Optimization of Inexpensive Agricultural By-Products as Raw Materials for Bacitracin Production in Bacillus licheniformis DW2

Bacitracin is a broad-spectrum antibiotic used extensively as a feed additive. In this study, inexpensive agricultural by-products were used as nitrogen sources for bacitracin production. Based on both the orthogonal tests, a combination of 7% soybean meal (SBM) +2% low protein rapeseed cake (LPRC) was optimal for bacitracin production. Compared to the original formula, the titer of bacitracin increased by 20.5% reaching 910.4 U/ml in flasks. The titer of bacitracin and the ratio of bacitracin A increased by 12.4 and 6.8% in a 50-l fermentor. Furthermore, this study also explored the effects of exogenously adding different amino acids on the yield of bacitracin. The addition of Cys and Glu enhanced bacitracin production by 5.7 and 5.0%, respectively. This study provided the inexpensive nutrient inputs into efficient bacitracin production and also the insight to further research enabling better utilization of oil cakes for economic viability of the bioprocess industry.