Simultaneous and selective production of levan and poly(gamma-glutamic acid) by Bacillus subtilis.

Bacillus subtilis(natto) Takahashi, used to prepare the fermented soybean product natto, was grown in a basal medium containing 5% (w/w) sucrose and 1.5% (w/w) L-glutamate and produced 58% (w/w) poly(gamma-glutamic acid) and 42% (w/w) levan simultaneously. After 21 h, 40-50 mg levan ml-1 had been produced in medium containing 20% (w/w) sucrose but without L-glutamate. In medium containing L-glutamic acid but without sucrose, mainly poly(gamma-glutamic acid) was produced.