Culture medium designing for semi-industrial production of Bacillus subtilis UTB96

The purpose of this research was to design a semi-industrial culture medium to obtain the maximum biomass production from bacterium Bacillus subtilis UTB96. In the first step, in order to reduce the cost of culture medium components, commercial products and industrial by products including, sugar beet molasses, sugar cane molasses, potato waste water and milk serum as carbon sources and corn steep liquor, as a nitrogen source were studied. In addition some inorganic compounds including ammonium sulfate, urea, granular fertilizer urea, dihydrogen ammonium phosphate were comparatively evaluated. The designed culture medium with defined components were applied in both laboratory and semi-industrial scale bioreactors and the biomass production and antagonistic effect of bacterium were compared with together. The results showed, sugar cane molasses and corn steep liquor as industrial carbon and nitrogen sources respectively, at concentrations of 10 and 2 g/lit respectively can be used in high-scale production of biological control agent B. subtilis UTB96. Finally, the designed culture medium application in semi-industrial scale bioreactor resulted in biomass production of 0.32 g/lit. The bacterium grown in this culture medium had antifungal activity on both pathogenic agents, Aspergillus flavus and Phytophthora drechsleri with 50 and 70% inhibition respectively. Whereas the application of designed culture medium in laboratory scale bioreactor resulted in biomass production of 0.31 g/lit. Bacterium grown in this bioreactor has antifungal effect on A. flavus and P. drechsleri with 78 and 54% inhibition, respectively.