A MODIFIED GROWTH-MEDIUM FOR BACILLUS-THURINGIENSIS

A published medium for the cultivation of Bacillus thuringiensis was m odified for use in high-density fed-batch fermentations. This medium w as diagnosed to have a complex nutrient limitation in batch and contin uous cultivations. By selective additions of different medium constitu ents to a chemostat culture, it was established that the limitations w ere alleviated only by the addition of yeast extract or corn steep liq uor; neither the addition of any salt nor that of individual amino aci ds influenced the culture behavior. In shake flask cultures, a reducti on in glucose concentration and addition of corn steep liquor made the medium carbon-limited; enrichment with corn steep liquor alone showed dual limitations. These modified media resulted in higher cell densit ies and showed an increase in the amounts as well as the potency of in secticidal protoxins.