Agricultural Feedstock Supplemented with Manganese for Biosurfactant Production by Bacillus subtilis

The greatest challenge in producing biomolecules at industrial scale is cost. In order to provide cheaper sources, the present study describes the production of biosurfactant using a low-cost medium supplemented with manganese. The feedstock used to produce biosurfactant was crude glycerol, a by-product of biodiesel production. Results showed that 5% (v/v) of glycerol and 0.05 mM of manganese was the best combination to produce biosurfactant. The produced biosurfactant was able to reduce surface tension and showed emulsification activity in diesel fuel. The main functional groups of the biosurfactant were identified by H-1 NMR and FTIR spectra. We identified the molecule as surfactin based on comparison with surfactin standard spectra described in the literature. This study showed conversion of low-value glycerol into value-added products as biosurfactant. The use of a by-product as a carbon source for biosurfactant production is a possible strategy for reducing production costs. In addition, biosurfactant production by Bacillus subtilis can be considered safe and commercially viable, because it is a non-pathogenic bacterium.