Dry Cell Weight Basis Research Articles

Quantitative physiology of Penicillium cyclopium grown on whey for production of microbial protein

A filamentous fungus Penicillium cyclopium, capable of growing on deproteinized whey was isolated and characterized for the purpose of production of microbial protein. This organism has a maximum specific growth rate of 0.2 h−1 at pH 3.0 to 4.5 and 28°C in a medium containing only ammonium nitrogen and deproteinized whey. The yield coefficients are 0.68 g biomass/g lactose, 12.0 g biomass/g nitrogen, and 2.10 g biomass/g oxygen, respectively. Crude protein and total nucleic acid contents of this organism are 47.5% and 7.4% (dry cell weight basis), respectively. The profile of essential amino acids shows that it could be a good source of animal feed or food protein.

Production and isolation of chitosan from Mucor rouxii.

A method for the lab-scale production and isolation of chitosan (polyglucosamine) from hyphal walls of Mucor rouxii was developed. Hyphal wall yields were generally 16 to 22% on a dry cell weight basis, of which 35 to 40% was glucosamine. Chitosan was readily extracted from purified, mycelial walls with acetic, formic, and hydrochloric acids; the last named was the most efficient. The yield of chitosan isolated ranged from 4 to 8% of the dry weight of the cell wall material.

5'-Phosphodiesterase Formation by Cultured Plant Cells

5' Phosphodiesterase (5'-PDase) which degrades RNA to nucleoside-5'-monophosphates was investigated in various kinds of plant calli, and the calli of Vinca rosea and Phytolacca americana were found to have the high activity. The liquid culture conditions of the cells of V. rosea were examined. Three mg of kinetin and 0.5mg of 2, 4-dichlorophenoxyacetic acid per liter in the Murashige and Skoog medium were optimal for the growth and the 5'-PDase formation. Under the optimal conditions, time courses of the cell growth and the enzyme formation were measured. The 5'-PDase of the cultured cells of V. rosea in suspension showed the maximal activity at pH 8.0 and 60°C. A comparison of 5'-PDase of the cultured cells and of the mother plant of V. rosea was carried out and it was found that the cultured cells had more than 30 times as much 5'-PDase activity as the mother plant on dry cell weight basis.