at a high level in cell extracts of a s. cerevisiae strain expressing the gene mles under the control of the alcohol dehydrogenase (adh1) promoter on ... | 1996 | 8904333 |
| the b form of dihydroorotate dehydrogenase from lactococcus lactis consists of two different subunits, encoded by the pyrdb and pyrk genes, and contains fmn, fad, and [fes] redox centers. | the b form of dihydroorotate dehydrogenase from lactococcus lactis (dhodehase b) is encoded by the pyrdb gene. however, recent genetic evidence has revealed that a co-transcribed gene, pyrk, is needed to achieve the proper physiological function of the enzyme. we have purified dhodehase b from two strains of escherichia coli, which harbored either the pyrdb gene or both the pyrdb and the pyrk genes of l. lactis on multicopy plasmids. the enzyme encoded by pyrdb alone (herein called the delta-enz ... | 1996 | 8910599 |
| fate of peptides in peptidase mutants of lactococcus lactis. | the utilization of exogenous peptides was studied in mutants of lactococcus lactis in which combinations of the peptidase genes pepn, pepc, pepo, pepx and pept were deleted. multiple mutants lacking pepn, pepc, pept plus pepx could not grow on peptides such as leu-gly-gly, gly-phe-leu, leu-gly-pro, ala-pro-leu and gly-leu-gly-leu, respectively, indicating that no other peptidases are present to release the essential amino acid leu. in these mutants, peptides accumulate intracellularly, demonstra ... | 1996 | 8843439 |
| molecular analysis of the rpod gene of enterococcus faecalis. | the complete nucleotide sequence of the rpod gene of enterococcus faecalis atcc19433 has been determined. this gene encodes a putative 368 amino acids (aa) polypeptide of a predicted mr of 41842 named sigma 42. upstream of the rpod gene and beginning from the end of the cloned chromosomal fragment is an open reading frame encoding a putative 264-aa polypeptide. it is reminiscent of the c-terminal domain of known dna primase from gram-positive bacteria indicating that the e. faecalis rpod gene is ... | 1996 | 8914262 |
| cloning, sequence analysis, and expression of the genes encoding lytic functions of bacteriophage phi g1e. | the lysis genes of a lactobacillus phage phi g1e were cloned, sequenced, and expressed in escherichia coli. nucleotide sequencing of a 3813-bp phi g1e dna revealed five successive open reading frames (orf), rorf50, rorf118, hol, and lys and rorf175, in the same dna strand. by comparative analysis of the dna sequence, the putative hol product (holin) has an estimated molecular weight is 14.2 kda, and contains two potential transmembrane helices and highly charged n- and c-termini, resembling pred ... | 1996 | 8918256 |
| characterization of an insertion sequence-like element identified in plasmid pcit264 from lactococcus lactis subsp. lactis biovar diacetylactis. | plasmid pcit264 from lactococcus lactis subsp. lactis biovar diacetylactis (l. diacetylactis) contains an insertion sequence (is)-like element located in the citrate utilization (citqrp) cluster. this 967-nucleotide long element is bounded by 17 bp perfect inverted repeats and contains an open reading frame (orf1) composed of 296 codons, which could encode a transposase. expression of the is from pcit264 generates two mrnas of 2900 and 1900 nucleotides. the transcription is driven by the p3 prom ... | 1996 | 8867382 |
| cloning, dna sequence, and regulation of expression of a gene encoding beta-galactosidase from lactococcus lactis. | the beta-galactosidase from escherichia coli is one of the most important enzymes in molecular biology. here we report the cloning and sequencing of a gene encoding beta-galactosidase from lactococcus lactis and compare the predicted amino acid sequence to that from other organisms. the beta-galactosidase from l. lactis was found to be a protein of 996 residues with 68.7% similarity to the e. coli enzyme and 65.8% similarity to the enzyme from klebsiella pneumoniae. the lactococcal beta-galactos ... | 1996 | 8988372 |
| physiology of pyruvate metabolism in lactococcus lactis. | lactococcus lactis, a homofermentative lactic acid bacterium, has been studied extensively over several decades to obtain sometimes conflicting concepts relating to the growth behaviour. in this review some of the data will be examined with respect to pyruvate metabolism. it will be demonstrated that the metabolic transformation of pyruvate can be predicted if the growth-limiting constraints are adequately established. in general lactate remains the major product under conditions in which sugar ... | 1996 | 8879410 |
| lactic acid bacteria as vaccine delivery vehicles. | 1996 | 8879413 | |
| the application of ph-sensitive fluorescent dyes in lactic acid bacteria reveals distinct extrusion systems for unmodified and conjugated dyes. | intracellular ph in bacteria can be measured efficiently between internal ph values of 6.5 and 8.5 with the fluorescent ph indicator 2',7'-bis-(2-carboxyethyl)-5[and-6]-carboxyfluorescein (bcecf). a new fluorescent ph probe with a lower pka(app) than bcecf was synthesized from fluorescein isothiocyanate and glutamate. the new probe, n-(fluorescein thio-ureanyl)-glutamate (ftug), was much less sensitive to changes in concentrations of kcl than was bcecf. similar to bcecf, an efflux of ftug indepe ... | 1996 | 8905646 |
| lantibiotic nisin z fermentative production by lactococcus lactis io-1: relationship between production of the lantibiotic and lactate and cell growth. | the influence of several parameters on the fermentative production of nisin z by lactococcus lactis io-1 was studied. considerable attention has been focused on the relationship between the primary metabolite production of bacteriocin and lactate and cell growth, which has so far not been clarified in detail. production of nisin z was optimal at 30 degrees c and in the ph range 5.0-5.5. the addition of ca2+ to the medium showed a stimulating effect on the production of nisin z. a maximum activit ... | 1996 | 8920177 |
| chemical composition of the cell wall of lactic acid bacteria and related species. | in order to examine the relationship between biological activities and the cell wall content, the murein type and the teichoic acid of the cell wall from five strains of bacteria were studied. two of these lactobacillus casei crl 431 and l. acidophilus crl 730, are used in a commercial fermented milk (bio milk), which is believed to be beneficial for health. the other strains, lactococcus lactis crl 526, pediococcus pentosaceus crl 923 and propionibacterium acidipropionici crl 1198 were included ... | 1996 | 8996856 |
| characterization of a mosaic iss1 element and evidence for the recent horizontal transfer of two different types of iss1 between streptococcus thermophilus and lactococcus lactis. | a 12-kb region of the streptococcus thermophilus cnrz368 chromosome was found to contain two copies of is981 (one complete and one truncated) and three copies of iss1 (two complete, iss1sa and iss1sc, and one truncated, delta iss1sb). comparison of the nucleotide sequences of these iss1 elements with those of previously identified iso-iss1 elements from lactococcus lactis and the enterococcus genus indicated that the iss1 group is divided into three distinct subgroups which we have named alpha, ... | 1996 | 8921885 |
| lactococcin g is a potassium ion-conducting, two-component bacteriocin. | lactococcin g is a novel lactococcal bacteriocin whose activity depends on the complementary action of two peptides, termed alpha and beta. peptide synthesis of the alpha and beta peptides yielded biologically active lactococcin g, which was used in mode-of-action studies on sensitive cells of lactococcus lactis. approximately equivalent amounts of both peptides were required for optimal bactericidal effect. no effect was observed with either the alpha or beta peptide in the absence of the compl ... | 1996 | 8550488 |
| sequence of a lactococcus lactis dna fragment homologous to the recf gene of bacillus subtilis. | the recf gene of lactococcus lactis atcc 7962 is located 3 kb downstream from the lacz gene and is transcribed in the opposite orientation. the recf gene is immediately preceded by a 121-codon orf, and both recf and orf121 may be transcribed from the same promoter. the deduced recf amino-acid sequence shows high homology to that of the bacillus subtilis and streptococcus pyogenes recf proteins. | 1996 | 8621080 |
| transposons tn916 and tn925 can transfer from enterococcus faecalis to leuconostoc oenos. | the streptococcal transposons tn916 and tn925 were transferred to several strains of leuconostoc (ln.) oenos using the filter mating method. the insertion of both transposons into the chromosome occurred at different sites. transconjugants of ln. oenos carrying tn916 could serve as donors in mating experiments with lactococcus lactis lm2301. further analysis of l. lactis lm2301 transconjugants showed that the insertion of the transposon tn916 into the chromosome was site-specific. these studies ... | 1996 | 8595855 |
| efficient insertional mutagenesis in lactococci and other gram-positive bacteria. | in lactococci, the study of chromosomal genes and their regulation is limited by the lack of an efficient transposon mutagenesis system. we associated the insertion sequence iss1 with the thermosensitive replicon pg+ host to generate a mutagenic tool that can be used even in poorly transformable strains. iss1 transposition is random in different lactococcal strains as well as in enterococcus faecalis and streptococcus thermophilus. high-frequency random insertion (of about 1%) obtained with this ... | 1996 | 8550537 |
| detection of cleavage of a prenisin-mimicking decapeptide by lactococcus lactis subsp. lactis endoproteinase activity. | as part of ongoing studies in the biosynthesis of the lantibiotic nisin, we investigated the proteolytic cleavage of a synthetic fmoc-labeled decapeptide mimicking a key amino acid sequence of the precursor prenisin in extracts of a lactococcus lactis subsp. lactis strain. reverse-phase high-performance liquid chromatography with photodiode array detection was used to trace and purify potential enzymatic conversion products. of the three newly appearing chromatographic peaks, one was identified ... | 1996 | 8824872 |
| inducer expulsion and the occurrence of an hpr(ser-p)-activated sugar-phosphate phosphatase in enterococcus faecalis and streptococcus pyogenes. | inducer expulsion, a phenomenon in which rapidly metabolizable sugars cause cytoplasmic dephosphorylation and efflux of pre-accumulated sugar-phosphates (sugar-p), has been documented for streptococcus pyogenes, streptococcus bovis, and lactococcus lactis, but not for other gram-positive bacteria. using intact cells and membrane vesicles, we show that enterococcus faecalis exhibits both inducer exclusion and inducer expulsion, and that the latter phenomenon is dependent on the metabolite-activat ... | 1996 | 8868433 |
| a resolvase-like protein is required for the site-specific integration of the temperate lactococcal bacteriophage tp901-1. | the integration system of the temperate lactococcal phage tp901-1 was characterized in lactococcus lactis subsp. cremoris lm0230 and mg1363 with the use of deletion derivatives of the integration vector pbc143 (b. christiansen, m. g. johnsen, e. stenby, f. k. vogensen, and k. hammer, j. bacteriol. 176:1069-1076, 1994). the phage-encoded elements necessary for integration were localized on a 2.8-kb nsii-ecori fragment including the phage attachment site, attp. this fragment was dna sequenced, and ... | 1996 | 8752334 |
| analysis of heat shock gene expression in lactococcus lactis mg1363. | the induction of the heat shock response in lactococcus lactis subsp. cremoris strain mg1363 was analysed at the rna level using a novel rna isolation procedure to prevent degradation. cloning of the dnaj and groel homologues was carried out. northern blot analysis showed a similar induction pattern for dnak, dnaj and groels after transfer from 30 degrees c to 43 degrees c when mg1363 was grown in defined medium. the dnak gene showed a 100-fold induction level 15 min after temperature shifting. ... | 1996 | 8757733 |
| molecular analysis of the regulation of nisin immunity. | the genetic determinants controlling immunity to nisin are coordinately regulated, along with biosynthesis genes, in response to an environmental signal, nisin or a nisin analogue. the nisr gene product, the putative response regulator of nisin biosynthesis, was found to be a vital component of this induction mechanism. this protein forms part of a two-component regulatory system which controls the expression of genes involved in nisin immunity and biosynthesis. analysis of the structural requir ... | 1996 | 8828206 |
| the structure of the lantibiotic lacticin 481 produced by lactococcus lactis: location of the thioether bridges. | the lantibiotic lacticin 481 is a bacteriocin produced by lactococcus lactis ssp. lactis. this polypeptide contains 27 amino acids, including the unusual residues dehydrobutyrine and the thioether-bridging lanthionine and 3-methyllanthionine. lacticin 481 belongs to a structurally distinct group of lantibiotics, which also include streptococcin a-ff22, salivaricin a and variacin. here we report the first complete structure of this type of lantibiotic. the exact location of the thioether bridges ... | 1996 | 8764998 |
| purification of tributyrin esterase from lactococcus lactis subsp. cremoris e8. | a tributyrin esterase was purified from lactococcus lactis subsp. cremoris e8 using fplc chromatography. this was the major esterase activity observed in strain e8 and was associated with a single protein with a subunit molecular mass of 29 kda and a holoenzyme of molecular mass 109 kda. the enzyme was active against tributyrin and p-nitrophenyl butyrate. the n-terminal sequence of the enzyme was determined. the enzyme had a ph optimum in the neutral range, was stable on freezing at -20 degrees ... | 1996 | 8655738 |
| characterization of pepb, a group b streptococcal oligopeptidase. | group b streptococci were recently reported to possess a cell-associated collagenase. although the enzyme hydrolyzed the synthetic collagen-like substrate n-(3-[2-furyl]acryloyl)-leu-gly-pro-ala, we found that neither the highly purified enzyme nor crude group b streptococcal cell lysate solubilized a film of reconstituted rat tail collagen, an activity regarded as obligatory for a true collagenase. we cloned and sequenced the gene for the enzyme (pepb). the deduced amino acid sequence showed 66 ... | 1996 | 8757883 |
| sequence analysis and identification of the pyrkdbf operon from lactococcus lactis including a novel gene, pyrk, involved in pyrimidine biosynthesis. | three genes encoding enzymes involved in the biosynthesis of pyrimidines have been found to constitute an operon in lactococcus lactis. two of the genes are the well-known pyr genes pyrdb and pyrf, encoding dihydroorotate dehydrogenase and orotidine monophosphate decarboxylase, respectively. the third gene encodes a protein which was shown to be necessary for the activity of the pyrdb-encoded dihydroorotate dehydrogenase; we propose to name the gene pyrk. the pyrk-encoded protein is homologous t ... | 1996 | 8759867 |
| the lactic acid stress response of lactococcus lactis subsp. lactis | the lactic acid tolerance response (latr) of the lactic acid bacterium lactococcus lactis subsp. lactis has been studied. a dramatic increase in survival to a severe acid stress (ph 3.9) was obtained by preexposing the cells for 30 min to a mildly acid shock at ph 5.5. whole-cell protein extract analysis revealed that during the acid tolerance response 33 polypeptides are induced over the level of naive cells. among these are the major heat shock proteins dnak and groel. in conjunction with a pr ... | 1996 | 8672097 |
| factors affecting the immunogenicity of tetanus toxin fragment c expressed in lactococcus lactis. | the relative immunogenicity of tetanus toxin fragment c (ttfc) has been determined in three different strains of inbred mice when expressed in lactococcus lactis as a membrane-anchored protein (strain ucp1054), as an intracellular protein (strain ucp1050), or as a secreted protein which is partly retained within the cell wall (strain ucp1052). protection against toxin challenge (20 x ld50) could be obtained without the induction of anti-lactococcal antibodies. when compared in terms of the dose ... | 1996 | 8809553 |
| cloning and sequencing of the novel abortive infection gene abih of lactococcus lactis ssp. lactis biovar. diacetylactis s94. | a gene which encodes resistance by abortive infection (abi+) to bacteriophage was cloned from lactococcus lactis ssp. lactis biovar. diacetylactis s94. this gene was found to confer a reduction in efficiency of plating and plaque size for prolate-headed bacteriophage phi 53 (group i of homology) and total resistance to the small isometric-headed bacteriophage phi 59 (group iii of homology). the cloned gene is predicted to encode a polypeptide of 346 amino acid residues with a deduced molecular m ... | 1996 | 8810513 |
| improved method for quantification of the bacteriocin nisin. | nisin, a bacteriocin produced by lactococcus lactis subsp. lactis, is used in some types of food preservation due to its inhibitory action on gram-positive bacteria and their spores. a commonly used agar diffusion bioassay technique for quantification of nisin in food samples was modified to increase its sensitivity, accuracy and precision. several variables were evaluated. results showed micrococcus luteus as the most sensitive organism tested, a lower agar concentration (0 x 75% compared 1 x 5 ... | 1996 | 8849648 |
| dramatic decay of phage transcripts in lactococcal cells carrying the abortive infection determinant abib. | the abortive infection determinant abib prevents growth of the sensitive phage bil170, but not of the resistant phage bil41, on lactococcus lactis strain il1403. here we show that abib promotes a dramatic degradation of sensitive phage transcripts, starting 10-15 min after infection. the decay of the transcripts is the probable cause of the arrest of the sensitive phage development. mapping of the 5' end of degradation products established that they result from endonucleolytic cleavage preferent ... | 1996 | 8825768 |
| detection and localization of peptidases in lactococcus lactis with monoclonal antibodies. | monoclonal antibodies against peptidases of lactococcus lactis were isolated and characterized: pepn1-4 against a lysyl aminopeptidase pepn, pept1-5 against a tripeptidase pept and pepd1-3 against a dipeptidase pepd. these monoclonal antibodies reacted specifically with their respective antigens in crude cell extracts of lc. lactis subspp. cremoris and lactis. a number of monoclonal antibodies cross reacted with proteins of other (lactic acid) bacteria. pept1, 2, 4 and 5 cross reacted weakly wit ... | 1996 | 8861346 |
| purification and characterization of dihydroorotate dehydrogenase a from lactococcus lactis, crystallization and preliminary x-ray diffraction studies of the enzyme. | lactococcus lactis is the only organism known to contain two dihydroorotate dehydrogenases, i.e., the a- and b-forms. in this paper, we report the overproduction, purification, and crystallization of dihydroorotate dehydrogenase a. in solution, the enzyme is bright yellow. it is a dimer of subunits (34 kda) that contain one molecule of flavin mononucleotide each. the enzyme shows optimal function in the ph range 7.5-9.0. it is specific for l-dihydroorotate as substrate and can use dichlorophenol ... | 1996 | 8732756 |
| splicing of a group ii intron involved in the conjugative transfer of prs01 in lactococci. | analysis of a region involved in the conjugative transfer of the lactococcal conjugative element prs01 has revealed a bacteria] group ii intron. splicing of this lactococcal intron (designated ll.ltrb) in vivo resulted in the ligation of two exon messages (ltrbe1 and ltrbe2) which encoded a putative conjugative relaxase essential for the transfer of prs01. like many group ii introns, the ll.ltrb intron possessed an open reading frame (ltra) with homology to reverse transcriptases. remarkably, se ... | 1996 | 8655550 |
| a genomic region of lactococcal temperate bacteriophage tp901-1 encoding major virion proteins. | two major structural proteins, mhp (major head protein) and mtp (major tail protein), from the lactococcal temperate phage tp901-1 were sequenced at their amino acid termini, and derived degenerate oligonucleotides were used to locate the corresponding genes in the phage genome. this genomic region was sequenced. the sequence characterized includes a total of 11 open reading frames (orfs) showing an operon structure. upstream of each orf, except orf b2 and orf x, potential ribosome-binding sites ... | 1996 | 8610457 |
| transcriptional activation of the citrate permease p gene of lactococcus lactis biovar diacetylactis by an insertion sequence-like element present in plasmid pcit264. | the lactococcal plasmid pcit264 contains a cluster of three genes (citq, citr and citp) involved in the transport of citrate in lactococcus lactis biovar diacetylactis. the cit cluster contains a copy of a newly discovered insertion sequence (is)-like element located between its promoter p1 and the first gene of the cluster. in this report, we show that this is-like element can act as a mobile switch for the downstream genes, creating two new transcriptional promoters named p2 and p2'. the p2 pr ... | 1996 | 8602160 |
| topology of lcnd, a protein implicated in the transport of bacteriocins from lactococcus lactis. | four in-frame translational fusions to both the reporter proteins beta-galactosidase and alkaline phosphatase support a topological model of lcnd, a protein implicated in the transport of several bacteriocins from lactococcus lactis, in which the n-terminal part is located intracellularly and one transmembrane helix spans the cytoplasmic membrane. | 1996 | 8626308 |
| sequence analysis and molecular characterization of the temperate lactococcal bacteriophage r1t. | the temperate lactococcal bacteriophage r1t was isolated from its lysogenic host and its genome was subjected to nucleotide sequence analysis. the linear r1t genome is composed of 33,350 bp and was shown to possess 3' staggered cohesive ends. fifty open reading frames (orfs) were identified which are, probably, organized in a life-cycle-specific manner. nucleotide sequence comparisons, n-terminal amino acid sequencing and functional analyses enabled the assignment of possible functions to a numb ... | 1996 | 8730875 |
| structure-activity relationships in the peptide antibiotic nisin: antibacterial activity of fragments of nisin. | the post-translationally modified peptide antibiotic nisin has been cleaved by a number of proteases and the fragments produced purified, characterised chemically, and assayed for activity in inhibiting the growth of lactococcus lactis mg1614 and micrococcus luteus ncdo8166. these results provide information on the importance of different parts of the nisin molecule for its growth-inhibition activity. removal of the c-terminal five residues leads to approximately a 10-fold decrease in potency, w ... | 1996 | 8706842 |
| positive selection, cloning vectors for gram-positive bacteria based on a restriction endonuclease cassette. | lactococcus lactis contains numerous restriction and modification (r/m) systems of different specificities. a novel iis type r/m system encoded by the llai operon has previously been characterized from the l. lactis conjugative plasmid ptr2030. the llai operon is composed of six genes: first, a small regulatory gene llaic precedes the methylase gene llaim. the following three genes, llai.1, llai.2, llai.3, are all essential for restriction endonuclease activity and are designed as the restrictio ... | 1996 | 8693025 |
| nucleotide sequence and analysis of pwc1, a pc194-type rolling circle replicon in lactococcus lactis. | a 2.8-kb cryptic plasmid showing no homology to either pfx3 (rolling circle, pe194-type) or pci305 (theta-type) lactococcal replicons was identified in lactococcus lactis subsp. cremoris 2204. the plasmid, pwc1, was compatible with both pci3340 (a pci305 derivative) and pfx3 in l. lactis subsp. cremoris 2204. sequence analysis of pwc1 showed one major orf encoding a protein with a deduced size of 316 amino acids (aa). database comparisons showed that the protein was distinct from the pfx- and pc ... | 1996 | 8700966 |
| purification and characterization of a malic enzyme from the ruminal bacterium streptococcus bovis atcc 15352 and cloning and sequencing of its gene. | malic enzyme (ec 1.1.1.39), which catalyzes l-malate oxidative decarboxylation and pyruvate reductive carboxylation, was purified to homogeneity from streptococcus bovis atcc 15352, and properties of this enzyme were determined. the 2.9-kb fragment containing the malic enzyme gene was cloned, and the sequence was determined and analyzed. the enzymatic properties of the s. bovis malic enzyme were almost identical to those of other malic enzymes previously reported. however, we found that the s. b ... | 1996 | 8702261 |
| structure-activity relationships in the peptide antibiotic nisin: role of dehydroalanine 5. | a mutant of the peptide antibiotic nisin in which the dehydroalanine residue at position 5 has been replaced by an alanine has been produced and structurally characterized. it is shown to have activity very similar to that of wild-type nisin in inhibiting growth of lactococcus lactis and micrococcus luteus but is very much less active than nisin as an inhibitor of the outgrowth of spores of bacillus subtilis. these observations, which parallel those of w. liu and j. n. hansen (appl. environ. mic ... | 1996 | 8702290 |
| an application in cheddar cheese manufacture for a strain of lactococcus lactis producing a novel broad-spectrum bacteriocin, lacticin 3147. | lactococcus lactis dpc3147, a strain isolated from an irish kefir grain, produces a bacteriocin with a broad spectrum of inhibition. the bacteriocin produced is heat stable, particularly at a low ph, and inhibits nisin-producing (nip+) lactococci. on the basis of the observation that the nisin structural gene (nisa) does not hybridize to dpc3147 genomic dna, the bacteriocin produced was considered novel and designated lacticin 3147. the genetic determinants which encode lacticin 3147 are contain ... | 1996 | 8593062 |
| regulation of sugar uptake via the phosphoenolpyruvate-dependent phosphotransferase systems in bacillus subtilis and lactococcus lactis is mediated by atp-dependent phosphorylation of seryl residue 46 in hpr. | by using both metabolizable and nonmetabolizable sugar substrates of the phosphoenolpyruvate-dependent phosphotransferase system (pts), we show that pts sugar uptake into intact cells and membrane vesicles of lactococcus lactis and bacillus subtilis is strongly inhibited by high concentrations of any of several metabolizable pts sugars. inhibition requires phosphorylation of seryl residue 46 in the phosphocarrier protein of the pts, hpr, by the metabolite-activated, atp-dependent protein kinase. ... | 1996 | 8655554 |
| cloning vectors for lactococci based on a plasmid encoding resistance to cadmium. | an 8.8-kb plasmid (pnd302) was identified in lactococcus lacti spp lactis m71 which encodes cadmium resistance (cdr). most of the commercial lactococcal strains tested were sensitive to cadmium. therefore, cdr should provide a useful selectable marker for constructing cloning vectors in lactococci. pnd302 was mapped with a number of restriction enzymes and found to contain a unique ecori site suitable for cloning. two e. coli/l lactis shuttle cloning vectors, pnd304 and pnd624, were constructed ... | 1996 | 8661686 |
| the ribonucleotide reductase system of lactococcus lactis. characterization of an nrdef enzyme and a new electron transport protein. | escherichia coli contains the genetic information for three separate ribonucleotide reductases. two of them (class i enzymes), coded by the nrdab and nrdef genes, respectively, contain a tyrosyl radical, whose generation requires oxygen. the nrdab enzyme is physiologically active. the function of the nrdef gene is not known. the third enzyme (class iii), coded by nrddg, operates during anaerobiosis. the dna of lactococcus lactis contains sequences homologous to the nrddg genes. surprisingly, an ... | 1996 | 8621514 |
| identical transcriptional control of the divergently transcribed prtp and prtm genes that are required for proteinase production in lactococcus lactis sk11. | we have investigated transcriptional regulation of the divergently transcribed genes required for proteinase production (prtp and prtm) of lactococcus lactis sk11. their promoters partially overlap and are arranged in a face-to-face configuration. the medium-dependent activities of both prtp and prtm promoters were analyzed by quantitative primer extension studies and beta-glucuronidase assays with l. lactis mg1363 cells harboring transcriptional gene fusions of each promoter with the promoterle ... | 1996 | 8626277 |
| nisin z, mutant nisin z and lacticin 481 interactions with anionic lipids correlate with antimicrobial activity. a monolayer study. | monomolecular layers of lipids at the air/water interface have been used as a model membrane to study membrane interactions of the lantibiotic nisin. the natural lantibiotics nisin a and nisin z proved to have a high affinity for the anionic lipids phosphatidylglycerol and bis(phosphatidyl)glycerol (cardiolipin). the interaction with zwitterionic phopholipids or neutral lipids is very low at surface pressures higher than 32 mn/m. nisin, nisin mutants and lacticin 481 show a remarkable correlatio ... | 1996 | 8631341 |
| beta-casomorphins: analysis in cheese and susceptibility to proteolytic enzymes from lactococcus lactis ssp. cremoris. | commercial cheese products were surveyed for beta-casomorphin peptides. two extraction methods were compared: 1) water and 2) chloroform and methanol. peptide profiles were determined using reverse-phase hplc and multiple wavelength detection. beta-casomorphin standards were used for comparison with cheese peptide profiles. results indicated that peptides were present in cheeses with hplc elution times that were similar to those for beta-casomorphins. however, comparison of absorbancies of the p ... | 1996 | 8675779 |