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
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
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
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 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
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
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 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
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
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
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
composition and differentiation of the genus streptococcus. 197831686
[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
[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
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
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
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
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
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
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
nisin: its preservative effect and function in the growth cycle of the producer organism. 1978103201
damage and recovery in streptococci. 1978103202
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
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
phosphoenolpyruvate and 2-phosphoglycerate: endogenous energy source(s) for sugar accumulation by starved cells of streptococcus 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
enhancement of plaque size of a staphylococcal phage. 1976131789
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
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
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
lacstrepcin-a bacteriocin produced by streptococcus lactis. 1977407986
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
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
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
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
[results from the central laboratory for streptococci research in kiel from 1965 to 1977 - a survey (author's transl)].at the central laboratory for streptococci research at the institute for hygiene of the federal dairy research centre in kiel a data bank has been established which comprises as well bibliographical data (until now more than 8000 titles out of the international literature concerning streptococci) as laboratory data of all strains which have been identified since 1965. for this present publication as a survey the total material covering 34,935 strains was analyzed and interpreted. besides a short ...1979543350
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
possible plasmid nature of the determinant for production of the antibiotic nisin in some strains of streptococcus lactis. 1975807679
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
[mastitis and streptococci of the l group. (author's transl)]. 1975808878
[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
[identification of bacteriophages that lyse industrial strains of the producer of the antibiotic nisin]. 1975810074
[antibody activity of blood serum and whey of cows immunized with phages of group n streptococci]. 1975814374
lipid composition of a nisin-producing strain of streptococcus lactis. 1975816109
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
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 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
selective advantages of various bacterial carbohydrate transport 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
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
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
[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
analysis of volatile amines contained in foodstuffs as possible precursors of n-nitroso compounds. 1976826477
[effect of iodoacetic acid and sodium fluoride on the development of lactic acid bacterium streptococcus lactis, a producer of the polypeptide antibiotic nisin]. 1976828507
[bacteriostatic effect of biologically acidified milk on some salmonella strains]. 1976829026
[streptococcus lactis bacteriophage in the oral cavity]. 1975829897
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
comparison of electrophoretic distribution patterns of ribosomal rna gene restriction fragments and of ribosomal subunit proteins of lactococci, streptococci, and pediococci.comparison of electrophoretic distribution patterns of ribosomal rna gene restriction fragments and of ribosomal subunit proteins are equally effective procedures for detecting differences and similarities in the lactococci, streptococci and pediococci examined. electrophoretic distribution patterns of ribosomal subunit proteins may be a useful tool in taxonomic studies.19921282368
regulation of nisin biosynthesis by continuous cultures and by resting cells of lactococcus lactis subsp. lactis.nisin production by lactococcus lactis subsp. lactis has been investigated using lactose as carbon source. whether or not continuous cultures were lactose-limited, maximum nisin titre was observed at an intermediate mu value with a sharp peak of activity between 0.2 and 0.3/h. the maximum specific growth rate obtained in the medium used was 0.6/h and the maximum titre of nisin at mu = 0.25/h (160 au/ml) was about nine-fold higher as compared with activity obtained at a dilution rate of 0.05/h or ...19921299840
[the effect of physicochemical environmental factors on the growth of gram-positive bacterial dissociants].the growth of r-, s- and m (g)-dissociants of streptococcus lactis, bacillus coagulans, rhodococcus rubropertinctus under the action of some physico-chemical factors: temperature, ph, ultraviolet (uv) rays, high concentration of nacl and storage have been compared. r-variants gain selective advantage under the influence of uv-irradiation, high temperature and storage; s-variants--at decreasing of active ph of medium; m (g)-variants--at decreasing of growth temperature, high values of ph, increas ...19921302518
[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
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
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
new tools for the physical and genetic mapping of lactococcus 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
inactivation of the antibiotic nisin. 197617112
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
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
isolation and characterization of is1165, an insertion sequence of leuconostoc mesenteroides subsp. cremoris and other lactic acid bacteria.we have cloned and characterized an insertion sequence from leuconostoc mesenteroides subsp. cremoris strain db1165. this element, designated is1165, is 1553 bp, has imperfect inverted repeat ends, contains an open reading frame of 1236 bp, and is not related to any previously described insertion sequence. the copy number of is1165 varies from 4 to 13 in l. mesenteroides subsp. cremoris strains allowing genetic fingerprinting of strains based on location and number of bands on hybridization. is1 ...19921325060
atp synthesis driven by a protonmotive force in streptococcus 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
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
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
transcriptional regulation of the tn5276-located lactococcus lactis sucrose operon and characterization of the saca gene encoding sucrose-6-phosphate hydrolase.the lactococcus lactis sucrose operon was located on the conjugative transposon tn5276 and the nucleotide sequence of the saca gene, encoding sucrose-6-phosphate hydrolase, and its surrounding regions was determined. northern blot analysis showed that the sucrose operon contains two divergent transcriptional units of 3.2 and 3.6 kb, the expression of which is considerably higher in cells grown on sucrose than in cells grown on glucose. this was confirmed by primer extension studies which demonst ...19921330831
comparison of membrane proteins from lactic streptococci by gel electrophoresis. 1979539224
colonization of the digestive tract of germ-free mice by genetically engineered strains of lactococcus lactis: study of recombinant dna stability.the ability of genetically engineered lactococcus lactis strains to become established in the digestive tract (dt) of germ-free mice was examined together with the stability of their genetic markers. seven l. lactis strains were genetically modified by insertion of genetic markers on different replicons: chloramphenicol resistance gene cat was carried by self-transmissible plasmid pil205, a derivative of plasmid pip501; erythromycin resistance gene erm, originating from pam beta 1, was inserted ...19921342637
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
location, characterization and expression of lytic enzyme-encoding gene, lyta, of lactococcus lactis bacteriophage phi us3.gene lyta, which encodes lytic enzyme (lyta), of the isometric lactococcus lactis bacteriophage phi us3, was cloned and expressed in escherichia coli. the lyta gene was located on the physical map of the phi us3 32-kb dna that contains cohesive ends. initial expression of lyta was detected by lysis of an overlay of cells of the phage-sensitive strain, l. lactis sk112. however, lyta appeared to have a broad spectrum and induced lysis in more than 30 different lactococcal strains. the nucleotide s ...19921355060
differences in short peptide-substrate cleavage by two cell-envelope-located serine proteinases of lactococcus lactis subsp. cremoris are related to secondary binding specificity.various chromophoric peptides have been tested as substates for two genetically related types (pi and piii) of cell-envelope proteinases of lactococcus lactis subsp. cremoris. the positively charged peptide methoxy-succinyl-arginyl-prolyl-tyrosyl-p-nitroanilide appeared to be cleaved with the highest catalytic efficiency by both enzymes, although in the case of piii only at high ionic strength. a cation binding site in the pi-type proteinase that is not present in the related piii-type appears t ...19901366743
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
in vitro expression of lac-pts and tagatose 1,6-bisphosphate aldolase genes from lactococcus lactis subsp. cremoris plasmid pdi-21.a 4.4-kb ecor1-ecor1 dna fragment from the lactococcus lactis subsp. cremoris plasmid pdi-21 encoded the tagatose 1,6-bisphosphate (tbp) aldolase gene and the lac-pts genes. in vitro transcription-translation using escherichia coli s30 extract showed the synthesis of 41,000-, 23,000- and 12,000-dalton proteins which correspond to the tbp-aldolase, lac-pts enzyme ii, and factor iii proteins respectively.19901367486
action of a cell wall proteinase from lactococcus lactis subsp. cremoris sk11 on bovine alpha s1-casein.the cell wall-associated proteinase from lactococcus lactis subsp. cremoris sk11 was partially purified and incubated with alpha s1-casein for various times up to 48 h. sixteen trifluoroacetic acid-soluble oligopeptide hydrolysis products were identified by determination of the amino acid sequence. eleven of these oligopeptides originated from the 78-residue sequence comprising the c-terminal region of alpha s1-casein and were present among the products after the first 60 min of digestion. three ...19911367548
specificity of a cell-envelope-located proteinase (piii-type) from lactococcus lactis subsp. cremoris am1 in its action on bovine beta-casein.the action of the cell-envelope proteinase (piii-type) from lactococcus lactis ssp. cremoris am1 on bovine beta-casein was studied. the results were compared with those obtained earlier with (pi-type) proteinases from the cell envelope of other l. lactis strains. from a 4-h digest (ph 6.2; 15 degrees c) of beta-casein made with the piii-type proteinase, 24 peptides were isolated and purified by selective precipitation followed by semi-preparative reversed-phase hplc. altogether, these peptides a ...19911367552
genus- and species-specific oligonucleotide probes derived from 16s rrna for the identification of vagococci.synthetic oligonucleotide probes specific for vagococci were designed from 16s rrna sequence data. molecular hybridizations with pcr-amplified rdna targets provided an unequivocal means of differentiating vagococci from related lactic acid bacteria (eg. carnobacterium, enterococcus, lactococcus) and identification at the generic and species levels.19921367902
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
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
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
[natural selection of streptococcus lactis, strain mgu that forms nisin]. 1979116692
batch cultures of recombinant lactococcus lactis subsp. lactis in a stirred fermentor. i. effect of plasmid content on bacterial growth and on genetic stability in pure cultures.the effect of plasmid introduction into lactococcus lactis subsp. lactis il2661 on the growth of this strain and on plasmid stability was studied in pure batch cultures. the plasmids used (coding for erythromycin or chloramphenicol resistance) were the following: pil205 (42 kb), pil252 (4.6 kb, 6-9 copies), pil253 (4.8 kb, 45-85 copies) and pe194 (inserted in the chromosome). growth and acidification of l. lactis subsp. lactis il2661 were similar to those of the derived recombinant lactococci. t ...19921368909
batch cultures of recombinant lactococcus lactis subsp. lactis in a stirred fermentor. ii. plasmid transfer in mixed cultures.the transfer of plasmids was studied in a stirred fermentor in the course of mixed batch cultures combining recombinant strains of lactococcus lactis subsp. lactis (donor strains) with l. lactis subsp. lactis cnrz 268m3 (recipient strain). donor strains contained one or two of the following plasmids (coding for erythromycin or chloramphenicol resistance): pil205 (self-transmissible), pil252, pil253 (non-transmissible but mobilizable by pil205, respectively small and large copy number) and pe194 ...19921368910
catalytic properties of x-prolyl dipeptidyl aminopeptidase from lactococcus lactis subsp. cremoris x-prolyl dipeptidyl aminopeptidase (x-pdap; ec was identified to be loosely bound on the inner cell membrane fraction of lactococcus lactis subsp. cremoris ntr. the biosynthesis of x-pdap was continuously increased before the late-log growth phase of the bacteria. both gly-pro-pna and ala-ala-pna were hydrolyzed by x-pdap; the kcat/km value of the former was about 10-fold that of the latter. the ki of x-pro and pro-x were more specific to x-pdap than those of x-ala. the enzyme split ...19921369485
localization and accessibility of antigenic sites of the extracellular serine proteinase of lactococcus lactis.lactococcus lactis strains produce an extracellular subtilisin-related serine proteinase in which immunologically different components can be distinguished. monoclonal antibodies specific for the different proteinase components have been raised and their epitopes were identified. by western-blot analysis it was found that all monoclonal antibodies recognize all denatured proteinase components. the distinction between the different components could be made under native conditions only, indicating ...19921371752
characterization of the lactococcus lactis lactose operon promoter: contribution of flanking sequences and lacr repressor to promoter activity.we determined the location, activity, and regulation of the promoter of the lactococcus lactis 8-kb lactose operon (lacabcdfegx), which encodes the enzymes of the lactose phosphotransferase system and the tagatose 6-phosphate pathway. the lac promoter sequence corresponds closely to the consensus promoter described for gram-positive bacteria and is located in a back-to-back configuration with the promoter of the divergently transcribed lacr gene, which encodes the lacr repressor. the transcripti ...19921372602
characterization of enterococcal isolates by restriction enzyme analysis of genomic dna.a restriction enzyme analysis (rea) of chromosomal dna for the intra-species characterization of enterococci is reported. the dna was extracted by a rapid method and digested with the restriction enzyme sal i to provide a characteristic 'fingerprint' consisting of 10-20 bands in the 1.6-5.0 kb range. one hundred and eighty enterococcal isolates were examined; 5 were type strains, 15 from an out-patient clinic and 160 from a geographically isolated british antarctic survey base. the epidemiologic ...19921379935
structure of the exopolysaccharide produced by lactococcus lactis subspecies cremoris h414 grown in a defined medium or skimmed milk.the structure of the exopolysaccharide of lactococcus lactis subsp. cremoris h414, isolated from a defined medium or skimmed milk, was established by linkage analysis on the native polysaccharide, and by characterisation of oligosaccharide fragments, obtained by smith degradation and partial acid hydrolysis, using methylation analysis, fabms, eims, and 1h-nmr spectroscopy. the polysaccharide has the branched-pentasaccharide repeating unit: [formula: see text]19921394319
plasmid involvement in the formation of a spontaneous bacteriophage insensitive mutant of lactococcus lactis.lactococcus lactis subsp. lactis biovar. diacetylactis dpc721 is a spontaneous bacteriophage insensitive mutant of strain dpc220, isolated after challenge with an industrial bacteriophage, phi d1. plasmid analysis demonstrated that the bacteriophage insensitivity was associated with the absence of two native dpc220 plasmids (pah82 and pah33), and the presence of a novel plasmid (pah90) in dpc721. the plasmids were transferred by conjugative mobilization to a plasmid free background where it was ...19921398028
[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
[immunoluminescent method for detecting enterococci in dairy products]. 1978100374
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
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