Production of antifungal lipopeptide from Bacillus subtilis in submerged fermentation using shake flask and fermentor

Optimization of the production of antifungal lipopeptide, iturin A, by B. subtilis was carried out in submerged cultural fermentation. In a shake-flask experiment, response surface methodology (RSM) was employed to optimize the cultivation conditions of Bacillus subtilis S3 for the enhancement of iturin A production. The optimal conditions for iturin A production obtained from RSM were pH 6.0, 0.93% maltodextrin, 1.11% glucose, 0.72% corn steep powder (C.S.P), 1.5 mM MgSO4, 0.75 mM KH2PO4, rotation speed 180 rpm and area of aeration 4.35 cm2. 57% increase of iturin A productivity (from 47.19 mg/L to 74.22 mg/L) was observed using the one-factor-at -a-time technique; however, 180% increase of iturin A productivity (from 47.19 mg/L to 132.23 mg/L) was observed with RSM. The iturin A production was further studied in a 5-L fermentor with a variation of agitation speed, aeration and baffles. In the 5-L fermentor, it was found that increased agitation speed improved the growth of B. subtilis and the production of iturin A. Aeration at 2 vvm gave excellent production of iturin A (175.52 mg/L) at 6 d of fermentation. The addition of baffles in the fermentor has significantly influenced the oxygen mass transfer coefficient (KLa) and iturin A production.