| heterogeneric conjugal transfer of the pheromone-responsive plasmid pip964 (inchlyi) of enterococcus faecalis in the apparent absence of pheromone induction. | erythromycin-resistant derivatives of the pheromone-responsive plasmid pip964 from enterococcus faecalis were constructed to study its host range. this was done by inserting the integrative vector pat112 and the related replicon ptcr1 harboring orir of the broad host range plasmid pam beta 1 into the hemolysin-bacteriocin operon of pip964, to give ptcr2 and ptcr3, respectively. plasmid ptcr2 was transferred by filter matings from e. faecalis to enterococcus faecium and listeria monocytogenes at ... | 1994 | 7958769 |
| cloning and characterization of upp, a gene encoding uracil phosphoribosyltransferase from lactococcus lactis. | uracil phosphoribosyltransferase catalyzes the key reaction in the salvage of uracil in many microorganisms. the gene encoding uracil phosphoribosyltransferase (upp) was cloned from lactococcus lactis subsp. cremoris mg1363 by complementation of an escherichia coli mutant. the gene was sequenced, and the putative amino acid sequence was deduced. the promoter was mapped by both primer extension and analysis of beta-galactosidase expressed from strains carrying fusion between upp promoter fragment ... | 1994 | 7961396 |
| mutational analysis of cat-86 gene expression controlled by lactococcal promoters in lactococcus lactis subsp. lactis and escherichia coli. | promoters were cloned from the chromosomal dna of lactococcus lactis subsp. lactis np4510 by using promoter-probe vector pgkv210. n-methyl-n'-nitro-n-nitrosoguanidine-induced mutagenesis of l. lactis-(pbv413), with low-level expression of the cat-86 gene, resulted in enhanced expression. subcloning and sequencing of the mutated plasmid designated pbv415 revealed that the mutation is located within the psti-hindiii fragment containing the coding sequence of the cat-86 gene (the 10th ctg codon was ... | 1994 | 7961430 |
| proton motive force-driven and atp-dependent drug extrusion systems in multidrug-resistant lactococcus lactis. | three mutants of lactococcus lactis subsp. lactis mg1363, termed ethr, daur, and rhor, were selected for resistance to high concentrations of ethidium bromide, daunomycin, and rhodamine 6g, respectively. these mutants were found to be cross resistant to a number of structurally and functionally unrelated drugs, among which were typical substrates of the mammalian multidrug transporter (p-glycoprotein) such as daunomycin, quinine, actinomycin d, gramicidin d, and rhodamine 6g. the three multidrug ... | 1994 | 7961458 |
| comparative analysis of gene expression in streptococcus pneumoniae and lactococcus lactis. | the pfl10 plasmid vector for translational fusions was constructed. pfl10 is based in the promiscuous pls1 replicon and contains the pc194 cat gene deprived of its transcriptional promoter and shine-dalgarno (sd) sequence. three promoters (pcit, ppola and ptetl) from gram-positive bacteria, inserted in pfl10, were tested for their ability to drive transcription in lactococcus lactis and streptococcus pneumoniae. these promoters were coupled to the sd sequence of the lactococcal citp gene fused t ... | 1994 | 7988870 |
| aminopeptidase n from streptococcus salivarius subsp. thermophilus ncdo 573: purification and properties. | a 96 kda aminopeptidase was purified from streptococcus salivarius subsp. thermophilus ncdo 573. the enzyme had similar properties to aminopeptidases isolated from lactococci and lactobacilli and showed a high degree of n-terminal amino acid sequence homology to aminopeptidase n from lactococcus lactis subsp. cremoris. it catalysed the hydrolysis of a range of aminoacyl 4-nitroanilides and 7-amido-4-methylcoumarin derivatives, dipeptides, tripeptides and oligopeptides. in common with aminopeptid ... | 1994 | 7989254 |
| antimicrobial activity of bark extracts of bridelia ferruginea (euphorbiaceae). | water and ethanol extracts of bridelia ferruginea were examined for phytochemical and antimicrobial properties. the extracts, which were tested at a final concentration of 5 mg/ml, produced in vitro antimicrobial activities in assays against hospital strains of staphylococcus aureus, candida albicans, staphylococcus epidermidis, escherichia coli, streptococcus lactis, proteus vulgaris, proteus mirabilis, streptococcus pyogenes and klebsiella sp. the zones of inhibition produced by the extracts i ... | 1994 | 7990492 |
| a lactococcus lactis gene encodes a membrane protein with putative atpase activity that is homologous to the essential escherichia coli ftsh gene product. | a gene, encoding a protein homologous to an essential escherichia coli protein, ftsh, was identified adjacent to the hpt gene and the trna operon in the gram-positive bacterium lactococcus lactis. the deduced amino acid sequence of the gene product showed full-length similarity to ftsh of e. coli, yme1p of saccharomyces cerevisiae and a conserved region found in a new family of putative atpases. in-frame fusions of l. lactis ftsh and phoa1 in e. coli, and immunodetection of the l. lactis ftsh pr ... | 1994 | 8000529 |
| genetic studies of lactococcal bacteriophages--taxonomic differentiations and dna analysis: evidence for 3' cohesive ends. | twenty-four bacteriophages of lactococcus lactis subsp. lactis and l. lactis subsp. cremoris were classified. two groups of bacteriophages morphologically defined as prolate or isometric types by electron microscopy were examined for their genome sizes, protein patterns and dna homologies. these criteria showed that prolate phages are quite homogeneous. in contrast, isometric phages exhibit more differences, particularly in particle sizes and protein compositions. analysis of dna hybridizations ... | 1994 | 8005832 |
| microencapsulation of lactococcus lactis subsp. cremoris. | lactococcus lactis subsp. cremoris was microencapsulated within alginate/poly-l-lysine (alg/pll), nylon or crosslinked polyethyleneimine (pei) membranes. toxic effects were observed with solvents and reagents used in nylon and pei membrane formation. alg/pll encapsulation resulted in viable and active cell preparations which acidified milk at a rate proportional to the cell concentration, but at rates less than that of free cell preparations. at 4 x 10(8) colony-forming units (cfu/ml milk), enca ... | 1994 | 8006766 |
| cloning, sequencing and characterization of the pepip gene encoding a proline iminopeptidase from lactobacillus delbrueckii subsp. bulgaricus cnrz 397. | the proline iminopeptidase (pepip) of lactobacillus delbrueckii subsp. bulgaricus is a major peptidase located in the cell envelope. its structural gene (pepip) has been cloned into puc18 and expressed at a very high level in escherichia coli to give a pepip activity 15,000-fold higher than that found in l. delbrueckii subsp. bulgaricus. the nucleotide sequence of the pepip gene revealed an open reading frame of 295 codons encoding a protein with a predicted m(r) of 33,006, which is consistent w ... | 1994 | 8012575 |
| purification and characterization of an endopeptidase from lactococcus lactis subsp. cremoris sk11. | an endopeptidase has been purified from lactococcus lactis subsp. cremoris sk11. the enzyme is a 70 kda monomer, strongly inhibited by the metalloproteinase inhibitors 1,10-phenanthroline and phosphoramidon but relatively insensitive to edta. it is not significantly inhibited by the thiol enzyme inhibitor p-chloromercuribenzoate nor by the serine protease inhibitor phenylmethylsulphonyl fluoride. the action of the endopeptidase in catalysing the hydrolysis of several peptide hormones has been st ... | 1994 | 8012609 |
| identification and characterization of the alpha-acetolactate synthase gene from lactococcus lactis subsp. lactis biovar diacetylactis. | the conversion of 3-13c-labelled pyruvate in an acetoin-producing clone from a lactococcus lactis subsp. lactis biovar diacetylactis strain dsm 20384 plasmid bank in escherichia coli was studied by 13c nuclear magnetic resonance analysis. the results showed that alpha-acetolactate was the first metabolic product formed from pyruvate, whereas acetoin appeared at a much slower rate and reached only low concentrations. this alpha-acetolactate production shows that the cells express the gene for alp ... | 1994 | 8017926 |
| cloning, expression, and nucleotide sequence of genes involved in production of lactococcin dr, a bacteriocin from lactococcus lactis subsp. lactis. | the partial nucleotide sequence of a lactococcus lactis subsp. lactis adria 85lo30 bacteriocin-producing operon was determined. the first two open reading frames of the operon are necessary to get bacteriocin expression in l. lactis il1403r. | 1994 | 8017945 |
| two different dihydroorotate dehydrogenases in lactococcus lactis. | the pyrimidine de novo biosynthesis pathway has been characterized for a number of organisms. the general pathway consists of six enzymatic steps. in the characterization of the pyrimidine pathway of lactococcus lactis, two different pyrd genes encoding dihydroorotate dehydrogenase were isolated. the nucleotide sequences of the two genes, pyrda and pyrdb, have been determined. one of the deduced amino acid sequences has a high degree of homology to the saccharomyces cerevisiae dihydroorotate deh ... | 1994 | 8021180 |
| conjugative transposition of tn916: preferred targets and evidence for conjugative transfer of a single strand and for a double-stranded circular intermediate. | transposition of conjugative transposons proceeds by excision and formation of a covalently closed circular intermediate that includes at its joint the six flanking bases from its previous host (coupling sequences). to elucidate the role of the coupling sequences in this process and to determine the sequence of targets used by tn916, we studied its insertion into a plasmid following conjugation. the results differ from those previously observed when tn916 was introduced by transformation. they s ... | 1994 | 8022279 |
| identification of the putative repressor-encoding gene ci of the temperate lactococcal bacteriophage tuc2009. | the putative repressor-encoding gene ci of the temperate lactococcal bacteriophage tuc2009 was cloned and sequenced. in the inferred amino-acid sequence, two domains can be recognized, one of which shows homology to dna-binding domains of various regulatory proteins, while the other is thought to be involved in oligomerisation. | 1994 | 8026765 |
| insertions of is256-like element flanking the chromosomal beta-lactamase gene of enterococcus faecalis cx19. | we have previously identified an inverted repeat characteristic of staphylococcal beta-lactamase transposons adjacent to the chromosomal beta-lactamase genes of enterococcus faecalis ch19 and its beta-lactamase-producing transconjugant cx19. nucleotide sequence analysis of the ch19 beta-lactamase structural gene (blaz) reveals it to be identical to the blaz gene from e. faecalis hh22 and to the blaz gene from the staphylococcal beta-lactamase transposon tn552. we also report the presence of nucl ... | 1994 | 8031032 |
| distribution and evolution of nisin-sucrose elements in lactococcus lactis. | the distribution, architecture, and conjugal capacity of nisin-sucrose elements in wild-type lactococcus lactis strains were studied. element architecture was analyzed with the aid of hybridizations to different probes derived from the nisin-sucrose transposon tn5276 of l. lactis nizo r5, including its left and right ends, the nisa gene, and is1068 (previously designated iso-is904), located between the left end and the nisa gene. three classes of nisin-sucrose elements could be distinguished in ... | 1994 | 8031080 |
| molecular characterization of lactococcal bacteriophage tuc2009 and identification and analysis of genes encoding lysin, a putative holin, and two structural proteins. | bacteriophage tuc2009 is a temperate bacteriophage with a small isometric head and is isolated from lactococcus lactis subsp. cremoris uc509. the phage genome is packaged by a headful mechanism, giving rise to circularly permuted molecules with terminal redundancy. the unit genome size is approximately 39 kb. a map of the phage genome on which several determinants could be localized was constructed: pac, the site of initiation of dna packaging; lys (1,287 bp), specifying the phage lysin; s (267 ... | 1994 | 8031083 |
| direct screening of recombinants in gram-positive bacteria using the secreted staphylococcal nuclease as a reporter. | a system for direct screening of recombinant clones in lactococcus lactis, based on secretion of the staphylococcal nuclease (snase) in the organism, was developed. the nuc gene (encoding snase) was cloned on both rolling-circle and theta-replicating plasmids. l. lactis strains containing these nuc+ plasmids secrete snase and are readily detectable by a simple plate test. a multicloning site (mcs) was introduced just after the cleavage site between leader peptide and the mature snase, without af ... | 1994 | 8051029 |
| effect of sodium dodecylsulphate on the binding of lactococcus lactis subsp. lactis t-80 cells with trp-p1. | | 1994 | 8063968 |
| purification and characterization of two phosphoglucomutases from lactococcus lactis subsp. lactis and their regulation in maltose- and glucose-utilizing cells. | two distinct forms of phosphoglucomutase were found in lactococcus lactis subsp. lactis, strains 19435 and 65.1, growing on maltose: beta-phosphoglucomutase (beta-pgm), which catalyzes the reversible conversion of beta-glucose 1-phosphate to glucose 6-phosphate in the maltose catabolism, and alpha-phosphoglucomutase (alpha-pgm). beta-pgm was purified to more than 90% homogeneity in crude cell extract from maltose-grown lactococci, and polyclonal antisera to the enzyme were prepared. the molecula ... | 1994 | 8071206 |
| identification of int and attp on the genome of lactococcal bacteriophage tuc2009 and their use for site-specific plasmid integration in the chromosome of tuc2009-resistant lactococcus lactis mg1363. | the dna sequence of the int-attp region of the small-isometric-headed lactococcal bacteriophage tuc2009 is presented. in this region, an open reading frame, int, which potentially encodes a protein of 374 amino acids, representing the tuc2009 integrase, was identified. the nucleotide sequence of the bacteriophage attachment site, attp, and the sequences of attb, attl, and attr in the lysogenic host lactococcus lactis subsp. cremoris uc509 were determined. a sequence almost identical to the uc509 ... | 1994 | 8074513 |
| purification and properties of the alpha-acetolactate decarboxylase from lactococcus lactis subsp. lactis ncdo 2118. | alpha-acetolactate decarboxylase from lactococcus lactis subsp. lactis ncdo 2118 was expressed at low levels in cell extracts and was also unstable. the purification was carried out from e. coli in which the enzyme was expressed 36-fold higher. the specific activity was 24-fold enhanced after purification. the main characteristics of alpha-acetolactate decarboxylase were: (i) activation by the three branched chain amino acids leucine, valine and isoleucine; (ii) allosteric properties displayed i ... | 1994 | 8076701 |
| the immune response to lactococcus lactis: implications for its use as a vaccine delivery vehicle. | the development of natural antibodies to lactococcus lactis in three inbred strains of mice and the effect of inoculating l. lactis into these mice has been investigated. all animals developed detectable levels of natural (systemic and secretory) anti-lactococcal antibodies. systemic anti-lactococcal antibodies were principally igg in young mice. an increase in anti-lactococcal igm occurred in all older animals. inoculation of l. lactis strains mg1820 or mg1363 by the oral and parenteral routes ... | 1994 | 8076800 |
| genetic analysis of the minimal replicon of the lactococcus lactis subsp. lactis biovar diacetylactis citrate plasmid. | using a combination of mutagenesis with the transposon gamma delta and polymerase chain reaction subcloning, the essential elements of the replication region of the lactococcus lactis subsp. lactis biovar diacetylactis citrate plasmid have been identified. an open reading frame, coding for a protein with homology to rep proteins from other lactococcus plasmids, is essential. this protein is trans-acting and could not be replaced by the rep protein from another lactococcus plasmid. a second open ... | 1994 | 8078463 |
| the majority of lactococcal plasmids carry a highly related replicon. | dna sequence analysis and southern hybridizations, together with complementation experiments, were used to study relationships between lactococcal plasmid replicons. pwvo2, pwvo4 and pwvo5, which co-exist in lactococcus lactis subsp. cremoris wg2, and pil7 (isolated from another strain) all contained a functional replication region which appeared to be very similar to that of some known lactococcal plasmids. they contain a gene encoding a highly conserved repb protein (60-80% amino acid identity ... | 1994 | 8081493 |
| cloning, sequencing and comparison of three lactococcal l-lactate dehydrogenase genes. | the conversion of pyruvate to lactate is a key feature of lactococcal strains. the enzyme which facilitates this conversion, l-lactate dehydrogenase (ldh), and the gene which encodes it (idh), are therefore of great significance. this paper presents the cloning and dna sequence analysis of three further lactococcal genes which are of key importance in the genetic manipulation of commercial starter strains. the idh gene from lactococcus lactis subsp. lactis biovar diacetylactis bu2-60 has been is ... | 1994 | 8081494 |
| membrane-associated proteins encoded by the nisin gene cluster may function as a receptor for the lantibiotic carnocin ui49. | carnocin ui49, a lantibiotic produced by carnobacterium piscicola shows bactericidal activity against many lactic acid bacteria. this paper describes the results of a study on the mode of action of carnocin ui49. it has previously been observed that nisin-producing lactococcus lactis subsp. lactis strains are at least 10-fold more sensitive to carnocin ui49 relative to other lactic acid bacteria. addition of carnocin ui49 to cells of l. lactis subsp. lactis nz9700 resulted in a dissipation of th ... | 1994 | 8081505 |
| bglr protein, which belongs to the bglg family of transcriptional antiterminators, is involved in beta-glucoside utilization in lactococcus lactis. | a fragment of the lactococcus lactis chromosome containing an open reading frame of 265 codons, denoted bglr, has been characterized. the polypeptide encoded by bglr shares 36 to 30% sequence identity with a family of regulatory proteins including arbg from erwinia chrysanthemi, bglg from escherichia coli, and sact and sacy from bacillus subtilis. these regulatory proteins are involved in positive control of the utilization of different sugars by transcription antitermination. for some of these ... | 1994 | 8083160 |
| monoclonal antibody-based enzyme immunoassay for pediocins of pediococcus acidilactici. | monoclonal antibody (mab) r2-ar against pediocin rs2 was developed. mice were immunized for 12 weeks with pediocin rs2 conjugated to a polyacrylamide gel. two hybridoma fusions yielded an mab that in western blots (immunoblots) reacted only with pediocins rs2 and ach (3 kda) from pediococcus acidilactici rs2 and h, respectively, and did not react with any other bacteriocin, including sakacin a from lactobacillus sake lb 706, leuconocin lcm1 from leuconostoc carnosum lm1, nisin from lactococcus l ... | 1994 | 8085814 |
| [the development of a nutrient medium for nisin-producing streptococci utilizing the waste products from a number of biotechnology plants]. | the possibility of using some waste products of the dairy and agricultural industries as nutrient substrates for the cultivation of nisin-producing streptococci was studied. yeast production wastes as well as potato liquor, whey and dried whey as waste products were shown suitable for the growth of streptococcus lactis and the biosynthesis of nisin. the level of the nisin production increased when corn steep liquor and glucose were added to whey and dried whey respectively. | 1993 | 8085890 |
| a conserved sequence in trna and rrna promoters of lactococcus lactis. | a trna operon (trna) from lactococcus lactis consisting of seven trna genes and a 5s rrna gene was cloned and sequenced. promoter-fusion of the trna promoter to a promoter-less beta-galactosidase gene of leuconostoc mesenteroides resulted in high levels of beta-galactosidase activity in l. lactis. searching for sequences with similarity to the sequence of the promoter region revealed a consensus sequence of promoters preceeding rrna operons and trna operons from lactococcus species including a n ... | 1994 | 8086451 |
| degradation and debittering of a tryptic digest from beta-casein by aminopeptidase n from lactococcus lactis subsp. cremoris wg2. | the mode of action of purified aminopeptidase n from lactococcus lactis subsp. cremoris wg2 on a complex peptide mixture of a tryptic digest from bovine beta-casein was analyzed. the oligopeptides produced in the tryptic digest before and after aminopeptidase n treatment were identified by analysis of the n- and c-terminal amino acid sequences and amino acid compositions of the isolated peptides and by on-line liquid chromatography-mass spectrometry. incubation of purified peptides with aminopep ... | 1993 | 8100130 |
| characterization of the lactococcal temperate phage tp901-1 and its site-specific integration. | the temperate lactococcal phage tp901-1, induced by uv light from lactococcus lactis subsp. cremoris 901-1, was characterized. the restriction map was found to be circular, and the packaging of tp901-1 dna was concluded to occur by a headful mechanism. the pac region was localized on the 38.4-kb phage genome. tp901-1 belongs to the class of p335 phages (v. braun, s. hertwig, h. neve, a. geis, and m. teuber, j. gen. microbiol. 135:2551-2560, 1989). evidence is presented that the phages tp936-1 (v ... | 1994 | 8106318 |
| influence of amino acid substitutions in the nisin leader peptide on biosynthesis and secretion of nisin by lactococcus lactis. | structural genes for small lanthionine-containing antimicrobial peptides, known as lantibiotics, encode n-terminal leader sequences which are not present in the mature peptide, but are cleaved off at some stage in the maturation process. leader sequences of the different lantibiotics share a number of identical amino acid residues, but they are clearly different from sec-dependent protein export signal sequences. we studied the role of the leader sequence of the lantibiotic nisin, which is produ ... | 1994 | 8106398 |
| carnocin ui49, a potential biopreservative produced by carnobacterium piscicola: large scale purification and activity against various gram-positive bacteria including listeria sp. | this paper describes a simple purification method for the purification of carnocin ui49, a potential biopreservative produced by carnobacterium piscicola ui49. the protocol was also applicable for the isolation of nisin z, which is a biopreservative produced by lactococcus lactis sik-83. the protocol consists of only two purification steps, xad chromatography and cation exchange chromatography. it is quick, easy, and can be used for large scale purification of these lantibiotics. the bactericida ... | 1993 | 8110598 |
| antimicrobial activity of neutralized extracellular culture filtrates of lactic acid bacteria isolated from a cultured indian milk product ('dahi'). | neutralized extracellular culture filtrate obtained from isolates of lactobacillus acidophilus, lactobacillus delbruecki ssp. bulgaricus, lactobacillus salivarius and lactococcus lactis ssp. lactis from 'dahi' showed weak to moderate inhibition of staphylococcus aureus, bacillus cereus, escherichia coli, bacillus brevis, bacillus circulans, bacillus coagulans, bacillus laterosporus, bacillus subtilis and pseudomonas aeruginosa when tested by the diffusion agar well assay method. the effective mi ... | 1993 | 8110603 |
| gene transfer from engineered lactococcus lactis strains to enterococcus faecalis in the digestive tract of gnotobiotic mice. | the introduction of genetically modified organisms into food products requires an evaluation of the behaviour and the dissemination of foreign genes of such organisms among the human intestinal microflora. the conjugal transfer, both in vitro and in vivo (in mice digestive tract) of dna from lactococcus lactis donor strains to an enterococcus faecalis strain isolated from human faecal flora was studied. we followed the transfer of (1) the self-transmissible plasmid pil205; (2) two non-self-trans ... | 1993 | 8111532 |
| identification of genes encoding ribosomal protein l33 from bacillus licheniformis, thermus thermophilus and thermotoga maritima. | three previously unrecognized genes from bacillus licheniformis, thermus thermophilus and thermotoga maritima, encoding ribosomal protein l33, have been identified and designated as rpmg genes. their sequence and context have been compared with the three known rpmg genes from escherichia coli, lactococcus lactis and b. subtilis. previously unrecognized open reading frames homologous to sece are located immediately downstream from rpmg in b. licheniformis, t. thermophilus and ta. maritima: beyond ... | 1994 | 8112583 |
| nucleotide metabolism in lactococcus lactis: salvage pathways of exogenous pyrimidines. | by measuring enzyme activities in crude extracts and studying the effect of toxic analogs (5-fluoropyrimidines) on cell growth, the metabolism of pyrimidines in lactococcus lactis was analyzed. pathways by which uracil, uridine, deoxyuridine, cytidine, and deoxycytidine are metabolized in l. lactis were established. they are similar to those found in escherichia coli except that lactococci are unable to utilize cytosine. | 1994 | 8113193 |
| growth phase-dependent regulation and membrane localization of spab, a protein involved in biosynthesis of the lantibiotic subtilin. | the information responsible for biosynthesis of the lantibiotic subtilin is organized in an operon-like structure that starts with the spab gene. the spab gene encodes an open reading frame consisting of 1,030 amino acid residues, and it was calculated that a protein having a theoretical molecular mass of 120.5 kda could be produced from this gene. this is consistent with the apparent molecular weight for spab of 115,000 which was estimated after sodium dodecyl sulfate-gel electrophoresis and id ... | 1994 | 8117069 |
| characterization of the lactobacillus helveticus cnrz32 pepc gene. | sequence analysis of the aminopeptidase c gene (pepc) from lactobacillus helveticus cnrz32 identified a 1,332-nucleotide open reading frame coding for a polypeptide with motifs characteristic of cysteine proteinases. homology to the pepc gene appears to be widely distributed among lactic acid bacteria. | 1994 | 8117086 |
| analysis of the cos region of the lactococcus lactis bacteriophage sk1. | the location, structure and nature of the cos site of the lactococcus lactis bacteriophage sk1 was determined using a taq dna polymerase runoff sequencing technique. the cos site contains a single-stranded 3' overhang of 11 nucleotides. the region surrounding cos contains several features which may be involved in the binding and catalytic action of a phage terminase. these include four putative terminase-binding sites which show some homology to lambda r-sites, an 11-bp direct repeat, a 10-bp in ... | 1994 | 8125289 |
| cloning and sequence analysis of the dnak gene region of lactococcus lactis subsp. lactis. | a 5.4 kb hindiii fragment of lactococcus lactis subsp. lactis was identified using a homologous dnak probe generated by pcr and cloned in escherichia coli. upstream sequences were generated by inverse pcr. the two cloned fragments partially overlapped, and sequencing of 5915 bp revealed the presence of four open reading frames in the order orf1-grpe-dnak-orf4. orf1 encodes a 39 kda protein of unknown function which shows considerable sequence homology with the orf39 and orfa proteins of bacillus ... | 1993 | 8126443 |
| cloning and sequence analysis of the gene encoding lactococcus lactis malolactic enzyme: relationships with malic enzymes. | malolactic enzyme is the key enzyme in the degradation of l-malic acid by lactic acid bacteria. using degenerated primers designed from the first 20 n-terminal amino acid sequence of lactococcal malolactic enzyme, a 60-bp dna fragment containing part of the mles gene was amplified from lactococcus lactis in a polymerase chain reaction. this specific probe was used to isolate two contiguous fragments covering the gene as a whole. the 1.9-kb region sequenced contains an open reading frame of 1623 ... | 1994 | 8132158 |
| crystallization and preliminary x-ray analysis of pepc, a thiol aminopeptidase from lactoccocus lactis homologous to bleomycin hydrolase. | crystals of the recombinant thiol aminopeptidase pepc, from lactoccocus lactis, have been obtained using the hanging-drop method of vapor diffusion from ammonium sulfate solutions. crystals are rhombohedral, the space group is r32, a = 175.2 a, c = 94.5 a (hexagonal setting). the asymmetric unit probably contains one monomer of a hexameric molecule-arrangement of 300 kda which exhibits the crystallographic point group of symmetry 32. the crystals diffract to at least 3 a resolution. | 1994 | 8133515 |
| use of the escherichia coli beta-glucuronidase (gusa) gene as a reporter gene for analyzing promoters in lactic acid bacteria. | a transcriptional fusion vector, designated pnz272, based on the promoterless beta-glucuronidase gene (gusa) of escherichia coli as a reporter gene, has been constructed for lactic acid bacteria. the replicon of pnz272 was derived from the lactococcus lactis plasmid psh71, allowing replication in a wide range of gram-positive bacteria and e. coli. the applicability of pnz272 and the expression of the gusa gene in l. lactis was demonstrated in shotgun cloning experiments with lactococcal chromoso ... | 1994 | 8135517 |
| effect of a defined continuous-flow derived bacterial culture and dietary lactose on salmonella typhimurium colonization in broiler chickens. | a defined bacterial culture protective against salmonella typhimurium cecal colonization in broiler chicks was derived utilizing a continuous-flow (cf) culture apparatus. chicks receiving the cf culture in combination with a diet containing dietary lactose were protected against cecal colonization by s. typhimurium. the culture consisted of a mixture of gram-positive and gram-negative facultative and strictly anaerobic bacteria. the isolates were identified as enterococcus avium, two strains of ... | 1993 | 8141728 |
| bactericidal potency of hydroxyl radical in physiological environments. | rates of radiolytic inactivation of bacteria suspended in n2o-saturated solutions were dramatically increased over normal background levels when the media contained chloride or bicarbonate ions. the bacteria could be protected from this enhanced toxicity by the addition of free radical scavengers (ethanol, ascorbate, hydrogen peroxide, mannitol, glucose, edta, picolinic acid), indicating that the lethal reactions were extracellular in origin. prior irradiation of chloride-containing solutions le ... | 1994 | 8144563 |
| identification and characterization of genes involved in excision of the lactococcus lactis conjugative transposon tn5276. | the 70-kb transposon tn5276, originally detected in lactococcus lactis nizo r5 and carrying the genes for nisin production and sucrose fermentation, can be conjugally transferred to other l. lactis strains. sequence analysis and complementation studies showed that the right end of tn5276 contains two genes, designated xis and int, which are involved in excision. the 379-amino-acid int gene product shows high (up to 50%) similarity with various integrases, including that of the tn916-related conj ... | 1994 | 8157585 |
| the di- and tripeptide transport protein of lactococcus lactis. a new type of bacterial peptide transporter. | lactococcus lactis takes up di- and tripeptides via a proton motive force-dependent carrier protein. the gene (dtpt) encoding the di-tripeptide transport protein of l. lactis was cloned by complementation of a dipeptide transport-deficient and proline auxotrophic escherichia coli strain. functional expression of the dipeptide transport gene was demonstrated by uptake studies of alanyl-[14c]glutamate and other peptides in e. coli cells. the di-tripeptide transport protein catalyzes proton motive ... | 1994 | 8157671 |
| specificity of hydrolysis of bovine kappa-casein by cell envelope-associated proteinases from lactococcus lactis strains. | the cell envelope-associated proteinases from lactococcus lactis subsp. cremoris h2 (a pi-type proteinase-producing strain) and sk11 (a piii-type proteinase-producing strain) both actively hydrolyze the kappa-casein component of bovine milk but with significant differences in the specificity of peptide bond hydrolysis. the peptide bonds ala-23-lys-24, leu-32-ser-33, ala-71-gln-72, leu-79-ser-80, met-95-ala-96, and met-106-ala-107 were cleaved by both proteinase types, although the relative rates ... | 1994 | 8161175 |
| regulation of nisin biosynthesis and immunity in lactococcus lactis 6f3. | the biosynthetic genes of the nisin-producing strain lactococcus lactis 6f3 are organized in an operon-like structure starting with the structural gene nisa followed by the genes nisb, nist, and nisc, which are probably involved in chemical modification and secretion of the prepeptide (g. engelke, z. gutowski-eckel, m. hammelmann, and k.-d. entian, appl. environ. microbiol. 58:3730-3743, 1992). subcloning of an adjacent 5-kb downstream region revealed additional genes involved in nisin biosynthe ... | 1994 | 8161176 |
| the cos region of lactococcal bacteriophage phi lc3. | the nucleotide sequence of the dna regions flanking the cohesive end site of the temperate lactococcal bacteriophage phi lc3 was determined. four pairs of sequence repeats of 8 to 13 base-pairs in length were revealed close to the cohesive ends. these repeats possibly represent signal sequences involved in phage dna maturation and packaging. the start of an open reading frame was localized only 42 nucleotides from the left end of the phi lc3 phage double-stranded region, implying that transcript ... | 1993 | 8161824 |
| inhibition of the phosphoenolpyruvate:lactose phosphotransferase system and activation of a cytoplasmic sugar-phosphate phosphatase in lactococcus lactis by atp-dependent metabolite-activated phosphorylation of serine 46 in the phosphocarrier protein hpr. | lactococcus lactis takes up lactose and the nonmetabolizable lactose analogue, thiomethyl-beta-galactoside (tmg), via the phosphoenolpyruvate:sugar phosphotransferase system (pts) which couples sugar transport to sugar phosphorylation. earlier studies had shown that tmg-phosphate, previously accumulated in l. lactis cells, is rapidly dephosphorylated in the cytoplasm and effluxes from the cells upon addition of glucose and that glucose inhibits further uptake of tmg. we have developed a vesicula ... | 1994 | 8163482 |
| a variant of the staphylococcal chloramphenicol resistance plasmid pc194 with enhanced ability to transform lactococcus lactis subsp. lactis. | in our attempts to transform lactococcus lactis subsp. lactis with pc194, a staphylococcal chloramphenicol resistance plasmid, only a few transformants could be obtained and only when relatively large amounts of plasmid dna were used. however, when pc194 dna from lactococcal transformants was introduced back to staphylococcus aureus and reisolated, it could be retransformed into l. lactis at substantially higher frequencies. it was concluded that pc194 had undergone mutation expanding its host r ... | 1994 | 8171121 |
| application of the ligase chain reaction to the detection of nisina and nisinz genes in lactococcus lactis ssp. lactis. | this paper reports on the application of the ligase chain reaction (lcr) to the specific detection of variants of the nisin structural gene (nisina and nisinz) in nisin producing strains of lactococcus lactis ssp lactis. the lcr assay was used to screen nisin producing strains to determine which form of the nisin structural gene they contained. this method of differentiating the nisin structural gene variants provides a useful alternative to the only other available genetic differentiation, that ... | 1994 | 8181709 |
| cloning and sequencing of the lactococcus lactis subsp. lactis dnak gene using a pcr-based approach. | the coding region for the dnak gene from lactococcus lactis subsp. lactis lm0230 was isolated and sequenced. an internal 789-bp fragment was amplified by the polymerase chain reaction (pcr) using a pair of degenerate oligodeoxyribonucleotide primers designed on the basis of amino acid (aa) sequences conserved in a number of dnak. this pcr product was cloned, sequenced and used as a southern hybridization probe to locate the flanking regions of the gene. the sequence of this central region from d ... | 1994 | 8181763 |
| tripeptidase gene (pept) of lactococcus lactis: molecular cloning and nucleotide sequencing of pept and construction of a chromosomal deletion mutant. | the gene encoding a tripeptidase (pept) of lactococcus lactis subsp. cremoris (formerly subsp. lactis) mg1363 was cloned from a genomic library in puc19 and subsequently sequenced. the tripeptidase of l. lactis was shown to be homologous to pept of salmonella typhimurium with 47.4% identity in the deduced amino acid sequences. l. lactis pept was enzymatically active in escherichia coli and allowed growth of a peptidase-negative leucine-auxotrophic e. coli strain by liberation of leu from a tripe ... | 1994 | 8188586 |
| characterization of is905, a new multicopy insertion sequence identified in lactococci. | is905 is a multicopy insertion sequence identified in lactococcus lactis. it is 1313 bp long, bounded by 28-bp imperfect inverted repeats, and encodes a putative transposase of 391 amino acids. one end of is905 contains sequences that are potentially promoter active. it displays sequence homology to the is256 class of elements. | 1994 | 8195098 |
| identification of a novel cell wall-associated endopeptidase in lactococcus lactis subspecies cremoris sk11. | | 1994 | 8206261 |
| purification and characterization of a cell wall peptidase from lactococcus lactis subsp. cremoris imn-c12. | a peptidase from the cell wall fraction of lactococcus lactis subsp. cremoris imn-c12 has been purified to homogeneity by hydrophobic interaction chromatography, two steps of anion-exchange chromatography, and gel filtration. the molecular mass of the purified enzyme was estimated to be 72 kda by gel filtration and 23 kda by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the enzyme has a pi of 4.0, and it has the following n-terminal sequence from the 2nd to the 17th amino acid resid ... | 1993 | 8215377 |
| nucleotide sequence of the lactococcus lactis ncdo 763 (ml3) rpod gene. | the complete nucleotide sequence of rpod gene from lactococcus lactis has been determined. the nucleotide data have indicated the presence of an open reading frame of 1020 base pairs encoding a polypeptide which shares the framework structure for principal sigma factors of eubacteria strains. | 1993 | 8218400 |
| sequence analysis of the lysin gene region of the prolate lactococcal bacteriophage c2. | approximately 80% of the genome of the prolate-headed lactococcal bacteriophage c2 was cloned into shuttle vectors psa3 and pfx3 in escherichia coli and transferred to lactococcus lactis. a 1.67-kilobase ecorv fragment containing the gene for the phage lysin was identified and the position and orientation of the phage lysin gene in the physical map of the phage were determined. the phage lysin was expressed in e. coli and its sequence was determined and compared with the sequences of other bacte ... | 1993 | 8221377 |
| conjugal transfer of the determinants for bacteriocin (lacticin 481) production and immunity in lactococcus lactis subsp. lactis cnrz 481. | the lacticin 481-producer (lct+), l. lactis subsp. lactis (l. lactis) cnrz 481 harbours 5 plasmids of 6.5, 7.5, 20, 37 and 69 kb. novobiocin treatment of l. lactis 481 led to the appearance of lacticin 481 deficient variants which had all lost the 69 kb plasmid. conjugal transfer of the lacticin 481 structural gene (lct) into the plasmid free strain l. lactis il1441 yielded lct+ transconjugants at a 10(-4) frequency, which carried a plasmid with an apparent size of 120-130 kb. southern hybridiza ... | 1993 | 8224796 |
| the contribution of lactococcal starter proteinases to proteolysis in cheddar cheese. | the contribution of the lactococcal proteinase to proteolysis and flavor development in cheddar cheese was investigated using the starter strains lactococcus lactis ssp. lactis uc317, its proteinase-negative derivative fh041, and variants of uc317 modified in proteinase production, location, and specificity. lactococcus lactis ssp. lactis fh041 was transformed by electroporation with plasmids pci3601, pci3602, or pnz521. plasmids pci3601 and pci3602 harbor the cloned proteinase genes of l. lacti ... | 1993 | 8227650 |
| genetic and biochemical characterization of the oligopeptide transport system of lactococcus lactis. | the nucleotide sequence of a chromosomal dna fragment of lactococcus lactis subsp. lactis ssl135, previously implicated in peptide utilization, has been determined. the genes oppdfbca, encoding the oligopeptide transport system (opp), and that encoding the endopeptidase pepo were located on this 8.9-kb dna fragment. the oppdfbca and pepo genes are probably organized in an operon. analysis of the deduced amino acid sequences of the genes indicated that the oligopeptide transport system consists o ... | 1993 | 8244921 |
| septic arthritis and unpasteurised milk. | green-top, or unpasteurised, milk is an increasing source of illness. a case of a previously unreported cause of septic arthritis of the hip joint, secondary to the ingestion of raw milk is reported. | 1993 | 8254098 |
| detection, identification and characterization of bacteriocin-producing lactic acid bacteria from retail food products. | forty bacteriocin-producing (bac+) lactic acid bacteria (lab) were isolated from food samples purchased from retail supermarkets and local farms. of the 40 bac+ isolates, 18 were isolated from 85 food samples by enrichment (21% isolation rate) whereas eight were obtained from 63 samples by direct plating (13% isolation rate). by direct plating, bac+ lab were detected at levels up to 2.4 x 10(5) cfu/g in ready-to-eat meats. the bac+ isolates were identified by carbohydrate fermentation patterns, ... | 1993 | 8257654 |
| [lantibiotics, a class of ribosomally synthesized peptide antibiotics]. | lantibiotics are defined as peptide antibiotics containing the unusual amino acids mesolanthionine, 3-methyllanthionine, dehydroalanine, and dehydrobutyrine. they are synthesized by some gram-positive bacteria. their inhibitory effect on certain other gram-positive bacteria is explained by detergent-like damage of cytoplasmic membranes. prominent members of the lantibiotics are nisin of lactococcus lactis, which can be used as a food preservative, subtilin of bacillus subtilis, which is similar ... | 1993 | 8264800 |
| insertion sequence analysis of protoplast fused strains of lactococcus lactis ssp. cremoris. | the use of insertion sequence probes for the analysis of fusants obtained following protoplast fusion is described. hybridization of both total and plasmid dna from parent and fusant strains with probes to is904 and iss1 showed that of the four protoplast fusions examined, three appeared to involve a rearrangement of genetic material while in the fourth the fusant appeared similar to one of the parental strains. this method of analysis provides more information about the changes induced by proto ... | 1993 | 8270197 |
| isolation, characterization and nucleotide sequence of the streptococcus mutans lactose-specific enzyme ii (lace) gene of the pts and the phospho-beta-galactosidase (lacg) gene. | the lace and lacg genes from streptococcus mutans have been isolated and characterized, and their nucleotide sequence has been determined. the lace gene encodes the lactose-specific enzyme ii component of the phosphoenolpyruvate-dependent phosphotransferase system (pts). the lacg gene encodes the phospho-beta-galactosidase which cleaves the lactose phosphate that is formed by the lactose pts. the s. mutans lace and lacg genes are located in the same operon as the tagatose genes. s. mutans metabo ... | 1993 | 8277252 |
| diversity of cell envelope proteinase specificity among strains of lactococcus lactis and its relationship to charge characteristics of the substrate-binding region. | the biochemical and genetical diversity of the subtilisin-like cell envelope proteinase (cep) among lactococcus lactis strains was investigated. the specificities of the proteinases of 16 strains toward the important cheese peptide alpha s1-casein fragment 1 to 23 and toward two differently charged chromophoric peptides have been determined. on the basis of the results, these strains could be classified into seven groups. the contribution to the specificity of specific residues in the large c-te ... | 1993 | 8285671 |
| a model system for the investigation of heterologous protein secretion pathways in lactococcus lactis. | the capacity of recombinant strains of lactococcus lactis to secrete a heterologous protein was investigated by constructing two expression-secretion vectors (plet2 and plet3) for use with a lactococcal gene expression system driven by the highly active t7 rna polymerase. the vectors incorporated different lactococcal secretion leaders and translation initiation sequences. when tetanus toxin fragment c (ttfc) was used as a test protein, the quantities of ttfc produced by the plet2-ttfc strain ex ... | 1993 | 8285699 |
| differences in sensitivity to nadh of purified pyruvate dehydrogenase complexes of enterococcus faecalis, lactococcus lactis, azotobacter vinelandii and escherichia coli: implications for their activity in vivo. | the effect of nadh on the activity of the purified pyruvate dehydrogenase complexes (pdhc) of enterococcus (ec.) faecalis, lactococcus lactis, azotobacter vinelandii and escherichia coli was determined in vitro. it was found that the pdhc of e. coli and l. lactis was active only at relatively low nadh/nad ratios, whereas the pdhc of ec. faecalis was inhibited only at high nadh/nad ratios. the pdhc of azotobacter vinelandii showed an intermediate sensitivity. the organisms were grown in chemostat ... | 1993 | 8288104 |
| conservation of a transcription antitermination mechanism in aminoacyl-trna synthetase and amino acid biosynthesis genes in gram-positive bacteria. | most of the aminoacyl-trna synthetase genes identified to date in the gram-positive bacterium bacillus subtilis have been found to be regulated by readthrough of a transcriptional terminator located in the mrna leader region, upstream of the start of the coding sequence. all of these leader regions contain a series of conserved structural features, as well as a single codon displayed at a precise position within the structure, which has been shown for tyrs to be responsible for the specificity o ... | 1994 | 8289305 |
| llaai and llabi, two type-ii restriction endonucleases from lactococcus lactis subsp. cremoris w9 and w56 recognizing, respectively, 5'-/gatc-3' and 5'-c/tryag-3'. | two type-ii restriction endonucleases have been purified from lactococcus lactis subsp. cremoris w9 and w56, the strains isolated from a mixed cheddar starter. their characterization showed that llaai was an isoschizomer of mboi from morexella bovis with the cleaving sequence, 5'/gatc-3', being sensitive to methylation of the adenine residue; llabi was an isoschizomer to sfci from streptococcus faceium with the cleaving sequence, 5'-c/tryag-3'. both llaai and llabi restriction-modification (r-m) ... | 1993 | 8294035 |
| 6-phospho-beta-galactosidases of gram-positive and 6-phospho-beta-glucosidase b of gram-negative bacteria: comparison of structure and function by kinetic and immunological methods and mutagenesis of the lacg gene of staphylococcus aureus. | the 6-phospho-beta-galactosidase of staphylococcus aureus, lactococcus lactis and lactobacillus casei and 6-phospho-beta-glucosidase b of escherichia coli build a subfamily inside a greater enzyme family, named the glycosal hydrolase family 1, which, in addition, contains nine beta-glycosidases of different origins. kinetic and immunological evidence is provided in this report which strengthens the relationship of the four 6-phospho-beta-glycosidases. it is shown that the 6-phospho-beta-galactos ... | 1993 | 8309940 |
| engineering of the substrate-binding region of the subtilisin-like, cell-envelope proteinase of lactococcus lactis. | the substrate-binding region of the cell-envelope proteinase of lactococcus lactis strain sk11 was modelled, based on sequence homology of the catalytic domain with the serine proteinases subtilisin and thermitase. substitutions, deletions and insertions were introduced, by site-directed and cassette mutagenesis of the prtp gene encoding this enzyme, based on sequence comparison both with subtilisin and with the homologous l.lactis strain wg2 proteinase, which has different proteolytic propertie ... | 1993 | 8309942 |
| proteolytic enzymes of lactococcus lactis. | | 1993 | 8320375 |
| the mip family of integral membrane channel proteins: sequence comparisons, evolutionary relationships, reconstructed pathway of evolution, and proposed functional differentiation of the two repeated halves of the proteins. | the major intrinsic protein (mip) of the bovine lens fiber cell membrane was the first member of the mip family of proteins to be sequenced and characterized. it is probably a homotetramer with transmembrane channel activity that plays a role in lens biogenesis or maintenance. the polypeptide chain of each subunit may span the membrane six times, and both the n- and c-termini face the cell cytoplasm. eighteen sequenced or partially sequenced proteins from bacteria, yeast, plants, and animals hav ... | 1993 | 8325040 |
| b-cell mitogen produced by slime-forming, encapsulated lactococcus lactis ssp. cremoris isolated from ropy sour milk, viili. | a substance, active as a b-cell mitogen, was isolated from the slime products produced by lactococcus lactis ssp. cremoris kvs20. the mitogenic substance was prepared by anion-exchange chromatography and gel filtration chromatography and then purified by proteinase digestion and hplc. chemical analysis determined that the mitogenic substance was a phosphopolysaccharide and consisted of rhamnose, glucose, galactose, and phosphorus. the activity of the mitogenic substance was higher than that of t ... | 1993 | 8326024 |
| gene inactivation in lactococcus lactis: branched-chain amino acid biosynthesis. | the lactococcus lactis subsp. lactis strains isolated from dairy products are auxotrophs for branched-chain amino acids (leucine, isoleucine, and valine), while most strains isolated from nondairy media are prototrophs. we have cloned and sequenced the leu genes from one auxotroph, il1403. the sequence is 99% homologous to that of the prototroph ncdo2118, which was determined previously. two nonsense mutations and two small deletions were found in the auxotroph sequence, which might explain the ... | 1993 | 8331070 |
| the fermentation of trahanas: a milk-wheat flour combination. | the fermented food, trahanas (a milk-wheat flour combination prepared in greece), was studied to determine the microbiological and chemical changes that occur during fermentation. it is a lactic acid bacterial fermentation in which streptococcus lactis, streptococcus diacetylactis, leuconostoc cremoris, lactobacillus lactis, lactobacillus casei, lactobacillus bulgaricus and lactobacillus acidophilus play the major acid- and aroma-producing role. the whole fermentation lasts about 50 hours. the p ... | 1993 | 8332586 |
| the primary structure of phosphofructokinase from lactococcus lactis. | the primary amino acid sequence of phosphofructokinase (ec2.7.1.11) from lactococcus lactis, obtained by edman analysis of peptides obtained from proteolytic digestions, is mkriavltsggdapgmnaairavvrkaisegievyginhgyagmvagdif pltsasvgdkigrggtflysarypefaqvegqlagieqlkkfgiegvvvi ggdgsyhgamrltehgfpavglpgtidndivgtdftigfdtavstvvdal dkirdtssshnrtfvvevmgrnagdialnagiaagaddisipelefkfen vvnninkgyekgknhhiiivaegvmtgeefatklkeagykgdlrvsvlgh iqrggsptardrvlasrmgaravellrdgiggvavgirneelvespilgt aeegalfsltteggikvnnph ... | 1993 | 8333872 |
| structure, organization, and expression of the lct gene for lacticin 481, a novel lantibiotic produced by lactococcus lactis. | the structural gene for the lactococcal lantibiotic lacticin 481 (lct) has been identified and cloned using a degenerated 20-mer dna oligonucleotide based on the amino-terminal 7 amino acid residues of the purified protein. the transcription of the lct gene was analyzed, and its promoter was mapped. dna sequence analysis of the lct gene revealed an open reading frame encoding a peptide of 51 amino acids. comparison of its deduced amino acid sequence with the amino-terminal sequence and the amino ... | 1993 | 8344922 |
| characterization and frequency distribution of species of lactic acid bacteria involved in the processing of mawè, a fermented maize dough from benin. | lactic acid bacteria involved in the natural fermentation of both home-produced and commercial mawè were investigated during a 72 h fermentation period. lactobacillus spp. constitute the majority (94%) of the strains of the lactic acid bacteria isolated, among which 89% represent the betabacterium group. they include l. fermentum (biotype cellobiosus) (41%), l. fermentum or l. reuteri (19%), l. brevis (26%), l. confusus (less than 2%), l. curvatus (less than 1%) and l. buchneri (less than 1%). o ... | 1993 | 8347427 |
| improved cloning vectors and transformation procedure for lactococcus lactis. | four shuttle vectors (pmig 1, 2, 2h and 3) have been constructed based on the broad host-range plasmid pck1. all the pmig vectors possess a multiple cloning site containing 12 or more unique restriction enzyme sites, and are stably maintained at either high or low copy number in lactococcus lactis and in escherichia coli. by cloning the e. coli puc replicon into one of these vectors a plasmid was constructed which can replicate to high copy number in reca strains of e. coli. the broad host-range ... | 1993 | 8349525 |
| integration and gene replacement in the lactococcus lactis lac operon: induction of a cryptic phospho-beta-glucosidase in lacg-deficient strains. | insertions, replacement mutations, and deletions were introduced via single or double crossover recombination into the lace (enzyme iilac) and lacg (phospho-beta-galactosidase) genes of the lactococcus lactis chromosomal lacabcdfegx operon. lacg production was abolished in strains missing the lacg gene or carrying multicopy insertions in the lace gene that affected expression of the lacg gene. however, these lacg-deficient strains could still ferment lactose slowly and were found to contain an e ... | 1993 | 8349556 |
| identification and sequence analysis of the replication region of the phage resistance plasmid pci528 from lactococcus lactis subsp. cremoris uc503. | the replication region of the phage resistance plasmid pci528 from lactococcus lactis subsp. cremoris uc503 was localised to within a 10-kb hindiii restriction fragment. a 6.3-kb bglii-hindiii subclone of this fragment, cloned into a replication probe vector, allowed replication in lactococcus but not in bacillus or lactobacillus. sequence analysis revealed an orf of 1152 bp preceded by a putative ori region containing a 22-bp sequence tandemly repeated three and three-quarter times, a second sm ... | 1993 | 8354458 |
| presumptive fecal streptococci in environmental samples characterized by one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis. | the use of fecal streptococci as fecal indicators requires better knowledge of the ecology of these bacteria. we isolated 371 presumptive fecal streptococci from environmental samples--domestic wastewater, forest industry wastewater, contaminated surface and seawater, well water, cow dung, bird droppings, and pristine waters--and clustered them according to their protein profiles in one-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. some clusters could be tentati ... | 1993 | 8357252 |
| lactococcus lactis: high-level expression of tetanus toxin fragment c and protection against lethal challenge. | to determine if the food-grade bacterium lactococcus lactis holds promise as a vaccine antigen delivery vector we have investigated whether this bacterium can be made to produce high levels of a heterologous protein antigen. a regulated expression system has been developed which may be generally suitable for the expression of foreign antigens (and other proteins) in l. lactis. the system utilizes the fast-acting t7 rna polymerase to transcribe target genes, and provides the first example of the ... | 1993 | 8361360 |
| characteristics and osmoregulatory roles of uptake systems for proline and glycine betaine in lactococcus lactis. | lactococcus lactis subsp. lactis ml3 contains high pools of proline or betaine when grown under conditions of high osmotic strength. these pools are created by specific transport systems. a high-affinity uptake system for glycine betaine (betaine) with a km of 1.5 microm is expressed constitutively. the activity of this system is not stimulated by high osmolarities of the growth or assay medium but varies strongly with the medium ph. a low-affinity proline uptake system (km, > 5 mm) is expressed ... | 1993 | 8366030 |
| cloning of a chromosomal gene required for phage infection of lactococcus lactis subsp. lactis c2. | a phage-resistant mutant with a defect in a membrane component required for phage infections in lactococcus lactis subsp. lactis c2 was transformed with a chromosomal library of the wild-type, phage-sensitive strain. of the 4,200 transformants screened for phage sensitivity, three were positively identified as phage sensitive. a cause-and-effect relationship between the cloned chromosomal fragments and the phage-sensitive phenotype was established on the basis of the following two criteria: (i) ... | 1993 | 8366036 |
| biosynthesis and secretion of a precursor of nisin z by lactococcus lactis, directed by the leader peptide of the homologous lantibiotic subtilin from bacillus subtilis. | the dna sequence encoding the leader peptide of the lantibiotic subtilin from bacillus subtilis was fused to the sequence encoding pronisin z, and this hybrid gene was expressed in a lactococcus lactis strain that produces nisin a. this strain simultaneously secreted nisin a and a protein of approximately 6 kda. amino acid sequencing of the purified 6 kda protein and structural analysis of its main tryptic fragment by two-dimensional 1h-nmr showed that it consists of the unmodified leader peptid ... | 1993 | 8370453 |
| the use of bacterial luciferase genes as reporter genes in lactococcus: regulation of the lactococcus lactis subsp. lactis lactose genes. | lactose metabolism is an important industrial trait in dairy lactococci. in lactococcus lactis, lactose is taken up via the phosphoenolpyruvate-dependent phosphotransferase system (pep-pts) and is subsequently metabolized via the glycolytic and tagatose 6-phosphate pathways. genes for the lactose-specific pep-pts proteins, phospho-beta-galactosidase and tagatose 6-phosphate pathway enzymes are encoded by a single 8 kb operon, lacabcdfegx, and there is a divergently transcribed lacr repressor gen ... | 1993 | 8371112 |
| association of the lactococcin a immunity factor with the cell membrane: purification and characterization of the immunity factor. | the physicochemical characteristics of the lactococcin a immunity protein, as deduced from its gene sequence, were used to devise a procedure for its purification. the protein was purified from cell extracts by cation-exchange and reverse-phase chromatography. as judged from the amino acid composition and amino acid sequencing, the immunity protein is not post-translationally processed by cleavage at its n- or c-terminus. consequently, the absorption coefficient at 280 nm, the isoelectric point, ... | 1993 | 8371113 |
| efficient plasmid mobilization by pip501 in lactococcus lactis subsp. lactis. | pip501 is a streptococcal conjugative plasmid which can be transmitted among numerous gram-positive strains. to identify a minimal mobilization (mob) locus of pip501, dna fragments of pip501 were cloned into nonconjugative target plasmids and tested for mobilization by pip501. we show that nonmobilizable plasmids containing a specific fragment of pip501 are transmitted at high frequencies between lactococcus lactis subsp. lactis strains if transfer (tra) functions are provided in trans by a pip5 ... | 1993 | 8376328 |