Publications
| Title | Abstract | Year(sorted ascending) Filter | PMID Filter |
|---|
| lactococcal plasmid pwv01 as an integration vector for lactococci. | a bacillus subtilis strain was constructed that contained the repa gene of the lactococcal plasmid pwvo1 in its chromosome. this strain was used to construct the pwvo1-based integration vector pint1, which lacked the repa gene. the 3.6-kb plasmid pint1 was not able to replicate in lactococcus lactis mg1363 but integrated into the chromosome via a campbell-like mechanism when a lactococcal chromosomal dna fragment was incorporated in the plasmid. transformants were obtained that carried between o ... | 1991 | 1768128 |
| chromosomal stabilization of the proteinase genes in lactococcus lactis. | the plasmid-encoded proteinase genes prtp and prtm of lactococcus lactis subsp. cremoris wg2 were integrated by a campbell-like mechanism into the l. lactis subsp. lactis mg1363 chromosome by using the insertion vector pklg610. two transformants were obtained that differed in the number of amplified pklg610 copies in head-to-tail arrangements on their chromosomes; mg610 contained approximately two copies, and mg611 contained about eight copies. the amplifications were stably maintained during gr ... | 1991 | 1768129 |
| plasmid-encoded determinants for bacteriocin production and immunity in a lactococcus lactis strain and purification of the inhibitory peptide. | lactococcin, a bacteriocin produced by lactococcus lactis subsp. lactis adria 85lo30, was purified as a 2.3-2.4 kda peptide. six non-bacteriocin-producing (bac-) and non-immune (imm-) strains were isolated after curing experiments. these strains had in common the loss or modification of two plasmids: pos4 (32 kb) and pos5 (70 kb). by comparing pos5 and several modified plasmids, a dna region from pos5 of about 10 kb, which was necessary for wild-type bacteriocin production and immunity, was iden ... | 1991 | 1770357 |
| the behavior of selected microorganisms during the manufacture of high moisture jack cheeses from ultrafiltered milk. | whole milk was pasteurized and concentrated two times by ultrafiltration. starter cultures, lactococcus lactis ssp. cremoris and lactococcus lactis ssp. lactis, were propagated in either reconstituted skim milk, two times uf retentate, or uf permeate, or a direct vat system was used for the starter culture. the cheese milk was simultaneously inoculated with starter culture and pseudomonas fragi 4973, staphylococcus aureus 196e, and salmonella typhimurium var. hillfarm. control whole milk, uf con ... | 1991 | 1779045 |
| aminopeptidase a from lactococcus lactis. | 1991 | 1783119 | |
| proteinase genes of cheese starter cultures. | the proteolytic enzymes of lactococci are of eminent importance for milk fermentations. by the combined action of proteinases and peptidases milk protein is degraded to peptides and amino acids which are required for cell growth and contribute to the organoleptic properties of the foods. the importance of the proteolytic system for dairy product quality has resulted in an increased fundamental research of the enzymes and genes involved. proteinase plasmids have been identified and plasmid stabil ... | 1991 | 1783195 |
| development of bacteriophage-resistant strains of lactic acid bacteria. | 1991 | 1783196 | |
| flavour peptides: the potential role of lactococcal peptidases in their production. | 1991 | 1783198 | |
| nucleotide sequence of a lactococcus lactis gene cluster encoding adenylate kinase, initiation factor 1 and ribosomal proteins. | we have previously isolated a putative promoter from the lactococcus lactis subsp. lactis chromosome. we now report the sequence of the promoter fragment and its extension in the 5'-direction. the region contains several open-reading frames which correspond to ribosomal protein l15, secy, adenylate kinase, initiation factor 1 and ribosomal proteins b and s13. the order of the genes, rplo (l15), secy, adk, infa, rpmj (b) and rpsm (s13), is similar to that in the spc and alpha operon region of bac ... | 1991 | 1783905 |
| bacteriocin-mediated inhibition of clostridium botulinum spores by lactic acid bacteria at refrigeration and abuse temperatures. | the bacteriocinogenicity of lactococcus lactis atcc 11454, pediococcus pentosaceus atcc 43200, p. pentosaceus atcc 43201, lactobacillus plantarum bn, l. plantarum lb592, l. plantarum lb75, and lactobacillus acidophilus n2 against clostridium botulinum spores at 4, 10, 15, and 35 degrees c was investigated by modified deferred and simultaneous antagonism methods. all the strains, except l. acidophilus n2, produced inhibition zones on lawns of c. botulinum spores at 30 degrees c. l. plantarum bn, ... | 1991 | 1785919 |
| purification and characterization of an endopeptidase from lactococcus lactis subsp. cremoris wg2. | an endopeptidase has been purified to homogeneity from a crude cell extract of lactococcus lactis subsp. cremoris wg2 by a procedure that includes diethyl-aminoethane-sephacel chromatography, phenyl-sepharose chromatography, hydroxylapatite chromatography, and fast protein liquid chromatography over an anion-exchange column and a hydrophobic-interaction column. gel filtration and sodium dodecyl sulfate-polyacrylamide gel electrophoresis indicated a molecular mass of the purified enzyme of 70,000 ... | 1991 | 1785932 |
| nisin treatment for inactivation of salmonella species and other gram-negative bacteria. | nisin, produced by lactococcus lactis subsp. lactis, has a broad spectrum of activity against gram-positive bacteria and is generally recognized as safe in the united states for use in selected pasteurized cheese spreads to control the outgrowth and toxin production of clostridium botulinum. this study evaluated the inhibitory activity of nisin in combination with a chelating agent, disodium edta, against several salmonella species and other selected gram-negative bacteria. after a 1-h exposure ... | 1991 | 1785933 |
| growth inhibition of listeria spp. on camembert cheese by bacteria producing inhibitory substances. | bacterial strains exhibiting antimicrobial activity towards other bacteria are quite common in nature. during the past few years several genera have been shown to exert inhibitory action against listeria. spp. in the present work strains of enterococcus, lactobacillus and lactococcus were tested for their influence on the development of listeria spp. on camembert cheese. partial or complete inhibition of growth of listeria spp. was observed using various inhibitory bacteria. complete inhibition ... | 1991 | 1790105 |
| a rapid and efficient method of lysis of listeria and other gram-positive bacteria using mutanolysin. | a rapid and simple procedure is described for cell lysis for preparation of nucleic acids and intact ribosomal rna from gram-positive bacteria. commercial mutanolysin (purified from streptomyces globisporus) was used for inducing lysis. listeria, lactobacillus and lactococcus strains were very sensitive to mutanolysin when compared to lysozyme. susceptibility to mutanolysin was improved by a preliminary treatment with acetone, and sodium dodecyl sulfate reduced the efficiency of lysis when used ... | 1991 | 1793575 |
| [the use of plasmid profiles for the identification of streptococcus lactis strains]. | in this study, the plasmid contents of streptococcus lactis strains, isolated from whey of white pickled cheese samples which produced using without industrial starter culture, were searched. it is determined that strains containing plasmids at a range of 1-10 with the molecular weight between 1.8 and 41 kilobases (kb). six of totally 28 streptococcus lactis strains were classified into three groups according to their identical plasmid contents, and the others were identified as different strain ... | 1991 | 1795662 |
| the influence of biotechnological developments on cheese manufacture. | 1991 | 1797018 | |
| [liver abscess and appendicular foreign body]. | we report a case of liver abscess secondary to appendicitis which was due to a wire within the appendix. appendicitis was asymptomatic, probably because of its retrocaecal position and/or previous antibiotic treatment. the abscess was treated with broad-spectrum antibiotics and percutaneous drainage, followed by a second stage appendicectomy. this case illustrates the value of gastrointestinal radiological investigations before considering the abscess as cryptogenetic. | 1991 | 1816016 |
| kinetic studies of mg(2+)-, co(2+)- and mn(2+)-activated d-xylose isomerases. | the kinetic parameters for the interconverting substrates d-xylose in equilibrium d-xylulose and d-glucose in equilibrium d-fructose were determined for several d-xylose isomerases, with mg2+, co2+ and mn2+ as metal ion activators. the km, kcat. and kcat./km values are tabulated for the anomeric mixtures (observed parameters) as well as for the respective reactive species, i.e. the alpha-pyranose anomers of d-xylose and d-glucose and the alpha-furanose forms of d-xylulose and d-fructose (real pa ... | 1991 | 1831974 |
| functional alteration of macrophages by a slime-forming lactococcus lactis ssp. cremoris. | the effect of a slime-forming, encapsulated lactococcus lactis ssp. cremoris kvs20 on macrophage function has been examined in vivo and in vitro in short-term studies. peritoneal macrophages in which 21 to 34% of macrophage was presenting fc gamma-receptor positive macrophages were elicited by intraperitoneal injection of 10 to 50 mg/kg of l. lactis ssp. cremoris kvs20. the peritoneal macrophage exhibited cytotoxic activity against sarcoma-180 cells in which the maximum activity was obtained in ... | 1991 | 1832696 |
| characterization of philc3, a lactococcus lactis subsp. cremoris temperature bacteriophage with cohesive single-stranded dna ends. | the temperate bacteriophage philc3, isolated from lactococcus lactis subsp. cremoris, has an isometric head and a flexible tail containing 1 major protein and 8 minor proteins. infection of a permissive l. lactis host strain yields a burst of about 50 phages per infected cell with a latent period of 60 min. a detailed restriction map of the phage chromosome was constructed by using 12 different restriction enzymes. the phage chromosome is a 33-kb linear double-stranded dna molecule with unique c ... | 1991 | 1840480 |
| nucleotide sequence and characterization of the broad-host-range lactococcal plasmid pwvo1. | the nucleotide sequence of the lactococcus lactis broad-host-range plasmid pwvo1, replicating in both gram-positive and gram-negative bacteria, was determined. this analysis revealed four open reading frames (orfs). orf a appeared to encode a trans-acting 26.8-kda protein (repa), necessary for replication. the orf c product was assumed to play a regulatory role in replication. both repa and the orf c product showed substantial sequence similarity with the rep proteins of the streptococcal plasmi ... | 1991 | 1840693 |
| natural transfer of conjugative transposon tn916 between gram-positive and gram-negative bacteria. | the conjugative streptococcal transposon tn916 was found to transfer naturally between a variety of gram-positive and gram-negative eubacteria. enterococcus faecalis hosting the transposon could serve as a donor for alcaligenes eutrophus, citrobacter freundii, and escherichia coli at frequencies of 10(-6) to 10(-8). no transfer was observed with several phototrophic species. mating of an e. coli strain carrying tn916 yielded transconjugants with bacillus subtilis, clostridium acetobutylicum, ent ... | 1991 | 1846142 |
| a transposon-like element on the lactose plasmid of lactococcus lactis subsp. lactis z270. | an inverted repeat previously called ir was identified on the lactose plasmid of lactococcus lactis subsp. lactis z270 by self-annealing; it was now named is1076. the two sequences were 3.3 kb apart. both copies were cloned in e. coli, sequenced and found to be identical, except for an additional 44 bp direct repeat at the 5' end of the right-hand copy; they were thus respectively 1296 bp (is1076r) and 1252 bp (is1076l) long. both elements end in near-perfect 39 bp inverted repeats, similar to t ... | 1991 | 1848522 |
| molecular organization of the minimal replicon of novel, narrow-host-range, lactococcal plasmid pci305. | plasmid pci305 is an 8.7-kb, narrow-host-range, cryptic plasmid originating from lactococcus lactis subsp. lactis uc317. the nucleotide sequence of the pci305 replication region was determined. a single open reading frame of 1158 bp was identified in the trans-active domain repb. the size of the predicted repb protein (46 kda) is in close agreement with the size of the repb product visualized in vivo in escherichia coli when repb was placed under control of the inducible phi t7 rna polymerase pr ... | 1991 | 1852014 |
| isolation and characterization of chromosomal promoters of streptococcus salivarius subsp. thermophilus. | a promoter probe vector, ptg244, was constructed with the aim of isolating transcription initiation signals from streptococcus thermophilus (streptococcus salivarius subsp. thermophilus). ptg244 is based on the escherichia coli-streptococcus shuttle vector ptg222, into which the promoterless chloramphenicol acetyltransferase gene of bacillus pumilus (cat-86) was cloned. random sau3a fragments from the s. thermophilus a054 chromosomal dna were cloned upstream of the cat-86 gene by using e. coli a ... | 1991 | 1854195 |
| the bacteriophage resistance plasmid ptr2030 forms high-molecular-weight multimers in lactococci. | lactococcus lactis me2 can transfer a 46-kb plasmid, ptr2030, which encodes abortive phage infection (hsp) and restriction/modification (r/m) activities. ptr2030 can be detected as a monomeric plasmid in transconjugants at low copy number, but not in me2. ptr2030-specific probes were cloned and used to determine the location of the element in me2. no homology was observed between these ptr2030-specific probes and the cscl-purified plasmid content of me2. however, probes specific for ptr2030 hybr ... | 1991 | 1857750 |
| 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 |
| engineering of the lactococcus lactis serine proteinase by construction of hybrid enzymes. | plasmids containing wild-type and hybrid proteinase genes were constructed from dna fragments of the prtp genes of lactococcus lactis strains wg2 and sk11. these plasmids were introduced into the plasmid-free strain l. lactis mg1363. the serine proteinases produced by these l. lactis strains were isolated, and their cleavage specificity and rate towards alpha s1- and beta-casein was investigated. the catalytic properties of both the sk11 and wg2 proteinases, which differ in 44 out of 1902 amino ... | 1991 | 1881875 |
| identification, cloning and sequencing of the replication region of lactococcus lactis ssp. lactis biovar. diacetylactis bu2 citrate plasmid psl2. | the replication region of the 7.8 kilobase (kb) citrate plasmid psl2 from lactococcus lactis ssp. lactis biovar. diacetylactis bu2 was identified. deletion derivatives of psl2 were introduced into plasmid-free strain bu2-60 and tested for their ability to replicate autonomously. the region necessary for replication was identified by comparison of the psl2 derivatives, cloned and sequenced. no homologies were detected by comparing the putative rep protein of psl2 with replicons of other plasmids ... | 1991 | 1884982 |
| specificity of two genetically related cell-envelope proteinases of lactococcus lactis subsp. cremoris towards alpha s1-casein-(1-23)-fragment. | the specificity of two genetically related cell-envelope serine proteinases (pi-type and piii-type) of lactococcus lactis subsp. cremoris towards the alpha s1-casein-(1-23)-fragment, an important intermediate product of primary chymosin-directed proteolysis in cheese, has been established. both enzymes showed, at ph 6.5 and under relatively low-ionic-strength conditions, a characteristic, mutually different, cleavage pattern that seems, in the first instance, to be determined by the charge n-ter ... | 1991 | 1899185 |
| construction of a family of lactococcal vectors for gene cloning and translational fusion. | a family of stable lactococcal vectors have been constructed based on the pfx1 replicon using either the alpha fragment or the complete escherichia coli lacz gene as a selective marker. these vectors also incorporate multiple cloning sites and examples are given of their use for gene cloning and translational fusion studies in lactococci. | 1991 | 1900800 |
| identification of a nucleotide sequence conserved in lactococcus lactis bacteriophages. | a genetic element which is conserved in the genomes of numerous lactococcus lactis bacteriophage isolates has been identified and its nucleotide sequence determined. approximately 95-99% of all l. lactis bacteriophages collected over a period of six years from two geographically distinct sources carry this conserved dna fragment. genetic variation in other regions of the genomes of these bacteriophages is exhibited by changes in the overall restriction patterns. the complete nt sequence for a 1. ... | 1991 | 1901561 |
| secretion of tem beta-lactamase with signal sequences isolated from the chromosome of lactococcus lactis subsp. lactis. | with tem beta-lactamase as a reporter gene, a set of expression-secretion-promoting fragments were isolated from the chromosome of lactococcus lactis subsp. lactis. the fact that only translocated beta-lactamase renders cells resistant to ampicillin allowed direct ampicillin selection with an escherichia coli vector (pkth33). the clones showing the greatest ampicillin resistance were subcloned onto a replicon capable of replication in lactic acid bacteria (pvs2), and the nucleotide sequences of ... | 1991 | 1901704 |
| improved vector for promoter screening in lactococci. | fragments of lactococcus lactis subsp. lactis np45 chromosomal dna provided promoter activity in escherichia coli when cloned into the promoter probe vector pgkv210. only 13% of these recombinant plasmids promoted detectable cat-86 activity when transferred to l. lactis, i.e., expressed chloramphenicol resistance. in these promoter-containing versions of pgkv210, the cat-86 gene specifies chloramphenicol-inducible chloramphenicol acetyltransferase expression. this could be a limiting factor for ... | 1991 | 1901705 |
| organization and nucleotide sequences of two lactococcal bacteriocin operons. | two distinct regions of the lactococcus lactis subsp. cremoris 9b4 plasmid p9b4-6, each of which specified bacteriocin production as well as immunity, have been sequenced and analyzed by deletion and frameshift mutation analyses. on a 1.8-kb scai-clai fragment specifying low antagonistic activity, three open reading frames (orfs) were present, which were organized in an operon. the first two orfs, containing 69 and 77 codons, respectively, were involved in bacteriocin activity, whereas the third ... | 1991 | 1901707 |
| genetic construction of nisin-producing lactococcus lactis subsp. cremoris and analysis of a rapid method for conjugation. | conjugation was used to construct nisin-producing lactococcus lactis subsp. cremoris strains. recipients were obtained by electroporation of l. lactis subsp. cremoris strains with the drug resistance plasmid pgk13 or pgb301. a method, direct-plate conjugation, was developed in which donor and recipient cells were concentrated and then combined directly on selective media. this method facilitated transfer of the nisin-sucrose (nip+ suc+) phenotype from the donor strain, l. lactis subsp. lactis 11 ... | 1991 | 1901708 |
| thermosensitive plasmid replication, temperature-sensitive host growth, and chromosomal plasmid integration conferred by lactococcus lactis subsp. cremoris lactose plasmids in lactococcus lactis subsp. lactis. | evidence is presented that lactose-fermenting ability (lac+) in lactococcus lactis subsp. cremoris am1, sk11, and ml1 is associated with plasmid dna, even though these strains are difficult to cure of lac plasmids. when the lac plasmids from these strains were introduced into l. lactis subsp. lactis lm0230, they appeared to replicate in a thermosensitive manner; inheritance of the plasmid was less efficient at 32 to 40 degrees c than at 22 degrees c. the stability of the l. lactis subsp. cremori ... | 1991 | 1901709 |
| species and type phages of lactococcal bacteriophages. | lactococcal phages are classified according to morphology and dna homology. phages are differentiated into 12 phage species, and type phages of each species are proposed. members and possible members of each species are named. available data on type phages are tabulated including morphology, dna characteristics and phage protein bands. | 1991 | 1901837 |
| molecular cloning, characterization, and nucleotide sequence of the tagatose 6-phosphate pathway gene cluster of the lactose operon of lactococcus lactis. | the tagatose 6-phosphate pathway gene cluster (lacabcd) encoding galactose-6-phosphate isomerase, tagatose-6-phosphate kinase, and tagatose-1,6-diphosphate aldolase of lactococcus lactis subsp. lactis mg1820 has been characterized by cloning, nucleotide sequence analysis, and enzyme assays. transcription studies showed that the four tagatose 6-phosphate pathway genes are the first genes of the lactose-inducible lactose-phosphotransferase operon consisting of the lacabcdfegx genes. using a t7 exp ... | 1991 | 1901863 |
| bacteriophage receptors of lactococcus lactis subsp. 'diacetylactis' f7/2 and lactococcus lactis subsp. cremoris wg2-1. | bacteriophage p008 revealed irreversible and uniform adsorption to cell walls of l. lactis subsp. 'diacetylactis' f7/2, whereas phage p127 adsorbed reversibly to a limited number of receptor sites on cell walls of l. lactis subsp. cremoris wg2-1. neither extraction of lipids, cell wall- and membrane-teichoic acids nor enzymatic degradation of proteins altered the binding efficiencies of both cell wall fractions. however, phage binding was inhibited, when cell walls were subjected to lysozyme, me ... | 1991 | 1903350 |
| 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 |
| molecular characterization of the nisin resistance region of lactococcus lactis subsp. lactis biovar diacetylactis drc3. | the nisin resistance determinant of lactococcus lactis subsp. lactis biovar diacetylactis drc3 was localized onto a 1.3-kb ecori-ndei fragment by subcloning and interrupting the ndei site by cloning random ndei fragments into it; the nisin resistance determinant was then sequenced. the nucleotide sequence revealed a large open reading frame containing 318 codons. putative transcription and translation signal sequences were located directly upstream from the initiation codon. immediately downstre ... | 1991 | 1903915 |
| genetic analysis of a lactococcal plasmid replicon. | the sequence and genetic organization was determined of the 2508 bp lactococcal portion of pfx2, which was derived from a cryptic lactococcus lactis subsp. lactis plasmid and used as the basis for construction of a series of lactococcal vectors. a lactococcal plasmid plus origin and two replication protein-coding regions (repa and repb) were located. repa has a helix-turn-helix motif, a geometry typical of dna-binding proteins. repb shows a high degree of homology to the plasmid replication init ... | 1991 | 1904536 |
| distance-dependent translational coupling and interference in lactococcus lactis. | the possibility of raising the expression level of a heterologous gene in lactococcus lactis by exploiting the principle of translational coupling was investigated. for this purpose, the escherichia coli lacz gene was transcriptionally fused to a short open reading frame (orf) of lactococcal origin. a shine-dalgarno (sd) sequence was introduced at the boundary of the two orfs. in a series of otherwise identical plasmids, the relative positions of the translational stop codon of the upstream orf ... | 1991 | 1904538 |
| capsular polysaccharide of a slime-forming lactococcus lactis ssp. cremoris lapt 3001 isolated from swedish fermented milk 'långfil'. | slime-forming lactococcus lactis ssp. cremoris strain lapt 3001 isolated from swedish ropy sour milk 'långfil' was investigated for the chemical nature of its capsule. the capsular material purified by gel filtration chromatography and ion-exchange chromatography consisted of rhamnose, glucose, galactose, glycerol and phosphorus. it is most likely a deacylated lipoteichoic acid. | 1991 | 1904758 |
| lactococcin a, a new bacteriocin from lactococcus lactis subsp. cremoris: isolation and characterization of the protein and its gene. | a new bacteriocin, termed lactococcin a (lcn-a), from lactococcus lactis subsp. cremoris lmg 2130 was purified and sequenced. the polypeptide contained no unusual amino acids and showed no significant sequence similarity to other known proteins. only lactococci were killed by the bacteriocin. of more than 120 l. lactis strains tested, only 1 was found resistant to lcn-a. the most sensitive strain tested, l. lactis subsp. cremoris ncdo 1198, was inhibited by 7 pm lcn-a. by use of a synthetic dna ... | 1991 | 1904860 |
| n5-(1-carboxyethyl)ornithine and related [n-carboxyalkyl]-amino acids: structure, biosynthesis, and function. | 1991 | 1905094 | |
| 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 |
| hydrophobic membrane thickness and lipid-protein interactions of the leucine transport system of lactococcus lactis. | the effect of the phospholipid acyl chain carbon number on the activity of the branched-chain amino acid transport system of lactococcus lactis has been investigated. major fatty acids identified in a total lipid extract of l. lactis membranes are palmitic acid (16:0), oleic acid (18:1) and the cyclopropane-ring containing lactobacillic acid (19 delta). l. lactis membrane vesicles were fused with liposomes prepared from equimolar mixtures of synthetic phosphatidylethanolamine (pe) and phosphatid ... | 1991 | 1905573 |
| cloning and nucleotide sequence of the major capsid protein from lactococcus lactis ssp. cremoris bacteriophage f4-1. | the gene (mcp) coding for the major capsid protein (mcp) of the lactococcus lactis ssp. cremoris bacteriophage f4-1 has been cloned and its nucleotide sequence determined. the mcp gene was localized, by western blotting with rabbit antiserum against intact bacteriophage, within a 3.3-kb hindiii-spe i fragment and the sequence of the entire region determined. the 35-kda mcp is coded for by a 905-bp open reading frame preceded by a putative ribosome-binding site. deletion analysis and n-terminal s ... | 1991 | 1905665 |
| in vivo genetic exchange of a functional domain from a type ii a methylase between lactococcal plasmid ptr2030 and a virulent bacteriophage. | the conjugative plasmid ptr2030 confers bacteriophage resistance to lactococci by two independent mechanisms, an abortive infection mechanism (hsp+) and a restriction and modification system (r+/m+). ptr2030 transconjugants of lactococcal strains are used in the dairy industry to prolong the usefulness of mesophilic starter cultures. one bacteriophage which has emerged against a ptr2030 transconjugant is not susceptible to either of the two defense systems encoded by the plasmid. phage nck202.50 ... | 1991 | 1906061 |
| lactococcal proteinase maturation protein prtm is a lipoprotein. | the production of enzymatically active proteinase by lactococci requires the joint presence of a proteinase gene, prtp, and a gene encoding a maturation protein, prtm. a 32-kda protein produced by escherichia coli upon expression of the prtm gene under the direction of the t7 rna polymerase promoter was purified and used to obtain prtm-specific antibodies. with these antibodies, immunogold labeling of lactococcal cells revealed that prtm was associated with the lactococcal cell envelope. western ... | 1991 | 1906066 |
| replacement recombination in lactococcus lactis. | in the puc18-derived integration plasmid pml336 there is a 5.3-kb chromosomal dna fragment that carries the x-prolyl dipeptidyl aminopeptidase gene (pepxp). the gene was inactivated by the insertion of an erythromycin resistance determinant into its coding sequence. covalently closed circular dna of pml336 was used for the electrotransformation of lactococcus lactis. in 2% of the erythromycin-resistant transformants the pepxp gene was inactivated by a double-crossover event (replacement recombin ... | 1991 | 1906872 |
| [cloning the gene of beta-galactosidase from the industrial strain of streptococcus lactis 111 in e. coli cells and conjugated transfer of this gene to streptococcus thermophilus cells]. | the ability of the industrial strains of streptococcus lactis to synthesize the enzyme beta-galactosidase was studied. five strains among sixteen were found to produce high levels of the enzyme. the beta-galactosidase gene in the most active strain streptococcus lactis 111 was shown to be located on the 50 kb conjugative plasmid. the plasmid was transferred by conjugation into streptococcus thermophilus cells and subsequently the gene for beta-galactosidase was studied in transconjugants. the be ... | 1991 | 1906985 |
| distribution and purification of aspartate racemase in lactic acid bacteria. | the distribution of aspartate racemase (ec 5.1.1.13) in various kinds of bacteria demonstrated that the enzyme occurs in lactic acid bacteria, such as streptococcus species and lactobacillus species. the enzyme from streptococcus thermophilus iam10064 was more thermostable than that from streptococcus lactis iam1198 which contained the enzyme most abundantly among the lactic acid bacteria we examined here. we purified the enzyme about 3400-fold to homogeneity from cell-free extract of s. thermop ... | 1991 | 1907199 |
| inhibition of clostridium tyrobutyricum by bacteriocin-like substances produced by lactic acid bacteria. | lactic acid bacteria were selected for their inhibitory activity against clostridium tyrobutyricum under conditions that eliminate the effects of lactic acid and hydrogen peroxide. four strains were isolated belonging to the species lactococcus lactis ssp. lactis. the sensitivity of the inhibitory substances to pronase and trypsine indicates that they are proteins or peptides different from nisin. their resistance to phospholipase d indicates that they are also different from lactostrepcin. the ... | 1991 | 1907300 |
| immunoblotting and culture positive endocarditis. | serum samples from patients with endocarditis due to streptococcus mutans, streptococcus pneumoniae, streptococcus agalactiae, streptococcus lactis and a "nutritionally" variant streptococcus were immunoblotted against antigenic extracts from all five species. in s mutans endocarditis there was an endocarditis specific pattern of igm against bands of 220, 200, and 190 kilodaltons. in s pneumoniae igm against antibody of a molecular weight greater than 150 kilodaltons was specific to endocarditis ... | 1991 | 1907617 |
| in lactococcus lactis subsp. cremoris sk110 protein, instead of lipoteichoic acid, reacts with the group-n-specific antiserum. | the reaction between cell-surface components, isolated from two lactococcus lactis subsp. cremoris strains, with their group-specific antiserum were studied. no reaction between purified lipoteichoic acid and the antiserum was observed. both strains, however, did belong to the lactococci (group-n streptococci), as was demonstrated by the positive reaction between the antiserum and an acid- (lancefield) or alkaline-extract. experiments with proteolytic enzymes demonstrated the involvement of prot ... | 1991 | 1908692 |
| nucleotide sequence of the secy gene from lactococcus lactis and identification of conserved regions by comparison of four secy proteins. | sec y is an integral membrane protein which participates in the translocation of proteins through the bacterial cell membrane. we have cloned the sec y gene of lactococcus lactis, and found its deduced protein sequence, 439 amino acids long, to be similar in length to the previously determined sec y proteins of escherichia coli, bacillus subtilis and mycoplasma capricolum. comparison of the l. lactis sec y to the 3 other sec y proteins revealed 90 conserved amino acid residues (21%). nearly half ... | 1991 | 1908794 |
| 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 |
| bacterial interactions with chromate. | hexavalent chromium compounds (chromates and dichromates) are highly toxic and are considered as mutagens and carcinogens. these compounds are discharged frequently to the environment as a result of diverse industrial processes. some microorganisms are able to reduce hexavalent chromium to the less toxic trivalent form. chromate pollution has promoted the selection of bacterial strains possessing chromate resistance determinants, usually carried by plasmids. strains combining both abilities, i.e ... | 1991 | 1909110 |
| identification of a reca-like protein in lactococcus lactis. | we have identified in lactococcus lactis, an analogue of escherichia coli reca protein. physiological responses such as ultraviolet (uv) and chemical mutagenesis and induction of prophage have been characterized and suggest the existence of reca-like functions in this commercially important species. the putative reca protein was detected at the position of an apparent molecular weight of 39 kda by western blot analysis by using antiserum against e coli reca protein. in addition, the protein leve ... | 1991 | 1909184 |
| processing of the lactococcal extracellular serine proteinase. | activity of the lactococcal cell envelope-located serine proteinase depends on the presence of membrane-associated lipoprotein prtm. to differentiate between the action of the proteinase and the action of prtm in the process of proteinase maturation, an inactive form of the lactococcal proteinase was constructed. this was done by mutating one of the three amino acids thought to constitute the active site of the enzyme. the secreted form of this inactivated proteinase was the same size as the ina ... | 1991 | 1909853 |
| 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 |
| comparison of lactococcal bacteriophage isolated in the united states and argentina. | bacteriophage of lactococcus lactis ssp. lactis and ssp. cremoris, isolated in the united states and argentina, were compared with respect to host range, adsorption, latent period, burst size and immunological cross-reactivity. only 1 out of 13 u.s. culture isolates was sensitive to argentinian phage. argentinian l. lactis ssp. lactis c2 mutants were resistant to 13 u.s. phage isolates (4 prolate and 9 isometric). while argentinian phage stl-3 multiplied on u.s. culture isolate 59-1, low adsorpt ... | 1991 | 1911085 |
| effect of lactic cultures on escherichia coli in ewes' milk stored at low temperatures. | the behaviour of escherichia coli in pasteurized ewes' milk inoculated with different lactic starter cultures and incubated at temperatures in the range 4-16 degrees c for 96 h was investigated. growth temperature of lactic starter cultures before inoculation had a significant effect on inhibition of e. coli. the growth temperature of lactic starter inoculum which resulted in the highest inhibitory activity was 24 degrees c. size of lactic starter inoculum also significantly influenced growth of ... | 1991 | 1911088 |
| stability of plasmids in lactococci during extended incubation in growth media. | the stability of plasmids in lactococcus lactis ssp. lactis strains c2 and ml3, and l. lactis ssp. cremoris strains ml1 and sc607, was investigated by extended incubation of bacterial cells in low nutrient media under acidic conditions. strains were grown overnight (16-18 h) in skim milk and unbuffered medium (m17-) at 32 degrees c and subsequently held at that temperature for extended periods (greater than or equal to 96 h). lac- variants were obtained from each strain in milk and (m17-) broth. ... | 1991 | 1913354 |
| malolactic fermentation: electrogenic malate uptake and malate/lactate antiport generate metabolic energy. | the mechanism of metabolic energy production by malolactic fermentation in lactococcus lactis has been investigated. in the presence of l-malate, a proton motive force composed of a membrane potential and ph gradient is generated which has about the same magnitude as the proton motive force generated by the metabolism of a glycolytic substrate. malolactic fermentation results in the synthesis of atp which is inhibited by the ionophore nigericin and the f0f1-atpase inhibitor n,n-dicyclohexylcarbo ... | 1991 | 1917837 |
| a membrane protein is required for bacteriophage c2 infection of lactococcus lactis subsp. lactis c2. | phage-resistant mutants, isolated from cultures of lactococcus lactis subsp. lactis c2 infected with phage c2, did not form plaques but bound phage normally. the mutants were sensitive to another phage, sk1, although the number of plaques was reduced approximately 56% and the plaques were four times smaller. binding to phage sk1 was reduced about 10%. another group of phage-resistant mutants, isolated from cultures infected with phage sk1, bound normally to both phages c2 and sk1 but did not for ... | 1991 | 1917843 |
| cloning and characterization of the determinant for abortive infection of bacteriophage from lactococcal plasmid pci829. | the genetic determinant for abortive infection of bacteriophage (abi) from the lactococcal plasmid pci829 was cloned on a 6.2 kb stui fragment in escherichia coli using the shuttle vector psa3. in lactococcus lactis subsp. lactis mg1363sm the resulting recombinant plasmid pci816 conferred complete insensitivity to the small isometric-headed phage 712 and a reduced plaque size in the case of the prolate-headed phage c2. the determinant was further localized by subcloning and nuclease bal31 deleti ... | 1991 | 1919509 |
| [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 |
| identification and characterization of the lantibiotic nisin z, a natural nisin variant. | lactococcus lactis strain nizo 22186 produces an extracellular, lanthionine-containing 3.5-kda polypeptide with antimicrobial activity. its retention time on reversed-phase (rp) hplc and its amino acid composition showed high similarities but no complete identity to nisin. the gene for this lantibiotic, designated nisz, has been cloned and its nucleotide sequence was found to be identical to that of the precursor nisin gene apart from a single mutation resulting in the substitution his27asn in t ... | 1991 | 1935953 |
| isolation, sequence and expression in escherichia coli, bacillus subtilis and lactococcus lactis of the dnase (streptodornase)-encoding gene from streptococcus equisimilis h46a. | a partial library of bcli-generated chromosomal dna fragments from streptococcus equisimilis h64a (lancefield group c) was constructed in escherichia coli. clones displaying either streptokinase or deoxyribonuclease (streptodornase; sdc) activities were isolated. the gene (sdc) expressing the sdc activity was allocated on the 1.1-kb acci dna subfragment. sequence analysis of this dna fragment revealed the presence of one open reading frame, which could encode a protein of 36.8 kda. the n-termina ... | 1991 | 1937032 |
| replication and temperature-sensitive maintenance functions of lactose plasmid psk11l from lactococcus lactis subsp. cremoris. | the replication region of psk11l, the lactose plasmid of lactococcus lactis subsp. cremoris (l. cremoris) sk11, was isolated on a 14.8-kbp pvuii fragment by shotgun cloning into an escherichia coli vector encoding erythromycin resistance and selection for erythromycin-resistant transformants of l. lactis subsp. lactis (l. lactis) lm0230. deletion analysis and tn5 mutagenesis of the resulting plasmid (pkmp1) further localized the replication region to a 2.3-kbp scai-spei fragment. dna sequence an ... | 1991 | 1938953 |
| purification and characterization of the free form of the lactococcal extracellular proteinase and its autoproteolytic cleavage products. | in addition to the cell wall proteinase, lactococcus lactis subsp. cremoris produced significant amounts of a free extracellular proteinase. the free proteinase activity was highest in the late exponential and early stationary phase of growth, whereas the cell wall activity was highest in the last half of the exponential phase. both proteinase forms had a ph optimum between 4-6 and 5-8, and they behaved similarly upon anion exchange and hydrophobic interaction chromatography, chromatofocusing an ... | 1991 | 1955854 |
| a gene (prsa) of bacillus subtilis involved in a novel, late stage of protein export. | a gene locus of bacillus subtilis identified by mutations (prs) conferring a defect in protein secretion was cloned from a lambdagem-11 expression library. the sites of three closely linked prs mutations (prs-3, prs-29 and prs-40) were found to reside in a 5.3 kb dna fragment, which also complemented the secretion defect in prs-3 and prs-29 mutants. partial sequencing of the fragment showed that these three mutations affect one distinct gene (prsa) encoding a putative protein of 292 amino acids ... | 1991 | 1956302 |
| continuous measurement of the cytoplasmic ph in lactococcus lactis with a fluorescent ph indicator. | the cytoplasmic ph of lactococcus lactis was studied with the fluorescent ph indicator 2',7'-bis-(2-carboxyethyl)-5 (and-6)-carboxyfluorescein (bcecf). a novel method was applied for loading bacterial cells with bcecf, which consists of briefly treating a dense cell suspension with acid in the presence of the probe. this results in a ph gradient, which drives accumulation of the probe in the cytoplasm. after neutralization the probe was well retained in cells stored on ice. bcecf-loaded cells we ... | 1991 | 1958707 |
| single-stranded dna plasmid, vector construction and cloning of bacillus stearothermophilus alpha-amylase in lactobacillus. | vector plasmids were constructed by ligating chloramphenicol and erythromycin resistance genes to taqi-digested dna of a cryptic plasmid from lactobacillus plantarum. the minimal region of lactobacillus plasmid dna that was required for dna replication was defined and a single-stranded dna intermediate replication system was observed. homologies with other origins of replication of plasmids from gram-positive bacteria, replicating via rolling circle mechanism, were found. it was shown that the c ... | 1991 | 1961976 |
| microtiter plate assays for the measurement of phage adsorption and infection in lactococcus and enterococcus. | three easy and rapid microtiter plate assays for determining phage sensitivity of lactococci and enterococci have been developed. in the microlysis assay, the degree of sensitivity was measured on the basis of the ability of the bacterial cells to grow in the presence of various concentrations of phage and to effect a color change of an acid-base indicator as a result of acid production. two assays that specifically measure phage adsorption to bacterial cells have been developed on the basis of ... | 1991 | 2035836 |
| aminotripeptidase activity in lactococcus lactis subsp cremoris am2. | 1991 | 2037168 | |
| ecology of accelerated natural lactic fermentation of sorghum-based infant food formulas. | accelerated natural lactic fermentation of mixed sorghum-cowpea (formula 1) and sorghum-milkpowder (formula 2) infant food formulas was achieved by repetitive (60 fermentation cycles of 24 h each) use of the previous batch as an inoculum at a rate of 10% (w/w) and resulted in a gradual establishment of mixed populations of lactic acid bacteria and yeasts. in formula 1, early fermentation stages (fermentation cycles 1-4) were dominated by leuconostoc and lactococcus spp. which caused conditions i ... | 1991 | 2049286 |
| the microflora of soak water during tempeh production from various beans. | the microflora of soak water was studied during the soaking of horsebean, pea, chickpea and soybean for tempeh production. lactic streptococci dominated the flora in both unacidified and acidified soak water. coliforms and yeast were found only in unacidified soak water. growth of micro-organisms in acidified and unacidified soak water resulted in a decrease in ph value of the cooked beans. microbial acidification during soaking is considered to be important in tempeh production. | 1991 | 2055793 |
| comparison of bovine beta-casein hydrolysis by pi and piii-type proteinases from lactococcus lactis subsp. cremoris [corrected]. | the action of the cell-wall-associated proteinases from lactococcus lactis subsp. cremoris strains h2 and sk112 on bovine beta-casein was compared. the proteinase from the h2 strain was characterised as a pi-type proteinase since it did not hydrolyse alpha s1-casein and the initial trifluoroacetic acid-soluble products of beta-casein hydrolysis were identical to those previously identified as hydrolysis products of pi-type lactococcal proteinase action. the time-course of product formation by th ... | 1991 | 1368045 |
| rapid method to characterize lactococcal bacteriophage genomes. | we present a rapid method to isolate and analyze bacteriophage dna. cells are infected and phage replication is allowed to proceed normally for 30 to 60 min. prior to dna packaging and cell bursts, the infected cells (1 ml) are harvested and lysed by using a combination of lysozyme and sodium dodecyl sulfate treatments. the total dna recovered is enriched for phage genomes, and restriction fragments of the phage dna can be readily visualized on agarose gels. this method was used to grossly compa ... | 1991 | 16348396 |
| antisense mrna-mediated bacteriophage resistance in lactococcus lactis subsp. lactis. | resistance to a broad class of isometric bacteriophages that infect strains of lactococcus lactis has been engineered into a dairy starter by expression of antisense mrna targeted against a conserved bacteriophage gene. maximum protection is obtained only when the entire 1,654-bp coding sequence for a 51-kda protein is positioned in the antisense orientation with respect to a promoter sequence that functions in l. lactis subsp. lactis. expression of the antisense mrna results in more than 99% re ... | 1991 | 16348458 |
| molecular characterization of three small isometric-headed bacteriophages which vary in their sensitivity to the lactococcal phage resistance plasmid ptr2030. | lactococcus lactis lma12-4 is a ptr2030 transconjugant that has been used as an industrial starter culture because of its resistance to phages predominant in cheese plants. plasmid ptr2030 interferes with susceptible phages in this host strain via two mechanisms, restriction and modification (r/m) and abortive infection (hsp). after prolonged use of lma12-4 transconjugants in the industry, two different bacteriophages, designated nck202.phi48 (phi48) and nck202.phi50 (phi50), were isolated which ... | 1991 | 16348479 |
| characterization of the heat shock response in lactococcus lactis subsp. lactis. | the heat shock response in lactococcus lactis subsp. lactis was characterized with respect to synthesis of a unique set of proteins induced by thermal stress. a shift in temperature from 30 to 42 degrees c was sufficient to arrest the growth of l. lactis subsp. lactis, but growth resumed after a shift back to 30 degrees c. heat shock at 50 degrees c reduced the viable cell population by 10; however, pretreatment of the cells at 42 degrees c made them more thermoresistant to exposure at 50 degree ... | 1991 | 16348482 |
| characterization of the cell wall-bound proteinase of lactobacillus casei hn14. | lactobacillus casei hn14, which was isolated from homemade cheese, produces an extracellular, cell wall-bound proteinase. the hn14 proteinase can be removed from the cell envelope by washing the cells in a ca-free buffer. the activity of the crude proteinase extract is inhibited by phenylmethylsulfonyl fluoride, showing that the enzyme is a serine-type proteinase. considering the substrate specificity, the hn14 proteinase is similar to the lactococcal pi-type enzyme, since it hydrolyzes beta-cas ... | 1991 | 16348511 |
| bacteriocin-producing strain of lactococcus lactis subsp. diacitilactis s50. | lactococcus lactis subsp. diacitilactis s50 produces a bacteriocin, designated bacteriocin s50, which has a narrow antibacterial spectrum. it was active only against lactococcus species, including a nisin producer exhibiting a bactericidal effect. the activity of bacteriocin s50 was sensitive to proteases. it retained antimicrobial activity after being heated to 100 degrees c for up to 60 min and in the ph range 2 to 11. | 1991 | 16348516 |
| ultrasound treatment for harvesting an aminopeptidase from lactic acid bacteria and quantitation of the enzyme by enzyme-linked immunosorbent assays. | ultrasound treatment of lactococcus lactis subsp. cremoris am2 was optimized to release a maximum amount of intracellular aminopeptidase without modifying the antigenicity of the enzyme. the cells were sonicated three times for 30 s at 23 w. antibodies produced against the aminopeptidase purified from l. lactis subsp. cremoris am2 enabled us to use immunoblotting to detect the enzyme in the lysates of all of the lactococci tested but not in the lysates of leuconostoc strains, lactobacilli, and s ... | 1991 | 16348536 |
| autoproteolysis of the extracellular serine proteinase of lactococcus lactis subsp. cremoris wg2. | the molecular masses of purified extracellular serine proteinase of a number of lactococcus lactis strains vary significantly, and these molecular mass values do not correspond to the values estimated on the basis of genetic data. the discrepancies can only partially be explained by n-terminal processing during maturation of the precursor enzyme and by c-terminal cleaving during the release from the cell envelope. with a monoclonal antibody that binds in the active site region of the l. lactis p ... | 1991 | 16348552 |
| differences between lactobacillus casei subsp. casei 2206 and citrate-positive lactococcus lactis subsp. lactis 3022 in the characteristics of diacetyl production. | lactobacillus casei subsp. casei 2206 exhibited much lower levels of diacetyl reductase activity than citrlactococcus lactis subsp. lactis 3022 but two-, three-, and more than eightfold-higher levels of diacetyl synthase, lactate dehydrogenase, and nadh oxidase activities, respectively. a requirement for metal ions by the diacetyl synthases in both species was observed. the extracts of strain 2206 but not strain 3022 produced more diacetyl from pyruvate when the reaction for diacetyl synthase wa ... | 1991 | 16348572 |
| study of the citrate metabolism of lactococcus lactis subsp. lactis biovar diacetylactis by means of c nuclear magnetic resonance. | the metabolic fate of citrate and pyruvate in four strains of lactococcus lactis subsp. lactis biovar diacetylactis has been studied by means of c nuclear magnetic resonance, using as a substrate either [3-c]pyruvic acid or custom-synthesized citric acid that is c labeled either at carbons 2 and 4 or at carbon 3. the fermentations were carried out batchwise in modified m17 broth. for the actual conversions of the c-labeled substrates, cells at the end of their logarithmic growth phase were used ... | 1991 | 16348592 |
| construction of a bacteriophage-resistant derivative of lactococcus lactis subsp. lactis 425a by using the conjugal plasmid pnp40. | lactococcus lactis subsp. lactis 425a is an atypical strain which excretes a high concentration of alpha-acetolactate when grown in milk. the conjugative lactococcal plasmid pnp40, which encodes phage and nisin resistance, was introduced to strain 425a by conjugation, using resistance to phage and nisin as a selection. no phage-nisin resistance mutants were encountered. transconjugants display complete resistance at both 21 and 39 degrees c to those phage previously identified as lytic for 425a. ... | 1991 | 16348595 |
| citrate fermentation by lactococcus and leuconostoc spp. | citrate and lactose fermentation are subject to the same metabolic regulation. in both processes, pyruvate is the key intermediate. lactococcus lactis subsp. lactis biovar diacetylactis homofermentatively converted pyruvate to lactate at high dilution (growth) rates, low ph, and high lactose concentrations. mixed-acid fermentation with formate, ethanol, and acetate as products was observed under conditions of lactose limitation in continuous culture at ph values above 6.0. an acetoin/butanediol ... | 1991 | 16348602 |
| high-concentration cultivation of lactococcus cremoris in a cell-recycle reactor. | high-cell concentration cultivation of lactococcus cremoris, a homofermentative lactic acid producer, in a cell-recycle fermentor is described. cross-flow filtration allowing continuous removal of the inhibitory metabolite, the influence of dilution rate on growth was investigated in total or partial cell-recycle cultures. the dependence of growth characteristics on operating conditions was identified and quantified using lactose as the carbon source. growth kinetics could be described by both l ... | 1991 | 18600671 |
| use of antisense rna to confer bacteriophage resistance in dairy starter cultures. | the strategy and implementation of a unique system for engineering bacteriophage resistant starter cultures of lactococcus lactis employing antisense rna is reviewed. as a necessary prerequisite for developing this system, we have cloned and sequenced a number of bacteriophage genes coding for minor and major structural proteins. in addition, we have also identified a series of genes whose function(s) is not known but their sequences appear to be conserved in a vast number of isolates. one of th ... | 1992 | 1368478 |
| antisense rna directed against the major capsid protein of lactococcus lactis subsp. cremoris bacteriophage 4-1 confers partial resistance to the host. | antisense rna targeted against the major capsid protein (mcp) of lactococcus lactis subsp. cremoris bacteriophage f4-1 reduced bacteriophage replication by up to 50%. the region containing the mcp gene was oriented to transcribe the antisense strand using a l. lactis subsp. cremoris wg2 promoter. the size of the mcp insert transcribed affected the level of bacteriophage inhibition and the greatest level of inhibition was achieved using a 301-bp fragment from the 5' end of the mcp. antisense mcp ... | 1992 | 1368503 |
| lysozyme expression in lactococcus lactis. | three lysozyme-encoding genes, one of eukaryotic and two of prokaryotic origin, were expressed in lactococcus lactis subsp. lactis. hen egg white lysozyme (hel) could be detected in l. lactis lysates by western blotting. no lysozyme activity was observed, however, presumably because of the absence of correctly formed disulphide bonds in the l. lactis product. the functionally related lysozymes of the e. coli bacteriophages t4 and lambda were produced as biologically active proteins in l. lactis. ... | 1992 | 1368776 |
| batch cultures of recombinant lactococcus lactis subsp. lactis in a stirred fermentor. i. effect of plasmid content on bacterial growth and on genetic stability in pure cultures. | the effect of plasmid introduction into lactococcus lactis subsp. lactis il2661 on the growth of this strain and on plasmid stability was studied in pure batch cultures. the plasmids used (coding for erythromycin or chloramphenicol resistance) were the following: pil205 (42 kb), pil252 (4.6 kb, 6-9 copies), pil253 (4.8 kb, 45-85 copies) and pe194 (inserted in the chromosome). growth and acidification of l. lactis subsp. lactis il2661 were similar to those of the derived recombinant lactococci. t ... | 1992 | 1368909 |