Showing papers on "Growth medium published in 1980"
TL;DR: Data obtained using fluorescence-activated cell sorting techniques indicate that simian virus 40-transformed human fibroblasts are arrested i the S and G2 phases of the cell cycle, in contrast to a G1-phase accumulation of cells, which occurs only in methionine-supplemented medium at very high densities.
Abstract: A reversible growth arrest of simian virus 40-transformed human fibroblasts has been produced by replacement of methionine in the growth medium by its immediate metabolic precursor, homocysteine, Although these arrested cells exhibit a greatly reduced cloning efficiency when plated in methionine-supplemented medium, they resume rapid proliferation without a lag when subconfluent cells are refed with methionine-supplemented medium. This growth arrest is accompanied by a reduction in the percentage of mitotic cells in the cell population. Furthermore, data obtained using fluorescence-activated cell sorting techniques indicate that the cells are arrested i the S and G2 phases of the cell cycle. This is in contrast to a G1-phase accumulation of cells, which occurs only in methionine-supplemented medium at very high densities and which is similar to the G1 block seen in cultures of normal fibroblasts at high density. The apparent relationship between specific events in the DNA-synthetic and premitotic phase of the cell cycle and methionine dependence in these transformed cultures is discussed.
126 citations
TL;DR: The enzyme cleaved only N-α-benzoyl-DL-lysine-and-arginine-nitroanilides but not the corresponding leucine or tyrosine derivatives nor a set of diand tripeptides, and was the dominant protein in the growth medium.
Abstract: Excretion of an extracellular protease of Serratia marcescens ATCC 25419 occurred during logarithmic growth and was highest (per cell) when cultures reached the stationary growth phase. Production of the extracellular protease was induced by leucine or casein in minimal medium or by growth in tryptone-yeast medium. In the late stationary phase an intracellular protease activity accumulated which was also observed in mutants with very low extracellular protease activity. The excreted protease was the dominant protein in the growth medium. The protease was purified to homogeneity by column chromatography on Bio-Gel P-100 and on DEAE-cellulose. Quantitative amino acid analysis revealed the absence of sulfur-containing amino acids. The enzyme consists of one polypeptide chain. A molecular weiht of 51,000 and 55,000 was estimated using polyacrylamide gel electrophoresis and chromatography on Bio-Gel P-100 respectively. The enzyme cleaved only N-alpha-benzoyl-DL-lysine-and-arginine-nitroanilides but not the corresponding leucine or tyrosine derivatives nor a set of di- and tripeptides.
108 citations
TL;DR: The Halomonas strain was found to have an absolute requirement for the Na+ cation, and when LiCl, NH4Cl, MgCl2∙6H2O, or KCl was substituted for NaCl, the medium would not support growth, suggesting that the type of growth medium used has a great effect on bacterial salt tolerance.
Abstract: The genus Halomonas (type species H. elongata) is a new bacterial genus composed of salt tolerant bacteria. The growth characteristics and morphology of the type strain of this bacterial group were studied using both complex and defined media. The salt tolerance of the bacterium decreased significantly on defined medium, suggesting that the type of growth medium used has a great effect on bacterial salt tolerance. Experiments on the effect of temperature on salt tolerance indicate that a temperature of 30 °C permits the greatest salt tolerance. In all of these experiments 0.375 and 1.37 M NaCl yielded the most rapid growth rates while 1.37 and 2.5 M NaCl permitted the greatest temperature tolerance. The Halomonas strain was found to have an absolute requirement for the Na+ cation. While NaNO3 and NaBr would substitute for NaCl in the growth medium, when LiCl, NH4Cl, MgCl2∙6H2O, or KCl was substituted for NaCl, the medium would not support growth. The bacterium consistently retained its rod shape regardles...
57 citations
TL;DR: It was found that the removal of O6-methylguanine did not depend upon xth gene function or the uvr endonuclease, however, the rate of elimination of this product was markedly decreased in polA strains, and the results indicate that the elimination of O 6-methylGuanine, but not of 3-methyladenine, requires protein synthesis.
Abstract: Cultures of Escherichia coli were treated with alkylnitrosoureas. The rates of removal of methylation and ethylation products from the DNA of strains defective in various repair pathways were compared with those of their respective wild-type strains. It was found that the removal of O6-methylguanine did not depend upon xth gene function or the uvr endonuclease. However, the rate of elimination of this product was markedly decreased in polA strains. O6-Ethylguanine (in contrast to its methyl analogue) was removed more slowly from the DNA of uvrA(-) than from that of uvrA(+) strains, indicating that the removal of O6-ethylguanine can be initiated by the uvr endonuclease. The composition of the medium in which methylated cells were resuspended following treatment with N-methyl-N-nitrosourea was also found to influence the rate at which O6-methylguanine was removed from the DNA of treated bacteria. No significant removal of this product from bacterial DNA occurred during treatment of cells in buffer, or when treated bacteria were resuspended in salts medium or in growth medium containing chloramphenicol. The results indicate that the elimination of O6-methylguanine, but not of 3-methyladenine, requires protein synthesis. Only very limited constitutive activity capable of removing O6-MeGua was detected.
51 citations
TL;DR: A mathematical model is formulated of this system which describes the histidine concentration at radius r and time t in a petri dish, the concentration of the growth medium’s buffer and the size of the bacterial population.
Abstract: A uniform distribution of histidine auxotrophic Salmonella Typhimurium on an agar gel exhibits a spatial pattern of growth in responsto a diffusing front of histidine. We formulate a mathematical model of this system which describes the histidine concentration (H(r,t)) at radius r and time t in a petri dish, the concentration of the growth medium’s buffer (G(r,t)) and the size of the bacterial population (B(r,t)). Histidine diffuses and is taken up by growing cells, the buffer also diffuses but it is neutralized by acids produced as byproducts of cell growth, and the bacterial population is fixed, as in a stiff top layer of agar.
41 citations
TL;DR: The experiments suggest that the adaptive regulation of glucose transport in these mammary tumor cell cultures occurred at the transcriptional level and was influenced by the rates of cellular growth.
Abstract: Transport of 3-O-methyl-(1-3H)-D-glucose (3-OMG) was studied in primary cell cultures of the R3230AC rat mammary adenocarcinoma. Fastest rates of carrier-mediated 3-OMG transport (vc) were temporally associated with fastest cell growth, as were the rates of 3H-labeled thymidine, uridine, and leucine incorporation into macromolecules. The decrease in vc for 3-OMG observed as cultured cells approached quiescence was due to a 4-fold decrease in Vmax with the Km remaining relatively constant (4–9mM). Provided adequate time was allowed for cells to adapt, (6–12hr), the vc for 3-OMG transport was found to be inversely related to the concentration of glucose in the medium. Within 6 hours after switching cells from standard growth medium (5mM glucose) to medium containing no glucose (5 mM fructose), a 2-fold increase in vc for 3-OMG transport was observed in both fast and slow growing cells. The glucose-starvation induced increase in 3-OMG transport was due to an increase in Vmax; the Km remained constant, and was not significantly influenced by the presence of serum (10%) or insulin (5 mg/ml) or by [5 mM] galactose, mannose, fructose, 2-deoxy-D-glucose, 3-OMG, or mannitol. Readdition of glucose (5 mM) to transport-activated cells (deprived of glucose for 9–11 hr) resulted in a rapid return of 3-OMG transport to basal levels. In the presence of cycloheximide (10 mg/ml) or actinomycin D (10 mg/ml), this glucose-induced decline in carrier function was largely blocked. In fast-growing cells, the addition of either of these inhibitors, in the presence or absence of glucose, resulted in an initial rise in the rates of 3-OMG transport, followed by a linear decrease. Compared to fast-growing cells, the cycloheximide-induced increase in 3-OMG transport was greater and longer sustained in slow-growing cells. Regardless of their growth rate, cell cultures preincubated in medium containing glucose and cycloheximide exhibited decreases in 3-OMG transport when transferred to medium containing fructose, with or without actinomycin D. Slow-growing cells preincubated in medium containing fructose and cycloheximide exhibited an increase in 3-OMG transport when switched to medium containing fructose, whereas similarly treated fast growing cell cultures displayed a slight decrease. These experiments suggest that the adaptive regulation of glucose transport in these mammary tumor cell cultures occurred at the transcriptional level and was influenced by the rates of cellular growth. A model in which a metabolite of glucose acts to enhance the synthesis or stabilization of a mRNA species specific for a putative carrier inactivator protein is proposed.
37 citations
TL;DR: Washing experiments demonstrated that the major nutritional factor inhibiting chlorophyll synthesis in stationary phase cultures grown on medium containing a high carbon to nitrogen ratio was the absence of nitrogen rather than the presence of utilizable organic carbon.
Abstract: Nitrogen deficiency and the presence of specific organic carbon sources prevent chloroplast development in Euglena. In exponentially growing cultures, chlorophyll levels were low and independent of the nitrogen content of the growth medium. Chlorophyll levels increased in stationary phase and the amount of chlorophyll formed was proportional to the initial nitrogen content of the growth medium; the greater the concentration of nitrogen, the greater the amount of chlorophyll synthesized during stationary phase. Washing experiments demonstrated that the major nutritional factor inhibiting chlorophyll synthesis in stationary phase cultures grown on medium containing a high carbon to nitrogen ratio was the absence of nitrogen rather than the presence of utilizable organic carbon. The light-induced synthesis of chlorophyll and of NADP-glyceraldehyde-3-phosphate dehydrogenase was inhibited when acetate or ethanol was added at the time of exposure of dark-grown resting cells to light. Malate addition, however, stimulated chlorophyll and enzyme synthesis. Both cell number and total cell protein increased after ethanol, acetate, or malate addition, indicating that the resting cells were not nitrogen-deficient. Ethanol and acetate specifically repress light-induced chlorophyll synthesis. NADP-glyceraldehyde-3-phosphate dehydrogenase synthesis was inhibited at a time, the first 24 hours of light exposure, when chlorophyll synthesis was unaffected by carbon addition.
34 citations
TL;DR: A primary role for membrane damage is suggested in the mechanism of heat killing of exponentially growing yeast cells by exposure to 52°C, which increased markedly as the growth temperature was increased.
Abstract: The resistance of exponentially growing yeast cells to killing by exposure to 52 degrees C increase markedly as the growth temperature was increased Identical killing curves were obtained for cells suspended in growth medium or in 09% saline Cells resistant to killing at 52 degrees C were quite sensitive to killing at slightly higher temperatures These results suggest a primary role for membrane damage in the mechanism of heat killing
30 citations
TL;DR: The conversion of yeastlike cells to hyphae inMucor rouxii, a dimorphic mold, was altered by increasing the glucose concentration in the growth medium, which inhibited germ tube biogenesis, reduced hyphal branching, and effected a significant increase in the rate of ethanol accumulation during an air-induced shift in vegetative cell type.
29 citations
TL;DR: Sucrose and glucose phosphoenolpyruvate-dependent phosphotransferase (PTS) activities were studied in growing cultures of Streptococcus mutans serotype c and d/g cells adapted to either glucose or sucrose, finding that S. mutans possesses at least two transport mechanisms for each substrate studied.
Abstract: Sucrose and glucose phosphoenolpyruvate-dependent phosphotransferase (PTS) activities were studied in growing cultures of Streptococcus mutans serotype c and d/g cells adapted to either glucose or sucrose. Both acid production and optical absorbance were used to monitor growth in pH-controlled defined growth medium. The sucrose PTS activity appeared to be significant only under conditions of substrate limitation or slow growth as a result of low environmental pH. However, under environmental conditions which permitted rapid growth sucrose PTS activity appeared to be repressed, and only when the cells approached substrate-limited stationary phase after growth on high sucrose-supplemented medium was significant sucrose PTS activity again observed. A mutant apparently defective in sucrose PTS activity grew rapidly and produced acid under conditions of high environmental sucrose level but showed no sucrose PTS activity when the culture approached stationary phase. The mutant, however, after adaptation to glucose, demonstrated significant glucose PTS once the culture had attained the stationary growth phase. During diauxie growth in the presence of glucose and sucrose, there were sequential apparent inductions and repressions of glucose and sucrose PTS activities corresponding to decreases and increases of growth rate on the two substrates. Thus, S. mutans possesses at least two transport mechanisms for each substrate studied. One system (PTS) functions under conditions permitting slow growth and another functions under conditions permitting rapid growth.
26 citations
Journal Article•
TL;DR: An ascogenous yeast with high potentialities for L-glutaminase and L-asparaginase formation was isolated from Egyptian soils by the application of the culture enrichment method and tests of enzyme activity have revealed that optimum pH values for L -glutamine and L -asparagine hydrolysis are 6.0 and 6.7.
Abstract: An ascogenous yeast with high potentialities for L-glutaminase and L-asparaginase formation was isolated from Egyptian soils by the application of the culture enrichment method. The organism, identified as Pichia polymorpha, was obtained through the enrichment of soil samples with a simple medium containing 0.5% L-glutaminase as a major carbon and nitrogen source at low pH values. The amidase activities were produced constitutively on a variety of media irrespective of the presence of their substrates in the growth medium. Assays of enzyme activity have revealed that optimum pH values for L-glutamine and L-asparagine hydrolysis are 6.0 and 6.7, respectively. The L-asparaginase activity of the cells was heat-stable for at least 10 minutes at 60 degrees C. The enzyme exhibited apparent Km of 1.37 x 10(-2) M and 1.95 x 10(-2) M for L-asparagine and L-glutamine, respectively. No metal requirement were detected for the amidase activities of the organism under study.
TL;DR: It is proposed that cellular proteolysis involves at least three mechanisms: induced autophagy; basal proteolysin occurring in lysosomes; and a neutral proteolytic mechanism that insulin inhibits the first at the initial presequestration stage, and NH 4 + inhibits thefirst two at a final intravacuolar proteolyses step.
TL;DR: It is suggested that thrombin's influence on cell growth can be stimulatory or inhibitory and suggest that the state of the cell surface determines the response.
Abstract: The ability of thrombin to alter the growth of human skin fibroblasts was studied under a variety of experimental conditions. In agreement with previous reports, we obtained a moderate level of cell growth in confluent cultures using 0.5-8.0 U/ml of thrombin. In subconfluent cultures, the effect was strikingly different and was found to be dependent upon the time in culture when the enzyme was added. Cultures exposed to thrombin 24 h after subculturing showed growth stimulation several days later. In contrast, thrombin added at the time of cell plating produced a complete block of DNA synthesis and cell growth that lasted for at least 3 d. Cells exposed to thrombin under these conditions were morphologically altered and smaller. These thrombin-induced effects were reversible and could be completely prevented by pretreatment of the enzyme with hirudin before it was added to the culture medium. Growth inhibition and altered morphology were found to be the result of changes generated in the growth medium by thrombin and could be blocked by higher serum concentrations. The results of this study indicate that thrombin's influence on cell growth can be stimulatory or inhibitory and suggest that the state of the cell surface determines the response.
TL;DR: A serum-free, chemically defined growth medium containing casein, insulin, transferrin, testosterone, and linoleic acid in Dulbecco's modified Eagle's medium/Ham's F12 medium, 1:1 (vol/vol), for growing murine T lymphomas should prove useful for studies of a variety of metabolic pathways and of differentiated functions of T-lymphoma cells.
Abstract: We have developed a serum-free, chemically defined growth medium containing casein, insulin, transferrin, testosterone, and linoleic acid in Dulbecco's modified Eagle's medium/Ham's F12 medium, 1:1 (vol/vol), for growing murine T lymphomas. This medium supports the growth in suspension of all murine T lymphomas tested, including S49, WEHI 7, EL4, BW5147, and R1.1. Growth of these cell lines was maintained indefinitely with doubling times approaching those of cells grown in 10% (vol/vol) horse serum. This medium also supports the growth of several of the S49 variants of the beta-adrenergic receptor/adenylate cyclase/cyclic AMP/protein kinase pathway, suggeting little or no involvement of this pathway in the routine growth of S49 cells or in the mechanism of action of the factors in this defined medium. This serum-free medium should prove useful for studies of a variety of metabolic pathways and of differentiated functions of T-lymphoma cells.
TL;DR: Streptococcus faecalis var.
Abstract: Streptococcus faecalis var. zymogenes was grown aerobically on a complex medium containing glycerol as the carbon source. Addition of haematin or bovine liver catalase to the growth medium resulted in a small increment in growth yield. Suspensions of bacteria that had been grown in the presence of haematin or catalase, respectively, translocated 0.83 to 1.98 and 1.33 to 2.53 protons per oxygen atom consumed in glycerol oxidation. Bacteria grown without haematin or catalase had nil or little respiratory-induced proton translocation during glycerol oxidation. Inclusion of haematin in the growth medium caused the bacterium to form a cyanide- and azide-sensitive catalase. Superoxide dismutase activity was similar whether or not haematin was added to the growth medium.
TL;DR: Data suggest that this secondary inhibition of ribonucleic acid and protein synthesis in whole cells is due to factors involved with the continued assembly of an intact, insoluble cell wall rather than with earlier stages of peptidoglycan synthesis.
Abstract: A method is described in which cells of Streptococcus mutans BHT can be converted to spherical, osmotically fragile protoplasts. Exponential-phase cells were suspended in a solution containing 0.5 M melezitose, and their cell walls were hydrolyzed with mutanolysin (M-1 enzyme). When the resultant protoplasts were incubated in a chemically defined growth medium containing 0.5 M NH4Cl, the protoplast suspensions increased in turbidity, protein, ribonucleic acid, and deoxyribonucleic acid in a balanced fashion. In the presence of benzylpenicillin (5 microgram/ml), balanced growth of protoplasts was indistinguishable from untreated controls. This absence of inhibition of protoplast growth in the presence of benzylpenicillin was apparently not due to inactivation of the antibiotic. When exponential-phase cells of S. mutans BHT were first exposed to 5 microgram of benzyl-penicillin per ml for 1 h and then converted to protoplasts, these protoplasts were also able to grow in chemically defined, osmotically stabilized medium. The ability of wall-free protoplasts to grow and to synthesize ribonucleic acid and protein in the presence of a relatively high concentration of benzylpenicillin contrasts with the previously reported rapid inhibition of ribonucleic acid and protein synthesis in intact streptococci. These data suggest that this secondary inhibition of ribonucleic acid and protein synthesis in whole cells is due to factors involved with the continued assembly of an intact, insoluble cell wall rather than with earlier stages of peptidoglycan synthesis.
TL;DR: When bacteria of a wide variety of species are stressed by high osmolarity in the growth medium, a common response they exhibit is that there is a pronounced elevation in the intracellular concentration of free L-proline, or L-glutamate, or, in a few instances, γ-amino butyric acid.
Abstract: When bacteria of a wide variety of species are stressed by high osmolarity in the growth medium, a common response they exhibit is that there is a pronounced elevation in the intracellular concentration of free L-proline, or L-glutamate, or, in a few instances, γ-amino butyric acid.1 In a number of cases in which the bacteria were grown in the absence of exogenously added amino acids this accumulation was due to the enhanced net rate of synthesis of these metabolites (Tempest et al-, 1970; Brown and Stanley, 1972; Makemson and Hastings, 1979), but in others, in which the cells were grown in a complex media it was not clear whether the increases in concentration were due to the stimulation of the synthesis or uptake of these compounds (Measures, 1975; Koujima et al., 1978). It was shown by Britten and McClure,(1962) that in E. coli the accumulation of L-proline the medium is stimulated in direct proportion to the external osmolarity. An explanation offered for the elevation of the concentration of these compounds is that it serves to balance the intracellular osmolarity against the osmolarity of the growth medium (Brown and Stanley, 1972; Measures, 1975).
TL;DR: Succinylated concanavalin A (ConA), a non-toxic, non-agglutinating derivative of the jack bean lectin ConA inhibits the growth of both normal and SV40-transformed 3T3 cells and can be modulated by the composition of the growth medium.
TL;DR: The mixed cultures exhibited a reciprocal relationship between dilution rate and biomass (and number of bacteria) and the two bacterial types, both Pseudomonas spp.
Abstract: Continuous culture methods were used to isolate bacteria from sediment from Lake Ontario. These mixed cultures were grown in chemostats at different dilution rates and the glucose concentration in the culture vessel, the optical density, the biomass of cells, and the number and types of bacteria present were monitored for at least 80 generations. Two bacterial types, bothPseudomonas spp., were present at all dilution rates in significant quantities. The mixed cultures exhibited a reciprocal relationship between dilution rate and biomass (and number of bacteria). When Hg was added to the growth medium at a concentration of 5 mg 1−1, the bacteria tolerated that concentration at a dilution rate of 0.117 h−1 substantial changes in the population were noted at a concentration of 10 mg 1−1 Hg. One of the isolates from the mixed culture would not grow at 5 or 10 mg 1−1 of Hg in continuous culture at a dilution rate of 0.066 h−1. In the mixed continuous culture the same isolate showed only minimal response to a Hg concentration of 10 mg 1−1.
TL;DR: In this article, the effect of glucose on growth of two Shewan's group II pseudo-monads was studied and the results support previous observations in meat of increased carbohydrate utilization and lowered pH, resulting in suppressed bacterial growth and delayed spoilage.
Abstract: The effect of glucose on growth of two Shewan's group II pseudo-monads was studied. Concentration of 05–10% glucose by weight in nutrient broth effected a decrease in growth lag and growth level. The pH of the growth medium decreased by as much as two units within the first 2 days of incubation. Glucose utilization and acid production increased with increase in glucose concentration. These results support previous observations in meat of increased carbohydrate utilization and lowered pH, resulting in suppressed bacterial growth and delayed spoilage in the presence of added glucose.
Journal Article•
TL;DR: A chemically defined medium and a relatively simple semidefined medium which allow good growth of Corynebacterium pyogenes, a nutritionally fastidious animal pathogen, were described.
Abstract: A chemically defined medium and a relatively simple semidefined medium (SDM) which allow good growth of Corynebacterium pyogenes, a nutritionally fastidious animal pathogen, were described. The SDM contained glucose, trypticase, yeast extract, hemin, minerals, cysteine x HCl, and NaHCO3. To obtain a chemically defined medium, yeast extract in SDM was replaced with a defined mixture of nucleic acid bases, vitamins, amino acids, and trace minerals, and trypticase was replaced by myo-inositol (1 microgram/ml of medium).
TL;DR: Addition of 1 mM L-threonine to the growth medium of Fomes annosus inhibited its glyoxylate deliydrogenase activity and the synthesis of oxalic acid and Malate synthetase was synthesized de novo in the presence of L-thyrene.
Abstract: Addition of 1 mM L-threonine to the growth medium of Fomes annosus inhibited its glyoxylate deliydrogenase activity and the synthesis of oxalic acid. Malate synthetase was synthesized de novo in the presence of L-threonine. Lignosulfonate completely blocked the effect of the amino acid in both glucose or cellobiose-containing medium.
TL;DR: Cells of 30 different strains of oral streptococci were grown in a chemically defined medium supplemented with [14C]glycerol to determine their ability to incorporate the labeled glycerol and found only two strains, the rat-type strains and strains isolated from wild rats, were able to incorporate this nonfermentable substrate.
Abstract: Cells of 30 different strains of oral streptococci were grown in a chemically defined medium supplemented with [14C]glycerol to determine their ability to incorporate the labeled glycerol. Of the five species tested, only two, the rat-type strains (Streptococcus rattus) and strains isolated from wild rats (Streptococcus ferus), were able to incorporate the nonfermentable substrate, glycerol. For those strains capable of incorporating glycerol, the amount incorporated ranged from 0.15 to 0.43% of the cellular dry weight and followed simple saturation kinetics. The amount of glycerol incorporated depended solely on the concentration of glycerol in the growth medium. As a result, cultures exposed to low concentrations of glycerol ceased incorporation of the labeled glycerol before cessation of exponential growth.
TL;DR: Serum proteins adsorbed from the culture medium were detected in Mycoplasma bovis antigens, the number and type of proteins depending on the serum used in the medium, but it appeared that production of specific antibodies to the mycoplasmas was not.
Abstract: Serum proteins adsorbed from the culture medium were detected in Mycoplasma bovis antigens, the number and type of proteins depending on the serum used in the medium. The alpha-globulins cross-reacted with alpha-globulins from different types of sera but the gamma-globulins did not. The removal of non-specific medium antibodies by absorption showed that they affected the gel diffusion and growth precipitation tests, producing cross-reactions between M. bovis and M. bovigenitalium, but that the complement fixation, tube agglutination, and growth inhibition tests were not similarly affected. The presence of serum proteins in the antigens changed their specific reactivity in all the tests. The production of antibodies to serum proteins was increased by the use of an adjuvant, but it appeared that production of specific antibodies to the mycoplasmas was not.
TL;DR: It is suggested that Cd together with hydrogen peroxide may induce oxidative damage to cells if there is not sufficient catalase available to decompose all the hydrogenperoxide formed.
Abstract: The effect of catalase on the toxicity of cadmium (Cd) in Cd-resistant Staphylococcus aureus 3719+ and its plasmid-negative Cd-sensitive variant 3719– was studied. Catalase on a solid medium increased the recovery of Gd-stressed S. aureus 3719– cells, and the addition of catalase into a liquid growth medium resulted in a shortened lag phase of growth especially in S. aureus 3719–. The catalase activity of S. aureus 3719+ cell suspensions was greater than the corresponding activity of S. aureus 3719– cell suspensions. Cd did not influence the activity of beef liver catalase or the catalase production of the bacterial cells. Catalase reduced the toxicity of Cd especially for S. aureus 3719–. The greater catalase production of S. aureus 3719+ might be one factor in its resistance against the toxic effects of Cd. It is suggested that Cd together with hydrogen peroxide may induce oxidative damage to cells if there is not sufficient catalase available to decompose all the hydrogen peroxide formed.
TL;DR: The importance of the cell cycle in modulating the activation of ornithine decarboxylase by asparagine and cAMP is demonstrated.
TL;DR: The influence of the growth medium and the growth temperature on the heat resistance of Citrobacter freundii has been established and stationary growth phase cells are much more heat resistant than logarithmic phase cells, whereas Mg2+-or glucose-starved cells are even slightly more heat stable than stationary phase cells.
Abstract: The influence of the growth medium and the growth temperature on the heat resistance of Citrobacter freundii has been established. Logarithmic growth phase cells grown on rich media have a higher heat resistance than cells of the same phase grown on minimal media. This finding was independent of type of carbon source in the growth medium, but the kind of carbon source has a definite influence on the heat resistance. Logarithmic phase cells grown at 37 degrees C are much more heat stable than cells grown at 20 or 41 degrees C. Stationary growth phase cells are much more heat resistance than logarithmic phase cells, whereas Mg2+ - or glucose-starved cells are even slightly more heat stable than stationary phase cells.
Journal Article•
TL;DR: The composition of the growth medium, especially the presence of divalent cations Mg2+ and Ca2+, affects the susceptibility of bacteria to aminoglycoside antibiotics and the bacteria were twofold or more susceptible in unsupplemented Mueller-Hinton broth than on Mueller- Hinton agar.
Abstract: The composition of the growth medium, especially the presence of divalent cations Mg2+ and Ca2+, affects the susceptibility of bacteria to aminoglycoside antibiotics. Regression lines were calculated for gentamicin and netilmicin with 146 fresh clinical isolates and by the use of the standardized disc diffusion and agar dilution methods on PDM-agar or Mueller-Hinton agar. At the break-point less than or equal to 4 micrograms/ml, denoting susceptibility different zones of inhibition were obtained on the different agar media. When performing regression line analysis from tests with 56 isolates by the disc diffusion method on Mueller-Hinton agar versus MIC's in Mueller-Hinton broth, the resulting lines were different from those when performing the MIC's in agar. Furthermore, the bacteria were twofold or more susceptible in unsupplemented Mueller-Hinton broth than on Mueller-Hinton agar.
Journal Article•
TL;DR: Chick embryo cells, human epithelial cells, and mouse cells in culture were tested for response to elevated levels of proline in the growth medium.
Abstract: Chick embryo cells, human epithelial cells, and mouse cells in culture were tested for response to elevated levels of proline in the growth medium. In none of the cell lines tested was the amount of collagen formed stimulated by addition of excess proline.
Patent•
08 May 1980
TL;DR: In this paper, it has been found that salicylates and closely related compounds will neutralize bacterial growth inhibitors present in the blood of many patients, and the addition of Salicylate to conventional growth medium also provides a reagent for monitoring the antibiotic levels in blood by enabling measurement of the effect of the antibiotic against a standard test organism without interference from the bacterial growth inhibitor present in sera.
Abstract: This invention encompasses methods and reagents for inactivation of bacterial growth inhibitors present in blood, serum or plasma. It has been found that salicylates and closely related compounds will neutralize bacterial growth inhibitors present in the blood of many patients. The addition of salicylate to conventional growth medium also provides a reagent for monitoring the antibiotic levels in blood by enabling measurement of the effect of the antibiotic against a standard test organism without interference from the bacterial growth inhibitor present in sera.