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S A Mostafa

Publications and source records attributed to S A Mostafa.

8 recordsLinked to original sources
PubMed1979

Identity and lipase productivity of a mesophilic actinomycete isolated from Egyptian soil.

1. A mesophilic lipolytic actinomycete was isolated from Egyptian soil and was identified as a strain of Streptomyces flavogriseus. 2. Lipase(s) produced by S. flavogriseus is (at least partly) constitutive in its (their) nature and can be produced in the absence of lipids, however, its production is stimulated in their presence. 3. S. flavogriseus was unable to grow at 40 degrees C or higher temperatures. However, lipase(s) produced at lower temperatures (e.g. 20, 25, 30 and 35 degrees C) were more active at 45 and 55 degrees C. This is probably due to the presence of a heat sensitive lipase inhibitor in the culture filtrate. 4. Optimum conditions for lipase(s) production by S. flavoriseus are pH 6.8, incubation for 48-72 hours at 35 degrees C with 0.8% castor oil as the carbon source in Dox liquid medium supplemented with 0.3% yeast extract. 5. Factors supporting good growth were not always the same as those stimulating lipase(s) production.

Culture Media↗
PubMed1979

L-asparaginase-producing Streptomyces from the soil of Kuwait.

Five actinomycete isolates (all belonged to the genus Streptomyces), capable of producing detectable amounts of L-asparaginase, were isolated from the soil of Kuwait after enrichment. The three most potent enzyme producers were identified as different strains of Streptomyces collinus. Factors affecting enzyme production by the strongest strain were examined. Synthetic media with asparagine as a nitrogen source stimulated more enzyme production than natural media. Starch and asparagine at final concentrations of 1 and 0.8%, respectively, were optimum for enzyme production. An initial pH of 8.5 for the growth medium and an incubation temperature of 28-30 degrees C in a static culture for 6 days stimulated enzyme production by the examined strain of Streptomyces collinus.

Asparaginase↗
PubMed1979

Activity of L-asparaginase in cells of Streptomyces karnatakensis.

Eight isolates capable of producing varying quantities of L-asparaginase and all identified as members of the genus Streptomyces were isolated from the soil and a suitable technique for the assay of intracellular L-asparaginase in actinomycetes was developed. The most potent L-asparaginase producer was identified as a strain of Streptomyces karnatakensis. Static cultures of S. karnatakensis showed maximum enzyme activity with almost maximum growth while shaken cultures exhibited their activity after 48 hours of growth. This phenomenon is discussed in terms of possible feedback mechanism and/or the biosynthesis of certain pigments. L-asparaginase of S. karnatakensis proved to be mostly intracellular and the presence of L-asparagine in the culture medium though, stimulating yet not essential for the enyzme biosynthesis. Cells grown on L-asparagine showed amidase activity with other amides but at a reduced rate.

Amidohydrolases↗
PubMed1979

Production of L-asparaginase by Streptomyces karnatakensis and Streptomyces venezuelae.

Production of L-asparaginase by two soil isolates, identified as S. karnatakensis and S. venezuelae, was investigated under different environmental and nutritional conditions. The presence of carbon sources, other than starch, in the growth medium or amino acids, other than L-asparagine-inhibited the enzyme biosynthesis. L-aspartic inhibited growth and enzyme production, due to a feedback mechanism, and/or lowering the pH value. Both organisms were stimulated to produce more enzyme with increasing concentrations of starch and L-asparagine, however, the optimum starch and L-asparagine concentration depended on the tolerance of the organism to low and high pH, respectively. Aeration stimulated growth, but not enzyme production, and both organisms produced more enzyme in static cultures than in shaken cultures.

Amino Acids↗
PubMed1978

Lipase productivity of a lipolytic strain of Thermoactinomyces vulgaris.

An attempt was made to evaluate the lipase productivity by Thermoactinomyces vulgaris with various nutritional and environmental factors. Results suggest optimum conditions for production, viz. age of inoculum 18 hours, 55 degrees C, pH 6.8, 0.2% yeast extract, specific substrates, and shaken cultures incubated for 24--36 hours. Lipases are induced by corn oil in presence of yeast extract or of certain substitutes; starch could replace these at 55 degrees C. A suggestion is given of a regulatory system of lipase synthesis, involving the supply of starch to initiate growth, allowing induction of lipase by the inductive substrate.

Culture Media↗
PubMed1978

Identity and lipase activity of an isolate of Thermoactinomyces vulgaris.

An actinomycete with thermophilic nature and strong lipolytic activity was isolated by enrichment from an Egyptian soil. It proved to be Thermoactinomyces vulgaris. Variabilities justifying Adansonian systematics were reported and discussed. The potential relation of an occasional drop in successfully resumed activity to an auto-inhibition phenomenon has been notified. Optimum conditions for the activity of the extracellular lipase(s), including stability, suggest the practical importance of the enzyme(s) in the growth filtrates.

Drug Stability↗
PubMed1976

Biological studies on a strain of Escherichia coli B resistant to chlorpromazine.

A strain of Escherichia coli B resistant to chlorpromazine was developed from the sensitive strain. Cells of the resistant strain were different from those of the sensitive strain. Thus, the permeability of the resistant cells (measured by the uptake of 14C-glutamic acid) was not interfered with by Cpz. Moreover, the resistant cells were able to cause detoxification or partial detoxification of the drug.

Chlorpromazine↗