Showing papers on "Growth medium published in 1974"

Amino acid uptake by marine phytoplankters1,2

Abstract: Axenic cultures of 25 species of unicellular marine algae were tested for their ability to utilize nine common amino acids, supplied at high concentrations in batch culture, as a nitrogen source; most species were able to use several amino acids, although growth was often slower than on nitrate nitrogen. The algae were also tested for their ability to t,ake up ‘“C-labclcd amino acids supplied at low, natural concentrations. In most cases, species that could grow on an amino acid at high concentration in culture could also take up amino acids at low concentrations. Uptake rates were higher in cells that had been deprived of nitrogen during growth. In some cases, uptake rates at low concentrations-if sustained-would bc sufficient to support moderate growth rates. The ability to accumulate amino acids from dilute solution occurs in many phytoplankters, particularly in spccics that normally occur in inshore and littoral habitats. The growth of phytoplankton in the sea often appears to be controlled by the availability of nitrogen (Dugdalc and Goering 1967). Ambient concentrations, uptake rates, assimilation and metabolism of the inorganic forms of nitrogen-nitrate and ammonia-have been studied to explore the relation between nitrogen nutrition and phytoplankton ecology, but the role of organic nitrogen has received much less attention. We wish to focus attention on the potential significance of amino acids as a nitrogen source for phytoplankters under natural conditions. Concentrations of dissolved free amino acids are usually in the range of 0.2 to 2.0 pg-atoms N liter-” for total amino acids (Bohling 1970; Clark et al. 1972; Riley and Segar 1970). A number of phytoplankters have been grown axenically with various organic sources of nitrogen, including amino acids ( Guillard 1963). However, in such growth experiments nitrogenous compounds are usually 1,000 times more concentrated than in natural waters. The ability of phytoplankton to use amino acids as nitrogen sources at high concentrations does not necessarily provide any insight into their potential significance at low concentrations. ‘This work was supported by NSF Grant GA 33904x. ’ N. Kaji and V. Cooke provided technical assistance and help in manuscript preparation. D. Staley assisted in the uptake measurements. To study growth directly in laboratory culture at natural concentrations it would be necessary to maintain axenic conditions in a large volume, to supply nutrients continuously to mimic a steady state, and to devise methods of assessing slow growth in a sparse suspension of cells. We have chosen to approach the issue by studying the short-tclm rate of amino acid uptake by phytoplankters from dilute solution in conjunction with growth studies at higher concentrations. Analysis of the kinetics of uptake allows estimation of entry rates under natural conditions, while growth experiments establish the substrate as a metabolically adequate nutrient. We have demonstrated uptake of amino acids from low concentrations and their oxidation and assimilation into synthetic pathways by the unicellular algae Plutymonas subcorcliformis and Nitxschiu oualis (e.g. North and Stephens 1967, 1969, and later). Amino acid transport systems in phytoplankters are extremely labile. Restriction of nitrogen availability in the culture decreases the nitrogen content of the cells and slows their growth rate; it also greatly accelerates the rate of amino acid uptake. In some cases, no uptake is observed until nitrogen in the growth medium is restricted. The possible contribution of amino acids to the nitrogen required for growth appears to depend on the nutritional history of the cells. Amino acids supplied at low levels LIMNOLOGY AND OCEANOGRAPHY 249 MARC11 1974, V. 19(2)

Isolation and Characterization of an Escherichia coli ruv Mutant Which Forms Nonseptate Filaments After Low Doses of Ultraviolet Light Irradiation

Abstract: Two ultraviolet light (UV)-sensitive mutants have been isolated from Escherichia coli K-12. These mutants, designated RuvA(-) and RuvB(-), were controlled by a gene located close to the his gene on the chromosome map. They were sensitive to UV (10- to 20-fold increase) and slightly sensitive to gamma rays (3-fold increase). Host cell reactivation, UV reactivation and genetic recombination were normal in these mutants. Irradiation of the mutants with UV resulted in the production of single-strand breaks in deoxyribonucleic acid, which was repaired upon incubation in a growth medium. After UV irradiation, these mutants resumed deoxyribonucleic acid synthesis at a normal rate, as did the parent wild-type bacteria, and formed nonseptate, multinucleate filaments. From these results we concluded that the mutants have some defect in cell division after low doses of UV irradiation, similar to the lon(-) or fil(+) mutant of E. coli. The ruv locus was divided further into ruvA and ruvB with respect to nalidixic acid sensitivity and the effect of minimal agar or pantoyl lactone on survival of the UV-irradiated cell. The ruvB(-)mutant was more sensitive to nalidixic acid than were ruvA(-) and the parent strain. There was a great increase in the surviving fraction of the UV-irradiated ruvB(-) mutant when it was plated on minimal agar or L agar containing pantoyl lactone. No such increase in survival was observed in the ruvA(-) mutant.

Microbial Water Relations: Features of the Intracellular Composition of Sugar-Tolerant Yeasts

Abstract: Several factors contributed to differences in intracellular composition between sugar-tolerant (osmophilic) and nontolerant species of yeast. One such factor was the difference in accumulation of those nonelectrolytes whose uptake was not dominated by vigorous metabolism. In such cases (lactose and glycerol), the sugar-tolerant species had a much lower capacity for the solute than did the nontolerant species. Sucrose uptake was consistently different between all sugar-tolerant strains on the one hand and all nontolerant strains on the other. The difference was attributable in part to metabolism of sucrose by the nontolerant yeasts. The major difference between the two types of yeast, however, was the presence of one or more polyhydric alcohols at high concentrations within each of the sugar-tolerant strains but none of the nontolerant strains. In most cases the major polyol was arabitol. The solute concentration (and, hence, water availability) of the growth medium affected both the amount of arabitol produced by Saccharomyces rouxii and the proportion retained by the yeast after brief washing with water at 0 C. When the yeast was suspended in a buffer at 30 C, the polyol leaked out at a slow, constant, reproducible rate. The polyene antibiotic amphotericin B caused rapid release of polyol by the yeast, the rate being proportional to amphotericin concentration. Contact of the yeast with glucose (1 mM) caused an extremely rapid ejection of polyol which lasted less than 40 s. Some implications of these results are discussed, as is the role of the polyol as a compatible solute in determining the water relations of the yeast.

Some cultural conditions that control biosynthesis of lipid and aflatoxin by Aspergillus parasiticus.

Abstract: Synthesis of total lipid and aflatoxin by Aspergillus parasiticus as affected by various concentrations of glucose and nitrogen in a defined medium and by different incubation temperatures was studied. Maximal yields of lipid and aflatoxin were obtained with 30% glucose, whereas mold growth, expressed as dry weight, was maximal when the medium contained 10% glucose. Maximal mold growth occurred when the medium contained 3% (NH4)2SO4; however, 1% (NH4)2SO4 favored maximum accumulation of lipid and aflatoxin. Growth of mold and synthesis of lipid and toxin also varied with the incubation temperature. Maximal mold growth occurred at 35 C, whereas most toxin appeared at 25 C. Maximal production of lipid occurred at 25 and 35 C but production was more rapid at 35 C. Essentially all glucose in the medium (5% initially) was utilized in 3 days at 25 and 35 C but not in 7 days at 15 and 45 C. Patterns for formation of lipid and aflatoxin were similar at 15 and 25 C when a complete growth medium was used and at 28 C when the substrate contained various concentrations of glucose or (NH4)2SO4. They were dissimilar when the mold grew at 35 or 45 C. At these temperatures lipid was produced preferentially and only small amounts of aflatoxin appeared.

The effect of growth medium of filament production in Candida albicans.

Abstract: Five liquid media were tested for their ability to promote filamentation in Candida albicans. Three isolates, including one atypical variant, all developed mycelium in the early stages of growth. The proportion of mycelium produced was highest in the complex media with slightly alkaline pH values (7·5 to 8·6). The time at which mycelial development reached a peak and gave way to the production of budding yeast cells was directly proportional to the minimum doubling time of C. albicans in each medium. The principal effect of the medium was initially to induce filamentation in a greater or lesser number of blastospores.

Effect of Glucose on Thermal Injury of Yeast that may Define the Maximum Temperature of Growth

Abstract: SUMMARY: Anaerobically grown yeast, suspended in glucose solution, leaked cell contents non-selectively. The rate of leakage increased with temperature but reached a maximum rate close to the maximum temperature of growth (T max) of the yeast. The total leakage induced by glucose was much greater above T max than below it, because above T max the yeast lost the ability to take up released material. The rate of uptake of 14C-labelled amino acids was also substantially slowed above T max-Yeast heat-stressed in the presence of glucose lost the ability to establish and maintain a concentration gradient of sorbose, and simultaneously ATPase activity could be measured, all characteristics of yeast with a ruptured cytoplasmic membrane. These effects were uniquely caused by utilizable sugars, were essentially independent of sugar concentration and could be partially inhibited by Ca2+ or inhibitors that prevent sugar utilization. Yeast heated above T max in water suspension was essentially undamaged as determined by the tests used, but if glucose was subsequently added below T max an effect of heat damage could be demonstrated. We conclude that one factor that determines the T max of a yeast is the temperature sensitivity of the cytoplasmic membrane in the presence of the utilizable sugar of the growth medium.

Effect of the Osmotic Pressure of the Growth Medium on fabB Mutants of Escherichia coli

Abstract: Temperature-sensitive, unsaturated fatty acid (fabB) auxotrophs of Escherichia coli can grow at the restrictive temperature in the absence of unsaturated fatty acid in a medium with a high osmotic pressure. If a mutant culture was starved for unsaturated fatty acids and harvested just before the lysis started, the fatty acid composition of the cells was the same as that of cells grown until late log phase in a high-osmotic medium. Evidence is presented that the in vivo unsaturated fatty acid biosynthesis is significantly increased in a high osmotic medium. The increase is probably due to a partial activation of the temperature-sensitive fabB product. Besides the stimulation of the temperature-sensitive fabB product, a minimal osmotic pressure of the medium appeared to be necessary to allow growth of cells containing lipids with a changed fatty acid composition. fabA mutants are unable to grow in a high-osmotic medium in the absence of unsaturated fatty acids. No increase in the in vivo unsaturated fatty acid biosynthesis could be detected in the temperature-sensitive fabA mutants.

Degradation of sucrose by whole cells and plaque of Actinomyces naeslundii.

Abstract: Whole cells of Actinomyces naeslundii ATCC 12104, either in a dispersed form or in the form of plaque, enzymatically degraded sucrose to glucose and fructose. Washed whole cells expressed β-fructofuranosidase specificity and hydrolyzed sucrose to essentially equimolar quantities of glucose and fructose. The cells readily hydrolyzed sucrose, raffinose, and Actinomyces viscosus or Aerobacter levanicum levan, but did not degrade melezitose, maltose, α-methyl-d-glucoside, melibiose, glucose-1-phosphate, or dextran T-500. Sucrose degradation occurred at a temperature optimum of 37 to 45 C and at a pH optimum of 5.7 to 6.0. The Km for sucrose was 0.05 M. Sucrose or raffinose in the growth medium resulted in cells with a specific activity that was fivefold greater than that of cells grown in medium supplemented with either glucose, fructose, maltose, lactose, or glucose and fructose, or grown in unsupplemented medium. Addition of sucrose to log-phase cells growing in glucose also increased the specific activity. Degradation of sucrose by whole cells in the form of plaque also occurred, but 6% less free fructose than free glucose was recovered. Sucrose-dependent synthesis of extracellular levan or glucan by whole cells or plaque could not be demonstrated. The ability of A. naeslundii to degrade sucrose and levan may be related to the pathogenic potential of this bacterium in plaque-associated oral diseases.

The effect of cultural conditions on the susceptibility of staphylococci to killing by the cationic proteins from rabbit polymorphonuclear leucocytes.

Abstract: Seventeen strains of Staph. aureus and 12 strains of Staph. epidermidis were tested for their susceptibility to killing by the cationic proteins from rabbit polymorphs, when cultured under different conditions. The resistance of the V strain of Staph. aureus of Adlam, Pearce and Smith (1970a,b) was confirmed and shown to be independent of the conditions of growth. All other strains were more or less susceptible when grown in brain heart infusion broth or proteose peptone broth, with or without lactate, but were highly resistant when grown in these media supplemented with glucose. The resistance was not due to changes in pH. Susceptibility was restored when the organisms were again grown on broth media without glucose. Since preliminary observations indicate that the cationic proteins inhibit the action of NADH oxidase, it is suggested that the organisms are susceptible only when growth depends on aerobic respiration. If the culture contains an energy source such as glucose which can be utilized by an alternative pathway, the organism loses its susceptibility. After culture in a chemically defined medium, most strains of Staph. aureus were resistant and most strains of Staph. epidermidis were susceptible to the cationic proteins. The resistance of Staph. aureus was not removed by adding vitamins, purine and pyrimidine bases or serum (from clotted cell free plasma) to the growth medium but was abolished by proteose peptone. The active fraction in proteose peptone was partially excluded by Sephadex G-25, but not by G-10. Some of its activity was lost on acid hydrolysis. The cause of the difference in susceptibility between Staph. aureus and Staph. epidermidis after growth in a chemically defined medium or in this medium supplemented with serum is not known. It may be related to the known difference between these organisms in their ability to grow in serum from clotted blood, which contains similar cationic proteins.

[42] Isolation, solubilization, and reconstitution of mycoplasma membranes

Abstract: Publisher Summary The mycoplasmas are minute prokaryotic organisms that differ from bacteria in having neither a cell wall nor mesosomes. Thus the plasma membrane is their only membranous structure. Moreover, because in the absence of appropriate biosynthetic pathways they depend on the external supply of many nutrients, including fatty acids, glycerol, and cholesterol, the composition of their membrane lipids may be controlled by regulating the supply of lipid precursors in the growth medium. Mycoplasmas are cultivated in complex media containing serum or serum components, heart infusion, peptone, and yeast extract. Only a few species have so far been cultivated in defined or semi-defined media.

Oligopeptides as sources of indispensable amino acids for mammalian cells in culture.

Abstract: The ability of peptides containing lysine to satisfy the lysine requirement of mammalian cells in a medium otherwise free of this indispensable amino acid was investigated. In contrast to bacteria, which are unable to utilize pentalysine and higher homologs, mammalian cells are able to grow in the presence of di- to decalysine. For each oligopeptide, the response was proportional to concentration within a limited range. The duration of the lag and logarithmic growth phases was directly proportional to peptide size, and the growth rate decreased with peptide size. Utilization of decalysine was not accompanied by the accumulation of smaller oligomers in the medium or in the trichloroacetic acid soluble fraction of a cell lysate. However, enzymes capable of hydrolyzing decalysine were clearly demonstrable inside the cells and in the spent culture medium. It is concluded that the rate of uptake is inversely proportional to peptide size and is growth rate-limiting, and that free lysine produced by intracellular peptidases is used as quickly as it is formed. Although the serum proteins used to supplement the growth medium contained more lysine in peptide linkage than is needed by the cells, this lysine is not available to the cells in significant amount.

The single cell suspension culture of the licorice plant, Glycyrrhiza glabra

Abstract: The cells of the licorice plant, Glycyrrhiza glabra, were cultured as a “single cell” suspension. Their growth behaviour, yield and metabolic products were studied. The suspension cultures of the licorice plant were established from the friable calluses obtained from the radicle, cotyledon and hypocotyl of the germinated seeds. The single cells, regardless of their origin showed little difference in cell size and morphology. After an apparent adjustment to the medium, the cells required 11-13 days of incubation to reach the maximum cell yield of 1.2 gm dry weight/100 ml medium. During the growth period, the pH of the growth medium decreased from pH 5.6 to pH 4.7 in the first few days and then increased to about pH 6. A level of 10% coconut milk in PRL-4-CM medium was found to support good cell growth; the lower the coconut milk level, the longer the growth period required to reach the maximum cell yield. It was also found that 0.5% yeast extract could be used to replace the coconut milk in the PRL-4-CCM medium. The metabolites detected and examined in the licorice single cell suspension culture included a volatile apple aroma, a polysaccharide pectin-like material, steroids and triterpenoids. The analyses of the licorice cell volatile apple aroma found under anaerobic conditions indicated the presence of ethanol and come related esters. The monosaccharides found in the pectin-like polysaccharide hydrolysate were glucose, fructose, galactose, arabinose, xylose, galacturonic acid and glucuronic acid. The pectin-like material in the cell preparations reached a maximum yield of 1.1 mg/ml after one month of growth. Glycyrrhizinic acid, the common licorice constituent found in the root, could not be detected in the suspension cultures. However, several other related compounds which gave typical steroid and triterpenoid reactions were found. Sorbitol, glucose and fructose were found to be the three major sugars which accumulated in free form in the licorice cell medium.

Cell Division, Macromolecular Synthesis and Morphology Dependent on the State of the Envelope in a Mutant of Klebsiella pneumoniae

Abstract: SUMMARY: Mutant Mir M7 of Klebsiella pneumoniae exhibits a pH-dependent morphological interconversion; growing cells are rod-shaped at pH 5.5 but round at pH 7. Round cells cannot divide or make DNA, RNA and proteins at pH 5.5. At this pH, cell division and DNA synthesis are resumed either when substances such as Mg2+, Na+, sucrose or spermine are added to the growth medium or immediately after the appearance of a normal rod morphology. Round cells, but not rods or the wild type, are lysed by low concentrations of detergents and are killed by DL-amino acids. Their growth rate is not improved by vigorous aeration and they make spheroplasts at an incubation temperature of 8 °C. This behaviour is the opposite of that of rods and the original strain. The transition from rods to round cells at pH 7 does not occur when cell division is inhibited by penicillin. Round cells must divide several times in an acid medium to give regular and uniform rods. The possibility of a different state of the membrane in round and rod-shaped cells and a dependence of cell division, DNA synthesis, and morphology on the state of the membrane are discussed.

Effect of High Sodium Chloride Concentrations in the Growth Medium on the Activity of Glucose-6-phosphate Dehydrogenase from Pea Roots

Abstract: The experiments reported in this paper examined discrepant results, obtained in earlier investigations, concerning the effects of NaCl in the growth medium of vascular plants on the specific activity of glucose-6-phosphate dehydrogenase (EC 1.1.1.49) extracted from the plants. NaCl at 120 mM or higher concentrations increased the specific activity of the enzyme in extracts from roots of germinating peas. However, this effect of NaCl was only clearly expressed when 0.1M phosphate was the buffer used to extract the enzyme. When organic buffers were used the observed increase in enzyme activity was either much smaller or absent. Increases in specific activity of glucose-6-phosphate dehydrogenase were only found in extracts from roots that showed severely retarded growth and some brown discoloration. No increase in activity was found either when 120 mM NaCl was added to the growth medium after seedling establishment, or if seeds were germinated in 75 mM NaCl. These observations account for the discrepancies reported in the literature.

Interferon Production and Resistance to Viral Infection Induced by Poly I · Poly C in Chick Embryo Cells

Abstract: Two different growth media, one based on Eagle's minimum essential medium (MEM) and the other on Earle's balanced salt solution–lactalbumin hydrolysate–yeast extract (YLE), were used for growing primary chick embryo cells (CEC), and resistance to viral infection and interferon production induced by polyinosinic-polycytidylic acid (poly I·poly C) were compared. In CEC grown in Eagle's MEM, treatment with poly I·poly C at a concentration as low as 1.0 ng/ml was sufficient to induce a detectable resistance to infection with vesicular stomatitis virus (VSV), while more than 300-fold concentrated poly I·poly C was required to induce a similar resistance when the cells were grown in YLE. The cells grown in YLE did not produce an appreciable amount of interferon, whereas a significantly higher level of interferon was produced by the cells grown in Eagle's MEM. A similar phenomenon was observed in the interferon production of chick embryo cells treated with ultraviolet light (UV)-irradiated Newcastle disease virus (NDV) and in the induction of resistance to vaccinia virus in cells treated with poly I·poly C. It was found that the response of cells, bathing in one growth medium, to poly I·poly C was not affected by replacing it with the other at the same time with the addition of poly I·poly C, and that the response of CEC was strongly dependent upon the medium used for cultivation. These facts suggested that the observed difference in the response of cells to poly I·poly C was not due to a direct interaction between the inducer and medium components but to the physiological state of CEC established during their growth. Which component of YLE was responsible for such a lowered response of cells to poly I·poly C was also examined, and the marked reduction of PDD50 by the replacement of lactalbumin hydrolysate of YLE with amino acids and the increase of PDD50 by addition of lactalbumin hydrolysate to MEM suggested that lactalbumin hydrolysate might play an important role in this phenomenon.

Endocytosis and the adaptive acid hydrolases in Tetrahymena pyriformis GL.

Abstract: Endocytosis of yeast cells by Tetrahymena pyriformis GL for a period of 2.5 h produced changes in cellular acid hydrolases. Acid phosphatase, acid deoxyribonuclease and acid proteinase activities were markedly increased, whereas there was a decrease in acid ribonuclease activity and little change in α-glucosidase activity. These alterations do not appear to be due to any alteration in the rates of secretion of these enzymes into the milieu. Evidence is presented that the cellular enzyme increases found upon endocytosis of yeast reflect changes in lysosomal enzymes, because it was shown that the acid phosphatase activity increase resulted in an increased amount of latent enzyme within the cell. The results also support the idea that there are at least 3 distinct populations of lysosomes, in addition to phagolysosomes, present in Tetrahymena pyriformis GL, with different modes of formation. There appears to be a large excess of lysosomes, uncombined with phagosomes, present in these fed cells since latency averaged 66% in broken-cell preparations which contained very few intact phagolysosomes. The phagolysosomal acid phophatase activity cannot account for more than 34% of that present in the cell. The endocytosis of yeast in the presence of growth medium resulted in a marked drop in the rate of cell division as compared to cells growing in the growth medium alone. The results are discussed.

Cell lines and virus culture

Abstract: A method for producing a human embryo liver cell line which comprises disaggregating human embryo liver, suspending the cells in a growth medium, replacing this with fresh medium if it becomes acid, and allowing a confluent sheet of spindle-shaped cells of the cell line to form. The cells of the cell line, which are designated by A.T.C.C. No. CL99, may be sub-cultured and may be used as the basis of a cell-culture system for the culturing of mammalian cells in tissue culture. Viruses may be cultivated in a culture system based on cells of the cell line to provide antigenic material for the preparation of vaccines.

Anti-tumour product of bacterial origin

Abstract: Wild strain Lechien of the organism Clostridium perfringens is attenuated with nitrosoguanidine. To produce an anti-tumor preparation, the attenuated organism is grown first on a growth medium then on a sporulation medium and the resulting growth recovered as a bacillary suspension, a spore suspension, or culture filtrates. The preparation in any of these forms has the property of inhibiting the growth of Ehrlich's solid tumor, of reducing the tumor size, and lengthening the survival time of the host.

Some aspects of catalase induction in baker's yeast (Saccharomyces cerevisiae)

Abstract: Yeasts grown in anaerobic liquid media produced catalase in response to the presence of H2O2 in the growth medium. The fact that some of the induced enzyme was active at the cell surface, bound either to the cell wall or cell-surface membrane, eliminated the need to crush cells in order to release the enzyme complement. Instead, catalase production was monitored by using H2O2-reagent strips to detect changes in the level of H2O2, in the growth medium. In addition, catalase induction in yeasts was found to be temperature-sensitive. It is suggested that biology teachers in schools might find the following experiments useful for demonstrating essential features of substrate-induced enzyme synthesis, based on the Jacob-Monod model, and for showing that the activity of certain genes can be modified by environmental temperature.

Growth of the peritrich Opercularia coarctata in axenic culture.

Abstract: SYNOPSIS A synthetic medium for Opercularia coarctata was developed that contains 20 amino acids, 10 vitamins, an 8-component balanced salt solution, Fe2(SO4)3·(NH4)2SO4·24H2O, Tween 80, stigmasterol, a 7-component nucleic acid mixture, phenol red as an indicator, and 2,500 U.S.P. units/ml penicillin to maintain sterility. This medium supported axenic survival for 96 hr. Multiple supplements of thioctic acid, niacin, niacinamide, inositol, PABA, oleic acid, and Fe(NO3)2·9H2O instead of Fe2(SO4)3·(NH4)2SO4·24H2O coverted the survival medium into a growth medium, which permitted 36–45 days continuous cultivation of populations in excess of 4 × 103 cells/3.0 ml final volume. Five generations were produced during the 48 hr logarithmic growth period. Serial transfers at 72 hr and during periods of greatest cell density produced a maximum of 8 generations 96 hr after initiation but the medium failed to sustain growth through more than 6 serial transfers. Extension of this investigation to formulating a minimal axenic medium is discussed.

Growth of Novikoff hepatoma cells in the presence of long-chain fatty acids.

Abstract: SummaryThe growth characteristics of Novikoff hepatoma cells growing in culture can be differentially altered by the addition of long-chain fatty acids to the growth medium. The greatest reduction in growth rate was obtained by adding sodium stearate to the growth medium and the least was when sodium oleate was added; the effect of sodium petroselenate was intermediate. The addition of the methyl ester to the growth medium caused a smaller reduction in cell proliferation than the corresponding sodium salt of the fatty acid.When each of the long-chain acids in their triglyceride form was added to the growth medium, there was no reduction in the growth rate of the cells even at very high concentrations. Possible reasons for these changes are discussed.This investigation was supported by Public Health Service Grant HL 08214 from the Program Projects Branch, Extramural Programs, National Heart and Lung Institute, Grant CA 14003 of the National Cancer Institute and The Hormel Foundation.

Extracellular proteases from soil actinomycetes. 3. Effect of growth medium and temperature on the protease production by an actinomycete, isolated from peat.

Abstract: Summary The ability of an actinomycete, isolated from peat (labelled A IV 17), to produce extracellular protease in various low-cost media has been examined. It has been found that for protease production with the strain A IV 17 glucose can be replaced as energy source by xylose or glycerol. Horn meal, representing a cheap slaughtery waste product, has been found to be a favourable nitrogen source for the production of A IV 17-protease. With small changes in the composition of the medium, used for protease production, the productivity of the organism in question has been more than doubled, as compared with the protease yields achieved in the skim-milk medium, originally used for the screening of extracellular proteases produced by actinomycetes, isolated from soil.