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[variability of lactic streptococci; plicated forms of streptococcus lactis and streptococcus diacetilactis]. 195114842791
[synthesis of acetoin by streptococcus diacetilactis]. 195213137993
role of citritase in acetoin formation by streptococcus diacetilactis and leuconostoc citrovorum.harvey, r. j. (university of california, davis) and e. b. collins. role of citritase in acetoin formation by streptococcus diacetilactis and leuconostoc citrovorum. j. bacteriol. 82:954-959. 1961.-cell-free extracts of streptococcus diacetilactis and leuconostoc citrovorum converted citrate to acetate, oxalacetate, pyruvate, carbon dioxide, and acetoin. the products, stoichiometry, and cofactor requirements of the citrate-splitting reaction were identical to those reported for citritase. coenzym ...196113905111
citrate transport system of streptococcus diacetilactis.harvey, r. j. (university of california, davis) and e. b. collins. citrate transport system of streptococcus diacetilactis. j. bacteriol. 83:1005-1009. 1962.-the uptake of citrate by streptococcus diacetilactis is mediated by a transport system that was distinguished from passive diffusion by inducibility and kinetics of uptake. in these characteristics the system is similar to the beta-galactoside permease of escherichia coli. the citrate transport system of s. diacetilactis differs from beta-g ...196213905110
cultural studies on streptococcus diacetilactis and other members of the lactic streptococcus group. 196214496856
the citritase of streptococcus diacetilactis.substrate, products, and equilibrium. 196314063286
roles of citrate and acetoin in the metabolism of streptococcus diacetilactis.harvey, r. j. (university of california, davis), and e. b. collins. roles of citrate and acetoin in the metabolism of streptococcus diacetilactis. j. bacteriol. 86:1301-1307. 1963.-streptococcus diacetilactis was unable to use citrate as a source of energy for growth, but the addition of citrate to a lactose-containing medium increased the specific growth rate 35%. besides serving as the precursor of acetoin, some of the pyruvate formed from citrate was incorporated into cell material, primarily ...196314086105
[physiological-biochemical characteristics of aroma-producing streptococcus diacetilactis cultures]. 196414241229
a magnetic resonance study on the citrate lyase of streptococcus diacetilactis. 196514340599
repression of staphylococcus aureus in associative culture.the growth of staphylococcus aureus mf 31 was suppressed when grown in association with streptococcus diacetilactis and other lactic streptococci. the data indicated that the initial proportion of staphylococci present in the medium was of less importance than the depletion of vital nutrients. investigation revealed that factors present in yeast nitrogen base medium could reverse the inhibition which was due to antagonism. the major factor found was nicotinamide, and further study revealed that ...19654222452
active transport of l-valine by streptococcus diacetilactis. 19655863518
[activation of diacetyl production in streptococcus diacetilactis]. 19666003018
effect of carbon dioxide, oxygen, and nitrogen on growth rate of streptococcus diacetilactis 18-16 in elliker's medium. 19666013286
molar growth yields of certain lactic acid bacteria as influenced by autolysis.molar growth yields determined from batch cultures of streptococcus diacetilactis and s. faecalis were appreciably greater at the peaks of maximal growth than after continued incubation and considerable autolysis. the higher molar growth yields were about equal to those determined in a continuous culture. autolysis during logarithmic growth was minimal. the average y value for adenosine triphosphate (atp), determined by using limiting concentrations of glucose, galactose, lactose, and maltose fo ...19684969603
chemical composition of a bacteriophage for streptococcus diacetilactis. 19685640400
role of galactose or glucose-1-phosphate in preventing the lysis of streptococcus diacetilactis.cells of streptococcus diacetilactis drci grown at 32 c in media containing glucose as the energy source were osmotically fragile and began to lyse immediately after growth was stopped (by the action of chloramphenicol or the exhaustion of glucose), unless they were then stabilized by hypertonic medium or spermine or by storage at low ph or low temperature, or both. in media containing excess glucose, with growth limited by exhaustion of some nutrient other than the energy source, the appearance ...19685640384
diacetyl biosynthesis in streptococcus diacetilactis and leuconostoc citrovorum.pyruvate was shown to be the precursor of diacetyl and acetoin in streptococcus diacetilactis, but dialyzed cell-free extracts of s. diacetilactis and leuconostoc citrovorum that had been treated with anion-exchange resin to remove coenzyme a (coa) formed only acetoin from pyruvate in the presence of thiamine pyrophosphate (tpp) and mg(++) or mn(++) ions. the ability to produce diacetyl was restored by the addition of acetyl-coa. acetyl-phosphate did not replace the acetyl-coa. neither diacetyl ...19685636815
roles of acetate and pyruvate in the metabolism of streptococcus diacetilactis.streptococcus diacetilactis required acetate, contained acetate kinase and phosphotransacetylase, and incorporated both radioactive exogenous acetate and acetate from citrate into cell lipids. dl-alpha-lipoic acid replaced acetate and was required for the oxidation of pyruvate. stimulation of s. diacetilactis by citrate was found to depend on pyruvate oxidation. resting cells of the organism produced acetate from 73% of the pyruvate they utilized. however, molar growth yields from glucose were n ...19704919981
characterization of diacetyl negative mutants of streptococcus diacetilactis. 19705413653
enzymatic removal of diacetyl from beer. ii. further studies on the use of diacetyl reductase.diacetyl removal from beer was studied with whole cells and crude enzyme extracts of yeasts and bacteria. cells of streptococcus diacetilactis 18-16 destroyed diacetyl in solutions at a rate almost equal to that achieved by the addition of whole yeast cells. yeast cells impregnated in a diatomaceous earth filter bed removed all diacetyl from solutions percolated through the bed. undialyzed crude enzyme extracts from yeast cells removed diacetyl very slowly from beer at its normal ph (4.1); at a ...19704315861
reduced nicotinamide adenine dinucleotide oxidase of streptococcus diacetilactis. 19704316699
induction of mutation in streptococcus diacetilactis by nitrosoguanidine and ultraviolet irradiation. 19715096115
diacetyl, acetoin, and acetaldehyde production by mixed-species lactic starter cultures. 19734762402
incorporation of radioactive acetate into diacetyl by streptococcus diacetilactis.streptococcus diacetilactis was grown in a partially defined, lipoic acid-free medium containing radioactive acetate with and without addition of 0.1% unlabeled sodium pyruvate. labeled carbon was incorporated into diacetyl, but neither the amount of diacetyl produced nor its specific activity was influenced by addition of pyruvate. acetoin had low specific activity, indicating that it was a mixture of radioactive and nonradioactive acetoin. the specific activity of acetoin was lower when pyruva ...19734148640
inactivation of citrate lyase from rhodopseudomonas gelatinosa by a specific deacetylase and inhibition of this inactivation by l-(+1-glutamate.a previously unrecognized enzyme, citrate lyase deacetylase, has been purified about 140-fold from cell extracts of rhodopseudomonas gelatinosa. it catalyzed the conversion of enzymatically active acetyl-s-citrate lyase into the inactive hs-form and acetate. the enzyme exhibited an optimal rate of inactivation at ph 8.1. because of the instability of acetyl-s-citrate lyase at acidic and alkaline ph values, all assays were carried out at ph 7.2, where the spontaneous hydrolysis of the acetyl-s-ci ...1975356
purification and properties of citrate lyase from streptococcus diacetilactis.citrate lyase from streptococcus diacetilactis has been purified to yield a protein that was homogeneous as judged by sedimentation velocity and sedimentation equilibrium experiments. the enzyme's sedimentation coefficient is 16.8 s and its molecular weight is around 585,000. it contains three nonidentical subunits of about 53,000, 34,000, and 10,000 daltons. the enzyme in its active form contains an acetyl group which turns over during the citrate cleavage reaction. removal of the acetyl group ...1975238987
citrate lyase from streptococcus diacetilactis. association with its acetylating enzyme.citrate lyase (ec 4.1.3.6) was purified 38-fold from cell-free extracts of streptococcus diacetilactis. the enzyme was homogeneous in analytical ultracentrifugation and polyacrylamide gel electrophoresis. the final enzyme preparation contained acetate: hs-citrate lyase ligase--an acetylating enzyme which converts inactive hs-citrate lyase into enzymatically active acetyl-s-citrate lyase. this enzyme activity was purified 25-fold over the crude extract and seemed to be associated with citrate lya ...19751115558
citrate utilization in milk by leuconostoc cremoris and streptococcus diacetilactis.citrate utilization and diacetyl, acetoin and acetaldehyde production by 2 strains each of leuconostoc cremoris and streptococcus diacetilactis in milk were studied. with the leuconostoc bacteria no growth and little citrate utilization occurred unless a stimulant (yeast extract) was present, when complete utilization of citrate without concomitant production of diacetyl or acetoin was obtained. the additon of mn2+ stimulated growth resulted in diacetyl and acetoin production. destruction of dia ...19751173068
[age changes in cells in streptococcus diacetilactis cultures].the activity of metabolism changed in the cultures of streptococcus diacetilactis, strain bogdan, with aging. the number of viable cells decreased as well as the ability to evolve oxygen, to produce c-4 compounds, and to react to ph changes by liberating acids upon alkalifying or neutral products upon acidifying. after the culture had been grown during 72 hours, 2,3-butyleneglycol was found in the cultural broth, and the number of viable cells was low. as was revealed by electron microscopy, the ...1976979685
end products and fermentation balances for lactic streptococci grown aerobically on low concentrations of glucose.maximum acetate produced aerobically by streptococcus diacetilactis and streptococcus cremoris was 14% of 1 to 7 mumol of glucose/ml in a partially defined medium that contained lipoic acid. y (glucose) values were 35.3 (s. diacetilactis) and 31.4 (s. cremoris) with low concentrations (1 to 7 mumol/ml) of glucose in the medium and 21 (s. diacetilactis) with higher concentrations (6 to 15 mumol/ml). y (adenosine 5'-triphosphate) values for the bacteria, determined by taking into account the end p ...1977836024
purification and properties of citrate lyase ligase from streptococcus diacetilactis.citrate lyase ligase (acetate: sh--[acyl-carrier protein] enzyme ligase (amp) from streptococcus diacetilactis was purified 920-fold with a yield of 6.3%. the molecular weight of the enzyme was estimated to be 41000; the ligase consisted of one polypeptide chain. the acetylation of 1 mol of deacetyl-citrate lyase to enzymatically active citrate lyase required 6 mol atp. the formation of amp and pyrophosphate in the acetylation reaction was demonstrated. citrate lyase ligase was specific for the ...1977923578
on the structure of the prosthetic group of citrate (pro-3s)-lyase.the prosthetic group of citrate (pro-3s)-lyase from klebsiella aerogenes as well as streptococcus diacetilactis was obtained eigher by beta elimination or pronase digestion of the enzyme and purified by deae-cellulose chromatography. the compound was shown to contain 3 mol of po4, 2 mol of ribose, and 1 mol of sulfhydryl/mol of adenine. 5'-amp and dephospho-coa are components of the prosthetic group. the evidence obtained so far support our proposed structure of 3' (or 2') leads to 1''-(5''-phos ...1977197081
lipid composition of cells and its variation during degradation of a culture of streptococcus diacetilactis.the process of dying of a culture of str. diacetilactis under conditions of prolonged culturing is accompanied by substantial changes in the composition of the cell lipids. in the lipids of young cells the basic components are mono- and diglucosyldiglycerides, as well as phospholipids--two glucophospholipids, cardiolipin, and phosphatidylglycerin; triglycerides and sterols are present in negligible amounts. as the str. diacetilactis culture develops and undergoes degradation, an increase is obse ...1979549660
evaluation of lactic acid streptococci for the preparation of frozen concentrated starter cultures.eight strains of streptococcus diacetilactis and streptococcus lactis were examined for viability, growth rate, lactic acid and diacetyl production in milk and proteolytic activity before and after freezing at --30 degrees c. concentrations of yeast autolysate, peptone, lactose and citrate as well as the usefulness of milk and whey culture media for active biomass production were investigated. after freezing and storage at --30 degrees c, with the use of non-fat milk as a cryoprotective agent, h ...19806158835
substrate specificity of citrate lyase deacetylase of rhodopseudomonas gelatinosa and rhodopseudomonas palustris.citrate lyase (ec 4.1.3.6) isolated from rhodopseudomonas palustris was investigated with regard to its kinetic properties and its subunit composition. this enzyme was inactivated by citrate lyase deacetylase (ec 3.1.2.-) of rhodopseudomonas gelatinosa. a corresponding cross-reaction was measured with partially purified deacetylase of r. palustris and citrate lyase of r. gelatinosa. the three different subunit types (alpha, beta, and gamma) of citrate lyase from r. gelatinosa wee purified to hom ...19816167565
amino acid sequence of a dodecapeptide from the substrate-binding region of the l-lactate dehydrogenase from lactobacillus curvatus, lactobacillus xylosus and bacillus stearothermophilus.the amino acid sequence of dodecapeptides from the substrate-binding region of 3 bacterial l-lactate dehydrogenases (lactobacillus xylosus, lactobacillus curvatus and bacillus stearothermophilus) were determined. they show a very high homology to the sequences of the corresponding known animal enzymes. there is, however, an essential difference between the sequences of pro- and eucaryotic enzymes: the asn residue in position 166, common to all eucaryotes, is replaced by serine in lactobacilli an ...19817346373
purification of l-glutamate-dependent citrate lyase from clostridium sphenoides and electron microscopic analysis of citrate lyase isolated from rhodopseudomonas gelatinosa, streptococcus diacetilactis and c. sphenoides.citrate lyase from clostridium sphenoides was purified 72-fold with a yield of 11%. in contrast to citrate lyase from other sources the activity of this enzyme was strictly dependent on the presence of l-glutamate. the purified enzyme was only stable in the presence of 150 mm l-glutamate or 7 mm l-glutamate plus glycerol, sucrose or bovine serum albumin. changes of the l-glutamate pool and of enzyme activity in growing cells of c. sphenoides indicated that citrate lyase activity in this organism ...19826127210
copurification of citrate lyase and citrate lyase ligase from rhodopseudomonas gelatinosa and subsequent separation of the two enzymes.a procedure has been worked out which allowed the purification and crystallization of a citrate lyase/citrate lyase ligase complex from rhodopseudomonas gelatinosa. the complex was subsequently separated to yield two homogeneous enzymes. citrate lyase ligase was purified 365-fold with a yield of 3.23%. the molecular weight of the enzyme was estimated to be 39500, the enzyme consisted of one polypeptide chain. the reaction rates for atp, acetate and citrate lyase (sulfhydryl form) followed michae ...19827128585
isolation of streptococcus lactis bacteriophages and their interaction with the host cell.phages may cause lysis of lactic acid bacteria used in cheese production. three virulent bacteriophages specific for streptococcus lactis subsp. lactis c2 were isolated and purified from cheese whey. they showed distinct plaque sizes, and although they had similar morphology by electron microscope examination, their dimensions were slightly different. the phage heads were elongated and hexagonal in shape, and the flexible tails appeared periodically cross-striated. they were dna phages based on ...198416346573
comparative peptide specificity of cell wall, membrane and intracellular peptidases of group n streptococci.solubilized cell walls of group n streptococci contain two electrophoretically distinct peptidases, one of which hydrolysed trileucine only, while the second hydrolysed a wide range of di- and tripeptides. neither enzyme possessed leucine aminopeptidase or endopeptidase activity. four and three peptidases, respectively, were separated in intracellular extracts of streptococcus lactis subsp. lactis and strep. lactis subsp. cremoris produced by osmotic lysis of spheroplasts. in contrast with the c ...19853924874
cloning of a streptococcus lactis subsp. lactis chromosomal fragment associated with the ability to grow in milk.a chromosomal fragment of 6.7 megadaltons (mda), apparently containing the genes for milk protein utilization by streptococcus lactis subsp. lactis ssl135, was cloned in s. lactis subsp. lactis mg1614, a proteinase-negative strain. for the cloning, the chromosomal dna of ssl135 was cleaved with restriction enzyme bamhi and the resulting fragments were ligated to the single bcli site of pvs2, a 3.3-mda chloramphenicol-erythromycin double-resistance plasmid constructed in this laboratory. s. lacti ...198716347386
construction of streptococcus lactis subsp. lactis strains with a single plasmid associated with mucoid phenotype.lactose-fermenting mucoid (lac muc) variants of plasmid-free streptococcus lactis subsp. lactis mg1614 were obtained by protoplast transformation with total plasmid dna from mucs. lactis subsp. cremoris arh87. by using plasmid dna from these variants for further transformations followed by novobiocininduced plasmid curing, lac muc mg1614 strains containing only a single 30-megadalton plasmid could be constructed. this plasmid, designated pvs5, appeared to be associated with the muc phenotype.198716347368
evidence for an essential histidine residue in d-xylose isomerases.diethyl pyrocarbonate inactivated d-xylose isomerases from streptomyces violaceoruber, streptomyces sp., lactobacillus xylosus and lactobacillus brevis with second-order rate constants of 422, 417, 99 and 92 m-1.min-1 respectively (at ph 6.0 and 25 degrees c). activity was completely restored by the addition of neutral hydroxylamine, and total protection was afforded by the substrate analogue xylitol in the presence of either mg2+ or mn2+ according to the genus studied. the difference spectra of ...19883355509
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 ...19892506592
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 ...19892506593
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 ...19892513247
reaction of woodward's reagent k with d-xylose isomerases. modification of an active site carboxylate residue.d-xylose isomerases from streptomyces violaceoruber, streptomyces sp., lactobacillus xylosus, lactobacillus brevis and bacillus coagulans were rapidly inactivated by woodward's reagent k. second-order rate constants in the absence of ligands, at ph 6.0 and 25 degrees c, were 41, 36, 22, 95 and 26 m-1.min-1 respectively. spectral analysis at 340 nm revealed that inactivation was correlated with modification of five, six, two, three and six carboxylate residues per monomer respectively. in the pre ...19892775179
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.19892506405
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 ...19892497708
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 ...19892494937
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 ...19892495760
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 ...19892504115
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., ...19892513778
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 ...19892515252
peptide utilization encoded by lactococcus lactis subsp. lactis ssl135 chromosomal dna.a cloned chromosomal fragment of lactococcus lactis subsp. lactis ssl135 on plasmid p vs8 in an l. lactis subsp. lactis mg1614 background enabled proteinase-negative strain mg1614 to grow in autoclaved milk. the strain (vs230) did not, however, degrade milk proteins and did not grow in pasteurized milk. in contrast, a strain (vs150) carrying p vs9, the proteinase plasmid of ssl135, in an mg1614 background degraded beta-casein but did not grow in milk. vs230 was shown to utilize peptides produced ...198916348035
localization of separate genetic loci for reduced sensitivity towards small isometric-headed bacteriophage sk1 and prolate-headed bacteriophage c2 on pgbk17 from lactococcus lactis subsp. lactis kr2.the mechanism of reduced sensitivity to the small isometric-headed bacteriophage sk1 encoded on a 19-kilobase (kb) hpaii fragment subcloned from pkr223 of lactococcus lactis subsp. lactis kr2 was examined. the reduced sensitivity to phage sk1 was due to a modest restriction/modification (r/m) system that was not active against prolate-headed phage c2. the genetic loci for the r/m system against sk1 and the abortive phage infection (abi) mechanism effective against phage c2 were then localized by ...198916348036
sugar utilization and acid production by free and entrapped cells of streptococcus salivarius subsp. thermophilus, lactobacillus delbrueckii subsp. bulgaricus, and lactococcus lactis subsp. lactis in a whey permeate medium.cells of streptococcus salivarius subsp. thermophilus and lactococcus lactis subsp. lactis entrapped in k-carrageenan-locust bean gum gel performed similarly to free cells in the conversion of lactose to lactic acid. bead diameter influenced the fermentation rate. cells entrapped in smaller beads (0.5 to 1.0 mm) showed higher release rates, higher lactose, glucose, and formic acid utilization, higher galactose accumulation, and higher lactic acid production than did cells entrapped in larger bea ...198916347822
resistance against industrial bacteriophages conferred on lactococci by plasmid paj1106 and related plasmids.plasmid paj1106 and its deletion derivative, plasmid paj2074, conferred lactose-fermenting ability (lac) and bacteriophage resistance (hsp) at 30 degrees c to lac proteinase (prt)-negative lactococcus lactis subsp. lactis and l. lactis subsp. lactis var. diacetylactis recipient strains. an additional plasmid, paj331, isolated from the original source strain of paj1106, retained hsp and conjugative ability without lac. paj331 was conjugally transferred to two l. lactis subsp. lactis and one l. la ...198916347947
acetoin fermentation by citrate-positive lactococcus lactis subsp. lactis 3022 grown aerobically in the presence of hemin or cu.citrlactococcus lactis subsp. lactis 3022 produced more biomass and converted most of the glucose substrate to diacetyl and acetoin when grown aerobically with hemin and cu. the activity of diacetyl synthase was greatly stimulated by the addition of hemin or cu, and the activity of nad-dependent diacetyl reductase was very high. hemin did not affect the activities of nadh oxidase and lactate dehydrogenase. these results indicated that the pyruvate formed via glycolysis would be rapidly converted ...199016348274
properties of 2,3-butanediol dehydrogenases from lactococcus lactis subsp. lactis in relation to citrate fermentation.two 2,3-butanediol dehydrogenases (enzymes 1 and 2; molecular weight of each, 170,000) have been partially purified from lactococcus lactis subsp. lactis (streptococcus diacetylactis) d10 and shown to have reductase activity with either diacetyl or acetoin as the substrate. however, the reductase activity with 10 mm diacetyl was far greater for both enzymes (7.0- and 4.7-fold for enzymes 1 and 2, respectively) than with 10 mm acetoin as the substrate. in contrast, when acetoin and diacetyl were ...199016348209
pambeta1-associated mobilization of proteinase plasmids from lactococcus lactis subsp. lactis uc317 and l. lactis subsp. cremoris uc205.a combination of plasmid curing and dna-dna hybridization data facilitated the identification of proteinase plasmids of 75 (pci301) and 35 kilobases (pci203) in the multi-plasmid-containing strains lactococcus lactis subsp. lactis uc317 and l. lactis subsp. cremoris uc205, respectively. both plasmids were transferred by conjugation to a plasmid-free background only after introduction of the conjugative streptococcal plasmid, pambeta1. all prt transconjugants from matings involving either donor c ...199016348091
identification of the minimal replicon of lactococcus lactis subsp. lactis uc317 plasmid pci305.replication functions of the stable, cryptic 8.7-kilobase (kb) plasmid pci305 from multi-plasmid-containing lactococcus lactis subsp. lactis uc317 were studied. analysis of this replicon was facilitated by the construction of replication probe vectors that consisted of the pbr322 replication region, a puc18-derived multiple cloning site, and either the cat gene of pc194 (pci341; 3.1 kb) or the erm gene of pambeta1 (pci3330; 4.0 kb). plasmid pci305 was introduced into plasmid-free l. lactis subsp ...199016348092
pulsed-field gel electrophoresis of smai digests of lactococcal genomic dna, a novel method of strain identification.the pulsed-field gel electrophoresis (pfge) pattern of smai digests of 29 strains of lactococcus lactis subsp. lactis and subsp. cremoris were determined. unrelated strains yielded markedly different patterns of digestion products. bacteriophage-resistant derivatives of four strains, generated by a method analogous to that used regularly in some cheese factories, yielded patterns that were identical or almost identical to that of the parent strain. it is proposed that a 16-h pfge run with a puls ...199016348318
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 ...19902104609
high-frequency, site-specific recombination between lactococcal and pam beta 1 plasmid dnas.in vivo recombination events involving the 75-kilobase lactose proteinase plasmid pci301 of lactococcus lactis subsp. lactis uc317 and the conjugative enterococcal plasmid pam beta 1 were analyzed. a fragment, identified as containing the pci301 recombination site, mediated greatly elevated levels of mobilization and recombination with pam beta 1 when cloned in a nonmobilizable l. lactis-escherichia coli shuttle vector. this latter recombination event was site and orientation specific on both pl ...19902111809
cloning of the citrate permease gene of lactococcus lactis subsp. lactis biovar diacetylactis and expression in escherichia coli.the citrate plasmid (cit+ plasmid) from lactococcus lactis subsp. lactis biovar diacetylactis was cloned into the ecori site of plasmid puc18. this recombinant plasmid enabled escherichia coli k-12 to transport and utilize citrate as a source of energy, indicating expression of the citrate permease from l. lactis biovar diacetylactis. the citrate permease was under the control of the lac promoter of puc18. genetic expression of the cit+ plasmid in maxicells revealed that the plasmid encoded two ...19902117878
cloning and characterization of the thymidylate synthase gene from lactococcus lactis subsp. lactis.the thymidylate synthase (thya) gene has been isolated from lactococcus lactis subsp. lactis. the cloned gene was strongly expressed in escherichia coli both in vivo and in vitro (maxicells and cell-free transcription and translation systems) and complemented e. coli thya mutants. dna-dna hybridizations demonstrated that the thya gene is encoded by the chromosome of l. lactis subsp. lactis. by sequential deletion of dna outside the complementing region, the thya gene was localized to a 1.1-kilob ...19902117882
thymidylate synthase gene from lactococcus lactis as a genetic marker: an alternative to antibiotic resistance genes.the potential of the thymidylate synthase thya gene cloned from lactococcus lactis subsp. lactis as a possible alternative selectable marker gene to antibiotic resistance markers has been examined. the thya mutation is a recessive lethal one; thya mutants cannot survive in environments containing low amounts of thymidine or thymine (such as luria-bertani medium) unless complemented by the thya gene. the cloned thya gene was strongly expressed in l. lactis subsp. lactis, escherichia coli, rhizobi ...19902117883
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 ...19902118509
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 ...19902118753
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 ...19902123812
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, ...19902125811
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 ...19902128962
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.19902163399
nucleotide sequence of is904 from lactococcus lactis subsp. lactis strain nizo r5. 19902165590
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 ...19902389931
high efficiency electroporation of lactococcus lactis subsp. lactis lm0230 with plasmid pgb301.electroporation-mediated transformation of lactococcus lactis with plasmid pgb301, a 9.8 kilobase pair vector (behnke et al. 1981), has been reported by mcintyre & harlander (1989a). improved transformation efficiencies of 10(2)-10(3)/micrograms dna were achieved by altering the conditions under which the bacteria were grown prior to electroporation (mcintyre & harlander 1989b). this present investigation sought to improve still further transformation efficiencies in order to provide a reliable ...19901367468
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 ...19902120190
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 ...19902177590
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 ...19902150659
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 ...19902120234
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 ...19911901709
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 ...19911770357
cloning and partial characterization of genes for ribosomal ribonucleic acid in lactococcus lactis subsp. lactis.a cosmid gene library of the genome of lactococcus lactis subsp. lactis 712 was probed for the presence of 16s rrna genes, using 32p 5' end-labelled 16s rrna fragments. cosmid dna from positive clones responsible for hybridisation was subcloned into a high copy number vector and a restriction map was constructed. the location of the 16s, 23s and 5s rrna genes was determined on this map. transcriptional promoter activity was identified upstream of the 5' end of the 16s rrna gene. by probing l. la ...19911710195
transposon-encoded sucrose metabolism in lactococcus lactis. purification of sucrose-6-phosphate hydrolase and genetic linkage to n5-(l-1-carboxyethyl)-l-ornithine synthase in strain k1.sucrose-6-phosphate hydrolase from lactococcus lactis subsp. lactis k1-23 (formerly streptococcus lactis k1-23) has been purified 600-fold to electrophoretic homogeneity. purification of the enzyme was achieved by deae-sephacel, phosphocellulose p-11, and gel exclusion (ultrogel aca 54) chromatography. the purified enzyme (specific activity 31 units/mg) catalyzed the hydrolysis of both 6-o-phosphoryl-alpha-d-glucopyranosyl-1,2-beta-d-fructofuranoside (sucrose 6-phosphate) and sucrose (km = 0.1 a ...19911650362
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 ...19911852014
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 ...19911917843
identification, dna sequence, and distribution of is981, a new, high-copy-number insertion sequence in lactococci.an insertion in the lactococcal plasmid pgbk17, which inactivated the gene(s) encoding resistance to the prolate-headed phage c2, was cloned, sequenced, and identified as a new lactococcal insertion sequence (is). is981 was 1,222 bp in size and contained two open reading frames, one large enough to encode a transposase. is981 ended in imperfect inverted repeats of 26 of 40 bp and generated a 5-bp direct repeat of target dna at the site of insertion. is981 was present on the chromosome of lactoco ...19911645511
construction of an is946-based composite transposon in lactococcus lactis subsp. lactis.an artificial composite transposon was constructed based on the lactococcal insertion sequence is946. a 3.0-kb element composed of the pc194 cat gene (cmr) flanked by inversely repeated copies of is946 was assembled on pbluescript ks+. when subcloned into the shuttle vector psa3 (emr), two putative transposons were created on the recombinant plasmid ptrk128: the 3.0-kb cmr element (tn-cma) and an inverse 11.5-kb emr element (tn-ema). ptrk128 was electroporated into the recombination-deficient st ...19911657893
purification and properties of fructokinase i from lactococcus lactis. localization of scrk on the sucrose-nisin transposon tn5306.two electrophoretically distinct proteins with fructokinase (atp:fructose-6-phosphotransferase) activity were detected in lactococcus lactis subsp. lactis k1. whereas fructokinase i was induced specifically by growth of the organism on sucrose, fructokinase ii was derepressed during growth on ribose, galactose, maltose, and lactulose. fructokinase i was purified about 1000-fold to electrophoretic homogeneity (specific activity 112 units/mg). the amino acid composition, n-terminal sequence, nucle ...19911658003
comparison of methods for discrimination between strains of listeria monocytogenes from epidemiological surveys.total cellular dna from 28 strains of listeria monocytogenes isolated from food implicated in food-borne illness and from patients with listeriosis was digested with the restriction endonucleases hindiii, haeiii, and ecori. following agarose gel electrophoresis, the fragments were subjected to southern blot hybridization with a digoxigenin-labeled cdna probe transcribed from escherichia coli 16s and 23s rrna. the patterns of bands from genomic (dna fingerprints) and rdna fingerprints (ribotypes) ...19911662932
chromosomal integration of plasmid dna by homologous recombination in enterococcus faecalis and lactococcus lactis subsp. lactis hosts harboring tn919.integration of pci192, a pbr322-derived vector plasmid containing homology to the chromosomally located conjugative transposon tn919 was observed in two strains that harbor tn919, namely, enterococcus faecalis gf590 and lactococcus lactis subsp. lactis ch919. hybridization analysis indicated that single-copy integration of the plasmid had occurred at low frequency. the tn919::plasmid structure was conjugated from an e. faecalis donor to a l. lactis recipient, although at lower frequencies than w ...19911662938
phage abortive infection mechanism from lactococcus lactis subsp. lactis, expression of which is mediated by an iso-iss1 element.a 5-kb dna fragment conferring a phage abortive infection phenotype (abi+) has been cloned from lactococcus lactis subsp. lactis il416. the abi+ determinant was subcloned on a 2-kb fragment which carried an iso-iss1 element and an open reading frame of 753 bp designated orfx. deletion within orfx entailed the loss of the abi+ phenotype, establishing that orfx is the structural abi-416 gene. the expression of abi-416 was shown to be mediated by the iso-iss1 element, which contains a sequence fitt ...19911664711
cloning and dna sequence analysis of an x-prolyl dipeptidyl aminopeptidase gene from lactococcus lactis subsp. lactis ncdo 763.lactococcus lactis subsp. lactis ncdo 763 (also designated ml3) possesses an x-prolyl dipeptidyl aminopeptidase (x-pdap; ec 3.4.14.5). x-pdap mutants were selected by an enzymatic plate assay on the basis of their inability to hydrolyze an l-phenylalanyl-l-proline-beta-naphthylamide substrate. a dna bank from l. lactis subsp. lactis ncdo 763 was constructed in one of these x-pdap mutants, and one clone in which the original x-pdap phenotype was restored was detected by the enzymatic plate assay. ...19911674656
isolation and characterization of lactococcus lactis subsp. lactis promoters.dna fragments with promoter activity were isolated from the chromosome of lactococcus lactis subsp. lactis. for the isolation, a promoter probe vector based on the cat gene was constructed, which allowed direct selection with chloramphenicol in bacillus subtilis and l. lactis. four of the putative promoters (p1, p2, p10, and p21) were analyzed further by sequencing, mapping of the 5' end of the mrna, northern (rna blot) hybridization, and chloramphenicol acetyltransferase activity measurements. ...19911707605
physical map of the chromosome of lactococcus lactis subsp. lactis dl11 and localization of six putative rrna operons.a physical map of the chromosome of lactococcus lactis subsp. lactis dl11 was constructed by using the contour-clamped homogeneous electric field mode of pulsed-field gel electrophoresis in one- and two-dimensional separations to analyze restriction digests of high-molecular-weight genomic dna. the map, which shows all the observed noti and smai sites (six and 21, respectively) and 8 of approximately 30 sali sites, is circular and yields a total size of 2.58 megabase pairs for the l. lactis subs ...19911708377
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 ...19911783905
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 ...19911785933
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 ...19911848522
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 ...19911854195
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