| analysis of the genetic determinant for production of the peptide antibiotic nisin. | the structural gene for the precursor of the peptide antibiotic nisin was isolated and characterized. as with other lanthionine-containing antibiotics, nisin is synthesized as a pre-propeptide which undergoes post-translational modification to generate the mature antibiotic. the sequence data obtained agreed with those of precursor nisin genes isolated by other workers from different lactococcus lactis strains. analysis of regions flanking the precursor nisin gene revealed the presence of a down ... | 1990 | 2118169 |
| relationship between utilization of proline and proline-containing peptides and growth of lactococcus lactis. | proline, which is the most abundant residue in beta-casein, stimulates growth of lactococcus lactis in a proline-requiring strain (lactococcus lactis subsp. cremoris wg2) and in a proline-prototrophic strain (lactococcus lactis subsp. lactis ml3). both strains lack a proline-specific uptake system, and free proline can enter the cell only by passive diffusion across the cytoplasmic membrane. on the other hand, lactococci can actively take up proline-containing peptides via the lactococcal di- an ... | 1990 | 2118509 |
| some chemical and physical properties of nisin, a small-protein antibiotic produced by lactococcus lactis. | nisin is a small gene-encoded antimicrobial protein produced by lactococcus lactis that contains unusual dehydroalanine and dehydrobutyrine residues. the reactivity of these residues toward nucleophiles was explored by reacting nisin with a variety of mercaptans. the kinetics of reaction with 2-mercaptoethane-sulfonate and thioglycolate indicated that the reaction pathway includes a binding step. reaction of nisin at high ph resulted in the formation of multimeric products, apparently as a resul ... | 1990 | 2119570 |
| nucleotide sequence and expression in escherichia coli of the lactococcus lactis citrate permease gene. | the plasmid-encoded citrate determinant of the lactococcus lactis subsp. lactis var. diacetylactis ncdo176 was cloned and functionally expressed in a cit- escherichia coli k-12 strain. from deletion derivative analysis, a 3.4-kilobase region was identified which encodes the ability to transport citrate. analysis of proteins encoded by the cloned fragment in a t7 expression system revealed a 32,000-dalton protein band, which correlated with the ability of cells to transport citrate. energy-depend ... | 1990 | 2120190 |
| molecular cloning, transcriptional analysis, and nucleotide sequence of lacr, a gene encoding the repressor of the lactose phosphotransferase system of lactococcus lactis. | the repressor gene (lacr) of the lactose phosphotransferase system of lactococcus lactis subsp. lactis strain mg1820 has been cloned and characterized. transcription of lacr, into a 1.2-kilobase monocistronic messenger, is repressed approximately 5-fold during growth on lactose. nucleotide sequence analysis of the lacr gene showed the presence of an open reading frame of 861 base pairs. the deduced amino acid sequence of lacr is homologous to three escherichia coli regulatory proteins (deor, fuc ... | 1990 | 2120234 |
| cloning, expression, and sequence determination of a bacteriophage fragment encoding bacteriophage resistance in lactococcus lactis. | a number of host-encoded phage resistance mechanisms have been described in lactococci. however, the phage genome has not been exploited as a source of additional resistance determinants. a 4.5-kb bamhi-hindiii fragment of phage nck202.50 (phi 50) was subcloned in streptococcus-escherichia coli shuttle plasmid psa3 and introduced into lactococcus lactis nck203 and mg1363 by protoplast transformation. this cloned phage fragment directed a bacteriophage resistance phenotype designated per (phage-e ... | 1990 | 2121714 |
| [various aspects of protoplast production in streptococcus lactis]. | the authors studied the effect of some factors, including the conditions of preincubation, the action of 2-mercaptoethanol, edta, alpha-amylase, on protoplast production in four strains of streptococcus lactis caused by lysozyme. the strains differed in the nisin-producing activity and in the structure of the cell walls that were not affected with lysozyme without either preincubation in 2-mercaptoethanol or in a salt medium with minimal inhibitory concentrations of dl-threonine. edta and alpha- ... | 1990 | 2122439 |
| microbiology of 'obiolor': a nigerian fermented non-alcoholic beverage. | obiolor is an acidic non-alcoholic beverage prepared by fermenting sorghum and millet malts. the traditional process for the production and microbiological characteristics of the beverage were investigated. bacillus spp., lactobacillus plantarum and streptococcus lactis were the associated micro-organisms most actively involved. yeasts were present in low numbers towards the end of the fermentation. other micro-organisms isolated did not appear to play a role in the fermentation process. variati ... | 1990 | 2123172 |
| cloning of usp45, a gene encoding a secreted protein from lactococcus lactis subsp. lactis mg1363. | we have cloned usp45, a gene encoding an extracellular secretory protein of lactococcus lactis subsp. lactis strain mg1363. unidentified secreted 45-kda protein (usp45) is secreted by every mesophilic l. lactis strain we tested so far and it is chromosomally encoded. the nucleotide sequence of the usp45 gene revealed an open reading frame of 1383 bp encoding a protein of 461 amino acids (aa), composed of a 27-aa signal peptide and a mature protein initiated at asp28. the gene contains a consensu ... | 1990 | 2123812 |
| isolation and characterization of lipoteichoic acid, a cell envelope component involved in preventing phage adsorption, from lactococcus lactis subsp. cremoris sk110. | the cell envelope of the phage-resistant lactococcus lactis subsp. cremoris sk110 differed from its phage-sensitive variant by the presence of a galactosyl-containing component. this component was present in material obtained from sk110 by a mild alkali treatment. in a similar fraction extracted from sk112, no galactosyl-containing components were detected. with respect to gel permeation chromatography and electrophoretic mobility, identical characteristics of the alkali-extracted material and p ... | 1990 | 2123864 |
| [joint culturing of streptococcus lactis, strain mgu with proteus vulgaris and bacillus mesentericus]. | nisin synthesis by streptococcus lactis, strain mgu, grown as a combined culture together with proteus vulgaris and bacillus mesentericus under stationary conditions or with stirring does not depend on the quantity of inoculated associated cells. nisin synthesis in the combined culture drops down by 10-20% at the initial ph 7.5 of the growth medium which is unfavourable for s. lactis producing nisin. the level of nisin biosynthesis does not rise when the ph of the medium is adjusted (either natu ... | 1990 | 2124650 |
| characterization of the lactose-specific enzymes of the phosphotransferase system in lactococcus lactis. | the plasmid-encoded lactose genes of the lactococcus lactis phosphotransferase system encoding enzyme iiilac (lacf) and enzyme iilac (lace) have been identified and cloned in escherichia coli and l. lactis. nucleotide sequence and transcription analysis showed that these genes are organized into a lactose-inducible operon with the gene order lacf-lace-lacg-lacx, the latter two genes encoding phospho-beta-galactosidase and a 34-kda protein with an unknown function, respectively. the lac-operon is ... | 1990 | 2125052 |
| molecular cloning and dna sequence of lace, the gene encoding the lactose-specific enzyme ii of the phosphotransferase system of lactobacillus casei. evidence that a cysteine residue is essential for sugar phosphorylation. | the gene coding for the lactose-specific enzyme ii of the lactobacillus casei phosphoenolpyruvate-dependent phosphotransferase system, lace, has been isolated by molecular cloning and expressed in escherichia coli. the dna sequence of the lace gene and the deduced amino acid sequence are presented. the putative translation product comprises a hydrophobic protein of 577 amino acids with a calculated molecular mass of 62,350 da. the deduced polypeptide has a high degree of sequence similarity with ... | 1990 | 2125053 |
| heterologous gene expression in lactococcus lactis subsp. lactis: synthesis, secretion, and processing of the bacillus subtilis neutral protease. | the bacillus subtilis npre gene lacking its own promoter sequence was inserted in the lactococcal expression vector pmg36e. upon introduction of the recombinant plasmid into lactococcus lactis subsp. lactis strain mg1363, neutral protease activity could be visualized by the appearance of large clearing zones around colonies grown on milk agar plates. by measuring the activities of the neutral protease and the intracellular enzyme lactate dehydrogenase in culture supernatants and cell fractions, ... | 1990 | 2125811 |
| scanning electron microscopic and texture studies on characteristic consistency of nordic ropy sour milk. | the characteristic consistency of nordic ropy sour milk was studied. skim milk, reconstituted from non-fat dry milk, was fermented at 20 degrees c for 24 h by addition of 5% (v/v) inoculum of slime-producing (ropy) strain of lactococcus lactis ssp. cremoris sbt 0495, isolated from finnish ropy sour milk 'viili' starter culture, and its non-ropy variant sbt 1275. measurements of texture showed that milk gel prepared by the ropy strain exhibited remarkably increased adhesiveness as compared to tha ... | 1990 | 2126446 |
| simultaneous conjugal transfer in lactococcus to genes involved in bacteriocin production and reduced susceptibility to bacteriophages. | conjugal matings were performed between lactococcus lactis drc1 (a lactose-fermenting (lac+), bacteriocin-producing (bac+) strain) and l. lactis hid113 (lac- and bac-). transconjugant derivatives of hid113 were identified on the basis of lactose fermentation, resistance to the drc1 bacteriocin (dricin) or reduced sensitivity to phage sk1. regardless of how they were identified, all transconjugants gave fewer and smaller plaques with phages c2 and sk1 than did hid113. all but one of 275 transconj ... | 1990 | 2126518 |
| growth of, and aflatoxin production by aspergillus parasiticus when in the presence of either lactococcus lactis or lactic acid and at different initial ph values. | aspergillus parasiticus was grown in a modified lab-lemco tryptone broth both as a single culture and in association with lactococcus lactis. total aflatoxin (b1 + g1) production was higher in the mixed cultures. this stimulation persisted when different batches of media, inoculation procedures and makes of ingredients were used. aflatoxin yields increased in media with an initial ph of 4.2 compared with a ph close to neutrality. hydrochloric and/or lactic acid had little effect. the substitutio ... | 1990 | 2127265 |
| [functional properties of plasmids in lactic streptococci]. | for over half a century studies of the lactic streptococci have reported instability of several metabolic properties vital successful dairy fermentation. little has been done explain this instability, however, and only in the last 10 years or so, with the advent of techniques for studying genetic composition of lactic streptococci, has it become possible to explanations for this phenomenon. it is now well established that diversity of plasmid sizes are found within strains of lactic streptococci ... | 1990 | 2128530 |
| [study of nisin, a polypeptide antibiotic produced by a culture of streptococcus lactis, strain msu]. | the drug nisin produced by the lactic acid bacteria s. lactis, strain msu, was identified and described. after 18-hour cultivation of the strain the fermentation broth was centrifuged. the centrifugate contained at an average 2000 iu/ml of the antibiotic. it was purified on silica gel c-3, the eluate was lyophilized and the dry substance was studied by disk electrophoresis in 20 per cent paag in the presence of sodium dodecylsulfate. it was found that s. lactis, strain msu, produced a polypeptid ... | 1990 | 2128734 |
| [prevention of caries with lactobacillus (final results of a clinical trial on dental caries with killed lactobacillus [streptococcus and lactobacillus] given orally)]. | caries prevention with lactic bacteria. (final results of a dental caries clinical trial using heat killed lactic bacteria [streptococci and lactobacilli] orally.) the results of a dental caries clinical trial in 245 seven-year-old children are reported. chewable tablets of two different types were prepared: a) containing pyridoxine (vit. b6) and heat killed lactic bacteria. b) placebo tablets with pyridoxine only. they were randomly given once a week for 16 weeks to experimental and control gro ... | 1990 | 2132274 |
| cloning of a chromosomal fragment from lactococcus lactis subsp. lactis partially complementing escherichia coli reca functions. | a reca-like gene was isolated from a gene library of lactococcus lactis subsp. lactis by intergeneric complementation of an e. coli reca mutant. a plasmid was obtained which fully complemented the reca response to dna damaging agents and uv inducibility of prophage, but not p1 plating efficiency in an e. coli reca mutant. the cloned dna fragment also partially complemented the rec mutation in lc. lactis mms36. hybridization studies showed that there was no detectable sequence homology between th ... | 1990 | 2150659 |
| simultaneous loss of n5-(carboxyethyl)ornithine synthase, nisin production, and sucrose-fermenting ability by lactococcus lactis k1. | a spontaneous derivative of lactococcus lactis subsp. lactis k1 (formerly streptococcus lactis k1) lacking n5-(carboxyethyl)ornithine synthase (ec 1.5.1.24) was isolated. this mutant had also lost the abilities to ferment sucrose and to produce the antibiotic nisin. hybridization studies indicate that these linked traits are encoded on the chromosome of l. lactis k1 and that they may be located on a conjugative transposon. | 1990 | 2163399 |
| characterization of insertion sequence is946, an iso-iss1 element, isolated from the conjugative lactococcal plasmid ptr2030. | the self-transmissible plasmid ptr2030 mobilized nonconjugative heterologous cloning vectors pgk12 (cmr emr) and psa3 (emr) at frequencies of 10(-5) to 10(-6) per input donor. transconjugants harbored a 51- or 58-kilobase (kb) plasmid not found in the parental strains that cotransferred at high frequency with cmr emr and ptr2030-encoded phage resistance (hsp+) in second-round matings (10(-1) per input donor). restriction endonuclease mapping and dna-dna hybridization identified the 51- to 58-kb ... | 1990 | 2165471 |
| nucleotide sequence of is904 from lactococcus lactis subsp. lactis strain nizo r5. | | 1990 | 2165590 |
| insertion elements on lactococcal proteinase plasmids. | dna segments of 809 and 808 nucleotides, with 18-base-pair terminal inverted repeats, are present on the proteinase plasmids pwv05 from lactococcus lactis subsp. cremoris wg2 and psk111 from l. lactis subsp. cremoris sk11, respectively. these dna segments are highly similar: 77% identical nucleotides and both contain an open reading frame that can encode a protein of 226 amino acids. furthermore, both dna segments are located downstream of the proteinase maturation gene prtm, but they differ ind ... | 1990 | 2166472 |
| taxonomic differentiation of 101 lactococcal bacteriophages and characterization of bacteriophages with unusually large genomes. | sixty-three virulent bacteriophages of lactococcus lactis were differentiated by dna-dna hybridization. the results, including those of a previous classification of 38 phages of the same bacterial species (p. relano, m. mata, m. bonneau, and p. ritzenthaler, j. gen. microbiol. 133:3053-3063, 1987) show that 48% of the phages analyzed belong to a unique dna homology group (group iii). phages of this most abundant group had small isometric heads. group i comprised 29% of the phages analyzed and wa ... | 1990 | 2167627 |
| in vivo genetic systems in lactic acid bacteria. | a review of in vivo genetic systems covers the key features of transduction and conjugation but emphasises the intramolecular and intermolecular dna interactions that are often associated with these processes. as well as the transfer of many lactose plasmids, conjugal transfer of nisin genes and the use of conjugation to construct bacteriophage-resistant dairy starter cultures are discussed. the discovery and characterization of insertion sequences in lactobacillus and lactococcus and the exploi ... | 1990 | 2176796 |
| plus-origin mapping of single-stranded dna plasmid pe194 and nick site homologies with other plasmids. | staphylococcus aureus plasmid pe194 manifests a natural thermosensitivity for replication and can be established in several species, both gram positive and gram negative, thus making it attractive for use as a delivery vector. like most characterized plasmids of gram-positive bacteria, pe194 generates single-stranded dna. the direction of pe194 replication is clockwise, as determined by the strandedness of free single-stranded dna. significant homology exists between a 50-base-pair sequence in t ... | 1990 | 2198265 |
| on the basic structure of poly(glycerophosphate) lipoteichoic acids. | poly(glycerophosphate) lipoteichoic acids from 24 gram-positive bacteria of the genera bacillus, enterococcus, lactobacillus, lactococcus, listeria, staphylococcus, and the streptococcal pyogenic and oral group were analyzed. the 1,3-linked poly(glycerophosphate) structure was proved by analysis of glycerol and glycerophosphates after acid and alkaline hydrolysis. using the molar ratios of glycolipid to phosphorus (a) and phosphomonoester to phosphorus after periodate oxidation followed by hydra ... | 1990 | 2350496 |
| isolation of a replication region of a large lactococcal plasmid and use in cloning of a nisin resistance determinant. | the replication region of a 28-kilobase-pair (kbp) cryptic plasmid from lactococcus lactis subsp. lactis biovar diacetylactis ssd207 was cloned in l. lactis subsp. lactis mg1614 by using the chloramphenicol resistance gene from the streptococcal plasmid pgb301 as a selectable marker. the resulting 8.1-kbp plasmid, designated pvs34, was characterized further with respect to host range, potential cloning sites, and location of replication gene(s). in addition to lactococci, pvs34 transformed lacto ... | 1990 | 2389931 |
| mechanism of action of lactostrepcin 5, a bacteriocin produced by streptococcus cremoris 202. | the mechanism of bactericidal activity of lactostrepcin 5 (las 5), a bacteriocin produced by streptococcus cremoris 202, was investigated. las 5 did not kill protoplasts of sensitive cells, and its activity was decreased about 10-fold after pretreatment of the cells with trypsin, suggesting the involvement of the cell wall in the activity of this bacteriocin. in susceptible cells, the bacteriocin slowed down and then stopped synthesis of dna, rna, and protein, although this did not appear to be ... | 1985 | 2408565 |
| isolation and characterization of streptococcus cremoris wg2-specific promoters. | by cloning mboi fragments in the promoter selection vector pgkv210, which replicates in streptococcus lactis, bacillus subtilis, and escherichia coli and carries a promoterless chloramphenicol acetyltransferase gene, we obtained a number of fragments endowed with promoter activity, partly by direct selection for chloramphenicol resistance in s. lactis il1403 and partly by selection in b. subtilis. five fragments were sequenced, and the promoters were mapped with s1 nuclease. the promoters agreed ... | 1987 | 2447829 |
| the place of listeria among gram-positive bacteria. | the genus listeria, containing the species listeria monocytogenes, listeria innocua, listeria seeligeri, listeria welshimeri, listeria ivanovii, listeria grayi and listeria murrayi is a well circumscribed taxon. numerical taxonomic and chemical studies indicate a very close phenetic similarity to the genus brochothrix and a more distant, but close, similarity to a number of other genera such as lactobacillus, streptococcus, lactococcus, enterococcus, staphylococcus, kurthia and bacillus. recent ... | 1988 | 2458321 |
| amine production by streptococcus lactis under different growth conditions. | the highest amount of histamine, tyramine and tryptamine were produced by s. lactis at 30 degrees c in 24 h at ph = 5.0. maximum amount of different amines was noted in a growth medium lacking nacl. after addition of nacl even at 0.5% concentration, slight inhibitory effect on the synthesis of these amines was obtained. | 1988 | 2462332 |
| 16s ribosomal ribonucleic acid sequence analyses of lactococci and related taxa. description of vagococcus fluvialis gen. nov., sp. nov. | the phylogenetic status of members of the genus lactococcus and some motile strains which react with lancefield group n antiserum was examined by reverse transcriptase sequencing of 16s ribosomal ribonucleic acid. in agreement with earlier nucleic acid hybridization and immunological studies of superoxide dismutase the 16s sequence data clearly demonstrate that the lactococci represent a distinct phylogenetic group equivalent in rank to the genera enterococcus and streptococcus. the motile group ... | 1989 | 2479630 |
| mechanism and energetics of dipeptide transport in membrane vesicles of lactococcus lactis. | alanyl-alpha-glutamate transport has been studied in lactococcus lactis ml3 cells and in membrane vesicles fused with liposomes containing beefheart cytochrome c oxidase as a proton-motive-force-generating system. the uptake of ala-glu observed in de-energized cells can be stimulated 26-fold upon addition of lactose. no intracellular dipeptide pool could be detected in intact cells. in fused membranes, a 40-fold accumulation of ala-glu was observed in response to a proton motive force. addition ... | 1989 | 2492499 |
| functional reconstitution of prokaryote and eukaryote membrane proteins. | a new strategy for the functional reconstitution of membrane proteins is described. this approach introduces a new class of protein stabilizing agents--osmolytes--whose presence at high concentration (10-20%) during detergent solubilization prevents the inactivations that normally occur when proteins are extracted from natural membranes. osmolytes that act in this way include compounds such as glycerol and higher polyols (erythritol, xylitol, sorbitol), sugars (glucose, trehalose), and certain a ... | 1989 | 2492790 |
| genetic transformation of intact lactococcus lactis subsp. lactis by high-voltage electroporation. | to apply recombinant dna techniques for genetic manipulation of the industrially important lactococci, an efficient and reliable high-frequency transformation system must be available. high-voltage electric pulses have been demonstrated to enhance uptake of dna into protoplasts and intact cells of numerous gram-negative and gram-positive microorganisms. the objective of this study was to develop a system for electroporating intact cells of lactococcus lactis subsp. lactis lm0230 (previously desi ... | 1989 | 2494937 |
| proportion of phage-insensitive and phage-sensitive cells within pure strains of lactic streptococci, and the influence of calcium. | | 1989 | 2495314 |
| construction of a lactococcal expression vector: expression of hen egg white lysozyme in lactococcus lactis subsp. lactis. | a pair of vectors for expression of heterologous genes in lactococcus lactis was constructed. in addition to an origin of replication that has a broad host range, these vectors contain a multiple cloning site flanked by gene expression signals originating from l. lactis subsp. cremoris wg2. the two vectors, about 3.7 kilobase pairs in size, differ only in the type of antibiotic resistance they confer to their hosts. pmg36 carries a kanamycin resistance marker, which was replaced by an erythromyc ... | 1989 | 2495760 |
| dry rehydratable films for enumeration of coliforms and aerobic bacteria in dairy products: collaborative study. | a collaborative study was conducted to compare proposed dry-film plating methods, using aerobic count plates and coliform count plates, to standard agar plating methods for quantifying aerobic bacteria and coliforms in dairy products. in this study, 5 food products (chocolate milk, pasteurized cheese, nonfat dry milk, evaporated milk, and vanilla ice cream), selected as representative dairy products, were analyzed by 11 collaborating laboratories. the results indicate that the dry-film plating m ... | 1989 | 2496099 |
| a maturation protein is essential for production of active forms of lactococcus lactis sk11 serine proteinase located in or secreted from the cell envelope. | the complete nucleotide sequence of a gene located immediately upstream of the lactococcus lactis subsp. cremoris sk11 prtp gene encoding the cell envelope-attached proteinase was determined. this gene, designated prtm, was found to be transcribed from the same promotor region as was the proteinase gene but in the opposite direction. the prtm gene directed the expression in escherichia coli of a protein with a size similar to the expected value of 33 kilodaltons, as deduced from the nucleotide s ... | 1989 | 2496115 |
| campbell-like integration of heterologous plasmid dna into the chromosome of lactococcus lactis subsp. lactis. | integrable vectors were constructed based on the plasmid phv60, which is essentially a pbr322 replicon carrying a chloramphenicol resistance marker, by inserting 1.3-kilobase chromosomal fragments of lactococcus lactis subsp. lactis mg1363 into this plasmid. three constructs as well as phv60 were electroporated to strain mg1363. transformants were obtained with all constructs, and also with phv60 (albeit with low frequency). by using southern hybridizations, it appeared that phv60 showed homolog ... | 1989 | 2497708 |
| a new simple method of curing plasmids in lactic streptococci (streptococcus cremoris; streptococcus lactis, plasmids). | a simple method for curing plasmid dna from lactic streptococci is described. when strains of lactic streptococci are grown overnight at 32 degrees c in an unbuffered medium (m17-) and held at the same temperature for an extended period (96 h), the acid environment induces loss of plasmid dna of different sizes. if the process of growth in m17- broth followed by extended incubation at 32 degrees c is repeated, most of the plasmids are lost, as revealed by gel electrophoretic profiles of dna. the ... | 1989 | 2498159 |
| product of the lactococcus lactis gene required for malolactic fermentation is homologous to a family of positive regulators. | malolactic fermentation is a secondary fermentation that many lactic acid bacteria can carry out when l-malate is present in the medium. the activation of the malolactic system in lactococcus lactis is mediated by a locus we call mler. induction of the genes necessary to perform malolactic fermentation occurs only in bacteria with a functional copy of mler. the mler gene consists of one open reading frame capable of coding for a protein with a calculated molecular mass of 33,813 daltons. the ami ... | 1989 | 2498286 |
| n5-(l-1-carboxyethyl)-l-ornithine:nadp+ oxidoreductase from streptococcus lactis. purification and partial characterization. | n5-(l-1-carboxyethyl)-l-ornithine:nadp+ oxidoreductase (ec 1.5.1.-) from streptococcus lactis k1 has been purified 8,000-fold to homogeneity. the nadph-dependent enzyme mediates the reductive condensation between pyruvic acid and the delta- or epsilon-amino groups of l-ornithine and l-lysine to form n5-(l-1-carboxyethyl)-l-ornithine and n6-(l-1-carboxyethyl)-l-lysine, respectively. the five-step purification procedure involves ion-exchange (de52 and phosphocellulose p-11), gel filtration (ultrog ... | 1989 | 2498334 |
| kinetic mechanism and specificity of the arginine-ornithine antiporter of lactococcus lactis. | the kinetic mechanism and specificity of the arginine-ornithine antiporter was investigated in membrane vesicles derived from lactococcus lactis. membrane vesicles loaded with ornithine, and diluted into an arginine-free medium, rapidly released a limited amount of ornithine during the first seconds of incubation. the amount of ornithine released was independent of the amount initially present on the inside and roughly matched the number of ornithine-binding sites in the membrane. net flow of or ... | 1989 | 2499577 |
| bioenergetics and solute transport in lactococci. | during the last few years the studies about the physiology and bioenergetics of lactic acid bacteria during growth and starvation have evolved from a descriptive level to an analysis of the molecular events in the regulation of various processes. considerable progress has been made in the understanding of the modes of metabolic energy generation, the mechanism of homeostasis of the internal ph, and the mechanism and regulatory processes of transport systems for sugars, amino acids, peptides, and ... | 1989 | 2500949 |
| effect of streptococcus lactis preparation in diet of mice on inhibiting age-dependent loss of superoxide dismutase activity in tissues. | sl-diet was prepared using commercial pellets supplemented with 1% pulverized streptococcus lactis (sl). sl fed group of icr strain mice were bred from 8 weeks up to 75 weeks. end-point age for survival in these mice was approximately 75 weeks. no significant differences in survival rate were observed at 75 weeks between the commercial diet and sl-diet group. the superoxide dismutase (sod) activities in the liver, brain and erythrocytes of 75-week-old mice significantly decreased compared with t ... | 1989 | 2501595 |
| molecular characterization of a cell wall-associated proteinase gene from streptococcus lactis ncdo763. | streptococcus lactis ncdo763 harbours a plasmid designated plp763. the cells harbouring plp763 are able to grow to a higher density in milk because of their proteinase-positive phenotype (prt+). the 6.2 kb hindiii-psti fragment from plp763 was found to be responsible for the prt+ phenotype. the dna fragment contains an incomplete large open reading frame (orf). further sequence analysis downstream from the psti site revealed that the orf consists of 5706 bases. it was found that the deduced amin ... | 1989 | 2501630 |
| [a mutant of streptococcus lactis with resistance to bacteriophages isolated in argentina and the united states of america]. | streptococcus lactis and streptococcus cremoris have an important role in the fermentation of milk during the manufacturing of lactic products. bacteriophages are spread in the plant environment and they may infect the starters causing technical and economic problems to the dairy industry. it is now known that the usual methods of control are not completely safe against the proliferation of phages. it is necessary therefore to include resistant strains to the phages which infect the plant. this ... | 1989 | 2501823 |
| genetic transfer systems for delivery of plasmid deoxyribonucleic acid to lactobacillus acidophilus adh: conjugation, electroporation, and transduction. | lactobacillus acidophilus adh is a bacteriocin-producing human isolate that adheres to human fetal intestinal cells and human ileal cells. we have employed both electroporation and conjugation methodologies to transfer various plasmids to l. acidophilus adh. furthermore, we have demonstrated transduction of plasmid dna within this strain by a temperate bacteriophage (phi adh) harbored by l. acidophilus adh. plasmid pgk12 was introduced into strain adh by electroporation at frequencies as high as ... | 1989 | 2503549 |
| plasmid transformation by electroporation of leuconostoc paramesenteroides and its use in molecular cloning. | in this report, we demonstrate the utility of electroporation as an efficient method for genetic transformation of leuconostoc paramesenteroides. we optimized several factors which determine the transformation frequency, resulting in transformation efficiencies of up to 4 x 10(3) transformants per micrograms of pnz12 dna, which contains the promiscuous lactococcus lactis psh71 replicon. slightly lower efficiencies were obtained with a deletion derivative of the broad-host-range plasmid pam beta ... | 1989 | 2504108 |
| localization, cloning, and expression of genetic determinants for bacteriophage resistance (hsp) from the conjugative plasmid ptr2030. | genetic determinants for a bacteriophage resistance mechanism (hsp+) encoded by plasmid ptr2030 (46.2 kilobases [kb]) were localized by mapping an 11.5-kb deletion that accompanied the transition of lactococcus lactis lma12-4 transconjugants (m. e. sanders, p. j. leonard, w. d. sing, and t. r. klaenhammer, appl. environ. microbiol. 52:1001-1007, 1986) from phage resistance to phage sensitivity. the deleted 34.7-kb replicon (ptr2023, hsp-) retained its conjugative ability, demonstrating that the ... | 1989 | 2504114 |
| insertion and amplification of foreign genes in the lactococcus lactis subsp. lactis chromosome. | the plasmid pe194 is unable to replicate in lactococcus lactis subsp. lactis (formerly streptococcus lactis). when linked to resident bacteriophage sequences, pe194 was able to integrate into the l. lactis subsp. lactis chromosome either by campbell-like recombination or by double crossing over with deletion. integration occurred into the dna of the prophage and prevented its multiplication. when a selective pressure was applied to an integrant in which pe194 was flanked by two direct repeats of ... | 1989 | 2504115 |
| conjugal transfer of plasmid pip501 from lactococcus lactis to lactobacillus delbrückii subsp. bulgaricus and lactobacillus helveticus. | plasmid pip501 was transferred by conjugation from lactococcus lactis to lactobacillus delbrückii subsp. bulgaricus and lactobacillus helveticus. only lb. delbrückii subsp. bulgaricus transconjugants could act as a donor in crosses with lc. lactis. no lactobacillus transconjugants were detected after inter- or intra-species lactobacillus crosses. plasmid pip501 has undergone no detectable deletion or rearrangement during transfer from lc. lactis to lactobacillus strains. | 1989 | 2506107 |
| response of lactococcus (streptococcus) lactis to n-methyl-n'-nitro-n-nitrosoguanidine: absence of adaptive response. | pretreatment of cells of lactococcus lactis subsp. lactis with low levels of n-methyl-n'-nitro-n-nitrosoguanidine does not reduce the cytotoxic and mutagenic effects caused by high concentration of this agent. this observation indicates that there is no efficient inducible error-free repair system for alkylation damage similar to the 'adaptive response' described in detail for escherichia coli. | 1989 | 2506405 |
| cloning and dna sequence analysis of a lactococcus bacteriophage lysin gene. | a gene for the lysin of lactococcus lactis bacteriphage phi vml3 was cloned using an escherichia coli/bacteriophage lambda host-vector system. the gene was detected by its expression of antimicrobial activity against l. lactis cells in a bioassay. the cloned fragment was analysed by sub-cloning on to e. coli plasmid vectors and by restriction endonuclease and deletion mapping. its entire dna sequence was determined and an open reading frame for the lysin structural gene was identified. the seque ... | 1989 | 2506424 |
| conjugal transfer of genetic material by lactococcus lactis subsp. lactis 11007. | conjugal transfer of genetic material by lactococcus lactis subsp. lactis 11007 was examined. a plasmid of 88 mda (pjs88) was identified in addition to the previously reported conjugally transferred plasmids of 32 (pkb32) and 4.8 mda. proteinase activity, reduced bacteriophage sensitivity, bacteriocin resistance, and conjugal transfer ability were encoded by pjs88. the ability to metabolize lactose (lac+) was encoded by pkb32, and the 4.8-mda plasmid was cryptic. when a strain containing both pk ... | 1989 | 2506592 |
| characterization of the genetic element coding for lactose metabolism in lactococcus lactis subsp. lactis kp3. | the lactococcus lactis subsp. lactis kp3 lac genetic element was investigated. kp3 is a lactose-positive (lac+) transconjugant which contains no detectable plasmid dna. the kp3 lac genetic element was self-transmissible (tra+) and encoded a reduced bacteriophage sensitivity (rbs+) phenotype. matings of kp3 with a recombination-deficient (rec-) recipient resulted in lac+ transconjugants which were phenotypically indistinguishable from kp3 and contained a 96-mda plasmid (pjs96). phenotypic and phy ... | 1989 | 2506593 |
| enzyme activities of cell-free extracts from mutant strains of lactic streptococci subjected to sublethal heating or freeze-thawing. | two mutant lactose-negative (lac-), proteinase-negative (prt-) strains of lactic streptococci, streptococcus lactis 25sp and s. cremoris kha2, and their parents, s. lactis c2 and s. cremoris kh lac+ prt+, were grown in a suitable medium with the ph maintained at 6.5 by addition of nh4oh. cells were harvested by centrifugation, resuspended, and then heated sublethally at 54 or 69 degrees c for 15 sec. cells also were frozen and stored for 1 week at -20 or -100 degrees c. cell-free extracts of cel ... | 1989 | 2507229 |
| secondary transport of amino acids by membrane vesicles derived from lactic acid bacteria. | lactococci are fastidious bacteria which require an external source of amino acids and many other nutrients. these compounds have to pass the membrane. however, detailed analysis of transport processes in membrane vesicles has been hampered by the lack of a suitable protonmotive force (pmf)-generating system in these model systems. a membrane-fusion procedure has been developed by which pmf-generating systems can be functionally incorporated into the bacterial membrane. this improved model syste ... | 1989 | 2508549 |
| dna-dna homology among lactose- and sucrose-fermenting transconjugants from lactococcus lactis strains exhibiting reduced bacteriophage sensitivity. | dna-dna homology between a reduced bacteriophage sensitivity (rbs+) probe and dna from both rbs+ and rbs- lactococcus lactis strains was examined. homology was detected between the probe and five plasmids (pci750, pcc34, peb56, pnp2, and pjs88) isolated from lactose-positive rbs+ transconjugants and between the probe and genomic dna of a sucrose-positive rbs+ transconjugant. additionally, hybridizations conducted between the probe and plasmids reported to encode abortive bacteriophage infection ... | 1989 | 2508557 |
| the conjugative plasmid ptr2030 encodes two bacteriophage defense mechanisms in lactococci, restriction modification (r+/m+) and abortive infection (hsp+). | ptr2030 is a conjugative plasmid which encodes resistance to bacteriophage in lactococci by a mechanism that aborts the phage infection (hsp+). subcloning and in vivo deletion events showed that two independent mechanisms of resistance are located on a 13.6-kilobase bg/ii fragment cloned in psa3; one mechanism is responsible for the abortive infection, and the other incodes a restriction modification system. the introduction of ptr2030 or the recombinant plasmid ptk6 resulted in the loss of a re ... | 1989 | 2508558 |
| peptide uptake is essential for growth of lactococcus lactis on the milk protein casein. | the chlorated dipeptide l-alanyl-beta-chloro-l-alanine (diaca) is very toxic for lactococcus lactis. spontaneous mutants resistant to the dipeptide were isolated from plates. the presence and activities of cell wall-associated proteinase, different peptidases in cell extracts, amino acid transport systems, and di- and oligopeptide transport systems were examined and compared in a diaca-resistant mutant and the wild type. only the rates of di- and tripeptide transport were found to be significant ... | 1989 | 2509429 |
| cloning of chromosomal genes of lactococcus by heterologous complementation: partial characterisation of a putative lactose transport gene. | a cosmid gene library of the genome of lactococcus lactis subsp. lactis 712 has been constructed in the broad host range plasmid plafr1 in escherichia coli le392. three lactococcal genes from the bank were identified by heterologous complementation of specific mutations in strains of e. coli. a cosmid clone encoding a putative lactose transport gene was identified by complementing an e. coli lacy mutant. the complemented clone supported the uptake of 14c lactose in transport assays. the dna frag ... | 1989 | 2513247 |
| improved electroporation efficiency of intact lactococcus lactis subsp. lactis cells grown in defined media. | the impact of growth conditions on electroporation of lactococcus lactis subsp. lactis lm0230 (previously designated streptococcus lactis lm0230) was evaluated. cells grown in m17 broth supplemented with 0.5% glucose (m17-glu) and two chemically defined synthetic media, fmc and rpmi 1640, all supplemented with 0.24% dl-threonine or 0.5% glycine, were harvested, washed with double-distilled water, diluted, and porated in the presence of 1 microgram of pgb301 dna with a transfector 100 (btx, inc., ... | 1989 | 2513778 |
| distribution analyses of chain substituents of lipoteichoic acids by chemical degradation. | the lipoteichoic acid from lactococcus lactis kiel 48337 was analyzed. it had 61% of its glycerophosphate residues substituted with alpha-d-galactopyranosyl residues. non-substituted glycerophosphate residues were split off by two alkaline hydrolyses and an intermediate enzymatic phosphomonoester cleavage. the resulting (galgrop)ngrogal and (galgrop)nglc2gro oligomers were separated by chromatography on deae-sephadex into 10 pairs of molecular species with n from 1 to 10. the relative frequencie ... | 1989 | 2514096 |
| bacterial growth in mastitic whey in relation to bacterial association with mastitis. | the growth of mastitis pathogens (eight strains) and non-pathogenic bacteria (eight strains) was studied using microturbidometry. all bacteria grew well in whey originating from uninflamed quarters. however, the growth of bacteria which are not considered to be mastitis pathogens (lactobacillus plantarum, bacillus subtilis, streptococcus lactis and pseudomonas fluorescens) became suppressed by whey from mastitic quarters. on the contrary, the growth of staphylococcus aureus and escherichia coli ... | 1989 | 2514482 |
| nisin, a peptide antibiotic: cloning and sequencing of the nisa gene and posttranslational processing of its peptide product. | nisin produced by streptococcus lactis is used as a food preservative and is the most important member of a group of antibiotics containing lanthionine bridges. to understand the genetic basis of these so-called lantibiotics (schnell et al., nature 333:276-278, 1988), we characterized the nisin structural gene, nisa, which is located on a plasmid and codes for a 57-amino-acid prepeptide. the prepeptide is processed posttranslationally to the pentacyclic antibiotic. although nisin and the recentl ... | 1989 | 2493449 |
| the phylogenetic position of streptococcus and enterococcus. | streptococcus pyogenes, s. equinus, s. bovis, s. salivarius, s. sanguis, s. mutans, s. rattus, s. cricetus, s. lactis, s. raffinolactis and enterococcus faecalis have been characterized by oligonucleotide cataloguing of their 16s ribosomal rna. all the organisms form a loose but coherent group that is phylogenetically equivalent to those of lactobacilli, bacilli, the brochothrix and listeria group, and related taxa that constitute one of several sublines within the 'clostridium' branch of gram-p ... | 1985 | 2410543 |
| identification of lactococci and enterococci by colony hybridization with 23s rrna-targeted oligonucleotide probes. | specific sequences of 23s rrna of lactococcus lactis, enterococcus faecalis, enteroccus faecium, and enterococcus malodoratus/enterococcus avium were identified, and complementary oligonucleotide probes were synthesized. the specificity of the probes was evaluated by dot blot and colony hybridizations. the probes can be used for the specific detection and identification of colonies of the corresponding species in mixed cultures. | 1990 | 2275539 |
| characterization of a plasmid involved with cointegrate formation and lactose metabolism in lactococcus lactis subsp. lactis ozs1. | a 55 kilobase (kb) plasmid (pozs550) in the non-clumping lactococcus lactis subsp. lactis strain ozs1 carrying genes for lactose metabolism was characterised. a mobilizable cointegrate plasmid which is formed between pozs550 and pozs448 carries the necessary information for conjugation and transfer. cointegrate formation was found to involve an insertional element located on pozs550. the insertion sequence was found to be identical to iss1 located on psk08 in the clumping l. lactis subsp. lactis ... | 1990 | 2177590 |
| integration and excision of plasmid dna in lactococcus lactis subsp. lactis. | the capacity of the 75-kb lactose-proteinase plasmid pci301 from lactococcus lactis subsp. lactis uc317 to recombine with the lactococcal chromosome was examined. low-frequency integration of pci301 sequences was detected following protoplast transformation of strain mg136sm with total plasmid dna from strain uc317. excision of integrated sequences was subsequently observed at a low level. excised sequences were rescued through recombination with and mobilization by the conjugative enterococcal ... | 1990 | 2128962 |
| separation of antibiotics by autofocusing. | the autofocusing separation of nine antibiotics was investigated: tetracycline and chloramphenicol in large-scale batches, and seven others in gram preparation amounts. all except one were found to be heterogeneous in autofocusing, and 2-4 well-characterized fractions emerged. these heterogeneities are described and the industrial utilization of the procedure is suggested. | 1990 | 2127743 |
| diagnosis of bacterial endocarditis caused by streptococcus lactis and assisted by immunoblotting of serum antibodies. | | 1990 | 2125626 |
| influence of aflatoxin b1 on gas production by lactic acid bacteria. | the main characteristic of homofermentative lactic acid bacteria is that they do not produce gas from glucose and other sugars. however, in these experiments lactobacillus casei, lb. plantarum and streptococcus lactis in broth media with glucose, galactose, lactose and sucrose, and aflatoxin b1 produces acid and also a significant amount of gas. in the control media without aflatoxin, these bacteria did not produce gas. the data suggest that lactic acid bacteria, known until now as homofermentat ... | 1990 | 2123930 |
| molecular cloning and expression of a proteinase gene from lactococcus lactis subsp. cremoris h2 and construction of a new lactococcal vector pfx1. | the 6.5 kb hindiii dna fragment of the lactococcus lactis subsp. cremoris h2 plasmid pdi21 was cloned into escherichia coli pop13 with lambda nm1149, and also directly into lactococcus lactis subsp. lactis 4125 using a newly-constructed broad host-range vector pfx1. proteinase was expressed in both transformed organisms. the proteinase resembles a pi type since it preferentially degraded beta-casein. the restriction map of the 6.5 kb proteinase gene fragment has minor differences from those of p ... | 1990 | 2118753 |
| conjugal mobilization of streptococcal plasmid pmv158 between strains of lactococcus lactis subsp. lactis. | pmv158, a non-self-transmissible plasmid encoding tetracycline resistance, was conjugally transferred from enterococcus faecalis jh203 to lactococcus lactis subsp. lactis il1403. this transfer appeared to be dependent on the cotransfer of the conjugative plasmids pam beta 1 or pip501. intraspecies conjugal transfer of pmv158 also occurred in strain il1403. in contrast to the transfer from e. faecalis, transfer in il1403 did not require the presence of a conjugative plasmid in the donor strain bu ... | 1990 | 2104609 |
| [ultrastructural features of rhodococcus rubropertinctus and streptococcus lactis dissociants]. | three rhodococcus rubropertinctus dissociants (r, s and m) and two streptococcus lactis dissociants (r and s) were compared using the electron microscopy method of negative contrasting. the cell wall of r.rubropertinctus dissociants had a thickness of 40 nm (r), 30 nm (s) and 20 nm (m). the cell wall of s. lactis dissociants was 35-55 nm (r) and 25-30 nm (s) thick. 1.5-2-fold variations in the thickness of cell walls could account for the different resistance of the dissociants against the actio ... | 1991 | 1921769 |
| expression of a beta-galactosidase gene from clostridium acetobutylicum in lactococcus lactis subsp. lactis. | a beta-galactosidase gene from clostridium acetobutylicum ncib 2951 was expressed after cloning into psa3 and electroporation into derivatives of lactococcus lactis subsp. lactis strains h1 and 7962. when the clostridial gene was introduced into a plasmid-free derivative of the starter-type lact. lactis subsp. lactis strain h1, the resulting construct had high beta-galactosidase activity but utilized lactose only slightly faster than the recipient. beta-galactosidase activity in the construct de ... | 1991 | 1910034 |
| binding of mutagens by fractions of the cell wall skeleton of lactic acid bacteria on mutagens. | the binding effect of cells and cell fractions, cell wall skeleton, cytoplasm, whole cells, and cell wall skeleton treated by lysozyme and alpha-amylase at 37 degrees c for 5 h, on trp-p-1 (3-amino-1,4-dimethyl-[5h]pyrido [4,3-b]indole) and trp-p-2 (3-amino-1-methyl-[5h]-pyrido[4,3-b]indole) were investigated. the cell and cell wall skeleton of streptococcus cremoris z-25 had greater binding activity, but cytoplasm and extract of cell wall skeleton did not bind trp-p-1 and trp-p-2. when the cell ... | 1991 | 1908865 |
| characterization of the nisin gene as part of a polycistronic operon in the chromosome of lactococcus lactis atcc 11454. | the location and organization of the nisin locus in lactococcus lactis atcc 11454 were studied. primer extension of in vivo mrna transcripts of the gene that encodes the nisin prepropeptide sequence indicated the presence of a promoter at least 4 kb upstream from the nisin gene and that the mrna has several processing sites. restriction fragment patterns using rare-cutting enzymes, orthogonal pulsed-field clamped homogeneous electric field (chef) agarose gel electrophoresis, and hybridization wi ... | 1991 | 1905517 |
| identification of a new genetic determinant for cell aggregation associated with lactose plasmid transfer in lactococcus lactis. | derivatives of the lactose miniplasmid pmg820 were constructed in which a staphylococcal erm gene was inserted and in which this was accompanied by subsequent deletion of the lactose genes. the resulting plasmids were thus marked with both erythromycin resistance and lactose utilization genes in pf1132 or solely erythromycin resistance in pf1133. these plasmids retained the normal conjugation properties characteristic of lactose plasmid plp712, including the generation by intermolecular rearrang ... | 1991 | 1903626 |
| shuttle vectors containing a multiple cloning site and a lacz alpha gene for conjugal transfer of dna from escherichia coli to gram-positive bacteria. | the mobilizable shuttle cloning vectors, pat18 and pat19, are composed of: (i) the replication origins of puc and of the broad-host-range enterococcal plasmid pam beta 1; (ii) an erythromycin-resistance-encoding gene expressed in gram- and gram+ bacteria; (iii) the transfer origin of the incp plasmid rk2; and (iv) the multiple cloning site and the lacz alpha reporter gene of puc18 (pat18) and puc19 (pat19). these 6.6-kb plasmids contain ten unique cloning sites that allow screening of derivative ... | 1991 | 1864514 |
| structure and expression of the lactococcus lactis gene for phospho-beta-galactosidase (lacg) in escherichia coli and l. lactis. | the lactococcus lactis subsp. lactis 712 lacg gene encoding phospho-beta-galactosidase was isolated from the lactose mini-plasmid pmg820 and cloned and expressed in escherichia coli and l. lactis. the low phospho-beta-galactosidase activity in l. lactis transformed with high-copy-number plasmids containing the lacg gene contrasted with the high activity found in l. lactis containing the original, low-copy-number lactose plasmid pmg820, and indicated that the original lactose promoter was absent ... | 1989 | 2515252 |
| cloning and expression of the lactococcus lactis subsp. cremoris sk11 gene encoding an extracellular serine proteinase. | the lactococcus lactis subsp. cremoris sk11 plasmid-located prtp gene, encoding a cell-envelope-located proteinase (prtp) that degrades alpha s1-, beta- and kappa-casein, was identified in a lambda embl3 gene library in escherichia coli using immunological methods. the complete prtp gene could not be cloned in e. coli and l. lactis on high-copy-number plasmid vectors. however, using a low-copy-number vector, the complete prtp gene could be cloned in strains mg1363 and sk1128, proteinase-deficien ... | 1989 | 2515994 |
| transport of basic amino acids by membrane vesicles of lactococcus lactis. | the uptake of the basic amino acids arginine, ornithine, and lysine was studied in membrane vesicles derived from cells of lactococcus lactis which were fused with liposomes in which beef heart mitochondrial cytochrome c oxidase was incorporated as a proton motive force (pmf)-generating system. in the presence of ascorbate n,n,n'n'-tetramethylphenylenediamine-cytochrome c as the electron donor, these fused membranes accumulated lysine but not ornithine or arginine under aerobic conditions. the m ... | 1989 | 2537818 |
| is257 from staphylococcus aureus: member of an insertion sequence superfamily prevalent among gram-positive and gram-negative bacteria. | the nucleotide sequences for the is257 family of insertion sequences from staphylococcus aureus were compared with those of the iss1 family from streptococcus lactis and the is15 family which is widespread amongst gram-negative bacteria. these elements have a striking degree of similarity in both their putative transposase polypeptide sequences and their nucleotide sequences (40 to 64% between pairs), including 12 out of 14 bp conservation in their terminal inverted repeats. the evolutionary dis ... | 1989 | 2546857 |
| general mechanism for the bacterial toxicity of hypochlorous acid: abolition of atp production. | the adenylate energy charges (ec) of escherichia coli 25922, pseudomonas aeruginosa 27853, and streptococcus lactis 7962 rapidly fell in nutrient-rich media from values in excess of 0.9 to below 0.1 when the organisms were exposed to lethal levels of hocl. the same cells maintained in energy-depleted states were incapable of attaining normal ec values necessary for biosynthesis and growth when challenged with nutrient energy sources after hocl exposure. these changes correlated quantitatively wi ... | 1989 | 2557918 |
| identification of enterococcus species isolated from human infections by a conventional test scheme. | streptococci (206 cultures) previously identified as enterococci were retrieved from storage and reidentified by using tests designed to identify species of the genus enterococcus. of these 188, 91% were correctly identified as enterococcus species. of the remaining strains, nine (4%) were unidentified and six (3%) and 3 (1.5%) were identified as leuconostoc sp. and lactococcus sp., respectively. two new enterococcus species were discovered: e. raffinosus and e. solitarius. dna-dna hybridization ... | 1989 | 2656745 |
| identification of a gene required for maturation of an extracellular lactococcal serine proteinase. | directly upstream of the lactococcus lactis subsp. cremoris wg2 proteinase gene is an oppositely directed open reading frame (orf1). the complete nucleotide sequence of orf1, encoding a 33-kilodalton protein, was determined. a protein of approximately 32 kilodaltons was synthesized when orf1 was expressed in escherichia coli by using a t7 rna polymerase-specific promoter. l. lactis subsp. lactis mg1363 transformants carrying the proteinase gene but lacking orf1 were phenotypically proteinase def ... | 1989 | 2708318 |
| genome comparison of lactococcus strains by pulsed-field gel electrophoresis. | the two restriction enzymes smai and apai were found to produce distributions of dna fragments useful for genome analysis of some lactic acid bacteria (lactococcus lactis and streptococcus salivarius subsp. thermophilus) by pulsed-field gel electrophoresis. the genome size was estimated to be 1750 to 2500 kb depending on the species. each strain displayed unique restriction patterns; nevertheless, the percentage of the comigrating fragments of two isogenic or closely related strains was about 80 ... | 1989 | 2737464 |
| cloning of two bacteriocin genes from a lactococcal bacteriocin plasmid. | lactococcus lactis subsp. cremoris 9b4 plasmid p9b4-6 (60 kilobases [kb]), which specifies bacteriocin production and immunity, was analyzed with restriction endonucleases, and fragments of this plasmid were cloned into shuttle vectors based on the broad-host-range plasmid pwvo1. two regions on p9b4-6 were identified which specify inhibitory activity on l. lactis indicator strains: one that could be confined to a 1.8-kb scai-clai fragment with low antagonistic activity and a 15-kb xbai-sali frag ... | 1989 | 2757379 |
| primary structure and organization of the gene for a procaryotic, cell envelope-located serine proteinase. | we have determined the complete nucleotide sequence of the gene for the cell envelope-located proteinase of lactococcus lactis sk11. the gene contains a very at-rich promoter region followed by the coding sequence of a protein of 1962 amino acids. comparison of the nh2-terminal amino acid sequence of the mature proteinase and the expected primary translation product of the proteinase gene indicates that the enzyme is probably synthesized as a pre-pro-protein. this is confirmed by expression stud ... | 1989 | 2760036 |
| arginine transport in streptococcus lactis is catalyzed by a cationic exchanger. | streptococcus lactis metabolizes arginine via the arginine deiminase pathway to ornithine, co2, nh3, and atp. the translocation of arginine and ornithine has been studied using membrane vesicles of galactose/arginine-grown cells of s. lactis fused with cytochrome c oxidase proteoliposomes by the freeze/thaw--sonication procedure earlier described. in the presence of reduced cytochrome c the fused membranes rapidly accumulate ornithine. addition of arginine releases accumulated ornithine. rapid u ... | 1987 | 2819865 |
| [nisin sorption and desorption on different silica adsorbents]. | nisin sorption on some silica adsorbents in columns was studied. silica gels, silochromes and sintered glass with various pore diameters, various specific surfaces, etc. were tested. correlation between the adsorbent adsorption capacity with respect to nisin and the adsorbent pore diameter was observed. the tested silochromes, silica gels with the pore diameters of 70-80 nm and sintered glass with the pore diameters of 65-112 nm had the highest adsorption capacity with respect to nisin. | 1987 | 2820297 |
| identification of a new insertion element, similar to gram-negative is26, on the lactose plasmid of streptococcus lactis ml3. | in streptococcus lactis ml3, the lactose plasmid (psk08) forms cointegrates with a conjugal plasmid (prs01). it has been proposed that cointegration is mediated by insertion sequences (is) present on psk08 (d. g. anderson and l.l. mckay, j. bacteriol. 158:954-962, 1984). we examined the junction regions of the cointegrate ppw2 and the corresponding regions of psk08 (donor) and prs01 (target) and identified a new is element on psk08 (iss1s) which was involved in and duplicated during formation of ... | 1987 | 2824436 |
| control of glycolysis by glyceraldehyde-3-phosphate dehydrogenase in streptococcus cremoris and streptococcus lactis. | the decreased response of the energy metabolism of lactose-starved streptococcus cremoris upon readdition of lactose is caused by a decrease of the glycolytic activity (b. poolman, e. j. smid, and w. n. konings, j. bacteriol. 169:1460-1468, 1987). the decrease in glycolysis is accompanied by a decrease in the activities of glyceraldehyde-3-phosphate dehydrogenase and phosphoglycerate mutase. the steady-state levels of pathway intermediates upon refeeding with lactose after various periods of sta ... | 1987 | 2824452 |
| bacillus subtilis generates a major specific deletion in pam beta 1. | pam beta 1, a 26.5-kilobase plasmid originally isolated from streptococcus faecalis, was conjugally transferred from streptococcus lactis to bacillus subtilis. no conjugal transfer of pam beta 1 from b. subtilis to s. lactis was observed. in addition, pam beta 1 which had been reintroduced in s. lactis after cycling through b. subtilis had lost its conjugal transferability to streptococcus cremoris, although under the same conditions noncycled pam beta 1 was transferred at high efficiency. restr ... | 1987 | 2827570 |