Response surface analysis of chlortetracycline and tetracycline production with K-carrageenan immobilized Streptomyces aureofaciens.

A full-factorial experimental design at three levels with two independent variables, carrageenan concentration (1.0, 1.5, and 2.0%) and potassium chloride concentration (0.3, 0.7, and 1.1 M) was studied in order to analyze the effect of both factors on the antibiotic production of K-carrageenan-immobilized mycelia of Streptomyces aureofaciens. The response surfaces obtained have indicated that both carrageenan and potassium chloride concentrations have a pronounced effect on the yield of chlortetracycline (CTC) and tetracycline (TC) produced by S. aureofaciens. By exclusively varying the immobilization conditions, the tetracycline production can be enhanced more than eight times (12.3 mg g-1 biomass for immobilized cells vs. 1.5 mg g-1 biomass for free cells) in comparison with free-cell mycelial cultures.

[Development of the system for protoplast generation in Streptomyces aureofaciens strains--chlortetracycline producers]. / Razrabotka sistemy protoplastirovaniia u shtammov Streptomyces aureofaciens--produtsentov khlortetratsiklina.

Conditions for preparation and regeneration of protoplasts in a commercial strain of the culture producing chlortetracycline and its derivatives were determined. The protoplasting level depended on the conditions of the mycelium cultivation and composition of a regeneration medium. Under the optimal conditions it amounted up to 10(6) protoplasts/ml. A mutant able to form regenerating protoplasts at a rate of 10(9) protoplasts/ml was isolated. An autoinhibition effect in regenerating protoplasts was observed. As a result ofprotoplast generationing, the morphological variation increased and the protoplast antibiotic activity changed within wide ranges. Variants with higher productivity in comparison to that of the initial strain were isolated. Stability of the inherited property of antibiotic production in the variants is being studied.

[Regulation of tetracycline biosynthesis by controlling the growth of the producer]. / Reguliatsiia biosinteza tetratsiklina putem upravleniia rostom produtsenta

Regulation of the rate growth of Act. aureofaciens in batch fermentation by maintaining the concentrations of phosphorus, ammonium nitrogen, glucose and pH values at the levels favourable for intensive growth at the beginning of the process and after accumulation of the biomass at the levels optimal for retarded growth of the organism resulted in significant prolongation of the period of intensive antibiotic production, i.e. intensification of the fermentation process. Microscopic investigation of the organism development under conditions of regulated fermentation revealed the presence of significant amounts of free peripheral highly basophilic hyphae for a prolonged period of time. The hyphae possessed a capacity for growth and intensive metabolism unlike the control culture which was liable to early autolysis.