| evaluation of the direct epifluorescent filter technique for assessing the hygienic condition of milking equipment. | the hygienic condition of 6 milking installations, 3 sanitized by circulation cleaning (cc) with chlorine-based chemicals and 3 by flushing with acidified boiling water (abw), was tested using rinses of quarter strength ringer's solution. the bacterial content of the rinses was determined using both colony counts and the direct epifluorescent filter technique (deft). a comparison of testing methods gave correlation coefficients between colony count and deft of 0.82 for plants using cc and 0.46 f ... | 1983 | 6341424 |
| relationship between phosphorylation potential and electrochemical h+ gradient during glycolysis in streptococcus lactis. | assays of intracellular atp, adp, and inorganic phosphate allowed calculation of the phosphorylation potential (delta g'atp/f) maintained during glycolysis by streptococcus lactis. at the same time, the electrochemical h+ gradient (delta mu-h+/f) was evaluated by distribution methods, using radioactive tetraphenylphosphonium bromide as a probe for the membrane potential and salicylic acid as a probe for the ph gradient. detailed comparisons were made at ph 5, when the reaction mediated by the pr ... | 1983 | 6402498 |
| plasmid complements of streptococcus lactis ncdo 712 and other lactic streptococci after protoplast-induced curing. | the production and regeneration of bacterial protoplasts promoted the loss of three different plasmid-specified traits in streptococcus lactis subsp. diacetylactis strains. the loss of five different plasmids, including small multicopy molecules, was readily detected in streptococcus lactis 712 by screening lysates of random protoplast regenerants on agarose gels. in this strain sequential rounds of protoplast regeneration were used to produce a plasmid-free strain and derivatives carrying only ... | 1983 | 6403500 |
| [preservation of lactic acid bacteria]. | the lyophilized streptococcus lactis, s. cremoris, s. diacetilactis, lactobacillus bulgaricus, l. casei c10, l. caucasicus cultures have had a great number of viable cells after 4 years storage. l. casei and s. cremoris strains endured 3 months storage at -30 degrees c and in the sterile vaseline oil for 8 months. after storage s. cremoris strains showed the high level of the lactic acid formation and of proteolytic and lipolytic activities. | 1983 | 6404311 |
| regulation of glycolysis and sugar phosphotransferase activities in streptococcus lactis: growth in the presence of 2-deoxy-d-glucose. | streptococcus lactis k1 has the capacity to grow on many sugars, including sucrose and lactose, in the presence of high levels (greater than 500 mm) of 2-deoxy-d-glucose. initially, growth of the organism was transiently halted by the addition of comparatively low concentrations (less than 0.5 mm) of the glucose analog to the culture. inhibition was coincident with (i) rapid accumulation of 2-deoxy-d-glucose 6-phosphate (ca. 120 mm) and preferential utilization of phosphoenolpyruvate via the man ... | 1983 | 6404888 |
| plasmid linkage of a bacteriocin-like substance in streptococcus lactis subsp. diacetylactis strain wm4: transferability to streptococcus lactis. | streptococcus lactis subsp. diacetylactis strain wm4 transferred lactose-fermenting and bacteriocin-producing (bac+) abilities to s. lactis lm2301, a lactose-negative, streptomycin-resistant (lac- strr), plasmid-cured derivative of s. lactis c2. three types of transconjugants were obtained: lac+ bac+, lac+ bac-, and lac-bac+.s. diacetylactis wm4 possessed plasmids of 88, 33, 30, 5.5, 4.8, and 3.8 megadaltons (mdal). in lac+ bac+ transconjugants, lactose-fermenting ability was linked to the 33-md ... | 1983 | 6408984 |
| isolation of a recombination-deficient mutant of streptococcus lactis ml3. | a recombination-deficient mutant of streptococcus lactis ml3 designated mms36 was isolated on the basis of its sensitivity to methyl methanesulfonate. this mutant also displayed sensitivity to uv irradiation. the inability of mms36 to mediate homologous recombination was demonstrated by transduction of plasmid-linked lactose fermenting ability but not chromosomally mediated streptomycin resistance. | 1983 | 6409888 |
| numerical taxonomy of streptococcus. | a numerical taxonomic study of strains of streptococcus, together with representatives of allied genera, showed 28 reasonably distinct phenons. the major areas, with their phenons, were: (a) enterococcal species group (s. faecalis, s. faecium, 's. avium' and a proposed new species 's. gallinarum'); (b) paraviridans species group (s. bovis, s. equinus, s. salivarius, 's. casseliflavus', s. mutans, s. raffinolactis and an unidentified oral group i); (c) lactic species group (s. lactis including s. ... | 1983 | 6409982 |
| identification of a streptococcal penicillin-binding protein that reacts very slowly with penicillin. | penicillin-binding protein (pbp) 5 of streptococcus faecium atcc 9790 has an unusually low affinity for penicillin (50% binding occurred at a penicillin level of 8 micrograms/ml after 60 min of incubation, and the protein only became labeled after 20 min of incubation with high concentrations of radioactive penicillin). pbps with similar properties are carried by strains of streptococcus durans, streptococcus faecalis, and streptococcus lactis but not by strains of groups a, b, c, and g streptoc ... | 1983 | 6411688 |
| involvement of lactose enzyme ii of the phosphotransferase system in rapid expulsion of free galactosides from streptococcus pyogenes. | streptococcus pyogenes accumulated thiomethyl-beta-galactoside as the 6-phosphate ester due to the action of the phosphoenolpyruvate:lactose phosphotransferase system. subsequent addition of glucose resulted in rapid efflux of the free galactoside after intracellular dephosphorylation (inducer expulsion). efflux was shown to occur in the apparent absence of the galactose permease, but was inhibited by substrate analogs of the lactose enzyme ii and could not be demonstrated in a mutant of s. lact ... | 1983 | 6413489 |
| genetic transfer systems in lactic acid bacteria. | gene transfer processes (transduction, conjugation, protoplast fusion mediated exchange, transformation in protoplasts) in lactic acid bacteria are reviewed in this paper. besides, the detailed molecular nature of lactose plasmids in the streptococcus lactis c2, 712 and ml3 strain complex is discussed. | 1983 | 6414366 |
| the use of mesophilic cultures in the dairy industry. | the use of mesophilic starter cultures, containing group n streptococcus and leuconostoc species, in the dairy industry is examined. bacteriophage attack is identified as the main cause of culture inhibition and criteria used to select stable mixed-strain starter cultures and phage-insensitive defined strains are established. the key aspects of culture propagation and storage are highlighted, as well as bulk-culture protection based on physical exclusion of phage and the use of phage-inhibitory ... | 1983 | 6414367 |
| simple and rapid method for isolating large plasmid dna from lactic streptococci. | a procedure for the rapid isolation of plasmid dna larger than 30 megadaltons from lactic streptococci is described. this protocol can be used on a preparative scale to isolate sufficient quantities of plasmid dna required for restriction analysis, cloning, or transformation experiments. a scaled-down protocol is very useful for rapidly screening the plasmid content of streptococcal strains. with this methodology, previously undetected large plasmids were observed. | 1983 | 6416164 |
| properties of a streptococcus lactis strain that ferments lactose slowly. | streptococcus lactis 7962, which ferments lactose slowly, has a lactose phosphoenolpyruvate-dependent phosphotransferase system and low phospho-beta-galactosidase activity, in addition to high beta-galactosidase activity. lactose 6'-phosphate accumulated to a high concentration (greater than 100 mm) in cells growing on lactose. in contrast, lactic streptococci, which ferment lactose rapidly and use only the lactose-phosphotransferase system for uptake, contained high phospho-beta-galactosidase a ... | 1984 | 6418719 |
| conjugative 40-megadalton plasmid in streptococcus lactis subsp. diacetylactis drc3 is associated with resistance to nisin and bacteriophage. | streptococcus lactis subsp. diacetylactis drc3 was examined for plasmid dna and found to contain a previously unreported plasmid of 40 x 10(6) daltons. this plasmid, designated pnp40, was conjugally transferred to a plasmid-cured derivative of s. lactis c2. transconjugants containing pnp40 acquired resistance to nisin produced by strains of s. lactis and to commercially available nisin when assay plates were incubated at 21, 32, and 37 degrees c. in addition, c2 phage growth was completely restr ... | 1984 | 6421231 |
| [further studies on the effect of fluorides on the lactic acid production of bacteria]. | | 1983 | 6425754 |
| microscale method for rapid isolation of covalently closed circular plasmid dna from group n streptococci. | a method for rapid purification of plasmid dna from lactic streptococci, utilizing microliter quantities of reagents, was developed by combination of a short lysozyme-mutanolysin cell wall digestion with a modification of the escherichia coli plasmid isolation procedure of mcmaster et al. (anal. biochem. 109:47-54, 1980). the preparations obtained were highly enriched for covalently closed circular dna, and the method was applicable to plasmids of at least 40 megadaltons. centrifugation in cscl- ... | 1984 | 6426385 |
| use of 31p nuclear magnetic resonance spectroscopy and 14c fluorography in studies of glycolysis and regulation of pyruvate kinase in streptococcus lactis. | high-resolution 31p nuclear magnetic resonance spectroscopy and 14c fluorography have been used to identify and quantitate intermediates of the embden-meyerhof pathway in intact cells and cell extracts of streptococcus lactis. glycolysing cells contained high levels of fructose 1,6-bisphosphate (a positive effector of pyruvate kinase) but comparatively low concentrations of other glycolytic metabolites. by contrast, starved organisms contained only high levels of 3-phosphoglycerate, 2-phosphogly ... | 1984 | 6427193 |
| factors affecting germination and growth of bacillus cereus spores in milk. | the effect of salt concentration, acidity, and storage temperature on the spore germination of bacillus cereus and the growth rate of the organism was investigated. increasing the amount of salt to more than 5% or acidifying the milk to ph 5.0 or 4.5 greatly affected the germination and growth of b. cereus spores. when a culture of streptococcus lactis was used as an acidifying agent, b. cereus showed a normal growth rate during the first 12 h, followed by a sharpe reduction in numbers. when b. ... | 1984 | 6428077 |
| [protoplast isolation from a nisin-forming culture of streptococcus lactis strain mgu]. | a procedure for protoplasts of str. lactis producing nisin was developed. the following lysing factors were used for obtaining the protoplasts: lycozyme, le enzyme, lysosubtilin and an enzyme isolated from the culture fluid a. levoris. the use of the above factors in different combinations provided an increase in the number of the formed protoplasts from 1-2 in the field of the microscope vision to 15-20, which amounted to 25 per cent of the total number of the cells visible under microscope. | 1984 | 6428305 |
| regulation of product formation during glucose or lactose limitation in nongrowing cells of streptococcus lactis. | nongrowing cells of streptococcus lactis in a ph-stat were dosed with sugar to allow fermentation at the maximum rate or were fed a continuous supply of sugar at rates less than the maximum. under anaerobic conditions, rapid fermentation of either glucose or lactose was essentially homolactic. however, with strain ml3, limiting the fermentation rate diverted approximately half of the pyruvate to formate, acetate, and ethanol. at limiting glucose fermentation rates, cells contained lower concentr ... | 1984 | 6435521 |
| transformation of streptococcus sanguis challis with streptococcus lactis plasmid dna. | streptococcus lactis plasmid dna, which is required for the fermentation of lactose (plasmid plm2001), and a potential streptococcal cloning vector plasmid (pdb101) which confers resistance to erythromycin were evaluated by transformation into streptococcus sanguis challis. plasmid plm2001 transformed lactose-negative (lac-) mutants of s. sanguis with high efficiency and was capable of conferring lactose-metabolizing ability to a mutant deficient in enzyme iilac, factor iiilac, and phospho-beta- ... | 1984 | 6435522 |
| identification of streptococci in a medical laboratory. | a total of 965 cultures of streptococci received at a reference unit for identification were examined with api-20 strep kits and also by established methods. the api method, although it needed to be supplemented with additional tests, largely overcame the difficulty that pyogenic streptococci are usually identified by their serological reactions and that biochemical tests are used for the identification of the other streptococci. representatives of at least 24 established or possible species wer ... | 1984 | 6436221 |
| characterization of phosphate:hexose 6-phosphate antiport in membrane vesicles of streptococcus lactis. | membrane vesicles of streptococcus lactis were used to characterize a novel anion exchange involving phosphate and sugar 6-phosphates. for vesicles loaded with 50 mm phosphate at ph 7, homologous phosphate:phosphate exchange had a maximal rate of 130 nmol/min/mg of protein and a kt of 0.21 mm external phosphate; among phosphate analogues tested, only arsenate replaced phosphate. heterologous exchange was studied by 2-deoxyglucose 6-phosphate entry into phosphate-loaded vesicles; this reaction ha ... | 1984 | 6436237 |
| [use of adsorbents for optimizing the process of isolating nisin from the culture broth]. | the results of the study on optimization of the process of nisin isolation from the cultural liquid are presented. different adsorbents, streptococcal cells, medium solid particles (biomass fermentalysates) and silica gel, were used for antibiotic adsorption. | 1984 | 6439110 |
| fate of aflatoxin b-1 in fermented dairy products. | polyacrylamide gel electropheresis and thin layer chromatography (tlc) were applied to detect the fate of aflatoxin b-1 in milk fermented with an active culture of streptococcus lactis (atcc-11454). tlc analysis revealed the formation of two fluorescent metabolites (b2a and r0) in fermented milk. electropheretic analysis of both casein and whey protein showed fluorescent bands in the region of kappa-casien and immunoglobulin which are glycoproteins in nature. the transformation of b-1 to the non ... | 1984 | 6440020 |
| [conjugational plasmid transfer from a, b and h streptococci to n streptococci]. | plasmid-mediated resistance to erythromycin and chloramphenicol was successfully transferred from group a, b and h streptococci to group n streptococci by a process akin to conjugation. the results showed that plasmids from streptococcal groups other than n were able to replicate in lactic streptococci as well. the transfer experiments were carried out by using a membrane filter mating technique. four of the five plasmids used (psm15346, psm10419, pip501, and pel1) were transferred at frequencie ... | 1984 | 6441362 |
| [trials of cheese-making using concentrated bacterial starters]. | studies about cheese preparation with frozen and concentrated bacterial starters have been carried out. the pategras cheeses were obtained from raw milk. the starters were prepared with a selected strain of streptococcus lactis, concentrated until reaching a value of 3.10(9) colony forming units/ml and resuspended in milk previously supplemented with 8% of yeast extract. these concentrates were frozen at -40 degrees c and kept at -20 degrees c for 60 days. three kinds of starters were tested: on ... | 1984 | 6443830 |
| lactose transport in streptococcus mutans: isolation and characterization of factor iiilac, a specific protein component of the phosphoenolpyruvate-lactose phosphotransferase system. | the transport of lactose in streptococcus mutans is mediated via an inducible phosphoenolpyruvate-lactose phosphotransferase system. this system requires for catalytic activity a membrane fraction (enzyme ii), two general proteins called enzyme i and hpr, and a soluble specific protein termed factor iiilac. this protein factor was purified from s. mutans atcc 27352 by chromatographies on deae-cellulose, hydroxylapatite, ultrogel aca 34, and phosphocellulose. the purified protein migrated as a si ... | 1984 | 6480107 |
| [new nutrient medium for the nisin producer, the lactic acid bacterium, streptococcus lactis]. | | 1980 | 6768338 |
| resistance of 17 mesophilic lactic streptococcus bacteriophages to pasteurization and spray-drying. | for 17 phages active against streptococcus cremoris, str. lactis and str. lactis subsp. diacetylactis, the killing efficiency of pasteurization (log no/n) at 72 degrees c for 15 s in skim-milk showed large variations from greater than 6 to 0; the efficienty of killing during spray-drying ranged from 3.7 to 0.2 and phages survived well storage of milk powder at room temperature. destruction in a heat exchanger was found to be greater than that calculated from biphasic curves obtained by heating p ... | 1980 | 6768773 |
| chemical changes in bovine colostrum preserved with formalin or by fermentation. | fresh bovine colstrum from second and third milkings postpartum was inoculated with either a yogurt culture or streptococcus lactis or preserved with .1% formalin in two separate experiments. there was a rapid decrease in ph of the fermented samples which corresponded to decreased lactose concentrations and increased lactate and titratable acidity. titratable acidity in the fermented colostrums increased further after 10 days from the production of volatile fatty acids, but ph did not decrease. ... | 1980 | 6768780 |
| pyruvate dehydrogenase activity in group n streptococci. | pyruvate dehydrogenase activity was detected in whole cells but not in cell-free extracts of streptococcus lactis. however, the three component enzymes (pyruvate decarboxylase, lipoate acetyltransferase and lipoyl dehydrogenase) of the pyruvate dehydrogenase complex were identified in the cell-free extracts. whole cells of the three species of group n streptococci formed acetoin and diacetyl only after the pathway forming acetate had become saturated. s. lactis subsp. diacetylactis drc2 formed m ... | 1980 | 6772148 |
| proton motive force during growth of streptococcus lactis cells. | experiments with the aerotolerant anaerobe streptococcus lactis provide the opportunity for determining the proton motive force (deltap) in dividing cells. the two components of deltap, deltapsi (the transmembrane potential) and deltaph (the chemical gradient of h(+)), were determined by the accumulation of radiolabeled tetraphenylphosphonium (tpp(+)) and benzoate ions. the deltapsi was calibrated with the k(+) diffusion potential in starved, valinomycin-treated cells. with resting, glycolyzing ... | 1980 | 6772626 |
| [adsorption of the antibiotic, nisin, to streptococcus lactis cells]. | nizin is produced by str. lactis, strain msu. during biosynthesis it is excreted into the fermentation broth and gradually adsorbed on the organism cells. this was confirmed by experiments with an inactive variant of str. lactis iia. the cells of this culture adsorbed nizin from "active" fermentation broth. adsorption of nizin depended on ph of the medium; at ph 2,3 the cells did not adsorbe the antibiotic and at ph 6.6 the amount of the antibiotic adsorbed by the cells was maximum. | 1980 | 6773472 |
| conjugal transfer of genetic information in group n streptococci. | streptococcus lactis strains ml3 and c(2)o and s. lactis subsp. diacetylactis strains drc3, 11007, and wm(4) were found to transfer lactose-fermenting ability to lm0230, an s. lactis c2 lactose-negative (lac(-)) derivative which is devoid of plasmid deoxyribonucleic acid (dna). lactose-positive streptomycin-resistant (lac(+) str(r)) recombinants were found when the lac(+) str(s) donor was mixed with lac(-) str(r) lm0230 in solid-surface matings. transduction and transformation were ruled out as ... | 1980 | 6773476 |
| high-frequency conjugation associated with streptococcus lactis donor cell aggregation. | conjugal transfer of the streptococcus lactis 712 lactose plasmid was found to occur at a low frequency. variants of this plasmid were selected which had much greater donor abilities and which also exhibited an unusual cell aggregation phenotype. | 1980 | 6773926 |
| [use of enzymatic hydrolysates of microorganism biomass in media for culturing str. lactis, the producer of nisin]. | fermentative hydrolysates (fh) of the protein-vitamin complex (pvc) were used for the first time in media for cultivation of str. lactis. it was found that the fh may be used in the media for cultivation of streptococci as a source of nitrogen instead of the yeast autolysate from baker's yeast and the level of nisin biosynthesis did not change. the replacement of the yeast autolysate by the fh is possible in both flasks with low volumes of the medium and 401 fermenters with 25 liters of the medi ... | 1980 | 6775588 |
| galactose fermentation by streptococcus lactis and streptococcus cremoris: pathways, products, and regulation. | all of the lactic streptococci examined except streptococcus lactis ml8 fermented galactose to lactate, formate, acetate, and ethanol. the levels of pyruvate-formate lyase and lactate dehydrogenase were elevated and reduced, respectively, in galactose-grown cells compared with glucose- or lactose-grown cells. reduced intracellular levels of both the lactate dehydrogenase activator (fructose, 1,6-diphosphate) and pyruvate-formate lyase inhibitors (triose phosphates) appeared to be the main factor ... | 1980 | 6776093 |
| galactose transport systems in streptococcus lactis. | galactose-grown cells of streptococcus lactis ml3 have the capacity to transport the growth sugar by two separate systems: (i) the phosphoenolpyruvate-dependent phosphotransferase system and (ii) an adenosine 5'-triphosphate-energized permease system. proton-conducting uncouplers (tetrachlorosalicylanilide and carbonyl cyanide-m-chlorophenyl hydrazone) inhibited galactose uptake by the permease system, but had no effect on phosphotransferase activity. inhibition and efflux experiments conducted ... | 1980 | 6776094 |
| [physiological characteristics of immobilized cells of streptococcus lactis, moscow state university strain]. | immobilized cells of streptococcus lactis, strain msu, synthesized nisin by 20--30 per cent of the possible maximum antibiotic production level. the immobilized cells of the streptococcus synthesized nisin by 40--50 per cent probably at the expense of the cell nutrient pools and by 50--60 per cent at the expense of the medium nutrient consumption. the electron microphotographs showed that the cells of str. lactis, strain msu, preserved their usual appearance in the granules of polyacrylamide gel ... | 1980 | 6778377 |
| multiple modification/restriction systems in lactic streptococci and their significance in defining a phage-typing system. | the reactions between 6 strains of mesophilic lactic streptococci and their respective phages were studied quantitatively. of 30 nonhomologous reactions, the bacteria were fully sensitive in 4 and restricted the phages in 23. a mathematical model was developed that was used to identify at least 4 and probably 5 modification restriction (m/r) systems of which up to 3 were found in the same strain. the model was based on 24 measured values and correctly predicted the values of 5 others. one of the ... | 1980 | 6778900 |
| the importance of inorganic phosphate in regulation of energy metabolism of streptococcus lactis. | this paper is concerned with the control of glycolysis in nongrowing streptococcus lactis 7962. changes were measured in the concentrations of glycolytic intermediates, intracellular inorganic phosphate (pi), and adenine nucleotides following addition of glucose to cells that were in a starved condition. we find that intracellular pi is a major factor in the control of glycolysis. in starved cells, the intracellular pi concentration is high, greater than 40 mm. the large phosphoenolpyruvate pool ... | 1981 | 6780554 |
| radiosensitization of hypoxic bacterial cells by nitroimidazoles of low lipophilicity: steady-state and rapid-mix studies. | | 1981 | 6782616 |
| lactose hydrolysing enzymes in streptococcus lactis and streptococcus cremoris and also in some other species of streptococci. | | 1980 | 6783605 |
| growth and aflatoxin production by aspergillus parasiticus when in the presence of streptococcus lactis. | | 1981 | 6783914 |
| comparison of the antibacterial activity of the hypothiocyanite anion towards streptococcus lactis and escherichia coli. | it has been suggested that the antibacterial activity of the lactoperoxidase/thiocyanate/hydrogen peroxide system is due to the hypothiocyanite anion. relatively pure solutions of hypothiocyanite can be prepared using an immobilized enzyme. these preparations have been used to examine the effect of the anion on the growth and on the membranes of escherichia coli and streptococcus lactis. escherichia coli is killed in the presence of the anion whereas the effect on streptococcus lactis is only ba ... | 1980 | 6785388 |
| regulation of methyl-beta-d-thiogalactopyranoside-6-phosphate accumulation in streptococcus lactis by exclusion and expulsion mechanisms. | starved cells of streptococcus lactis ml3 (grown previously on galactose, lactose, or maltose) accumulated methyl-beta-d-thiogalactopyranoside (tmg) by the lactose:phosphotransferase system. more than 98% of accumulated sugar was present as a phosphorylated derivative, tmg-6-phosphate (tmg-6p). when a phosphotransferase system sugar (glucose, mannose, 2-deoxyglucose, or lactose) was added to the medium simultaneously with tmg, the beta-galactoside was excluded from the cells. galactose enhanced ... | 1981 | 6787017 |
| recombinant plasmid associated cell aggregation and high-frequency conjugation of streptococcus lactis ml3. | lactose-positive (lac+) transconjugants resulting from matings between streptococcus lactic ml3 and s. lactis lm2301 possess a single plasmid of approximately 60 megadaltons (mdal) which is nearly twice the size of the lactose plasmid of the donor. the majority of these lac+ transconjugants aggregated in broth and were able to transfer lactose-fermenting ability at a frequency higher than 10(-1) per donor on milk agar plates or in broth. lac+ transconjugants which did not clump conjugated at a m ... | 1981 | 6787018 |
| reviews of the progress of dairy science: genetics of lactic acid bacteria. | | 1981 | 6795247 |
| the biological aspects of oral pathogenicity. | the bacteria in the oral region tend to localize in the form of plaque deposits on tooth surfaces and in gingival crevices. the "metabolic nature" of this complex flora focuses on the reversible interactions between the plaque flora and their environmental modifications. the environmental circumstances will influence the range of expression in situ for the plaque (oral) organisms. then, it is suggested that the potential for caries induction or periodontal disease may develop when conditions app ... | 1981 | 6798108 |
| [nisin adsorption on substrate particles and the elaboration of the antibiotic extraction method]. | | 1981 | 6798921 |
| [conditions for nisin adsorption by streptococcus lactis cells]. | some conditions for absorption of nisin, a polypeptide antibiotic by the cells of str. lactis were studied. the amounts of nisin adsorbed by the cells depended on the culture age: at the late stationary phase the adsorption level was 2 times higher than that at the logarithmic phase. the cells grown on a "poor" medium adsorbed 85-90 per cent of nisin added to the solution, while the cells grown on the "rich" medium adsorbed 50 per cent of the antibiotic. the adsorption level of nisin by the cell ... | 1981 | 6798922 |
| distinct galactose phosphoenolpyruvate-dependent phosphotransferase system in streptococcus lactis. | lactose-negative (lac-) mutants were isolated from a variant of streptococcus lactis c2 in which the lactose plasmid had become integrated into the chromosome. these mutants retained their parental growth characteristics on galactose (lac- gal+). this is in contrast to the lac- variants obtained when the lactose plasmid is lost from s. lactis, which results in a slower growth rate on galactose (lac- gal+). the lac- gal+ mutants were defective in [14c]thiomethyl-beta-d-galactopyranoside accumulat ... | 1982 | 6799488 |
| [effect of regulators on bacterial autolysis]. | the aim of this work was to study the effect of autolysis regulators (the fraction of microbial teichoic acids) on the rate of autolysis and the activity of bacterial extracellular lytic enzymes. the regulators of autolysis isolated from 23 cultures belonging to 10 microbial species regulated the rate of autolysis in bacillus, e. coli and streptococcus lactis. the regulators either activated or inhibited autolysis depending on the substrate (of a bacterium to be subjected to autolysis). the quan ... | 1982 | 6803114 |
| d-alanine ester-containing glycerophosphoglycolipids in the membrane of gram-positive bacteria. | | 1982 | 6807353 |
| d-tagatose 1,6-diphosphate aldolase from lactic streptococci: purification, properties, and use in measuring intracellular tagatose 1,6-diphosphate. | two d-ketohexose 1,6-diphosphate aldolases are present in streptococcus cremoris e8 and s. lactis c10. one aldolase, which was induced by growth on either lactose or galactose, was active with both tagatose 1,6-diphosphate (tdp) and fructose 1,6-diphosphate (fdp), having a lower km and a higher vmax with tdp as the substrate. this enzyme, named tdp aldolase, had properties typical of a class i aldolase, being insensitive to edta and showing substrate-dependent inactivation by sodium borohydride. ... | 1982 | 6807956 |
| electron microscopy of streptococcus lactis phage plaque margins. | ultrathin sections of plaques produced by streptococcus lactis phages o712 and m13 were examined by transmission electron microscopy. the clear central area of the plaque was found to contain hardly any cellular material but the turbid margin contained abundant plasma membranes and some partially lysed cells whose appearance suggests a novel mechanism for the termination of plaque growth. | 1982 | 6808084 |
| hpr proteins of different microorganisms studied by hydrogen-1 high-resolution nuclear magnetic resonance: similarities of structures and mechanisms. | the hpr proteins of streptococcus lactis, streptococcus faecalis, bacillus subtilis, and escherichia coli were studied by 1h nmr at 360 mhz. the "active-center" histidines of all hpr proteins are characterized by a low pk value between 5.6 and 6.1 and similar spectral parameters. phosphorylation of the histidyl residues leads to an increase of the pk value of 2-3 units and spectral changes characteristic for n-1 phosphorylation of the histidyl ring. the spectra of the hpr proteins of s. lactis, ... | 1982 | 6809041 |
| [nisin inactivation in a culture of the producer streptococcus lactis strain mgu]. | the intensive biosynthesis of nizin on the glucose-yeast medium is observed during the logarithmic and early lag phases of the staphylococcal growth. the ratio of nizin in the fermentation broth (free nazin) and that bound with the cells depended on ph of the medium. when ph was maintained at 6.6-6.8, the amount of nazin in the cells during and growth logarithmic phase was equal to its amount in the fermentation broth filtrate. during the lag phase marked inactivation of nizin was noted. periodi ... | 1982 | 6816139 |
| oral bacteriotherapy in clinical practice. i. the use of different preparations in infants treated with antibiotics. | | 1982 | 6816601 |
| oral bacteriotherapy in clinical practice. ii. the use of different preparations in the treatment of acute diarrhoea. | | 1982 | 6816602 |
| pyruvate kinase from streptococcus lactis. | | 1982 | 6818419 |
| [effect of sodium fluoride on the growth and lactate production of streptococcus salivarius, streptococcus lactis and streptococcus faecalis]. | | 1982 | 6821302 |
| effect of fermentation and formalin preservation on the protein component of bovine colostrum. | colostrum was inoculated with streptococcus lactis or yogurt culture or preserved with .1% (vol/vol) formalin in two separate experiments. all preparations then were stored at ambient temperature for 24 days. with increasing storage time, a larger proportion of the total colostrum nitrogen was not precipitated in 10% (wt/vol) trichloroacetic acid. by day 24, this represented 30 to 35% for the fermented samples and 10 to 15% for the formalin preserved samples. the majority of this nonprecipitable ... | 1981 | 7298968 |
| molecular characterization of genes involved in the production of the bacteriocin leucocin a from leuconostoc gelidum. | leucocin a is a small heat-stable bacteriocin produced by leuconostoc gelidum ual187. a 2.9-kb fragment of plasmid dna that contains the leucocin structural gene and a second open reading frame (orf) in an operon was previously cloned (j. w. hastings, m. sailer, k. johnson, k. l. roy, j. c. vederas, and m. e. stiles, j. bacteriol. 173:7491-7500, 1991). when a 1-kb drai-hpai fragment containing this operon was introduced into a bacteriocin-negative variant (ual187-13), immunity but no leucocin pr ... | 1995 | 7486992 |
| improvement of solubility and stability of the antimicrobial peptide nisin by protein engineering. | nisin is a 3.4-kda antimicrobial peptide that, as a result of posttranslational modifications, contains unsaturated amino acids and lanthionine residues. it is applied as a preservative in various food products. the solubility and stability of nisin and nisin mutants have been studied. it is demonstrated that nisin mutants can be produced with improved functional properties. the solubility of nisin a is highest at low ph values and gradually decreases by almost 2 orders of magnitude when the ph ... | 1995 | 7487019 |
| bacteriolytic activity caused by the presence of a novel lactococcal plasmid encoding lactococcins a, b, and m. | lactococcus lactis subsp. lactis biovar diacetylactis dpc938 was identified as a bacteriocin-producing strain which exhibited a bacteriolytic effect on other lactococci. lysis of such target strains was associated with decreases in optical density and release of the intracellular enzyme lactate dehydrogenase. dpc938 exhibits cross-immunity to l. lactis subsp. cremoris 9b4 (m.j. van belkum, b.j. hayema, a. geis, j. kok, and g. venema, appl. environ. microbiol. 55:1187-1191, 1989), a strain which ... | 1995 | 7487031 |
| oligopeptides are the main source of nitrogen for lactococcus lactis during growth in milk. | the consumption of amino acids and peptides was monitored during growth in milk of proteinase-positive (prt+) and -negative (prt-) strains of lactococcus lactis. the prt- strains showed monophasic exponential growth, while the prt+ strains grew in two phases. the first growth phases of the prt+ and prt- strains were in same, and no hydrolysis of casein was observed. also, the levels of consumption of amino acids and peptides in the prt+ and prt- strains were similar. at the end of this growth ph ... | 1995 | 7487034 |
| characterization of plasmid-encoded citrate permease (citp) genes from leuconostoc species reveals high sequence conservation with the lactococcus lactis citp gene. | the citrate permease determinant (citp) in several leuconostoc strains was demonstrated to be plasmid encoded by curing experiments and hybridization studies with a dna fragment containing the citp gene from lactococcus lactis subsp. lactis biovar diacetylactis ncdo176. cloning and nucleotide sequence analysis of leuconostoc lactis nz6070 citp revealed almost complete identity to lactococcal citp. | 1995 | 7487049 |
| the isolation of lactococcal promoters and their use in investigating bacterial luciferase synthesis in lactococcus lactis. | 18 different promoter elements, encompassing a 71-fold range of activity, were isolated from the chromosome of lactococcus lactis (ll) mg1363 and from an uncharacterised small isometric bacteriophage of ll. the vibrio fischeri (vf) luciferase-encoding gene (lux) was used as a reporter in ll, so that the promoters could be identified strictly on the basis of their activity in the homologous host. sequence and primer extension analysis of six of the promoters has provided a new consensus sequence ... | 1995 | 7489923 |
| an archaeal gene upstream of grpe different from eubacterial counterparts. | in some eubacteria with a dnak locus in which grpe is close upstream of dnak, grpe is preceded by an open reading frame (orf) believed to be a heat-shock gene. we also found an orf, orf16, upstream of grpe in the archaeon methanosarcina mazei s-6, but this gene differs from the eubacterial counterpart: it is shorter, does not respond to a temperature upshift as heat-shock genes do, and the deduced protein orf16, does not resemble the proteins coded by the eubacterial equivalents. orf16 is expres ... | 1995 | 7495860 |
| expression of foreign genes and selection of promoter sequences in acholeplasma laidlawii. | the stable maintenance and expression of foreign genes in mollicutes (mycoplasmas) have been difficult to achieve due to the lack of suitable vectors. in this paper we show for the first time that a replicating vector can been used to express foreign genes other than antibiotic resistance genes in acholeplasma laidlawii. plasmids derived from the lactococcal vector pnz18 could introduce and maintain four different genes for many generations in a. laidlawii. one of these, encoding the dominant me ... | 1995 | 7496518 |
| in vitro fructooligosaccharide utilization and inhibition of salmonella spp. by selected bacteria. | in vitro experiments were conducted to determine: 1) inhibitory capacities of potential direct-fed microbial bacteria against salmonella serotypes; and 2) the ability of bifidobacterium bifidum, enterococcus faecium, lactobacillus casei, lactococcus lactis, pediococcus sp., and salmonella spp. to grow in media containing fructooligosaccharides (fos-50 or fos pure formulation) as the only carbohydrate source. thirteen bacteria (two strains of bacillus coagulans, bacillus licheniformis, bacillus s ... | 1995 | 7501585 |
| genetic and molecular analysis of the rpod gene from lactococcus lactis. | a gene of lactococcus lactis atcc19435, the product of which is homologous with the principal sigma factors of escherichia coli and bacillus subtilis, was cloned and sequenced. the deduced amino acid sequence of the 340-residue protein and the upstream open reading frame of the cloned gene showed a homology to b. subtilis sigma 43 factor (the rpod product) and dna primase (the dnae product), respectively, suggesting that l. lactis also has the rpod operon. surprisingly, introduction of the clone ... | 1993 | 7503808 |
| physiological and genetic regulation of rrna synthesis in lactococcus. | the macromolecular composition of lactococcus was regulated by growth rate in the same general way as that of less fastidious bacteria such as escherichia coli and salmonella typhimurium. the ratios of rna:dna and rna:protein increased approximately threefold over a 13.5-fold increase in growth rate, whereas the ratio of dna:protein remained approximately constant. using reporter genes fused to a dna fragment of a cloned lactococcal rrna operon, promoter activity was located upstream of the 16s ... | 1993 | 7504067 |
| isolation of lactococcus lactis subsp. cremoris from nature by colony hybridization with rrna probes. | lactococcus lactis subsp. cremoris is widely used in the manufacture of fermented milk products. despite numerous attempts, efforts to isolate new strains by traditional plating and identification methods have not been successful. previously, we described oligonucleotide probes for 16s rrnas which could be used to discriminate l. lactis subsp. cremoris from related strains. these probes were used in colony hybridization experiments to screen large numbers of colonies obtained from enrichment cul ... | 1993 | 7506898 |
| in vivo restriction by llai is encoded by three genes, arranged in an operon with llaim, on the conjugative lactococcus plasmid ptr2030. | the llai restriction and modification (r/m) system is encoded on ptr2030, a 46.2-kb conjugative plasmid from lactococcus lactis. the llai methylase gene, sequenced previously, encodes a functional type iis methylase and is located approximately 5 kb upstream from the abia gene, encoding abortive phage resistance. in this study, the sequence of the region between llaim and abia was determined and revealed four consecutive open reading frames (orfs). northern (rna) analysis showed that the four or ... | 1995 | 7528201 |
| evidence for a large dispensable segment in the subtilisin-like catalytic domain of the lactococcus lactis cell-envelope proteinase. | the lactococcus lactis sk11 cell-envelope proteinase contains various inserts, located in external loops of the catalytic domain compared with related subtilisins. in this study, protein engineering was employed to determine the function of the largest loop insertion (residues 238-388) relative to the subtilisin structure. by site-directed mutagenesis we have deleted the fragment of the proteinase gene encoding these 151 residues and analyzed the mutant delta 238-388 proteinase for activity, (au ... | 1994 | 7528919 |
| [the immunostimulating action of lactobacteria on the cytotoxicity of natural killer cells and interferon production]. | | 1994 | 7533464 |
| mode of action of lcia, the lactococcin a immunity protein. | monoclonal antibodies were raised against a fusion between the escherichia coli maltose-binding protein and lcia, the immunity protein that protects lactococcus lactis against the effects of the bacteriocin lactococcin a. one of the antibodies directed against the lcia moiety of the fusion protein was used to locate the immunity protein in the l. lactis producer cell. lcia was present in the cytosolic, the membrane-associated, and the membrane fractions in roughly equal amounts, irrespective of ... | 1994 | 7533883 |
| the lactococcus lactis triosephosphate isomerase gene, tpi, is monocistronic. | triosephosphate isomerase (ec 5.3.1.1) from lactococcus lactis was purified to electrophoretic homogeneity. approximately 3 mg purified enzyme (specific activity 3300 u mg-1) was obtained from 70 g (wet wt) cells. in solution, triosephosphate isomerase (pi 4.0-4.4) was observed to exist as a homodimer (m(r) 57,000) of noncovalently linked subunits. the sequence of the first 37 amino acid residues from the nh2-terminus were determined by step-wise edman degradation. this sequence, and that of a r ... | 1995 | 7534588 |
| citrate utilization gene cluster of the lactococcus lactis biovar diacetylactis: organization and regulation of expression. | the transport of citrate in lactococcus lactis biovar diacetylactis is mediated by the citrate permease p. this polypeptide is encoded by the citp gene carried by plasmid pcit264. in this report, we characterize the citp transcript, identify a cluster of two genes cotranscribed with citp and describe their post-transcriptional regulation. the transcriptional promoter is located 1500 nucleotides upstream of the citp gene and the transcriptional terminator is positioned next to the 3'-end of this ... | 1995 | 7535377 |
| specific antibody-mediated detection of brochothrix thermosphacta in situ in british fresh sausage. | a rabbit polyclonal antibody-linked probe was developed which detected 76% of 800 food isolates of the spoilage bacterium brochothrix thermosphacta when cells were bound to nitrocellulose. in slide cross-reaction tests all six environmental isolates tested were stained but the type strain was not. the antibody did not cross-react with listeria grayi, l. monocytogenes, lactobacillus plantarum, lactococcus lactis, streptococcus mutans, bacillus cereus or b. subtilis. the antibody-linked probe dete ... | 1995 | 7538105 |
| characterization of prokaryotic mrnas by rt-pcr. | | 1995 | 7542457 |
| enhancement of antigen-specific antibody production by extracellular slime products from slime-forming lactococcus lactis subspecies cremoris sbt 0495 in mice. | the effect of extracellular slime products (esp) produced by lactococcus lactis subspecies cremoris sbt 0495 on antigen specific antibody production was studied in mice. esp contained 48.5% protein, 15.4% neutral sugar, and 1.1% of phosphorus. the optimum dose of esp was between 100 to 500 micrograms per mouse. esp administered intraperitoneally (200 micrograms per mouse) enhanced the production of specific antibody in mice. these results indicate that esp may act as an adjuvant. | 1995 | 7547146 |
| transformation of lactococcus by electroporation. | | 1995 | 7550735 |
| nucleotide sequence of the lantibiotic pep5 biosynthetic gene cluster and functional analysis of pepp and pepc. evidence for a role of pepc in thioether formation. | the biosynthesis of pep5, a lanthionine-containing antimicrobial peptide, is directed by the 20-kbp plasmid ped503. we identified a 7.9-kbp dna-fragment within this plasmid which covers the information for pep5 synthesis in the homologous host staphylococcus epidermidis 5 which has been cured of ped503. this fragment contained, in addition to the previously described structural gene pepa and the immunity gene pepi [reis, m., eschbach-bludau, m., iglesias-wind, m. i., kupke, t. & sahl, h.-g. (199 ... | 1995 | 7556197 |
| characterization of superoxide dismutase genes from gram-positive bacteria by polymerase chain reaction using degenerate primers. | an internal fragment representing approximately 85% of sod genes from seven gram-positive bacteria was amplified by using degenerate primers in a polymerase chain reaction assay. the dna sequences of sod polymerase chain reaction products from clostridium perfringens, enterococcus faecalis, enterococcus faecium, lactococcus lactis, staphylococcus aureus, streptococcus agalactiae, streptococcus pneumoniae, and streptococcus pyogenes were determined. comparisons of their deduced amino acid sequenc ... | 1995 | 7557308 |
| the cellular location and effect on nisin immunity of the nisi protein from lactococcus lactis n8 expressed in escherichia coli and l. lactis. | lactococcus lactis cells secreting the lantibiotic nisin, commercially used for food preservation, must protect their cell membrane against the pore-forming activity of extracellular nisin. the nisi gene product has been suggested to be a lipoprotein, which due to the location on the extracellular surface would be an ideal candidate for an immunity protein. in vivo labelling of nisi from l. lactis n8 expressed in escherichia coli proved that nisi is a lipoprotein. expression of nisi in the nisin ... | 1995 | 7557313 |
| construction of a streptococcus pyogenes reca mutant via insertional inactivation, and cloning and sequencing of the complete reca gene. | to facilitate future genetic studies with streptococcus pyogenes (sp), a reca mutant (rec11) was constructed using a streptococcal integration vector carrying a pcr-derived internal reca fragment. the insertion of the plasmid in the mutant chromosome was identified by southern hybridization. resistance to uv and the ability to accept linear dna transformation by rec11 were greatly decreased, confirming its reca phenotype. using the pcr-derived fragment as a probe, we cloned and sequenced the com ... | 1995 | 7557418 |
| a family of bacteriocin abc transporters carry out proteolytic processing of their substrates concomitant with export. | lantibiotic and non-lantibiotic bacteriocins are synthesized as precursor peptides containing n-terminal extensions (leader peptides) which are cleaved off during maturation. most non-lantibiotics and also some lantibiotics have leader peptides of the so-called double-glycine type. these leader peptides share consensus sequences and also a common processing site with two conserved glycine residues in positions -1 and -2. the double-glycine-type leader peptides are unrelated to the n-terminal sig ... | 1995 | 7565085 |
| novel insertion sequence-like element is982 in lactococci. | a novel insertion sequence-like (is) element, designated is982, was found on the lactose plasmid, psk11l, from lactococcus lactis subsp. cremoris sk11 and was located between the origin of replication and the oligopeptide transport gene cluster. the 1003-base pair (bp) is982 was flanked by 18-bp perfect inverted repeats. is982 contained an open reading frame encoding a putative transposase of 296 amino acids. an almost identical is-like element (99% dna sequence identity) was cloned and partiall ... | 1995 | 7568469 |
| the proteolytic pathway of lactococcus lactis. | | 1995 | 7570167 |
| virion positions and relationships of lactococcal temperate bacteriophage tp901-1 proteins. | the major proteins of phage tp901-1 virion were characterized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and structural relations were determined using specific antibodies, obtained by affinity purification from a polyclonal serum. a 23-kda protein was identified as the major tail protein, and a 31-kda molecule as the major head protein, respectively. labeling experiments with antibodies against two proteins, with molecular masses of 20 and 19 kda, indicated that they were base ... | 1995 | 7571429 |
| applications of confocal microscopy to fat globule structure in cheese. | | 1995 | 7572372 |
| cloning and molecular analysis of the dihydrofolate reductase gene from lactococcus lactis. | the lactococcus lactis gene encoding trimethoprim resistance has been cloned and expressed in escherichia coli and bacillus subtilis. several lines of evidence indicate that the cloned gene encodes dihydrofolate reductase (dhfr). (i) it fully complements the fol "null" mutation in e. coli. (ii) nucleotide sequencing of the cloned fragment revealed the presence of one open reading frame encoding a protein that shares homology with the family of bacterial dhfr enzymes. (iii) overexpression of this ... | 1995 | 7574597 |
| detection and characterization of lactose-utilizing lactococcus spp. in natural ecosystems. | the presence of lactose-utilizing lactococcus species in nondairy environments was studied by using identification methods based on pcr amplification and (sub)species-specific probes derived from 16s rrna sequences. environmental isolates from samples taken on cattle farms and in the waste flow of a cheese production plant were first identified to the genus level, using a lactococcus genus-specific probe. isolates which showed a positive signal with this probe were further identified to the (sub ... | 1995 | 7574616 |
| expression of lactococcin a and pediocin pa-1 in heterologous hosts. | pediocin pa-1 production, immunity and secretion are specified by a cluster of four genes in pediococcus acidilactici pac1.0. the production by, secretion of, and immunity to lactococcin a of lactococcus lactis are also determined by four genes. here, expression of the pediocin operon in lactococcus lactis is reported, which could only be achieved by placing it under control of a lactococcal promoter. expression of the lactococcin a operon in pediococcus is also described: recombinant clones of ... | 1995 | 7576505 |
| 16s-23s and 23s-5s intergenic spacer regions of streptococcus thermophilus and streptococcus salivarius, primary and secondary structure. | the 16s-23s intergenic spacer region (spacer region 1) of streptococcus salivarius, s. thermophilus, and lactococcus lactis subsp. cremoris and the 23s-5s intergenic spacer region (spacer region 2) of s. salivarius and l. lactis subsp. cremoris were sequenced and compared with the spacer regions 1 and 2 of other streptococci. a high degree of intraspecific conservation was observed for s. thermophilus and l. lactis, and very similar sequences were found for s. salivarius and s. thermophilus. whe ... | 1995 | 7580797 |