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characterization and distribution of two insertion sequences, is1191 and iso-is981, in streptococcus thermophilus: does intergeneric transfer of insertion sequences occur in lactic acid bacteria co-cultures?a chromosomal repeated sequence from streptococcus thermophilus was identified as a new insertion sequence (is), is1191. this is the first is element characterized in this species. this 1313 bp element has 28 bp imperfect terminal inverted repeats and is flanked by short direct repeats of 8 bp. the single large open reading frame of is1191 encodes a 391-amino-acid protein which displays homologies with transposases encodes by is1201 from lactobacillus helveticus (44.5% amino-acid sequence identi ...19957651138
[data on the cultural and morphologic features of dissociation forms of nisin-producing streptococcus].colonies and cells of s and g variants of streptococcus lactis, strain msu were studied comparatively. it was shown that in the g form the growth rate and other biosynthetic peculiarities and in particular the capacity for the nisin synthesis were lower. morphological properties of the colonies and cells of the s and g variants of the nisin-producing streptococcus were investigated.19957654096
behavior of listeria monocytogenes in mozzarella cheese in presence of lactococcus lactis.the behavior of listeria monocytogenes (scott a) on fully processed italian mozzarella cheese was examined in presence and in absence of bacteriocins produced by lactococcus lactis ssp. lactis strains (dip 15 and dip 16). these strains, isolated from raw milk, produced heat stable bacteriocins that were inactivated by pronase, alpha- chymotrypsin and proteinase k, but not by pepsin, trypsin and catalase. the addition of crude bacteriocins to the growing culture of listeria monocytogenes resulted ...19957654515
glucose metabolism and internal ph of lactococcus lactis subsp. lactis cells utilizing nmr spectroscopy.the metabolism of glucose was studied in lactococcus lactis subsp. cnrz 125 by 13c nmr. the initial rate of glucose utilization was higher for exponential phase cells than for stationary phase cells [150 vs 85 nmol g (dry wt)-1 s -1]. 31p nmr was used to determine changes in glycolytic phosphorylated intermediates (fructose-1,6-diphosphate, dihydroxyacetone phosphate and phosphoglycerate). the internal phs of l. lactis subsp. lactis cnrz 141 and cnrz 125 were also measured by 31p nmr as a functi ...19957662330
stress response in lactococcus lactis: cloning, expression analysis, and mutation of the lactococcal superoxide dismutase gene.in an analysis of the stress response of lactococcus lactis, three proteins that were induced under low ph culture conditions were detected. one of these was identified as the lactococcal superoxide dismutase (soda) by n-terminal amino acid sequence analysis. the gene encoding this protein, designated soda, was cloned by the complementation of a soda sodb escherichia coli strain. the deduced amino acid sequence of l. lactis soda showed the highest degree of similarity to the manganese-containing ...19957665513
streptococcus lactis septicemia in a patient with chronic lymphocytic leukemia. 19957668230
a milk-based method for detecting antimicrobial substances produced by lactic acid bacteria.a new technique for the detection of antimicrobial substances produced by lactic acid bacteria has been developed. in this technique, milk agar plates were supplemented with tetrazolium chloride or tetrazolium blue dyes. comparisons of milk agar assays with m17 agar plates indicated that, out of 30 bacterial strains, 13 strains produced bacteriocins or inhibitory substances that were detectable on milk agar plates but not on m17 agar plates. multiple-strain lactococcal cultures are used in milk ...19957673514
oligopeptidases from lactococcus lactis. 19957674946
molecular characterization of genes involved in the production of the bacteriocin leucocin a from leuconostoc gelidum.leucocin a is a small heat-stable bacteriocin produced by leuconostoc gelidum ual187. a 2.9-kb fragment of plasmid dna that contains the leucocin structural gene and a second open reading frame (orf) in an operon was previously cloned (j. w. hastings, m. sailer, k. johnson, k. l. roy, j. c. vederas, and m. e. stiles, j. bacteriol. 173:7491-7500, 1991). when a 1-kb drai-hpai fragment containing this operon was introduced into a bacteriocin-negative variant (ual187-13), immunity but no leucocin pr ...19957486992
improvement of solubility and stability of the antimicrobial peptide nisin by protein engineering.nisin is a 3.4-kda antimicrobial peptide that, as a result of posttranslational modifications, contains unsaturated amino acids and lanthionine residues. it is applied as a preservative in various food products. the solubility and stability of nisin and nisin mutants have been studied. it is demonstrated that nisin mutants can be produced with improved functional properties. the solubility of nisin a is highest at low ph values and gradually decreases by almost 2 orders of magnitude when the ph ...19957487019
bacteriolytic activity caused by the presence of a novel lactococcal plasmid encoding lactococcins a, b, and m.lactococcus lactis subsp. lactis biovar diacetylactis dpc938 was identified as a bacteriocin-producing strain which exhibited a bacteriolytic effect on other lactococci. lysis of such target strains was associated with decreases in optical density and release of the intracellular enzyme lactate dehydrogenase. dpc938 exhibits cross-immunity to l. lactis subsp. cremoris 9b4 (m.j. van belkum, b.j. hayema, a. geis, j. kok, and g. venema, appl. environ. microbiol. 55:1187-1191, 1989), a strain which ...19957487031
oligopeptides are the main source of nitrogen for lactococcus lactis during growth in milk.the consumption of amino acids and peptides was monitored during growth in milk of proteinase-positive (prt+) and -negative (prt-) strains of lactococcus lactis. the prt- strains showed monophasic exponential growth, while the prt+ strains grew in two phases. the first growth phases of the prt+ and prt- strains were in same, and no hydrolysis of casein was observed. also, the levels of consumption of amino acids and peptides in the prt+ and prt- strains were similar. at the end of this growth ph ...19957487034
characterization of plasmid-encoded citrate permease (citp) genes from leuconostoc species reveals high sequence conservation with the lactococcus lactis citp gene.the citrate permease determinant (citp) in several leuconostoc strains was demonstrated to be plasmid encoded by curing experiments and hybridization studies with a dna fragment containing the citp gene from lactococcus lactis subsp. lactis biovar diacetylactis ncdo176. cloning and nucleotide sequence analysis of leuconostoc lactis nz6070 citp revealed almost complete identity to lactococcal citp.19957487049
the isolation of lactococcal promoters and their use in investigating bacterial luciferase synthesis in lactococcus lactis.18 different promoter elements, encompassing a 71-fold range of activity, were isolated from the chromosome of lactococcus lactis (ll) mg1363 and from an uncharacterised small isometric bacteriophage of ll. the vibrio fischeri (vf) luciferase-encoding gene (lux) was used as a reporter in ll, so that the promoters could be identified strictly on the basis of their activity in the homologous host. sequence and primer extension analysis of six of the promoters has provided a new consensus sequence ...19957489923
an archaeal gene upstream of grpe different from eubacterial counterparts.in some eubacteria with a dnak locus in which grpe is close upstream of dnak, grpe is preceded by an open reading frame (orf) believed to be a heat-shock gene. we also found an orf, orf16, upstream of grpe in the archaeon methanosarcina mazei s-6, but this gene differs from the eubacterial counterpart: it is shorter, does not respond to a temperature upshift as heat-shock genes do, and the deduced protein orf16, does not resemble the proteins coded by the eubacterial equivalents. orf16 is expres ...19957495860
expression of foreign genes and selection of promoter sequences in acholeplasma laidlawii.the stable maintenance and expression of foreign genes in mollicutes (mycoplasmas) have been difficult to achieve due to the lack of suitable vectors. in this paper we show for the first time that a replicating vector can been used to express foreign genes other than antibiotic resistance genes in acholeplasma laidlawii. plasmids derived from the lactococcal vector pnz18 could introduce and maintain four different genes for many generations in a. laidlawii. one of these, encoding the dominant me ...19957496518
in vitro fructooligosaccharide utilization and inhibition of salmonella spp. by selected bacteria.in vitro experiments were conducted to determine: 1) inhibitory capacities of potential direct-fed microbial bacteria against salmonella serotypes; and 2) the ability of bifidobacterium bifidum, enterococcus faecium, lactobacillus casei, lactococcus lactis, pediococcus sp., and salmonella spp. to grow in media containing fructooligosaccharides (fos-50 or fos pure formulation) as the only carbohydrate source. thirteen bacteria (two strains of bacillus coagulans, bacillus licheniformis, bacillus s ...19957501585
molecular cloning and nucleotide sequence of the gene encoding the major peptidoglycan hydrolase of lactococcus lactis, a muramidase needed for cell separation.a gene of lactococcus lactis subsp. cremoris mg1363 encoding a peptidoglycan hydrolase was identified in a genomic library of the strain in puc19 by screening escherichia coli transformants for cell wall lysis activity on a medium containing autoclaved, lyophilized micrococcus lysodeikticus cells. in cell extracts of l. lactis mg1363 and several halo-producing e. coli transformants, lytic bands of similar sizes were identified by denaturing sodium dodecyl sulfate (sds)-polyacrylamide gels contai ...19957883712
a di- and tripeptide transport system can supply listeria monocytogenes scott a with amino acids essential for growth.listeria monocytogenes takes up di- and tripeptides via a proton motive force-dependent carrier protein. this peptide transport system resembles the recently cloned and sequenced secondary di- and tripeptide transport system of lactococcus lactis (a. hagting, e. r. s. kunji, k. j. leenhouts, b. poolman, and w. n. konings, j. biol. chem. 269:11391-11399, 1994). the peptide permease of l. monocytogenes has a broad substrate specificity and allows transport of the nonpeptide substrate 5-aminolevuli ...19957887604
a 7-base-pair sequence protects dna from exonucleolytic degradation in lactococcus lactis.linear dna molecules are subject to degradation by various exonucleases in vivo unless their ends are protected. it has been demonstrated that a specific 8-bp sequence, 5'-gctggtgg-3', named chi, can protect linear double-stranded dna from the major escherichia coli exonuclease recbcd. chi protects linear replication products of rolling-circle plasmids from recbcd degradation in vivo, in agreement with observations in vitro. a unique 7-bp sequence, 5'-gcgcgtg-3', is shown to protect similar repl ...19957892255
functional expression in saccharomyces cerevisiae of the lactococcus lactis mles gene encoding the malolactic enzyme.malolactic fermentation, a crucial step in winemaking, results mostly in degradation by lactic acid bacteria of l-malic acid into l-lactic acid. this direct decarboxylation is catalysed by the malolactic enzyme. recently we, and others, have cloned the mles gene of lactococcus lactis encoding malolactic enzyme. heterologous expression of mles in saccharomyces cerevisiae was tested to perform simultaneously alcoholic and malolactic fermentations by yeast. mles gene was cloned in a yeast multicopy ...19957867919
an aminopeptidase p from lactococcus lactis with original specificity.an aminopeptidase p (e.c. 3.4.11.9) that cleaves the arg-1-pro-2 bond of bradykinin has been isolated for the first time from lactococcus lactis. the peptidase was purified to homogeneity in a 3-step procedure and characterized. it is a monomeric metalloenzyme with a 43 kda molecular mass, activated by mn2+ and inhibited by dtt. it differs from the majority of aminopeptidases p already described by displaying a specificity for x-pro-pro n-terminal and probably an extended binding site that could ...19957873564
genetic aspects of aromatic amino acid biosynthesis in lactococcus lactis.polymerase chain reaction (pcr) primers designed from a multiple alignment of predicted amino acid sequences from bacterial aroa genes were used to amplify a fragment of lactococcus lactis dna. an 8 kb fragment was then cloned from a lambda library and the dna sequence of a 4.4 kb region determined. this region was found to contain the genes tyra, aroa, arok, and phea, which are involved in aromatic amino acid biosynthesis and folate metabolism. tyra has been shown to be secreted and arok also h ...19957823907
transport of beta-casein-derived peptides by the oligopeptide transport system is a crucial step in the proteolytic pathway of lactococcus lactis.in the proteolytic pathway of lactococcus lactis, milk proteins (caseins) are hydrolyzed extracellularly to oligopeptides by the proteinase (prtp). the fate of these peptides, i.e. extracellular hydrolysis followed by amino acid uptake or transport followed by intracellular hydrolysis, has been addressed. mutants have been constructed that lack a functional di-tripeptide transport system (dtpt) and/or oligopeptide transport system (opp) but do express the p1-type proteinase (specific for hydroly ...19957829486
primary structure and functional analysis of the lysis genes of lactobacillus gasseri bacteriophage phi adh.the lysis genes of the lactobacillus gasseri bacteriophage phi adh were isolated by complementation of a lambda sam mutation in escherichia coli. nucleotide sequencing of a 1,735-bp dna fragment revealed two adjacent coding regions of 342 bp (hol) and 951 bp (lys) in the same reading frame which appear to belong to a common transcriptional unit. proteins corresponding to the predicted gene products, holin (12.9 kda) and lysin (34.7 kda), were identified by in vitro and in vivo expression of the ...19957836307
two lactococcus lactis genes, including lacx, cooperate to trigger an sos response in a reca-negative background.a 4.3-kb ecori fragment from a lactococcus lactis genomic library alleviates the methyl methanesulfonate, mitomycin c, and uv sensitivities of an escherichia coli reca mutant (m. novel, x. f. huang, and g. novel, fems microbiol. lett. 72:309-314, 1990). it complements reca1 and delta reca mutations but not reca13. three proteins (with molecular masses of 20, 35, and 23 kda) were produced from this fragment in a t7-directed system, and three corresponding genes were detected by dna sequencing, na ...19957814316
preparation of bacterial x-prolyl dipeptidyl aminopeptidase and its stabilization by organic cosolvents.to obtain large amounts of the x-prolyl dipeptidyl aminopeptidase from lactococcus lactis subsp lactis (pepx, e.c. 3.4.14.5), pepx was purified from a commercial l. lactis cell extract. the enzyme was purified in only three steps and the last one was performed by hplc on a c4 reverse-phase column using acetonitrile as an eluent. despite its high molecular mass (175 kda), the enzyme was recovered with a good activity yield (75%). advantages and drawbacks of this technique compared to the classica ...19957710078
distribution of proteins similar to iiimanh and iiimanl of the streptococcus salivarius phosphoenolpyruvate:mannose-glucose phosphotransferase system among oral and nonoral bacteria.in streptococcus salivarius, the phosphoenolpyruvate (pep):mannose-glucose phosphotransferase system, which concomitantly transports and phosphorylates mannose, glucose, fructose, and 2-deoxyglucose, is composed of the general energy-coupling proteins ei and hpr, the specific membrane-bound iiiman, and two forms of a protein called iiiman, with molecular weights of 38,900 (iiimanh) and 35,200 (iiimanl), that are found in the cytoplasm as well as associated with the membrane. several lines of evi ...19957730253
construction of a food-grade host/vector system for lactococcus lactis based on the lactose operon.a plasmid-based food-grade vector system was developed for lactococcus lactis by exploiting the genes for lactose metabolism. l. lactis mg5267 is a plasmid-free strain containing the entire lactose operon as a chromosomal insertion. the lacf gene was deleted from this strain by a double cross-over homologous recombination event. the lacf-deficient strain produced a lac- phenotype on indicator agar. a cloned copy of the lacf gene expressed on a plasmid was capable of complementing the lacf-defici ...19957737470
locating nisin-producing lactococcus lactis in a fermented meat system.antibody-linked probes were used to locate nisin in a fermented meat system. free nisin or nisin bound to susceptible cells or food components was not detected. colonies of nisin-producing lactococcus lactis were stained at all times during growth. the position of nisin-producing l. lactis colonies was noted and compared with the location of spoilage organisms or the distribution of areas with a fermented meat appearance. no relationship between the distribution of starter culture and the locati ...19957744718
cloning, expression, sequence analysis, and site-directed mutagenesis of the tn5306-encoded n5-(carboxyethyl)ornithine synthase from lactococcus lactis k1.the gene (ceo) encoding n5-(carboxyethyl)ornithine synthase (ec 1.5.1.24) has been isolated from the sucrose-nisin transposon tn5306 of lactococcus lactis k1, sequenced, and expressed at high level in escherichia coli. the cloned enzyme has allowed the synthesis of the novel n omega-carboxypropyl amino acids n5-(1-carboxypropyl)-l-ornithine and n6-(1-carboxypropyl)-l-lysine. comparison of the deduced amino acid sequence of n5-(1-carboxyethyl)-l-ornithine synthase (m(r) = 35,323) to the functiona ...19957744873
secretion of biologically active murine interleukin-2 by lactococcus lactis subsp. lactis.secretion of functional recombinant murine interleukin-2 (mil2) by lactococcus lactis was achieved by fusion of the sequence encoding mature mil2 to the secretion signal leader of the lactococcal usp45 gene placed under transcriptional control of the phage t7 promoter-t7 rna polymerase expression system. the recombinant mature mil2 was one of only a few proteins which accumulated in the growth medium. sequence analysis revealed correct processing at the first amino acid of the mature protein. a ...19957747977
physical and genetic map of the lactococcus lactis subsp. cremoris mg1363 chromosome: comparison with that of lactococcus lactis subsp. lactis il 1403 reveals a large genome inversion.a physical and genetic map of the chromosome of the lactococcus lactis subsp. cremoris reference strain mg1363 was established. the physical map was constructed for noti, apai, and smai enzymes by using a strategy that combines creation of new rare restriction sites by the random-integration vector prl1 and ordering of restriction fragments by indirect end-labeling experiments. the mg1363 chromosome appeared to be circular and 2,560 kb long. seventy-seven chromosomal markers were located on the ...19957751295
use of continuous culture for the selection of plasmids with improved segregational stability.in this report a method that enables the selection of stable plasmid variants and the isolation of dna sequences that improve plasmid maintenance is described. the method is based on the principle that in populations of cells carrying derivatives of a plasmid that differ only in the level of segregational stability, when grown in a chemostat under conditions with selective pressure on the plasmid, cells that carry more stable plasmid variants will be enriched. we developed the system for lactoco ...19957753912
repair of oxidative dna damage in gram-positive bacteria: the lactococcus lactis fpg protein.the formamidopyrimidine dna glycosylase gene (fpg-l) of the gram-positive microaerophilic bacterium lactococcus lactis subsp. cremoris ml3 has been cloned, characterized and sequenced. the fpg-l gene is composed of 819 bp encoding a protein of 31.3 kda (fpg-l). the deduced amino acid sequence of the fpg-l protein shows 59% similarity and 38% identity with the escherichia coli fpg protein (fpg-e). polyclonal antibodies against fpg-e react with the fpg-l protein. the fpg-l protein was purified to ...19957704272
sequence analysis, distribution and expression of an aminopeptidase n-encoding gene from lactobacillus helveticus cnrz32.lactobacillus (lb.) helveticus cnrz32 possesses a 97-kda metalloenzyme with aminopeptidase activity (pepn; ec 3.4.11.2). a 3.8-kb fragment encoding pepn was cloned into pil253 and designated psuw34. transformation of lactococcus (lc.) lactis lm0230 with psuw34 resulted in > 180-fold increase in general aminopeptidase (ap) activity using l-lysine-p-nitroanilide. southern hybridization was conducted to determine the distribution of homology to the cnrz32 pepn gene among lactic-acid bacteria (lab). ...19957698673
isolation of nisin-producing lactococcus lactis strains from dry fermented sausages.a total of 4608 lactic acid bacteria (lab) were isolated from 24 spanish fermented sausages and screened for bacteriocin production. two strains, bb24 and g18, produced bacteriocins that inhibited a broad spectrum of gram-positive bacteria. bb24 and g18 were tentatively identified as lactococcus lactis by carbohydrate fermentation patterns and other biochemical characteristics. the characterization of their bacteriocins suggested that both could be the well-known lantibiotic nisin. this was conf ...19957698947
in vivo restriction by llai is encoded by three genes, arranged in an operon with llaim, on the conjugative lactococcus plasmid ptr2030.the llai restriction and modification (r/m) system is encoded on ptr2030, a 46.2-kb conjugative plasmid from lactococcus lactis. the llai methylase gene, sequenced previously, encodes a functional type iis methylase and is located approximately 5 kb upstream from the abia gene, encoding abortive phage resistance. in this study, the sequence of the region between llaim and abia was determined and revealed four consecutive open reading frames (orfs). northern (rna) analysis showed that the four or ...19957528201
segregational stability and copy number of the theta-type lactococcal replicon rep22 in lactococcus.rep22 is the replication region of the lactococcal theta replicating pucl22 plasmid. the copy number of rep22-based plasmids in lactococcus was determined by using a chromosomal dna fragment from lactococcus lactis subsp. lactis mms368 as reference. segregational behavior appeared to be linked to copy number and therefore indicated random distribution of copies to daughter cells. nevertheless, an active partitioning system was detected in the parental plasmid pucl22. a pucl22 138-bp dna restrict ...19957765880
identification and molecular analysis of lactococcus lactis rpod operon.the complete nucleotide sequence of an open reading frame (orf) preceding the lactococcus lactis rpod gene is reported. it was suggested that this orf encodes lactococcus lactis dna primase and that the l. lactis rpod operon consists of only two genes. northern hybridization analysis showed that i) there are four mrnas transcribing the rpod gene (from upstream, m1-m4), ii) only the 3.7-kb transcript m1 includes the entire rpod operon, iii) the shortest transcript m4 exists at both logarithmic an ...19957765979
medium-dependent regulation of proteinase gene expression in lactococcus lactis: control of transcription initiation by specific dipeptides.transcriptional gene fusions with the escherichia coli beta-glucuronidase gene (gusa) were used to study the medium- and growth-dependent expression of the divergently transcribed genes involved in proteinase production (prtp and prtm) of lactococcus lactis sk11. the results show that both the prtp and prtm genes are controlled at the transcriptional level by the peptide content of the medium and, to a lesser extent, by the growth rate. a more than 10-fold regulation in beta-glucuronidase activi ...19957768792
the extracellular pi-type proteinase of lactococcus lactis hydrolyzes beta-casein into more than one hundred different oligopeptides.the peptides released from beta-casein by the action of pi-type proteinase (prtp) from lactococcus lactis subsp. cremoris wg2 have been identified by on-line coupling of liquid chromatography to mass spectrometry. after 24 h of incubation of beta-casein with purified prtp, a stable mixture of peptides was obtained. the trifluoroacetic acid-soluble peptides of this beta-casein hydrolysate were fractionated by high-performance liquid chromatography and introduced into the liquid chromatography-ion ...19957768856
lactococcus lactis glyceraldehyde-3-phosphate dehydrogenase gene, gap: further evidence for strongly biased codon usage in glycolytic pathway genes.the gene gap, encoding glyceraldehyde-3-phosphate dehydrogenase (ec 1.2.1.12), was isolated from a genomic library of lactococcus lactis lm0230 dna. plasmids containing the l. lactis gene were able to complement a gap mutant of escherichia coli. the nucleotide sequence of gap predicted a polypeptide chain of 337 amino acids for the enzyme and a subunit molecular mass of 36,043. the codon usage in gap and four other glycolytic genes from l. lactis showed a high degree of bias, when compared with ...19957773380
genes involved in immunity to the lantibiotic nisin produced by lactococcus lactis 6f3.the lantibiotic nisin is produced by several strains of lactococcus lactis. the complete gene cluster for nisin biosynthesis in l. lactis 6f3 comprises 15 kb of dna. as described previously, the structural gene nisa is followed by the genes nisb, nist, nisc, nisi, nisp, nisr, and nisk. further analysis revealed three additional open reading frames, nisf, nise, and nisg, adjacent to nisk. approximately 1 kb downstream of the nisg gene, three open reading frames in the opposite orientation have be ...19957793910
cloning and sequencing of lladchi [corrected] restriction/modification genes from lactococcus lactis and relatedness of this system to the streptococcus pneumoniae dpnii system.the natural 7.8-kb plasmid psrq700 was isolated from lactococcus lactis subsp. cremoris dch-4. it encodes a restriction/modification system named lladchi [corrected]. when introduced into a phage-sensitive l. lactis strain, psrq700 confers strong phage resistance against the three most common lactococcal phage species, namely, 936, c2, and p335. the lladchi [corrected] endonuclease was purified and found to cleave the palindromic sequence 5'-gatc-3'. it is an isoschizomer of streptococcus pneumo ...19957793939
a system to generate chromosomal mutations in lactococcus lactis which allows fast analysis of targeted genes.a system for generating chromosomal insertions in lactococci is described. it is based on the conditional replication of lactococcal pwv01-derived ori+ repa- vector pori19, containing lacz alpha and the multiple cloning site of puc19. chromosomal alui fragments of lactococcus lactis were cloned in pori19 in repa+ helper strain escherichia coli ec101. the frequency of campbell-type recombinants, following introduction of this plasmid bank into l. lactis (repa-), was increased by combining the sys ...19958522504
characterization of transposon tn5469 from the cyanobacterium fremyella diplosiphon.a transposon, designated tn5469, was isolated from mutant strain fdr1 of the filamentous cyanobacterium fremyella diplosiphon following its insertion into the rcac gene. tn5469 is a 4,904-bp noncomposite transposon with 25-bp near-perfect terminal inverted repeats and has three tandemly arranged, slightly overlapping potential open reading frames (orfs) encoding proteins of 104.6 kda (909 residues), 42.5 kda (375 residues), and 31.9 kda (272 residues). insertion of tn5469 into the rcac gene in s ...19958522506
nucleotide sequence and characterization of peb4a encoding an antigenic protein in campylobacter jejuni.the 29-kda protein peb4, a major antigen of campylobacter jejuni, is present in all c. jejuni strains tested and elicits an antibody response in infected patients. by screening a lambda gt11 library of chromosomal dna fragments of c. jejuni strain 81-176 in escherichia coli y1090 cells with antibody raised against purified peb4, a recombinant phage with a 2-kb insert expressing an immunoreactive protein of 29 kda was isolated. dna sequence analysis revealed that the insert contains two complete ...19958525063
involvement of enzyme-substrate charge interactions in the caseinolytic specificity of lactococcal cell envelope-associated proteinases.three series of oligopeptides were synthesized to investigate the proposal that a major factor in determining the differences in specificity of the lactococcal cell surface-associated proteinases against caseins is the interactions between charged amino acids in the substrate and in the enzyme. the sequences of the oligopeptides were based on two regions of kappa-casein (residues 98 to 111 and 153 to 169) which show markedly different susceptibilities to pi- and piii-type lactococcal proteinases ...19958526506
metabolic engineering of lactococcus lactis: influence of the overproduction of alpha-acetolactate synthase in strains deficient in lactate dehydrogenase as a function of culture conditions.the als gene for alpha-acetolactate synthase of lactococcus lactis mg1363 was cloned on a multicopy plasmid under the control of the inducible l. lactis laca promoter. more than a hundredfold overproduction of alpha-acetolactate synthase was obtained in l. lactis under inducing conditions as compared with that of the host strain, which contained a single chromosomal copy of the als gene. the effect of alpha-acetolactate synthase overproduction on the formation of end products in various l. lacti ...19958526510
sequence analysis of the lactococcus lactis temperate bacteriophage bk5-t and demonstration that the phage dna has cohesive ends.the lactococcus lactis temperate bacteriophage bk5-t is a type phage in the lactococcal phage classification (a. w. jarvis, g. f. fitzgerald, m. mata, a. mercenier, h. neve, i. b. powell, c. ronda, m. saxelin, and m. teuber, intervirology 32:2-9, 1991). the nucleotide sequence of 18,935 bp of the genome of bk5-t was determined and analyzed for the presence of open reading frames and other structural features. thirty-two open reading frames longer than 60 codons were identified, and these appeare ...19958526523
identification of prophage genes expressed in lysogens of the lactococcus lactis bacteriophage bk5-t.bacteriophage bk5-t is a small isometric-headed temperate phage that infects lactococcus lactis subsp. cremoris. northern (rna) analysis of mrna produced by lysogenic strains containing bk5-t prophage revealed four major bk5-t transcripts that are 0.8, 1.3, 1.8, and 1.8 kb in size and enabled a transcription map of the prophage genome to be prepared. the position and size of each transcript corresponded closely to the position and size of open reading frames predicted from the nucleotide sequenc ...19958526524
spontaneous deletion mutants of the lactococcus lactis temperate bacteriophage bk5-t and localization of the bk5-t attp site.spontaneous deletion mutants of the temperate lactococcal bacteriophage bk5-t were obtained when the phage was grown vegetatively on the indicator strain lactococcus lactis subsp. cremoris h2. one deletion mutant was unable to form stable lysogens, and analysis of this mutant led to the identification of the bk5-t attp site and the integrase gene (int). the core sequences of the bk5-t attp and host attb regions are conserved in a number of lactococcal phages and l. lactis strains.19958526525
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.19958528613
cloning and dna sequence analysis of two abortive infection phage resistance determinants from the lactococcal plasmid pnp40.the lactococcal plasmid pnp40, from lactococcus lactis subsp. lactis biovar diacetylactis drc3, confers complete resistance to the prolate-headed phage phi c2 and the small isometric-headed phage phi 712 in l. lactis subsp. lactis mg1614. a 6.0-kb ncoi fragment of pnp40 cloned in the lactococcal escherichia coli shuttle vector pam401 was found to confer partial resistance to phi 712. subcloning and deletion analysis of the recombinant plasmid ppg01 defined a 2.5-kb scaihpai fragment as conferrin ...19958534099
sequencing and analysis of the prolate-headed lactococcal bacteriophage c2 genome and identification of the structural genes.the 22,163-bp genome of the lactococcal prolate-headed phage c2 was sequenced. thirty-nine open reading frames (orfs), early and late promoters, and a putative transcription terminator were identified. twenty-two orfs were in the early gene region, and 17 were in the late gene region. putative genes for a dna polymerase, a recombination protein, a sigma factor protein, a transcription regulatory protein, holin proteins, and a terminase were identified. transcription of the early and late genes p ...19958534101
a non-essential glutamyl aminopeptidase is required for optimal growth of lactococcus lactis mg1363 in milk.degenerate pcr primers were designed from the n-terminal amino acid sequence of a glutamyl aminopeptidase (pepa) from lactococcus lactis. these primers were used to screen a lambda library for clones containing the gene (pepa) encoding pepa. the dna sequence of a 2.1 kb fragment containing pepa was determined. the sequence revealed the presence of one complete and two incomplete open reading frames (orfs). the complete orf encodes a putative protein of 353 amino acids with a predicted n-terminal ...19958535515
the three-dimensional structure of 6-phospho-beta-galactosidase from lactococcus lactis.the enzyme 6-phospho-beta-galactosidase hydrolyzes phospholactose, the product of a phosphor-enolpyruvate-dependent phosphotransferase system. it belongs to glycosidase family 1 and no structure has yet been published for a member of this family.19958535789
purification, crystallization, and preliminary x-ray analysis of pepx, an x-prolyl dipeptidyl aminopeptidase from lactococcus lactis.the x-prolyl dipeptidyl aminopeptidase pepx, a serine peptidase isolated originally from lactococcus lactis subsp lactis ncdo 763, was cloned and overproduced in escherichia coli. the enzyme was isolated in its active form in two purification steps. crystals of pepx were grown by the hanging drop vapor diffusion method using polyethyleneglycol 4000 as precipitant at ph 5.0. the crystals are orthorhombic with cell dimensions a = 92.8 a, b = 102.6 a, and c = 101.6 a, space group p2(1)2(1)2, and pr ...19958592708
the reca gene of lactococcus lactis: characterization and involvement in oxidative and thermal stress.the role of reca in lactococcus lactis, a microaerophilic fermenting organism, was examined by constructing a reca-disrupted strain. this single alteration had a surprisingly pleiotropic effect. in addition to its roles in homologous recombination and dna repair, reca is also involved in responses to oxygen and heat stresses. we found that oxygen stress induced by aeration causes reductions in growth and stationary-phase survival of the reca strain. toxicity is a consequence of hydroxyl radical ...19958594331
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.19958919927
cloning of a gene encoding the precursor of nisin by pcr.the structural gene for the precursor of nisin was synthesized by polymerase chain reaction and then cloned in puc18. the nucleotide sequence of the cloned precursor nisin gene was determined by dideoxy termination method. the sequence data obtained agreed with those of precursor nisin genes isolated by other workers from different lactococcus lactis strains.19958739107
[isolation and reassociation of acetogen and methanogen in a syntrophobic coculture degrading butyrate anaerobically].anaerobic coculture bf2 which degraded butyrate into acetate and produced methane was isolated from granular methanogenic sludge. the coculture is associated syntrophically the syntrophomonas subsp. saponavida strain cf2 with methanobacterium formicicum strain mf2 and appeared to degraded c4 approximately c18 fatty acids including isobutyrate. the optimal temperature and ph for growth was 37 degrees c and 7.7 respectively. the strain cf2 was obtained in pure culture with crotonate as substrate a ...19958745550
[effects of sl-probiotic preparation on the body weight and phagocytosis of white mice].effects of sl-probiotic preparation on the body weight and the phagocytic functions in white mice were studied. bioassay of its toxicity showed sl-p was non-toxic. body weight of the treated mice increased significantly as compared with that of controls 10 days after treatment with sl-probiotic preparation. phagocytic activity, acid phosphatase activity, lysozyme activity of the peritoneal macrophages of the tested mice were enhanced significantly as compared with those of normal controls. the s ...19958745551
extraction of rna from gram-positive bacteria. 19958747648
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.19958825377
structural and functional analysis of the single-strand origin of replication from the lactococcal plasmid pwv01.the single-strand origin (sso) of the rolling-circle (rc), broad-host-range lactococcal plasmid pwvo1 was functionally characterized. the activity of this sso in the conversion of single-stranded dna to double-stranded dna was tested both in vivo and in vitro. in addition, the effect of this sso on plasmid maintenance was determined. the functional pwvo1 sso comprises a 250 bp region, containing two inverted repeats (irs). the activity of each ir was tested, separately and in combination, in a p ...19958552032
use of capillary zone electrophoresis in an investigation of peptide uptake by dairy starter bacteria.a capillary zone electrophoresis (cze) method to separate the peptide series val-glyn, where n is 1 to 4, has been evaluated and compared to separation by reversed-phase high-performance liquid chromatography (rp-hplc). the method was able to quantitate peptides present a very low concentrations (down to 0.05 mm) with high reproducibility and accuracy and was capable of separating peptides differing in size by only a single glycine residue. it could also separate the peptides val-gly and leu-gly ...19958556163
maturation pathway of nisin and other lantibiotics: post-translationally modified antimicrobial peptides exported by gram-positive bacteria.lantibiotics form a family of highly modified peptides which are secreted by several gram-positive bacteria. they exhibit antimicrobial activity, mainly against other gram-positive bacteria, by forming pores in the cellular membrane. these antimicrobial peptides are ribosomally synthesized and contain leader peptides which do not show the characteristics of signal sequences. several amino acid residues of the precursor lantibiotic are enzymatically modified, whereafter secretion and processing o ...19958559062
comparison of proteolytic activities in various lactobacilli.a total of 169 lactobacillus strains from 12 species (lb. acidophilus, lb. brevis, lb. buchneri, lb. casei, lb. delbrueckii subsp. bulgaricus, lb. delbrueckii subsp. delbrueckii, lb. delbrueckii subsp. lactis, lb. fermentum, lb. helveticus, lb. paracasei subsp. paracasei, lb. plantarum and lb. rhamnosus), isolated from raw milk and various milk products, and 9 lactococcus lactis strains were evaluated for peptidase activities with five chromogenic substrates and a tryptic digest of casein. withi ...19958568030
an x-prolyl dipeptidyl aminopeptidase (pepx) gene from lactobacillus helveticus.the x-prolyl dipeptidyl aminopeptidase gene (pepx) of an industrially used lactobacillus helveticus strain has been detected by nucleic acid hybridization, cloned, characterized and sequenced. one orf of 2379 bp with coding capacity for a 90.6 kda protein (pepx) was found. the orf was preceded by a typical prokaryotic promoter region. an inverted repeat structure with delta g of -84.1 kj mol-1 was found downstream of the coding region. the deduced amino acid sequence of the 90.6 kda protein show ...19958574400
a study of the substrate specificity of aminopeptidase n from lactococcus lactis subsp. cremoris wg2.a systematic study was made of the ability of aminopeptidase n from lactococcus lactis subsp. cremoris wg2 to hydrolyse different peptide substrates. the enzyme showed a marked preference for substrates containing arginine as the n-terminal residue but, to a lesser extent, was also capable of cleaving other residues such as lysine and leucine. there was a tendency for the activity to increase with the hydrophobicity index of the c-terminal residue of dipeptide substrates. it was also observed th ...19958579823
characteristics of tn5307 exchange and intergeneric transfer of genes associated with nisin production.transfer of the lactococcus lactis 11454 nisin-sucrose conjugative transposon, tn5307, was investigated to develop a methodology for conjugation of this element to other lactic acid bacteria. tn5307 exchange was sensitive to temperature and ph but was not affected by protease or amylase treatments to donor cells. moreover, conjugation studies demonstrated that the direct-plate method could be employed to rapidly identify lm2301 transconjugants able to transfer tn5307 at least ten times more effi ...19958579827
genomic organization of lactococci.the genus lactococcus contains four species of which l. lactis is the most thoroughly studied. its genome is a+t-rich and consists of a circular chromosome of 2.0 to 2.7 mbp, a wide range of plasmids, and frequently one or more prophages. insertion sequence elements are commonly present in both the chromosome and the plasmids, while one conjugative transposon of 68 kbp has been described. genetic maps of the chromosomes of a number of different l. lactis strains have been determined and found to ...19958586212
molecular analysis of the lactococcus lactis sex factor. 19958586213
metabolic operons in lactococci.the genes for the biosynthesis of histidine, tryptophan and branched-chain amino acids (ilv for isoleucine, leucine and valine) are clustered in large operons. in addition to genes encoding the pathway enzymes, the his and the ilv operons contain 4 and 3 other genes, respectively. the functions of two of these, orf3 and aldb are regulatory. the second gene of the his operon, orf3, encodes a protein homologous to the histidyl-trna synthetases. it is involved in transcription attenuation upstream ...19958586214
environmentally regulated promoters in lactococci. 19958586215
stress response in lactococcus lactis. 19958586216
reca gene involvement in oxidative and thermal stress in lactococcus lactis.the reca gene is best known for its effects on homologous recombination and dna repair via sos induction. there is gathering evidence that reca also affects expression of genes associated with different types of stress. we studied reca properties in lactococcus lactis by generating a reca-disrupted mutant of mg1363 and comparing it with the wild type strain. reca appears to have an important role in cell survival upon oxygen or thermal stress, in addition to its conserved role in dna repair. oxy ...19958586217
polysaccharide expression in lactococci.lactococcus lactis produces polysaccharide under defined environmental conditions. three approaches are being used to identify regulators of polysaccharide synthesis in the organism. i) two new lactococcal vectors, each of which contains a promoterless reporter gene, have been developed. they are being used to select for chromosomal insertions that affect expression of polysaccharide ii) genetic complementation with lactococcal genomic libraries identified two classes of lactococcal genomic acti ...19958586218
lon and clp-like atp-dependent proteases of lactococcus lactis. 19958586220
genetic modification and the proteolytic system of lactococci. 19958586222
genetics of peptide degradation in lactococcus: gene cloning, construction and analysis of peptidase negative mutants. 19958586223
plasmid-mediated oligopeptide transport system in lactococci. 19958586224
integration strategies and vectors. 19958586226
nonsense suppression in lactococcus lactis: construction of a "food-grade" cloning vector. 19958586227
specificity of insertion of tn1545 transposon family in lactococcus lactis subsp. lactis.a collection of lactococcus lactis subsp. lactis strains carrying a derivative of tn1545 inserted in the chromosome was generated. some 34 insertions were cloned in escherichia coli and the flanking dna sequences determined. insertions are distributed non randomly and several hot spots were observed. the hot spots do not have sequence features which would distinguish them from other insertion sites, suggesting that they may have special structural properties. insertions in open reading frames oc ...19958586228
characterization of the conjugation system associated with the lactococcus lactis ssp. lactis plasmid prs01. 19958586229
high expression of a foreign reporter gene in streptococcus thermophilus. 19958586230
a protein, belonging to a family of rna-binding transcriptional anti-terminators, controls beta-glucoside assimilation in lactococcus lactis. 19958586232
characterization of a cloned gene (pip) from lactococcus lactis required for phage infection. 19958586234
specific chromosomal sequences can contribute to the appearance of a new lytic bacteriophage in lactococcus. 19958586235
bacteriophage resistance in lactococcus: molecular characterization of the scrfi restriction/modification system from lactococcus lactis subsp. cremoris uc503. 19958586236
c.llai is a bifunctional regulatory protein of the llai restriction modification operon from lactococcus lactis. 19958586237
physical and genetic maps of the chromosome of the lactococcus lactis subsp. lactis strain il1403 and lactococcus lactis subsp. cremoris strain mg1363. 19958586238
lactococcal expression systems for protein engineering of nisin. 19958586239
genetics of the nisin operon and the sucrose-nisin conjugative transposon tn5276. 19958586240
analysis of lactococcin secretion and immunity in lactococcus lactis. 19958586246
role of scalar protons in metabolic energy generation in lactic acid bacteria.lactic acid bacteria are able to generate a protonmotive force across the cytoplasmic membrane by various metabolic conversions without involvement of substrate level phosphorylation or proton pump activity. weak acids like malate and citrate are taken up in an electrogenic process in which net negative charge is translocated into the cell thereby generating a membrane potential. the uptake is either an exchange process with a metabolic end-product (precursor/ product exchange) or a uniporter me ...19958595982
the occurrence of two intracellular oligoendopeptidases in lactococcus lactis and their significance for peptide conversion in cheese.two intracellular oligopeptide-preferring endopeptidases have been detected in lactococcus lactis. a neutral thermolysin-like oligoendopeptidase (nop) has been purified to homogeneity and an alkaline oligoendopeptidase has been partially purified. the specificity of the oligoendopeptidases towards important intermediary cheese peptides, produced by chymosin action on the caseins, clearly differs from that of the cell-envelope proteinase (cep). nop is active under conditions prevailing in cheese ...19958597539
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