PubMed Health⌕ Search

Biomedical subjects

M S Foda

Publications and source records attributed to M S Foda.

At least 19 recordsLinked to original sources
PubMed2001

Optimization of alpha-galactosidase production in Streptomyces erythrus.

Physiological studies on Streptomyces erythrus NRRL ISP 5517 grown on fourteen different media have revealed that the enzyme was formed and released in the medium with different levels depending upon the type of the medium and the carbon source used. The results indicate that S. erythrus produced the highest level of extracellular and endocellular enzyme when grown in modified Czapek-Dox's medium (containing 2% D-galactose as the only carbon source). The highest levels of enzyme formation was obtained upon using D-galactose (9.94 Units/ml and 2.92 Units/ml), raffinose (8.87 Units/ml and 2.69 Units/ml) or melibiose (8.14 Units/ml and 2.52 Units/ml) at a final concentration of 2% as inducers for extra- and endocellular enzyme, respectively. With respect to nitrogen sources tested, sodium nitrate produced the highest level of alpha-galactosidase in both fractions optimally at 2.0 g/l. Studies revealed that the extracellular enzyme levels were produced optimally at initial pH in culture of 7.0 and air:medium ratio in flasks corresponding to 1:5 and after 5 days of incubation at 30 degrees C. On testing the effect of the addition of eight leguminous seeds powders (at a final concentration of 2%), it was found that soybean powder gave the highest induction effect. The addition of sodium nitrate at a concentration of 2 g/l to Dox's soybean medium, the adjustment of initial pH value of the medium to 7.0 and the air:medium ratio in flasks to 1:5 for an incubation period of 4 days produced the highest level of extracellular alpha-galactosidase.

Culture Media↗
PubMed1983

Utilization of fodder yeast and agro-industrial by-products in production of spores and biologically - active endotoxins from Bacillus thuringiensis.

A number of newly-devised fermentation media were evaluated with respect to their ability to support sporulation and biosynthesis of endotoxins by strains of Bacillus thuringiensis that are biologically active against Spodoptera littoralis, Heliothis armigera, and Spodoptera exigua. Fodder yeast from dried cells of Saccharomyces cerevisiae could be used as a complete mono-component medium for production of highly active spore-delta-endotoxin complexes from B. thur., vars. entomocidus, kurstaki and galleriae. Highest sporulation titers were obtained at 2% fodder yeast concentration with endotoxin yields ranging between 7 to 9 grams per liter of medium. Ground horse beans and kidney bean seeds could also be used successfully as complete media for sporulation and endotoxin production. Extracts of potato tubers and sweet potato roots were efficient media for active endotoxin production from B. thur. var. kurstaki, although the obtained yields were much lower than those produced in fodder yeast media. The utilization of fish meal, cotton seed meal, and residues of chicken from the slaughter-house as media for the production of endotoxins active against Spodoptera littoralis, was not successful. On the other hand, minced citrus peels, ground seeds of dates, and wheat bran could be successfully used in combination with fodder yeast as media for production of endotoxins, active against Heliothis armigera and Spodoptera exigua. Re-utilization of culture supernatants in a second fermentation cycle after supplementation with some nutrients gave promising results with some of the strains tested. The data obtained are discussed in view of their feasibility of application.

Bacillus thuringiensis↗
PubMed1980

Formation and properties of L-glutaminase and L-asparaginase activities in Pichia polymorpha.

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.

Ascomycota↗
PubMed1979

Distribution of extracellular proteolytic activities among various yeast.

A general screening test for extracellular proteolytic activities was carried out on 24 cultures belonging to 14 genera of yeasts. The screening was performed using gelatine and casein as sole nitrogen sources under two sets of pH conditions. Potent proteolytic yeast cultures belonging to both Ascomycetes and Deuteromycetes were detected, particularly certain members of the genera Endomycopsis, Metschnikowia, Debaromyces, Rhodotorula, and Candida spec. Most detected proteolytic cultures were active on both casein and gelatine substrates, possibly suggesting one enzyme system in each case with wide substrate specificity. Physiological studies revealed that maximum proteolysis occurred after 3--4 days of aerobic incubation and that some strains were able to hydrolyze egg albumin.

Caseins↗
PubMed1979

Screening studies of yeasts capable of utilizing petroleum fractions.

In these studies, 23 yeast cultures belonging to 10 genera of ascosporogenous, ballistosporogenous, and asporogenous yeasts, were screened with respect to their abilities of hydrocarbon utilization in synthetic media. Thus, kerosene, n-hexadecane, and wax distillate were compared as sole carbon sources in 2% final concentration. Kerosene exhibited marked inhibition on the growth of the majority of the strains, whereas active growth was observed with Debaryomyces vanrijii and many species of the genus Candida in media with n-hexadecane or wax distillate as sole source of carbon. In addition, some cultures belonging to the genera Sporobolomyces, Hansenula, Cryptococcus, and Trigonopsis could utilize some of these substrates, but to a lesser extent. Highest yield of cells and protein was obtained with Candida lipolytica NRRL 1094 in n-hexadecane medium, supplied with 0.03% yeast extract and trace element solutions. The results are discussed with respect to the possibilities of using new yeast genera, with special reference to the genus Debaryomyces, in microbiol protein production.

Alkanes↗
PubMed1978

Purification and properties of rennin-like enzyme from Aspergillus ochraceus.

An active milk-clotting enzyme was purified some 40-fold from culture supernatant of Aspergillus ochraceus. The purification steps included ammonium sulfate precipitation, G-100 Sephadex gel filtration, and ion exchange chromatography, using DEAE Cellulose column. The enzyme exhibited milk-clotting activity and proteolytic behaviour, an optimum at pH 6.0 and in the range of 7--8.5, respectively. The purified enzyme was actively proteolytic against casein, haemoglobin, and bovine serum albumin at pH 8. The milk-clotting activity was greatly enhanced by manganous ions and by increasing concentrations of calcium chloride. Copper, zinc, and ammonium ions were potent inhibitors of the milk-curdling activity of the purified enzyme. Significant inhibition was also noted with sodium chloride at concentrations of 3% or more. Under the specified reaction condition, maximum rate of proteolysis against casein was obtained at 0.4% substrate concentration, whereas the milk-clotting time was linear proportional to dry skim milk concentration in the range of 8 to 24%. The results are discussed in comparison with other microbial milk-clotting enzymes, and limitations of applicability are also presented.

Animals↗
PubMed1976

Kinetics and properties of L-glutaminase and L-asparaginase activities of Pseudomonas ovalis.

Pseudomonas ovalis produces L-glutaminase and L-asparaginase activities simultaneously upon induction by L-glutamine or L-asparagin in the growth medium. Both activities are confined to the cell during active growth and are not released into the medium. The apparent Km values are 1.4 X 10(-2) M and 6 X 10(-3) M for L-glutamine and L-asparagine substrates, respectively. Induction of both activities is substantially favoured in media with initial pH values higher than 7. In buffered yeast extract L-asparagine medium, significant amounts of L-glutaminase and L-asparaginase activities appeared towards the end of the exponential phase and along the stationary phase. The process of enzyme formation showed a firm link to the cell active growth, as evidenced by the use of growth inhibitors.

Asparaginase↗
PubMed1976

Production of Candida utilis on slop by-product of fermentation industries.

The slop (vinas) liquor, a major by-product a alcohol fermentation industries, has been used as growth medium for production of the torula yeast, Candida utilis. Supplementation of the slop with 0.2% ammonium sulphate and 1% to 5% molasses improved the cell yield significantly. The crude slop gave better results than the diluted or centrifuged liquors. Under optimal conditions, more than 15 grams of yeast were obtained on dry weight basis. The application feasibility of these results is presented.

Alcoholic Beverages↗
PubMed1976

Production physiology and properties of a novel fungal fibrinolytic enzyme.

A potent extracellular fibrinolytic enzyme was obtained from cultures of the imperfect fungus Fusarium semitectum under certain growth conditions. Nitrate addition to cultures increased enzyme production. The enzyme showed a versatile proteolytic activity against several protein substrates including casein, gelatin, haemoglobin, bovine serum albumin, and fibrin from both buffalo and human sources. Optimal fibrinolysis occurred at pH values around 7.0. The fibrinolytic activity exhibited marked heat stability in enzyme samples heated at 60 degrees C, and retained more than 40% of its activity in samples heated to 100 degrees C for 10 min. Fibrinolysis proceeded optimally in the temperature range between 50--60 degrees C. Copper ions significantly activated the enzyme. Other biochemical properties are also reported.

Caseins↗
PubMed1976

Physiology and characterization of a fungal milk-clotting enzyme from Aspergillus flavus.

Aspergillus flavus produced extracellularly an active rennin-like enzyme when grown aerobically in whey media. The enzyme was detected at early stages of growth reaching a maximum after three to four days at 25 degrees. The activity was destroyed by heating to temperatures higher than 50 degrees, whereas the presence of skim milk during heating preserved the enzyme activity, at least, up to 70 degrees. Calcium chloride significantly stimulated the milk-clotting activity up to 1% final concentration. The clotting time was inversely proportional to protein concentration in the range 0.2-0.6 mg/ml and the enzyme exhibited marked stability when stored at 37 degrees at pH 6.

Animals↗
PubMed1971

Effect of sodium chloride and pH on enterotoxin C production.

Growth and production of enterotoxin C by Staphylococcus aureus strain 137 in 3% + 3% protein hydrolysate powder N-Z Amine NAK broths with 0 to 12% NaCl and an initial pH of 4.00 to 9.83 were studied during an 8-day incubation period at 37 C. Growth was initiated at pH values as low as 4.00 and as high as 9.83 at 0% salt level as long as the inoculum contained at least 10(8) cells per ml. Rate of growth decreased as the NaCl concentration was increased gradually to 12%. Enterotoxin C was produced in broths inoculated with 10(8) cells per ml and above and having initial pH ranges of 4.00 to 9.83, 4.40 to 9.43, 4.50 to 8.55 and respective NaCl concentrations of 0, 4, and 8%. In the presence of 10% NaCl, the pH range supporting enterotoxin C production was 5.45 to 7.30 for an inoculum level of 10(8) cells per ml and 6.38 to 7.30 for 3.6 x 10(6) cells per ml. In repeated experiments in which the inoculum contained 10(8) cells per ml, we failed to demonstrate enterotoxin C production in broths with 12% NaCl and a pH range of 4.50 to 8.55 and concentrated up to 14 times. The effect of NaCl on enterotoxin C production followed the same pattern as its effect on enterotoxin B production. As the concentration of NaCl increased from 0 to 10%, yields of enterotoxin B and C decreased to undetectable amounts.

Culture Media↗