Abstract: “Surfactin produced by B.subtilis BDCC-TUSA-3 from Maldex-15 as a growth associated product in conventional batch process. Maldex-15 is a cheap industrial by-product recovered during manufacturing of high fructose syrup from corn starch. Surfactin production was greatly improved in exponential fed-batch fermentation. Maldex-15 and other nutrients were exponentially fed into the culture based on the specific growth rate of the bacterium. In order to maximize surfactin yield and productivity, conversion of different quantities of Maldex-15 into surfactin was investigated in five different fermentation runs. In all runs, most of Maldex-15 was consumed and converted into surfactin and cell biomass with appreciable efficiencies. The best results were obtained with fermentation run supplied with 204 g Maldex-15. Up to 36.1 g.l-1 of surfactin and cell biomass of 31.8 g.l-1 were achieved in 12 hrs. Also, markedly substrate yield of 0.272 g/g and volumetric reactor productivity of 2.58 g.1-1.h-1”

Keywords: Bacillus subtilis; Fed-batch cultivation