Batch and continuous culture production of the mosquito larval toxin ofBacillus sphaericus 2362

Abstract

Batch and continuous culture were used to investigate the production ofBacillus sphaericus mosquito larvicide. In batch culture, control of the pH at 7.2–7.3 rather than allowing the normal rise to about 8.6 decreased the toxicity of the cells. Oxygen was required for toxin formation but increasing the level of dissolved oxygen in the medium by use of pure oxygen in the gas stream lowered toxin production. Sporulation and toxin production occurred in continuous culture and were greater at lower dilution rates. However, toxin yield in continuous culture was too low to be a likely alternative to batch culture.