A. Abou-Zeid

Fermentative production of citric acid by yeasts

Abstract Different strains of yeast were grown on different fermentation media for citric acid production. Candida lipolytica (Y-1095) produced a higher yield of citric acid than the other experimental yeasts. The best incubation period for the production of citric acid was found to be 144 h. Glycerol and glucose were the best carbon sources for citric acid production by Candida lipolytica (Y-1095). The optimum concentrations of glycerol and glucose were 80 and 120 g litre −1 , respectively. The best organic and inorganic nitrogen sources were Hochest dry corn-steep, yeast extract, NH 4 Cl and (NH 4 ) 2 SO 4 . The concentration of yeast extract and corn-steep powder (Hochest) which supported the greatest production of citric acid was 1·0 g litre −1 , while the best concentrations of (NH 4 ) 2 SO 4 and NH 4 C were 2·0 g litre −1 and 1·5 g litre −1 respectively. KH 2 PO 4 was the most suitable phosphorus source for citrici acid formation at a concentration of 1·5 g litre −1 and in the presence of MgSO 4 .7H 2 O at 1·2 g litre −1 .

Induction and selection of improved yeast mutants for citric acid production

The yeast strain Candida lipolytica (Y-1095) was treated with two different mutagens, UV-irradiation and NTG. Citric acid production, yield of dry cells and protein content of each of some selected isolates were determined. It was found that the UV-irradiation was better in inducing more productive isolates. Four mutants, each of them giving a yield of about 75–80% of citric acid more than the original parent without any loss of the protein yield, were selected.

Utilisation of food industry by-products in the production of oxytetracycline by Streptomyces rimosus 93060

Abstract Different carbon sources were utilised in the biosynthesis of oxytetracycline by S. rimosus 93060. Glucose was the best carbon source for antibiotic production in a medium with peptone as the nitrogen source. Two agricultural wastes were used as cheap partial replacements for glucose. The first was Egyptian black-strap molasses. The influence of Egyptian black-strap molasses obtained from different sugar cane manufacturers was tested. Abou-Korkas molasses was the best for the production of oxytetracycline. Potassium ferrocyanide, EDTA and methylene blue were used in the chelation or reduction of inorganic salts present in Abou-Korkas molasses. These materials did not give high titres of oxytetracycline. The suitability of Abou-Korkas molasses was due to its micronutrients. A second substrate tested for antibiotic production was the freeze-dried olive water obtained from the pressing and separation of olive oil. The chemical composition of olive water was investigated. Olive water alone was a poor substrate for antibiotic production, but with glucose it was as effective as molasses.

Microbiological production of acetone-butanol by Clostridium acetobutylicum.

Trials succeeded in raising the efficiencies of the fermentation medium, used in the fermentative production of acetone-butanol by Clostridium acetobutylicum. Egyptian black strap molasses (50.0% sugars) was suitable as carbon source in the fermentation medium, and (NH4)2SO4 was utilized with great success as inorganic nitrogen source. 140.0 g/l black strap molasses (about 7.0% sugars) and 3.0 g/l (NH4)2SO4 were the optimum concentrations for obtaining good yields of acetone and butanol. Molasses and (NH4)2SO4 were preferred because they are cheaper than the other carbon and organic nitrogen sources, used in the fermentative production of acetone-butanol. The percentage increase of the total solvents produced in the fermentation (production medium) was increased by 64.0. The slop (by-product of the acetone-butanol fermentation after distillation) was re-used in the fermentation medium as organic nitrogen source and supported the microorganisms for a good production of acetone and butanol, while when stillage was used in the production medium, the total solvents output was less than that produced in the medium containing slop.

Cellulose-decomposing fungi

The present article gives a survey of the cellulose-decomposing fungi. It is concerned with the micro-organisms having the capability of degradating cellulose sources. It includes the factors influencing cellulose-decomposing fungi, cellulose-decomposing enzymes, mechanisms of degradation, and factors influencing the cellulolytic enzymes (cellulases).

Production of ethyl alcohol by Saccharomyces cerevisiae, including utilization of onion juice

Abstract The production of ethyl alcohol by Saccharomyces cerevisiae in nine synthetic culture media was influenced by their composition. Generally, no correlation seemed to exist between mycelial growth and ethyl alcohol production. Different cultural conditions were investigated using one basal synthetic medium. Sodium or potassium nitrate had an adverse effect while ammonium dihydrogen phosphate, yeast extract, casein, soybean meal, peptone and meat extract had stimulating effects on the production of alcohol. The effect of the addition of other substances, including onion juice, to the synthetic culture medium was also investigated. In higher concentration, onion juice alone fulfilled all the requirements for the production of a good yield of ethyl alcohol by Saccharomyces cerevisiae . This was also associated with a good yield of yeast cells.

Fermentative Production of Ethyl Alcohol by Saccharomyces Species

Summary The paper is concerned with the investigation of yeast strains, especially Saccharomyces species, inducing fermentative production of ethyl alcohol.

Production of oxytetracycline by Streptomyces rimosus 12,907 as an animal feed supplement.

Summary Production of oxytetracycline by Streptomyces rimosus 12907 as an animal feed supplement was achieved with a fermentation medium, containing the following ingredients (g/litre): black strap molasses, 30; fodder yeast, 20; rice bran, 10; KH2PO4, 0.2; and tap water to 1,000 ml. The dry mash, containing Oxytetracycline, was 50 g/litre of fermentation medium. The amount of oxytetracycline, present in the dry mash, was about 4.0%. The dry mash, containing oxytetracycline, contained the following amino acids: L-arginine, L-histidine, L-lysine, L-isoleucine, L-leucine, L-phenylalanine, Dl-methionine, and L-tryptophan.

Fermentative production of fodder yeasts

Fermentative production of fodder yeasts are achieved by different microorganisms of yeast. Influence of some biochemical factors on the formation of fodder yeast are examined. The raw ingredients and by-products which are used in the fermentative formation of fodder yeast are also reviewed.

Antibiotic NRC-501, a new antibiotic produced by Streptomyces species.

A new antibiotic, NRC-501, was isolated and purified from the fermentation broth of Streptomyces species NRC-501. Physical, chemical, and biological characteristics of the antibiotic NRC-501 were revealed.