Propagation of Streptomyces aureofaciens MY18 in the fermentor as batch and continuous cultures

الملخص EN

Streptomyces aureofaciens MY18 (local isolate) was grown in thefennentor as batch and continuous chemostat cultures.

The constant and suitable environment in batch cultures increased biomass and antibiotic productivity by this strain.

Respiratory quotient was approximately constant; whereas °2- uptake aJ)d CO2 production increased gradually to reach their maximum on 7th day of incubation.

Continuous cultivation at different dilution rates revealed that the highest efficiency in the utilization of added nutrients was achieved at 0.0255 h-1 (25.5 ml h-' flow rate).

The steady state of this dilution rate gave constant values of starch consumed, starch utilization efficiency, accumulation of antibiotics, °2- uptake and CO2 production.

The increase in dilution rate to 0.0321 h-1 (32.1 ml fresh medium h-l) caused general decreases of all biological activities leading to the phenomenon of washing out.

Optimum pH in chemostat.culture was 7, and increase or decrease of pH than this level decreased respiration rate, and, consequently, the production of biomass and antibiotic was reduced.

The crude antibiotic extracted by n-butanol from the culture filtrate gave a considerable antibiotic activity as compared to tetracycline.