| 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 |
| reverse dot blot hybridization: a useful method for the direct identification of lactic acid bacteria in fermented food. | a rapid method for a reliable and simultaneous identification of different lactic acid bacteria in fermented food has been developed. various 16s and 23s rrna-targeted, species-specific oligonucleotides were applied as capture probes in a non-radioactive reverse dot blot hybridization. a simple and fast dna extraction method in combination with in vitro amplification of rrna gene fragments enables the direct detection of typical starter organisms without any preceding enrichment or cultivation s ... | 1994 | 8181717 |
| 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 |
| effect of antioxidative lactic acid bacteria on rats fed a diet deficient in vitamin e. | lactic acid bacteria, including bifidobacterium, with antioxidative activity were selected by in vitro screening. the effect of the antioxidative activity was investigated by in vivo experiments using rats that were deficient in vitamin e. in the first stage of screening, 570 strains were examined; intracellular cell-free extracts of 19 strains (16 lactobacilli, 2 streptococci, and 1 lactococci) had antioxidative activity as determined by an assay using rat liver microsomes and thiobarbituric ac ... | 1993 | 8227652 |
| 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 |
| high- and low-copy-number lactococcus shuttle cloning vectors with features for clone screening. | high- and low-copy-number shuttle cloning vectors were constructed by incorporating the escherichia coli p15a plasmid origin of replication into the pam beta 1-derived vectors, pil252 and pil253. the resulting vectors were structurally stable in lactococcus, which is a common feature of theta-replicating plasmids, and also displayed good structural stability in e. coli, possibly due to lack of a resolvase-encoding gene. all the vectors expressed erythromycin resistance (err) in both; brain heart ... | 1993 | 8299952 |
| 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 |
| microflora present in kefir grains of the galician region (north-west of spain. | | 1993 | 8320374 |
| 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 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 |
| analysis of a region from the bacteriophage resistance plasmid pci528 involved in its conjugative mobilization between lactococcus strains. | a 10-kb hindiii fragment of pci528 cloned into the nonconjugative shuttle vector pci3340 could be transferred by conjugative mobilization from lactococcus lactis subsp. lactis mg1363, whereas other hindiii fragments of pci528 or the vector alone were nonmobilizable. subcloning of this 10-kb region identified a 4.4-kb bglii-ecori fragment which contained all the dna essential for transfer. sequence analysis of a 2-kb region within this 4.4 kb-segment revealed a region rich in inverted repeats and ... | 1993 | 8376345 |
| transposable elements in lactococci: a review. | genetic studies have identified the presence of transposable elements within the genus lactococcus, which includes industrially important microorganisms used in the production of fermented dairy products. three insertion sequences have been fully characterized in addition to several reports of transpositionlike events. the three insertion sequence elements, iss1, is904, and is981, exhibit the physical and genetic properties characteristic of known insertion sequences. they are closely related to ... | 1993 | 8382229 |
| two genes present on a transposon-like structure in lactococcus lactis are involved in a clp-family proteolytic activity. | the lactose-protease plasmid pucl22 of lactococcus lactis subsp. lactis strain cnrz270 contained two inverted copies of is 1076 flanking a region of 3.7 kb. this internal region was sequenced and found to contain two large open reading frames, orf1 and orfp in opposite orientations. orf1 consists of 2289 bp; the deduced 763-amino-acid sequence is similar to the atpases of the clpa family. it contains two well-conserved consensus atp-binding sites. it was named clpl. orfp consists of 930 bp encod ... | 1993 | 8387149 |
| copy number and location of insertion sequences iss1 and is981 in lactococci and several other lactic acid bacteria. | genomic dna from 49 lactococcal strains was screened by southern hybridization for the presence and relative copy number of lactococcal insertion sequence iss1: iss1 was found in 47 of 49 strains giving 1 to 20 hybridizing bands per strain. southern hybridizations of undigested plasmid dna from 17 lactococcal strains probed with iss1 and is981 showed that iss1 was present on plasmids in all 17 strains, whereas is981 was present on plasmids in 14 of the 17 strains. both insertion sequences were p ... | 1993 | 8389385 |
| insertion of lipids and proteins into bacterial membranes by fusion with liposomes. | | 1993 | 8395638 |
| phenotypic and phylogenetic evidence for a close relationship between lactococcus garvieae and enterococcus seriolicida. | cultural, biochemical and protein profiling studies were performed on l. garvieae strains isolated from diseased rainbow trout and on the fish pathogen enterococcus seriolicida atcc 49156. the results, confirmed by 16 rrna sequence analyses, indicate that e. seriolicida atcc 49156 should be reclassified in the genus lactococcus. contrary to previous reports, both l. garvieae and e. seriolicida were found to be beta-haemolytic. | 1993 | 8397967 |
| energy transduction in lactic acid bacteria. | in the discovery of some general principles of energy transduction, lactic acid bacteria have played an important role. in this review, the energy transducing processes of lactic acid bacteria are discussed with the emphasis on the major developments of the past 5 years. this work not only includes the biochemistry of the enzymes and the bioenergetics of the processes, but also the genetics of the genes encoding the energy transducing proteins. the progress in the area of carbohydrate transport ... | 1993 | 8398212 |
| the physiology and biochemistry of the proteolytic system in lactic acid bacteria. | the inability of lactic acid bacteria to synthesize many of the amino acids required for protein synthesis necessitates the active functioning of a proteolytic system in those environments where protein constitutes the main nitrogen source. biochemical and genetic analysis of the pathway by which exogenous proteins supply essential amino acids for growth has been one of the most actively investigated aspects of the metabolism of lactic acid bacteria especially in those species which are of impor ... | 1993 | 8398214 |
| organization and regulation of genes for amino acid biosynthesis in lactic acid bacteria. | the recent description of large clusters of biosynthetic genes in the chromosome of lactococcus lactis and, to a lesser extent, of lactobacillus, has brought some information on gene organization and control of gene expression in these organisms. the genes involved in a given amino acid biosynthetic pathway are clustered at a single chromosomal location and form an operon. additional genes which are not required for the biosynthesis are present within some operons. genetic signals are, in genera ... | 1993 | 8398216 |
| genetics of bacteriocins produced by lactic acid bacteria. | lactic acid bacteria produce a variety of bacteriocins that have recently come under detailed investigation. the biochemical and genetic characteristics of these antimicrobial proteins are reviewed and common elements are discussed between the different classes of bacteriocins produced by these gram-positive bacteria. | 1993 | 8398217 |
| characterization of bacteriocins from enterococcus faecium with activity against listeria monocytogenes. | laboratory cultures and environmental isolates of bacteria were screened for antagonism towards listeria monocytogenes using an agar spot test. seven of the 163 strains that were tested, one streptococcus bovis, one enterococcus casseliflavus, two e. avium and three e. faecium, consistently displayed antilisterial activity. cell-free, ph-neutralized supernatants prepared from the three e. faecium strains (jbl1061, jbl1083 and jbl1351) exhibited strong antilisterial activity against l. monocytoge ... | 1993 | 8398626 |
| cloning, sequence and expression of the gene encoding the malolactic enzyme from lactococcus lactis. | many lactic acid bacteria can carry out malolactic fermentation. this secondary fermentation is mediated by the nad- and mn(2+)-dependent malolactic enzyme, which catalyses the decarboxylation of l-malate to l-lactate. the gene we call mles, coding for malolactic enzyme, was isolated from lactococcus lactis. the mles gene consists of one open reading frame capable of coding for a protein with a calculated molecular mass of 59 kda. the amino acid sequence of the predicted mles gene product is hom ... | 1993 | 8405453 |
| rapid isolation of genes from bacterial lambda libraries by direct polymerase chain reaction screening. | a method for the direct screening of bacterial lambda libraries by polymerase chain reaction technology has been developed. this technique permits the identification and isolation of specific dna sequences without the need for any filter hybridisation or radioactive probing. this strategy has been used to isolate a gene encoding lactate dehydrogenase from a lactococcus lactis lambda library. | 1993 | 8405949 |
| cloning, nucleotide sequence and expression in streptomyces lividans and escherichia coli of pabb from lactococcus lactis subsp. lactis ncdo 496. | a gene (pabb) encoding the aminase activity of p-aminobenzoate (paba) synthase in lactococcus lactis subsp. lactis was cloned in pij41 and expressed in streptomyces lividans strains defective in paba biosynthesis. expression of the gene was associated with a 1.2 kb deletion between the aph promoter and the cloning site in pij41. subcloning in pbr322 and expression in escherichia coli ab3295 of the cloned l. lactis dna fragment localized the pabb-complementing gene in a 1.9 kb segment. the nucleo ... | 1993 | 8409921 |
| functional analysis of the lactococcus lactis usp45 secretion signal in the secretion of a homologous proteinase and a heterologous alpha-amylase. | the ups45 gene encodes the major extracellular protein from lactococcus lactis. the deduced sequence of the 27 residue leader peptide revealed the tripartite characteristics of a signal peptide. this leader peptide directed the efficient secretion of the homologous proteinase (prtp) in l. lactis, indicating that the putative signal peptide of prtp can be replaced by the 27 residue usp45 leader peptide. in addition, the 27 residue leader peptide could be used to secrete the bacillus stearothermop ... | 1993 | 8413193 |
| 15n- and 13c-labeled media from anabaena sp. for universal isotopic labeling of bacteriocins: nmr resonance assignments of leucocin a from leuconostoc gelidum and nisin a from lactococcus lactis. | a procedure for universal 13c and/or 15n labeling of microbial peptides which are produced by fermentation in complex media and its application to two food-preserving bacteriocins from lactic acid bacteria are described. isotopic enrichment of nisin a (from lactococcus lactis) and of leucocin a (from leuconostoc gelidum) is readily achieved using a soluble peptone derived from enzymatic hydrolysis (pepsin and chymopapain) of anabaena sp. atcc 27899 cells grown on sodium [13c]bicarbonate and/or s ... | 1993 | 8418850 |
| molecular analysis of lipid macroamphiphiles by hydrophobic interaction chromatography, exemplified with lipoteichoic acids. | analyzed were (i) the oligoglucosyl-, alanyl-substituted poly(glycerophosphate) lipoteichoic acid of enterococcus hirae containing glc(alpha 1-2)glc(alpha 1-3)acyl2-gro and a phosphatidyl derivative thereof as lipid anchor, (ii) the poly(digalactosyl, galactosylglycerophosphate) lipoteichoic acid of lactococcus garvieae containing the same glycolipid and an acyl derivative of it, and (iii) the n-acetylglucosaminyl-, alanyl-substituted poly(glycerophosphate)lipoteichoic acid of staphylococcus aur ... | 1993 | 8434795 |
| properties of nisin z and distribution of its gene, nisz, in lactococcus lactis. | two natural variants of the lantibiotic nisin that are produced by lactococcus lactis are known. they have a similar structure but differ in a single amino acid residue at position 27; histidine in nisin a and asparagine in nisin z (j.w.m. mulders, i.j. boerrigter, h.s. rollema, r.j. siezen, and w.m. de vos, eur. j. biochem, 201:581-584, 1991). the nisin variants were purified to apparent homogeneity, and their biological activities were compared. identical mics of nisin a and nisin z were found ... | 1993 | 8439149 |
| cloning and sequencing of pepc, a cysteine aminopeptidase gene from lactococcus lactis subsp. cremoris am2. | a gene coding for an aminopeptidase (pepc) from lactococcus lactis subsp. cremoris am2 was cloned by complementation of an escherichia coli mutant lacking aminopeptidase activity. the nucleotide sequence was determined. a portion of the predicted amino acid sequence of pepc (436 amino acids) showed strong homology to the active site of cysteine proteases. no signal sequence was found, indicating an intracellular location of the enzyme. | 1993 | 8439160 |
| stability analysis of the lactococcus lactis drc1 lactose plasmid using pulsed-field gel electrophoresis. | pulsed-field agarose gel electrophoresis of smai digests of genomic dna was used to examine lactose plasmid copy number and stability in lactococcus lactis. in l. lactis strain drc1, the plasmid was found to exist as a single-copy plasmid. transconjugants of strain hid113 carrying this plasmid were unstable. variants were isolated with improved phenotypic stability resulting from improved maintenance of the lactose plasmid or from integration of part of the plasmid into the lactococcal chromosom ... | 1993 | 8441771 |
| in vitro pore-forming activity of the lantibiotic nisin. role of protonmotive force and lipid composition. | nisin is a lantibiotic produced by some strains of lactococcus lactis subsp. lactis. the target for nisin action is the cytoplasmic membrane of gram-positive bacteria. nisin dissipates the membrane potential (delta psi) and induces efflux of low-molecular-mass compounds. evidence has been presented that a delta psi is needed for nisin action. the in vitro action of nisin was studied on liposomes loaded with the fluorophore carboxyfluorescein. nisin-induced efflux of carboxyfluorescein was observ ... | 1993 | 8444179 |
| production and characterization of antibacterial compounds produced by pediococcus damnosus and pediococcus pentosaceus. | the broad-spectrum antibacterial activity exhibited by three pediococcus strains isolated from beer was preliminarily characterized. factors affecting the production rate of bacterial inhibitors were screened and the effects of simultaneous cultivation of lactococcus and pediococcus on the production of inhibitory substances were studied. the antibacterial activity against a range of gram-negative test organisms was not affected by catalase or proteolytic enzymes and was extremely thermotolerant ... | 1993 | 8444642 |
| cloning, nucleotide sequence, and regulatory analysis of the lactococcus lactis dnaj gene. | the dnaj gene of lactococcus lactis was isolated from a genomic library of l. lactis nizo r5 and cloned into puc19. nucleotide sequencing revealed an open reading frame of 1,137 bp in length, encoding a protein of 379 amino acids. the deduced amino acid sequence showed homology to the dnaj proteins of escherichia coli, mycobacterium tuberculosis, bacillus subtilis, and clostridium acetobutylicum. the level of the dnaj monocistronic mrna increased approximately threefold after heat shock. the tra ... | 1993 | 8449872 |
| characterization of genetic elements required for site-specific integration of the temperate lactococcal bacteriophage phi lc3 and construction of integration-negative phi lc3 mutants. | the genetic elements required for the integration of the temperate lactococcal bacteriophage phi lc3 into the chromosome of its bacterial host, lactococcus lactis subsp. cremoris, were identified and characterized. the phi lc3 phage attachment site, attp, was mapped and sequenced. dna sequence analysis of attp and of the bacterial attachment site, attb, as well as the two phage-host junctions, attr and attl, in the chromosome of a phi lc3 lysogen, identified a 9-bp common core region, 5'-ttcttca ... | 1993 | 8449882 |
| gene organization, primary structure and rna processing analysis of a ribosomal rna operon in lactococcus lactis. | southern blot analysis of genomic dna of the mesophilic lactic bacterium lactococcus lactis subsp. lactis strain il1403, illuminated six rrna gene clusters. each cluster contains one copy each of three rrna genes, displaying the typical eubacterial organization of physically linked 16 s, 23 s and 5 s rrna genes. five of the six rrna clusters were cloned into plasmid pbr322. one recombinant plasmid, pslcm6, containing a 6500 base-pair genomic dna fragment, was characterized by physical mapping an ... | 1993 | 8450551 |
| di-tripeptides and oligopeptides are taken up via distinct transport mechanisms in lactococcus lactis. | lactococcus lactis ml3 possesses two different peptide transport systems of which the substrate size restriction and specificity have been determined. the first system is the earlier-described proton motive force-dependent di-tripeptide carrier (e. j. smid, a. j. m. driessen, and w. n. konings, j. bacteriol. 171:292-298, 1989). the second system is a metabolic energy-dependent oligopeptide transport system which transports peptides of four to at least six amino acid residues. the involvement of ... | 1993 | 8458848 |
| cloning and sequencing of the gene for a lactococcal endopeptidase, an enzyme with sequence similarity to mammalian enkephalinase. | the gene specifying an endopeptidase of lactococcus lactis, named pepo, was cloned from a genomic library of l. lactis subsp. cremoris p8-2-47 in lambda embl3 and was subsequently sequenced. pepo is probably the last gene of an operon encoding the binding-protein-dependent oligopeptide transport system of l. lactis. the inferred amino acid sequence of pepo showed that the lactococcal endopeptidase has a marked similarity to the mammalian neutral endopeptidase ec 3.4.24.11 (enkephalinase), wherea ... | 1993 | 8458851 |
| lysines 72, 80 and 213 and aspartic acid 210 of the lactococcus lactis lacr repressor are involved in the response to the inducer tagatose-6-phosphate leading to induction of lac operon expression. | site-directed mutagenesis of the lactococcus lactis lacr gene was performed to identify residues in the lacr repressor that are involved in the induction of lacabcdfegx operon expression by tagatose-6-phosphate. a putative inducer binding domain located near the c-terminus was previously postulated based on homology studies with the escherichia coli deor family of repressors, which all have a phosphorylated sugar as inducer. residues within this domain and lysine residues that are charge conserv ... | 1993 | 8475045 |
| identification of a novel operon in lactococcus lactis encoding three enzymes for lactic acid synthesis: phosphofructokinase, pyruvate kinase, and lactate dehydrogenase. | the discovery of a novel multicistronic operon that encodes phosphofructokinase, pyruvate kinase, and lactate dehydrogenase in the lactic acid bacterium lactococcus lactis is reported. the three genes in the operon, designated pfk, pyk, and ldh, contain 340, 502, and 325 codons, respectively. the intergenic distances are 87 bp between pfk and pyk and 117 bp between pyk and ldh. plasmids containing pfk and pyk conferred phosphofructokinase and pyruvate kinase activity, respectively, on their host ... | 1993 | 8478320 |
| characterization of the lactococcus lactis nisin a operon genes nisp, encoding a subtilisin-like serine protease involved in precursor processing, and nisr, encoding a regulatory protein involved in nisin biosynthesis. | biosynthesis of the lantibiotic peptide nisin by lactococcus lactis nizo r5 relies on the presence of the conjugative transposon tn5276 in the chromosome. a 12-kb dna fragment of tn5276 including the nisa gene and about 10 kb of downstream dna was cloned in l. lactis, resulting in the production of an extracellular nisin precursor peptide. this peptide reacted with antibodies against either nisin a or the synthetic leader peptide, suggesting that it consisted of a fully modified nisin with the n ... | 1993 | 8478324 |
| scrfi restriction-modification system of lactococcus lactis subsp. cremoris uc503: cloning and characterization of two scrfi methylase genes. | two genes from the total genomic dna of dairy starter culture lactococcus lactis subsp. cremoris uc503, encoding scrfi modification enzymes, have been cloned and expressed in escherichia coli. no homology between the two methylase genes was detected, and inverse polymerase chain reaction of flanking chromosomal dna indicated that both were linked on the lactococcus genome. neither clone encoded the cognate endonuclease. the dna sequence of one of the methylase genes (encoded by pci931m) was dete ... | 1993 | 8481004 |
| [utilization of lactic bacteria in the control of pathogenic microorganisms in food]. | the lactic acid bacteria have the potential to inhibit the growth of pathogenic and spoilage bacteria and the possibility exists of using them to improve the hygienic quality and to extend the shelf-life of different foods. among the many inhibitory substances produced by the lactic acid bacteria, the bacteriocins are of particular interest. it has been the objective of this work to review the bacteriocins produced by lactic acid bacteria from the genera lactococcus, lactobacillus and pediococcu ... | 1993 | 8484916 |
| cloning and sequencing of the lactococcus lactis subsp. lactis groesl operon. | the operon (groesl) coding for the lactococcus lactis subsp. lactis heat-shock proteins groel and groes, has been isolated and its complete nucleotide (nt) sequence determined. a set of degenerate pcr primers, deduced from amino acids which are conserved in a number of prokaryotic groels, were synthesized and used to amplify a 957-bp fragment. this pcr fragment was used as a probe to isolate a 5.0-kb ecori chromosomally derived fragment. a region of this 5.0-kb ecori fragment was sequenced and r ... | 1993 | 8486277 |
| enterocin 226nwc, a bacteriocin produced by enterococcus faecalis 226, active against listeria monocytogenes. | enterococcus faecalis 226, isolated from natural whey cultures utilized as starters in the manufacture of mozzarella cheese from water-buffalo milk, produces a bacteriocin designated enterocin 226nwc. the bacteriocin was isolated from culture supernatant fluids of the producer strain and was active against strains of the same species and listeria monocytogenes, but not against useful lactic acid bacteria. enterocin 226nwc is a protein with an apparent molecular weight of about 5800; it is relati ... | 1993 | 8486543 |
| monitoring tripeptidase activity using capillary electrophoresis. comparison with the ninhydrin assay. | capillary electrophoresis (ce) was used to assay the activity of a tripeptidase from a crude extract of lactococcus lactis subsp. lactis ncdo 712 against the substrate, gly-gly-phe and a comparison with a standard ninhydrin assay was made. standard curves of the substrates and products showed a significantly variable colorimetric reaction to ninhydrin making accurate quantification of the tripeptidase problematic. the ce assay further demonstrated that the presence of contaminating enzymes in cr ... | 1993 | 8491837 |
| influence of intracellular ph on light emission from a luxa/b derivative of lactococcus lactis subsp. diacetylactis. | high levels of constitutive aldehyde-dependent light emission were obtained from nongrowing cells of lactococcus lactis subsp. diacetylactis f712 transformed with iuxa/b when they were suspended in buffered solutions. inductions of light emission was time-dependent and was not due to growth, synthesis of luciferase or stimulation of metabolism by fermentable carbohydrate. the major factor controlling light emission in such cells appears to be the intracellular ph value. experiments with ionophor ... | 1993 | 8493883 |
| application of in vivo bioluminescence to the study of ionophoretic action. | ionophores (carbonyl cyanide m-chlorophenylhydrazone; valinomycin; and the hop-derived compounds colupulone, trans-isohumulone and trans-humulinic acid) reduced the rate of dodecanal-dependent light emission from iuxa/b-transformed cells of lactococcus lactis subsp. diacetylactis f712 when the cells were suspended in a buffered medium (ph 6.4) containing glucose. this allowed an assay for ionophores to be devised and permitted measurement of the effects of such compounds on the test organism by ... | 1993 | 8493884 |
| high-efficiency gene inactivation and replacement system for gram-positive bacteria. | a system for high-efficiency single- and double-crossover homologous integration in gram-positive bacteria has been developed, with lactococcus lactis as a model system. the system is based on a thermosensitive broad-host-range rolling-circle plasmid, pg+host5, which contains a pbr322 replicon for propagation in escherichia coli at 37 degrees c. a nested set of l. lactis chromosomal fragments cloned onto pg+host5 were used to show that the single-crossover integration frequency was logarithmical ... | 1993 | 8501066 |
| a simple, low energy requiring method of coagulating leaf proteins for food use. | a simple method for coagulating proteins in aqueous leaf extract, through microbial fermentation, has been reported. the leaf protein concentrate (lpc) obtained through this fermentation has been compared with those obtained through conventional heat coagulation methods to show that the former improves the yield and nutritional quality of lpc. | 1993 | 8506239 |
| cloning and expression of the manganese superoxide dismutase gene of escherichia coli in lactococcus lactis and lactobacillus gasseri. | the escherichia coli soda gene encoding the antioxidant enzyme mn-containing superoxide dismutase (mnsod), was cloned in the expression vector pmg36e. this vector has a multiple cloning site downstream of a promoter and shine-dalgarno sequences derived from lactococcus. the protein-coding region of soda from e. coli was amplified by the polymerase chain reaction, using a thermocycler and taq dna polymerase before cloning into pmg36e. when introduced into e. coli, the recombinant plasmid expresse ... | 1993 | 8510661 |
| 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 ... | 1995 | 8522504 |
| 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 ... | 1995 | 8522506 |
| 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 ... | 1995 | 8525063 |
| 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 ... | 1995 | 8526506 |
| 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 ... | 1995 | 8526510 |
| 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 ... | 1995 | 8526523 |
| 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 ... | 1995 | 8526524 |
| 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. | 1995 | 8526525 |