Publications

TitleAbstractYear
Filter
PMID
Filter
mutants of streptococcus lactis subsp. diacetylactis lacking diacetyl reductase activity.three strains of streptococcus lactis subsp. diacetylactis, namely drc-1, drc-2 and drc-3 which produced diacetyl up to 120 h of incubation were exposed to the ultraviolet irradiation as well as n-methyl-n'-nitro-n-nitrosoguanidine (ntg) to isolate mutants lacking diacetyl reductase activity. uv irradiation did not produce any isolate completely devoid of diacetyl reductase activity, though, 99.5% loss in activity could be achieved. ntg treatment proved to be more effective and seven survivors e ...197886283
growth requirements and the effect of organic components of the synthetic medium on the biosynthesis of the antibiotic nisin in streptococcus lactis strain.a synthetic medium sm-3 has been elaborated for growth of streptococcus lactis strain 51, which contains the minimal number of organic components required for the growth of this strain and nisin production. this medium contains 9 amino acids, 4 vitamins from b group, glucose and mineral salts. addition of biotin to the medium stimulated the growth of the strain, while the addition of purines and/or pyrimidines had no effect. hitherto biotin has been considered to be necessary for the growth of s ...197775664
[effect of kh2po4 on streptococcus lactis growth and nisin synthesis when the medium is kept at a constant ph].when the ph of the medium was maintained at the level of 6.6--6.8 and the content of kh2po4 in it was decreased, the biosynthetic activity of streptococcus lactis, strain mgu, became lower. the culture assimilated low quantities of phosphorus from kh2po4 at a high concentration of this salt in the medium; presumably, the culture required large quantities of potassium ions. if the ph of the medium is maintained at a constant value, the fermentation can be stopped 21 hr after the beginning of cult ...197938379
[dynamics of nisin accumulation in a culture of streptococcus lactis].the dynamics of nisine accumulation by its producer streptococcus lactis, str. msu was studied. in the course of the producer cultivation on the liquid nutrient medium there was a correlation between total, cellular and filtrate nysine. the content of cellular nysine increased gradually to reach maximum by the 6th day of the strain cultivation. the content of filtrate nisine reached maximum on the 2nd day and declined two-fold by the 7th day of cultivation.197937497
composition and differentiation of the genus streptococcus. 197831686
nisin formation by immobilized cells of the lactic acid bacterium, streptococcus lactis.the problem of microbial cell immobilization at present attracts the ever increasing attention of the scientists, since such organisms may be the source of various enzymes. production of nizin by the immobilized cells of str. lactis was studied. it was found that the cells of str. lactis incorporated into polyacrylamide gel produced nizit on definite media. still, the amount of the antibiotic was 2-3 times lower than in case of using free cells. the effect of a number of factors on the process o ...197830390
lactostrepcins--acid bacteriocins produced by lactic streptococci.all 47 non-nisin producing strains of streptococcus lactis and 12/13 strains of str. lactis subsp. diacetylactis examined produced bacteriocins, for which the term lactostrepcins is suggested. seven strains of str. cremoris examined produced no bacteriocins active against 3 lactic streptococci strains used as indicators. the strains examined were divided into 3 groups: i, those producing lactostrepcins active against only one streptomycin resistant mutant of str. lactis 60 indicator strain; ii, ...197827542
influence of ph on nisin production by streptococcus lactis cultures.the ph effect on the nisine biosynthesis during the cultivation of streptococcus lactis was studied at ph 5,8 6,7 and 7,2. the ph maintenance at the specified level did not stimulate the growth of str. lactis, did not increase the total yield of nisine and did not produce a significant effect on the level or cellular nisine. this indicates an important physiological difference between the culture-nisine producer described by hirsh and our culture str. lactis, str. moscow university.197721390
properties and function of fumarate reductase (nadh) in streptococcus lactis.the fumarate reductase (nadh) present in cell-free extracts of s. lactis c10 was purified approximately 100-fed by chromatography on deae-cellulose in the presence of the non-ionic detergent teric x-10, and some of the properties of this partially purified enzyme were characterized. fumarate was able to act as a terminal electron acceptor and decreased the amount of lactate formed and oxygen used during the metabolism of pyruvate by resting cells of s. lactis. anaerobic growth of s. lactis on gl ...197944997
obligatory coupling between proton entry and the synthesis of adenosine 5'-triphosphate in streptococcus lactis.proton influx was measured after imposition of an electrochemical potential difference for protons (delta muh+) across the cell membrane of the anaerobe, streptococcus lactis. as delta muh+ was increased, there was an approximately parallel increase in proton entry, until delta muh+ attained 175 to 200 mv. at this point, a new pathway became available for proton entry, allowing an abrupt increase in both the rate and extent of h+ influx. this gated response depended upon the value of delta muh+ ...197721165
desugarization of egg white by microorganisms.glucose was eliminated from egg whites, using microorganisms, to prevent melanoidin formation which may damage the product. desugarization was achieved by means of acetobacter xylinum, streptococcus lactis, propionibacterium shermanii, pr. petersonii and propionicacid cocci. optimal conditions of desugarization were found, depending on the physiological characteristics of the above microorganisms. propionibacterium shermanii may be well used to ferment a liquid egg white. these bacteria have no ...197617113
inactivation of the antibiotic nisin. 197617112
effects of potassium ions on the electrical and ph gradients across the membrane of streptococcus lactis cells.bacteria transduce and conserve energy at the plasma membrane in the form of an electrochemical gradient of hydrogen ions (deltap). energized cells of streptococcus lactis accumulate k+ ions presumably in exchange for h+. we reasoned that if the movement of h+ is limited, then an increase in h+ efflux, effected by potassium transport inward, should result in changes in the steady-state deltap. we determined the electrical gradient (deltapsi) from the fluorescence of a membrane potential-sensitiv ...197716864
the effect of monovalent and divalent cations on the activity of streptococcus lactis c10 pyruvate kinase.the pyruvate kinase (atp: pyruvate 2-o-phosphotransferase, ec 2.7.1.40) from streptococcus lactis c10 had an obligatory requirement for both a monovalent cation and divalent cation. nh+4 and k+ activated the enzyme in a sigmoidal manner (nh =1.55) at similar concentrations, whereas na+ and li+ could only weakly activate the enzyme. of eight divalent cations studied, only three (co2+, mg2+ and mn2+) activated the enzyme. the remaining five divalent cations (cu2+, zn2+, ca2+, ni2+ and ba2+) inhibi ...197714688
characteristics and energy requirements of an alpha-aminoisobutyric acid transport system in streptococcus lactis.galactose-grown cells of streptococcus lactis ml3 acculated alpha-aminoisobutyric acid (aib) by using energy derived from glycolysis and arginine catabolism. the transport system displayed low-affinity michaelis-menten saturation kinetics. using galactose or arginine as energy sources, similar v max and k m values for aib entry were obtained, but on prolonged incubation the intracellular steady-state concentration of aib in cells metabolizing arginine was only 65 to 70% that attained by glycolyz ...19768422
effect of the initial ph value of the medium on the growth of streptococcus lactis and the biosynthesis of nisin.the effect of the initial ph value of the medium within 4.0 to 6.6 on the growth of str. lactis and biosynthesis of nicin was studied. it was found that at the initial ph 4.0--4.5 of the medium the growth of the culture was poor, i.e. 11--14% of the control (initiral ph 6.6). with an increase in the value of the initial ph at least to 5.0 the growth of str. lactis also increased. at the initial ph 4.0 no biosynthesis of nicin was observed. under the experimental conditions the antibiotic synthes ...19767995
citric acid metabolism in hetero- and homofermentative lactic acid bacteria.the effect of citrate on production of diacetyl and acetoin by four strains each of heterofermentative and homofermentative lactic acid bacteria capable of utilizing citrate was studied. acetoin was quantitatively the more important compound. the heterofermentative bacteria produced no acetoin or diacetyl in the absence of citrate, and two strains produced traces of acetoin in its presence. citrate stimulated the growth rate of the heterofermentative lactobacilli. acidification of all heteroferm ...19765054
effects of sodium ions on the electrical and ph gradients across the membrane of streptococcus lactis cells.energized cells of streptococcus lactis conserve and transduce energy at the plasma membrane in the form of an electrochemical gradient of hydrogen ions (deltap). an increase in energy-consuming processes, such as cation transport, would be expected to result in a change in the steady state deltap. we determined the electrical gradient (deltapsi) from the fluorescence of a membrane potential-sensitive cyanine dye, and the chemical h+ gradient (deltaph) from the distribution of a weak acid. in gl ...197722778
fructose 1,6-diphosphate-activated l-lactate dehydrogenase from streptococcus lactis: kinetic properties and factors affecting activation.the l-(+)-lactate dehydrogenase (l-lactate:nad+ oxidoreductase, ec 1.1.1.27) of streptococcus lactis c10, like that of other streptococci, was activated by fructose 1,6-diphosphate (fdp). the enzyme showed some activity in the absence of fdp, with a ph optimum of 8.2; fdp decreased the km for both pyruvate and reduced nicotinamide adenine dinucleotide (nadh) and shifted the ph optimum to 6.9. enzyme activity showed a hyperbolic response to both nadh and pyruvate in all the buffers tried except p ...197717595
[lytic enzymes produced by actinomyces levoris].the composition of the enzyme complex produced by actinomyces levoris which exhibits lytic action on the cell walls of streptococcus lactis was studied by gel filtration on sephadex g-25, ion exchange chromatography and isoelectric focusing. the complex was found to contain at least seven enzymes having different isoelectric points and substrate specificity. the enzymes were divided into three groups. (1) the enzyme with pi 10.2 seems to be a specific glucosidase; it possesses a high activity of ...197897500
further characterization of lactostrepcins--acid bacteriocins of lactic streptococci. 197989798
aerobic growth thermograms of streptococcus lactis obtained with a complex medium containing glucose.with different culturing methods both simple and complex thermograms were obtained with streptococcus lactis grown aerobically in a complex medium containing growth-limiting concentrations of glucose. the thermogram profiles have been interpreted in relation to growth rate, glucose degradation, and molar growth yields calculated for different time intervals during growth.197898515
aflatoxin b1 effect on beta-d-galactosidase in some starter cultures.six starter cultures were examined for their ability to induce beta-d-galactosidase activity. the maximum (713 x 10(-4) units/ml) and minimum (140 x 10(-4) units/ml) enzyme activity was shown by lactobacillus bulgaricus and streptomyces thermophilus, respectively. the maximum inhibition by aflatoxin b1 of induction and activity of enzyme in vitro was observed at 60 micrograms/ml in all cultures. however, low levels of the toxin stimulated induction of the enzyme in streptococcus lactis and s. th ...197992172
atp synthesis driven by a protonmotive force in streptococcus lactis.an electrochemical potential difference for hydrogen ions ( a protonmotive force) was artifically imposed across the membrane of the anaerobic bacterium streptococcus lactis. when cells were exposed to the ionophore, valinomycin, the electrical gradient was established by a potassium diffusion potential. a chemical gradient of protons was established by manipulating the transmembrane ph gradient. when the protonmotive force attained a value of 215 mv or greater, net atp synthesis was catalyzed b ...19753650
damage and recovery in streptococci. 1978103202
membrane h+ conductance of streptococcus lactis.membrane conductance to h+ was measured in the anaerobic bacterium streptoccus lactis by a pulse technique employing a low driving force (0.1 ph unit; 6 mv). over the ph range of 3.7 to 8.5, a constant value for passive h+ conductance was observed, corresponding to 0.2 mumol of h+/s per p/ unit per g, dry weight (1.6 micros/cm2 of surface area). the ph insensitivity of this low basal h+ conductance supports the idea that a circulation of protons can mediate highly efficiency engery transductions ...197940951
in vivo regulation of glycolysis and characterization of sugar: phosphotransferase systems in streptococcus lactis.two novel procedures have been used to regulate, in vivo, the formation of phosphoenolpyruvate (pep) from glycolysis in streptococcus lactis ml3. in the first procedure, glucose metabolism was specifically inhibited by p-chloromercuribenzoate. autoradiographic and enzymatic analyses showed that the cells contained glucose 6-phosphate, fructose 6-phosphate, fructose-1,6-diphosphate, and triose phosphates. dithiothreitol reversed the p-chloromercuribenzoate inhibition, and these intermediates were ...1978101523
influence of the lactose plasmid on the metabolism of galactose by streptococcus lactis.streptococcus lactis strain dr1251 was capable of growth on lactose and galactose with generation times, at 30 degrees c, of 42 and 52 min, respectively. phosphoenolpyruvate-dependent phosphotransferase activity for lactose and galactose was induced during growth on either substrate. this activity had an apparent k(m) of 5 x 10(-5) m for lactose and 2 x 10(-2) m for galactose. beta-d-phosphogalactoside galactohydrolase activity was synthesized constitutively by these cells. strain dr1251 lost th ...1979106044
nisin: its preservative effect and function in the growth cycle of the producer organism. 1978103201
[immunoluminescent method for detecting enterococci in dairy products]. 1978100374
acyldiglucosyldiacylglycerol-containing lipoteichoic acid with a poly(3-o-galabiosyl-2-o-galactosyl-sn-glycero-1-phosphate) chain from streptococcus lactis kiel 42172.the lipoteichoic acid of streptococcus lactis kiel 42172 was isolated. the lipid portions were released by hf and were established to be 3-o-[o-alpha-d-galactopyranosyl-(1 leads to 6)-alpha-d-galactopyranosyl]-2-o-alpha-d-galactopyranosyl-sn-glycero-1-phosphate, they are joined by phosphodiester bonds nosyl)]glycerol. the repeating units of the hydrophilic chain were established to be 3-o-[o-alpha-d-galactopyranosyl-(1 leads to 6)-alpha-d-galactopyranosyl]-2-o-alpha-d-galactopyranosyl-sn-glycero ...1978103572
[lipid fraction makeup of streptococcus lactis strain mgu]. 1979115384
change from homo- to heterolactic fermentation by streptococcus lactis resulting from glucose limitation in anaerobic chemostat cultures.lactic streptococci, classically regarded as homolactic fermenters of glucose and lactose, became heterolactic when grown with limiting carbohydrate concentrations in a chemostat. at high dilution rates (d) with excess glucose present, about 95% of the fermented sugar was converted to l-lactate. however, as d was lowered and glucose became limiting, five of the six strains tested changed to a heterolactic fermentation such that at d = 0.1 h(-1) as little as 1% of the glucose was converted to l-l ...1979108249
effect of lipophilicity of nitroimidazoles on radiosensitization of hypoxic bacterial cells in vitro.the effect of radiosensitization of hypoxic bacterial cells by 9 nitroimidazoles was measured in the bacterial strains e. coli ab 1157 and s. lactis 712. seven of these compounds were similar to misonidazole in their redox properties, but differed widely in their lipophilicites. the dependence of sensitization enhancement on reduction potential was similar to that reported in mammalian cells. the efficiency of sensitization was similar for compounds of low lipophilicity, but increased if the oct ...1979109112
characterization of groups n and d streptococci isolated from rumen fluids.twelve strains of streptococci of serological groups n and d were isolated from rumen fluids of nine cows on four rations although both groups were not isolated from the same animal. the twelve were representative of a larger number of streptococci isolated by enrichment in milk. generally, the physiological characteristics of the isolates indicated members of the lactic or enterococcus groups; however, several were atypical in one or more of the tolerance tests. physiologically typical streptoc ...1979110856
[natural selection of streptococcus lactis, strain mgu that forms nisin]. 1979116692
studies on the relationship between glycerophosphoglycolipids and lipoteichoic acids. iv. trigalactosylglycerophospho-acylkojibiosyldiacylglycerol and related compounds from streptococcus lactis kiel 42172.streptococcus lactis kiel 42172 contains at least six unusually polar glycerophosphoglycolipids. the predominant one was composed of d-galactose, d-glucose, glycerol, acyl groups and phosphorus in a molar ratio of approx. 3 : 2 : 2 : 3 : 1. by analysis of the breakdown products of hf hydrolysis and smith-degradation the structure was established to be [galp (alpha 1 leads to 6)galp(alpha 1 leads to 3)-sn-glycero(2 comes from 1 alpha galp)-1-phospho] leads to 6glcp(alpha 1 leads to 2), acyl leads ...1979117837
lactose metabolism in streptococcus lactis: phosphorylation of galactose and glucose moieties in vivo.starved cells of streptococcus lactis ml3 grown previously on lactose, galactose, or maltose were devoid of adenosine 5'-triphosphate contained only three glycolytic intermediates: 3-phosphoglycerate, 2-phosphoglycerate, and phosphoenolpyruvate (pep). the three metabolites (total concentration, ca 40 mm) served as the intracellular pep potential for sugar transport via pep-dependent phosphotransferase systems. when accumulation of [14c]lactose by iodoacetate-inhibited starved cells was abolished ...1979118155
enhancement of plaque size of a staphylococcal phage. 1976131789
the distribution of isoprenoid quinones in streptococci of serological groups d and n.the isoprenoid quinone contents of streptococci of serological groups d and n were investigated. streptococcus faecalis, s. faecalis subsp. liquefaciens and s. faecalis subsp. zymogenes strains contained demethylmenaquinones with nine isoprene units as their major isoprenologues. menaquinones with eight isoprene units predominated in s. faecium subsp. casseliflavus and s. faecium subsp. mobilis whereas menaquinones with nine isoprene units constituted the major components in strains of s. cremor ...1979118232
occurence of lactose-negative mutants in chemostat cultures of lactic streptococci.batch and chemostat cultures of streptococcus cremoris hp and streptococcus lactis 829 were examined for lactose-hegative (lac-)mutants on indicator agar. in batch cultures, s. cremoris hp gave less than 1% of the total count as lac- colonies while s. lactis 829 consistently contained about 15% of the total as lac- colonies. in chemostat cultures of s. cremoris hp in 2% skim milk containing casamino acids and yeast extract (0.1% each), the percentage of lac- colonies increased markedly when the ...1975234782
inorganic salts resistance associated with a lactose-fermenting plasmid in streptococcus lactis.present evidence indicates that lactose metabolism in group n streptococci is linked to plasmid deoxyribonucleic acid. lactose-positive (lac+) streptococcus lactis and lactose-negative (lac-) derivatives were examined for their resistance to various inorganic ions. lac+ s. lactis strains ml3, m18, and c2 were found more resistant to arsenate (7.5- to 60.2-fold), arsenite (2.25- to 3.0-fold), and chromate (6.6- to 9.4-fold), but more sensitive to copper (10.0- to 13.3-fold) than their lac- deriva ...1977404284
partial characterization of a new c3-type capsule-dissolving phage of streptococcus cremoris.a viscous, ropy, sour milk product, called 'viili,' is produced in finland. capsule-forming strains of streptococcus cremoris are the typical starters for this product. occasionally fermentation fails and results in a non-ropy clot. the reasons for these failures, however, are obscure. in one batch of spoiled 'viili,' a new c3-type bacteriophage, termed ksy1, was isolated. the head of the phage was about 230 nm long and about 50 nm wide and the tail was 35 nm long and carried a complex collar st ...1979119574
species differences and effect of incubation time on lactic streptococcal intracellular proteolytic enzyme activity.ruptured cells of streptococcus lactis c2, s. cremoris ml 1 and a lactose-negative proteinase-negative (lac-prt-) mutant of s. lactis c2 (lmo220) were fractionated into the soluble, particulate, and ribosome fractions by differential centrifugation. s. lactis c2 possessed higher activity of intracellular proteinase, alanylglycinase, particulate associated dipeptidase and ribosome associated dipeptidase and ribosome associated dipeptidase than did s. cremoris ml1. lmo220 was lower in intracellula ...1977411810
[bacterial symbiosis and its significance in dentistry]. 1977412347
phosphoenolpyruvate and 2-phosphoglycerate: endogenous energy source(s) for sugar accumulation by starved cells of streptococcus lactis.in the absence of an exogenous energy source, galactose-grown cells of streptococcus lactis ml3 rapidly accumulated thiomethyl-beta-d-galactopyranoside (tmg) and 2-deoxyglucose to intracellular concentrations of 40 to 50 mm. starved cells maintained the capacity for tmg uptake for many hours, and accumulation of the beta-galactoside was insensitive to proton-conducting ionophores (tetrachlorosalicylanilide and carbonylcyanide-m-chlorophenyl hydrazone) and sulfydryl group reagents including iodoa ...1977122509
improved lysis of group n streptococci for isolation and rapid characterization of plasmid deoxyribonucleic acid.procedures for effective cellular lysis and plasmid deoxyribonucleic acid (dna) isolation from group n streptococci were developed. cells were grown at 32 degrees c for 4 h in a modified elliker broth containing 20 mm dl-threonine. after cellular digestion with 2 mg of lysozyme per ml for 7 min at 37 degrees c, 1% sodium dodecyl sulfate exposure resulted in complete and immediate lysis. lactose (lac) plasmid species in streptococcus lactis c2 and s. cremoris b1 (30 and 37 megadaltons, respective ...1978416755
on the relationship between glycerophosphoglycolipids and lipoteichoic acids in gram-positive bacteria. ii. structures of glycerophosphoglycolipids.1. eight glycerophosphoglycolipids were isolated from six gram-positive bacteria. besides sn-glycero-1-phospho-beta-gentiobiosyldiacylglycerol (i) and sn-glycero-1-phospho-alpha-kojibiosyldiacylglycerol (ii), three novel structures have been established: 1,2-di-o-acyl-3-o-[6-(sn-glycero-1-phospho)-alpha-d-glucopyranosyl-(1 leads to 2)-(6-o-acyl-alpha-d-glucopyranosyl)]glycerol (iii), 1,2-di-o-acyl-3-o-[6-(sn-glycero-1-phospho)-beta-d-glucopyranosyl-(1 leads to 6)-alpha-d-galactopyranosyl-(1 lead ...1978416848
catabolite inhibition and sequential metabolism of sugars by streptococcus lactis.growth of galactose-adapted cells of streptococcus lactis ml(3) in a medium containing a mixture of glucose, galactose, and lactose was characterized initially by the simultaneous metabolism of glucose and lactose. galactose was not significantly utilized until the latter sugars had been exhausted from the medium. the addition of glucose or lactose to a culture of s. lactis ml(3) growing exponentially on galactose caused immediate inhibition of galactose utilization and an increase in growth rat ...1978417061
on the relationship between glycerophosphoglycolipids and lipoteichoic acids of gram-positive bacteria. iii. di(glycerophospho)-acylkojibiosyldiacylglycerol and related compounds from streptococcus lactis ncdo 712.1. streptococcus lactis ncdo 712 contains at lease three unusually polar glycerophosphoglycolipids. one of them was composed of d-glucose, glycerol, fatty acid ester, and phosphorus in the molar ratio of approx. 2 : 3 : 3 : 2. the structure was established as 1,2-di-o-acyl-3-o-[6-(sn-glycero-1-phospho-3-sn-glycero-1-phospho)-alpha-d-glucopyranosyl-(1 leads to 2)-(6-o-acyl-alpha-d-glucopyranosyl)]-glycerol. 2. the second glycerophosphoglycolipid was shown to have the same core structure but is la ...1978418818
acetaldehyde: an intermediate in the formation of ethanol from glucose by lactic acid bacteria.group n streptococci formed acetaldehyde and ethanol from glucose. as the enzymes aldehyde dehydrogenase, phosphotransacetylase and acetate kinase were present this would enable these organisms to reduce acetyl-coa to acetaldehyde and convert acetyl-coa to acetyl phosphate and acetate. a pentose phosphate pathway which converted ribose-5-phosphate to glyceraldehyde-3-phosphate was also present. acetaldehyde could not be formed via the hexose monophosphate shunt or by direct decarboxylation of py ...1976177470
peptide utilization by group n streptococci.the rate of glycylleucine uptake by group n streptococci varied widely. one strain of streptococcus cremoris did not transport the dipeptide or utilize tripeptides. in peptide-utilizing strains, amino acid, dipeptide and tripeptide transport were distinct, although dipeptides inhibited tripeptide utilization. specificity determinants for peptide transport and utilization were similar to those reported in gram-negative bacteria. peptide utilization in s. lactis was not completely dependent on the ...1978416171
heterotrophic bacteria present in hindguts of wood-eating termites [reticulitermes flavipes (kollar)].strict anaerobic culture techniques were used to quantitate heterotrophic bacteria present in hindguts of reticulitermes flavipes. the grand mean number of viable cells per hindgut was 0.4 x 10(5) (first-instar larvae), 1.3 x 10(5) (third-instar larvae), 3.5 x 10(5) (workers), and 1.5 x 10(5) (soldiers). of a total of 344 isolates, 66.3% were streptococci that were always obtained regardless of the origin of termites, their developmental stage or caste, or their length of captivity. most of the ...1978655709
active transport of thallous ions by streptococcus lactis.tl+ ions have been shown to mimic or compete with k+ in a number of membrane systems. we confirmed that in starved, valinomycin-treated cells of streptococcus lactis 7962, tl+ ions distributed themselves across the bacterial membrane in response to the potassium diffusion potential. in glucose-energized cells, however, tl+ was taken up by a system specifically stimulated by sodium salts. the intracellular levels of tl+ exceeded those attained by [3h]triphenylmethylphosphonium ion, a lipophilic c ...1979468811
[procedure for isolating nisin from streptococcus lactis].the paper describes a method for obtaining the antibiotic nisine from streptococcus lactis str. msu via 50% acetic acid extraction. the concentrate is dried in the anhydro spray drier (denmark). the preparation is inactivated during a one-year storage in the refrigerator by 20-25%.1979514994
polarographic assay of hydrogen peroxide accumulation in microbial cultures.a method is described for determining low concentrations of hydrogen peroxide by using a polarographic oxygen electrode to measure the oxygen released into solution on addition of catalase. a sample can be assayed directly without prior manipulation in 3 min. the method is capable of assaying hydrogen peroxide concentrations as low as 7 mum. the method has proved extremely useful for the assay of hydrogen peroxide secreted into milk by lactic acid bacteria.1975803813
lacstrepcin-a bacteriocin produced by streptococcus lactis. 1977407986
possible plasmid nature of the determinant for production of the antibiotic nisin in some strains of streptococcus lactis. 1975807679
the metabolism of [14c]bicarbonate by streptococcus lactis: the synthesis of succinic acid.whole cells of streptococcus lactis c10, when incubated with an energy source, converted fumarate to succinate and malate to lactate. cell-free extracts of str. lactis c10 contained fumarate reductase, but no aspartase, adenylosuccinate synthetase and lyase or argininosuccinate synthetase and lyase activity could be detected. cells grown in the presence of [14c]bicarbonate produced labelled succinate during the synthesis of purine bases. however, the amount of succinate produced by this pathway ...1978711956
the metabolism of [14c]bicarbonate by streptococcus lactis: the fixation of [14c]bicarbonate by pyruvate carboxylase.the fixation of [14c]bicarbonate into aspartate by streptococcus lactis c10 was achieved by the combined reactions of pyruvate carboxylase (e.c. 6.4.1.1) and glutamate-oxaloacetate transaminase (e.c. 2.6.1.1). the pyruvate carboxylase from str. lactis c10, which was most active at ph 8.0, was activated by the divalent metal ions mn2+, mg2+ and co2+, and inhibited by sulphydryl reagents. the enzyme was inhibited non-competitively by aspartic acid and competitively by oxaloacetate.1978711957
[effect of age and the amount of inoculate on the growth of streptococcus lactis and its formation of nisin].the cells of streptococcus lactis, strain mgu, synthesize considerable amounts of nisine in the course of their growth. the rate of metabolic processes is not increased by stirring if the medium is complete and easily assimilated. utilization of a young inoculate (1.5, 3, and 6 hours) reduces the process of nisine production by 1.5--2 times. the amount of the inoculate exceeding 1.5 volume percent has no significant effect on the biosynthesis.1975809641
[some properties of bacteriophages isolated in brynza manufacture].according to the spectrum of lytic action towards 253 strains of streptococcus lactis, 75 bacteriophages were subdivided into eight groups. according to their antigenic properties and morphology of their particles, the phages can be divided into three groups. only two types of negative colony were found in the phages. the results of this study may be used to select bacterial strains during production of cheese.1975809646
the nature of the stimulation of the growth of streptococcus lactis by yeast extract.yeast extract was fractionated on sephadex g-25 into 7 fractions. the fraction most stimulatory to the growth of streptococcus lactis c10 contained over 70% of the amino n present in yeast extract and consisted of a wide variety of free amino acids and a small amount of peptide material. examination of possible replacement factors for this fraction revealed that the amino -acid material present was largely responsible for the stimulation of str. lactis c10. purine and pyrimidine bases and inorga ...1975235576
incidence and properties of temperate bacteriophages induced from lactic streptococci.sixty-three strains of lactic streptococci isolated from commercial lactic streptococcal starter cultures were examined for lysogeny by treatment with ultraviolet light or mitomycin c. after treatment with the inducing agent, all strains, whether or not they lysed, were examined for evidence of phage release by electron microscopy. thirty-eight strains yielded intact phages or phage particles of varying morphology. all the temperate phages had isometric heads and noncontractile tails; some had c ...1977402110
plasmid distribution and evidence for a proteinase plasmid in streptococcus lactis c2-1.five plasmids, distinguishable by their molecular weights (10(6), 2 x 10(6), 5 x 10(6), 10(7), 3 x 10(7), respectively) were isolated from streptococcus lactis c2. a spontaneous proteinase-negative derivative of this strain lacked the 10(7) plasmid.1975804856
herd incidence of bovine mastitis in four danish dairy. districts ii. evaluation of the effect of the mastitis control scheme.bacteriological and cytological examinations have been carried out on samples from 6,808 cows belonging to 339 herds in four danish dairy districts. after a discussion of differences between the districts as regards intensivity of mastitis control, public health surveillance, etc., definitions are given of certain terms, such as presence of bacteria, infection, pathogenic versus non-pathogenic (less pathogenic) organisms. the rate of infection with pathogenic organisms varies between districts f ...1975807908
lipid composition of a nisin-producing strain of streptococcus lactis. 1975816109
[mastitis and streptococci of the l group. (author's transl)]. 1975808878
clinical significance of lancefield groups l-t streptococci isolated from blood and cerebrospinal fluid.the aim of a study of all groups l-t streptococci isolated at the massachusetts general hospital during a 10-year period (1964-1974) was to ascertain the clinical significance of the less frequently occurring serological groups of streptococci. no organisms of groups p,r,s, or t were found during this time. the case records of 109 clinical isolates of alpha-reacting streptococci of lancefield groups l,m,n, and o from blood and cerebrospinal fluid cultures were reviewed. there were six cases of e ...1976816972
isolation and examination of transducing bacteriophage particles from streptococcus lactis c2.two defective transducing bacteriophages induced by exposure of streptococcus lactis c2 to ultraviolet irradiation have been isolated and characterized. these temperate phages designated c2t1 and c2t2 were isolated by cesium chloride equilibrium density gradient centrifugation of phage preparations concentrated by polyethylene glycol precipitation. the equilibrium gradient contained two visually apparent phage bands positioned at densities of 1.487 and 1.463 g cm-3 respective for c2t1 and c2t2. ...1976816826
[antibody activity of blood serum and whey of cows immunized with phages of group n streptococci]. 1975814374
activator specificity of pyruvate kinase from lactic streptococci.the pyruvate kinase from lactic streptococci was activated by 20 structurally dissimilar sugar phosphates and glycolytic intermediates. nine compounds were more effective activators than fructose-1,6-diphosphate.1976815244
the use of gel-filtration for the isolation of pure nisin from commercial products.commercial nisin was fractionated using a bio-gel p-10 column and ion-exchange chromatography on cm-sephadex c-25. pure nisin having a titre of 40 x 10(6) units per gram was obtained. in polyacrylamide-gel electrophoresis the pure nisin gave three bands. it is suggested that heterogeneity of nisin is due to the presence of several biological polypeptides. the pure nisin is digested by chymotrypsin but it is not affected by tpck-trypsin and pepsin.1976820164
[effect of vitamins on the biosynthesis of nisin by a streptococcus lactis culture].milk is the natural medium for str. lactis, strain msu. it is known that in winter and spring the growth and acid production by acidolactic streptococci are decreased. this is due, in particular, to the absence of vitamins in winter and spring milk. a number of vitamins present in complex natural products, such as tomato juice, milk and casein hydrolysates, beaf extract, etc. was studied with respect to their effect on the synthesis of nisin. the organic complexes had a positive effect on the gr ...1975817654
selective advantages of various bacterial carbohydrate transport mechanisms.at least four strategies have been developed by bacteria for capturing carbohydrates. they are typified by the transport mechanisms for glycerol, glucose, lactose, and galactose in escherichia coli. glycerol enters the cell by facilitated diffusion catalyzed by specific membrane protein. once inside the cell, the substrate is trapped by phosphorylation mediated by an adenosine triphosphate (atp)-dependent kinase. glucose is phosphorylated in transit by a membrane-associated phosphoenolpyruvate p ...1976820574
electron microscopy of virulent phages for streptococcus lactis.electron microscopic studies were made on eight virulent streptococcus lactis bacteriophages. these phages were taken as representative of eight host range groups established in a study of 75 phage isolates and 253 hosts (213 s. lactis, 22 s. cremoris, 18 s. diacetilactis). the phages studied were shown to have an isometric hexagonal head and noncontractile tails, usually several times longer than the head diameter. the virus heads were octahedral. the phages investigated represented three morph ...1976817668
[inspection of the bovine udder (author's transl)].cell counts were made once and the presence or absence of str. agalactiae, str. uberis, str. dysgalactiae and st. aureus were determined once in all quarter samples on seventeen normal dairy farms. of 1,416 quarters studied, 347 (24.5%) showed a cell count of greater than 500,000/ml. and, of 354 udders examined, 202 (57.1%) showed a cell count of greater than 500,000/ml. the total number of quarters infected with pathogenic agents was 287 (20.3%), the number of infected udders being 159 (48.3%). ...1976818733
purification and properties of pyruvate kinase from streptococcus lactis.the pyruvate kinase (atp: pyruvate 2-o-phosphotransferase, ec 2.7.1.40) of streptococcus lactis c10 is activated by fructose 1,6-diphosphate (fru-1,6-p2), activity being a sigmoidal function of activator concentration. the fdp0.5v (fru-1,6-p2 concentration giving half-maximal velocity) is markedly increased in the presence of low concentrations of inorganic phosphate; 1 mm phosphate increases the fdp0.5v value 6-fold. although the intracellular level of fru-1,6-p2 (12-18 mm) in exponentially gro ...1976820379
[the effect of purine and pyrimidine bases on the growth of streptococcus lactis and the biosynthesis of nisin].the method of mathematical modelling of the experiment was used to determine optimum concentrations of purine and pyrimidine bases for the growth of streptococcus lactis and the biosynthesis of nisin. these bases were introduced into the medium at different concnetrations. thymine at a concentration of 4 mcg/ml stimulated the biosynthesis of nisin, and adenine and hypoxanthine at a concentration of 15 mcg/ml produced a favourable effect on the growth of the culture.1976820940
transductional evidence for plasmid linkage of lactose metabolism in streptococcus lactis c2.a lactose-negative (lac-), proteinase-negative (prt-) mutant, designated c145 was isolated from streptococcus lactis c2 after treatment with nitrosoguanidine and ultraviolet irradiation. the mutant appeared to be cured of the prophage(s) present in s. lactis c2 based on non-inducibility by ultraviolet irradiation or mitomycin c. when cleared lysate material from c145 was subjected, to cesium chloride-ethidum bromide (eb) density gradient centrifugation, no plasmid peak was observed, suggesting t ...1976823867
plasmids in streptococcus lactis: evidence that lactose metabolism and proteinase activity are plasmid linked.populations of lactose positive (lac+) and proteinase positive (prt+) cells from streptococcus lactis m18, c10, and ml3 grown at 39 degrees c gave rise to increasing proportions of lac- prt- clones. the deficiencies did not appear until after a number of generations at the elevated temperature, and the rate depended on the strain.lac- prt+ and lac+ prt- mutants were isolated after treatment with ethidium bromide. plasmid deoxyribonucleic acid was isolated by cesium chloride-ethidium bromide equi ...1976823866
[bacteriostatic effect of biologically acidified milk on some salmonella strains]. 1976829026
[streptococcus lactis bacteriophage in the oral cavity]. 1975829897
analysis of volatile amines contained in foodstuffs as possible precursors of n-nitroso compounds. 1976826477
proceedings: serum uracil + uridine levels in normal subjects. 1975812427
[effect of iodoacetic acid and sodium fluoride on the development of lactic acid bacterium streptococcus lactis, a producer of the polypeptide antibiotic nisin]. 1976828507
functional reconstitution of membrane proteins in monolayer liposomes from bipolar lipids of sulfolobus acidocaldarius.membranes of sulfolobus acidocaldarius, an extreme thermophilic archaebacterium, are composed of unusual bipolar lipids. they consist of macrocyclic tetraethers with two polar heads linked by two hydrophobic c40 phytanyl chains which are thought to be arranged as a monolayer in the cytoplasmic membrane. fractionation of a total lipid-extract from s. acidocaldarius yielded a lipid fraction which forms closed and stable unilamellar liposomes in aqueous media. beef heart cytochrome c-oxidase could ...19921309769
characterization of the novel nisin-sucrose conjugative transposon tn5276 and its insertion in lactococcus lactis.a novel, chromosomally located conjugative transposon in lactococcus lactis, tn5276, was identified and characterized. it encodes the production of and immunity to nisin, a lanthionine-containing peptide with antimicrobial activity, and the capacity to utilize sucrose via a phosphotransferase system. conjugal transfer of tn5276 was demonstrated from l. lactis nizo r5 to different l. lactis strains and a recombination-deficient mutant. the integration of tn5276 into the plasmid-free strain mg1614 ...19921310502
selective adsorption of heterophile polyglycerophosphate antigen from antigen extracts of streptococcus mutans and other gram-positive bacteria.hot saline extracts of streptococcus mutans have been shown to contain antigenic substances which occasionally react nonspecifically with some antisera against whole cells of various serological groups and types of streptococci. chromatography of the extract of s. mutans strain mt703 (serotype e) on a diethylaminoethyl-sephadex a-25 column gave two principal antigens. one antigen was eluted without adsorption to the resin and was identified as the serotype-specific polysaccharide. the other anti ...1976825468
[identification of bacteriophages that lyse industrial strains of the producer of the antibiotic nisin]. 1975810074
[changes in dentin permeability for microorganisms during caries treatment].effects of a number of chemicals and of the time elapsed since the preparation on dentine permeability for microorganisms were under study. dentine permeability was found the highest immediately after the preparation and after acid treatment. potassium oxalate and calcium hydroxide reduced dentine permeability.19921307146
is946-mediated integration of heterologous dna into the genome of lactococcus lactis subsp. lactis.the lactococcal insertion sequence is946 was used to construct suicide vectors for insertion of heterologous dna into chromosomal and plasmid sequences of lactococcus lactis subsp. lactis. electroporation of l. lactis strains, including the recombination-deficient strain mms362, with the suicide vector ptrk145 yielded 10(1) to 10(3) transformants per micrograms of dna. ptrk145 insertions occurred primarily in the chromosome, with one insertion detected in a resident plasmid. vector-specific prob ...19921319132
antibacterial and antiviral activity of camel milk protective proteins.lysozyme (lz), lactoferrin (lf), lactoperoxidase (lp), immunoglobulin g and secretory immunoglobulin a were extracted from camel milk. the activity of these protective proteins was assayed against lactococcus lactis subsp. cremoris, escherichia coli, staphylococcus aureus, salmonella typhimurium and rotavirus. comparative activities of egg white lz, bovine lz and bovine lf are also presented. the antibacterial activity spectrum of camel milk lz was similar to that of egg white lz, and differed f ...19921319434
new tools for the physical and genetic mapping of lactococcus strains.tools for the genetic and physical analysis of the lactococcus lactis subsp. lactis genome were developed. plasmid prc1 does not replicate in gram+ bacteria; it contains unique apai, noti and smai restriction sites and an erythromycin-resistance (err) encoding gene, ermam, functional in l. lactis subsp. lactis. when a chromosomal l. lactis subsp. lactis dna fragment was cloned into this vector, the resulting plasmid became integrated, after transformation, into the bacterial chromosome by homolo ...19921312498
streptococcus mutans serotype c tagatose 6-phosphate pathway gene cluster.dna cloned into escherichia coli k-12 from a serotype c strain of streptococcus mutans encodes three enzyme activities for galactose utilization via the tagatose 6-phosphate pathway: galactose 6-phosphate isomerase, tagatose 6-phosphate kinase, and tagatose-1,6-bisphosphate aldolase. the genes coding for the tagatose 6-phosphate pathway were located on a 3.28-kb hindiii dna fragment. analysis of the tagatose proteins expressed by recombinant plasmids in minicells was used to determine the sizes ...19921328153
physical and genetic map of the chromosome of lactococcus lactis subsp. lactis il1403.a combined physical and genetic map of the chromosome of lactococcus lactis subsp. lactis il1403 was determined. we constructed a restriction map for the noti, apai, and smai enzymes. the order of the restriction fragments was determined by using the randomly integrative plasmid prl1 and by performing indirect end-labeling experiments. the strain il1403 chromosome was found to be circular and 2,420 kb in size. a total of 24 chromosomal markers were mapped on the chromosome by performing hybridiz ...19921328163
lithium chloride-sodium propionate agar for the enumeration of bifidobacteria in fermented dairy products.lithium chloride-sodium propionate agar has been developed for the enumeration of bifidobacteria in fermented dairy products. the medium contains lithium chloride and sodium propionate to inhibit the growth of other lactic acid bacteria. pure cultures of bifidobacteria, lactobacilli, and streptococci were tested for growth in this medium. with one exception, all bifidobacteria were able to grow in this medium and in a nonselective agar with a difference not exceeding .4 log units. however, none ...19921317893
development of a lactococcal integration vector by using is981 and a temperature-sensitive lactococcal replication region.a vector (pkmp10) capable of campbell-like integration into the lactococcus lactis subsp. lactis lm0230 chromosome via homologous recombination with chromosomal is981 sequences was constructed from the replication region of lactococcal plasmid psk11l, an internal fragment of is981, and the erythromycin resistance gene and escherichia coli replication origin of pva891. the psk11l replication region is temperature sensitive for maintenance in l. lactis subsp. lactis lm0230, resulting in loss of un ...19921319131
transfer of tn916 between lactococcus lactis subsp. lactis strains is nontranspositional: evidence for a chromosomal fertility function in strain mg1363.lactococcus lactis subsp. lactis mg1363 can act as a conjugative donor of chromosomal markers. this requires a chromosomally located fertility function that we designate the lactococcal fertility factor (laff). using inter- and intrastrain crosses, we identified other l. lactis strains (lmo230 and mms373) that appear to lack laff. the selectable marker in our crosses was tcr, carried by tn916, a transposon present on the chromosome. the transfer of tcr was not due to tn916-encoded conjugative fu ...19921325966
characterization of the lactococcus lactis pepn gene encoding an aminopeptidase homologous to mammalian aminopeptidase n.the nucleotide sequence of the pepn gene from lactococcus lactis encoding a zinc-metallo aminopeptidase has been determined. the open reading frame of 2,538 base pairs encodes a protein with a calculated m(r) of 95,368, which agrees with the apparent m(r) of 95,000 of the gene product which was identified by polyclonal antibodies raised against the purified aminopeptidase. the amino acid sequence of the aminopeptidase of l. lactis was found to be similar to the corresponding enzymes of human, ra ...19921352755
Displaying items 1 - 100 of 5589