Enhanced production of violacein by Chromobacterium violaceum using agro-industrial waste soybean meal

Abstract

Aims: The research is aimed at developing an economic and sustainable growth medium using abundantly available and highly nutritive agro-industrial waste soybean meal as the substrate for the production of violacein by Chromobacterium violaceum. Methods and Results: Violacein produced using soybean meal medium was compared with the commercial complex growth media. Upon utilization of 2% w/v soybean meal (SM2) medium, 496 mg/L crude violacein was achieved after 48-hr incubation time, which was 1.62-fold higher than the crude violacein produced in Luria-Bertani (LB) broth. Additionally, supplementation of 100 mg/L L-tryptophan to 1% and 2% w/v soybean meal (SMT1 and SMT2) medium yielded 1217 mg/L (3.96-fold higher as compared to LB) and 1198 mg/L (3.90-fold higher as compared to LB) crude violacein respectively. Optimization of culture conditions and concentration of L-tryptophan using Box–Behnken design (BBD) model produced as high as 1504.5 mg/L crude violacein. To the best of our knowledge, this is the highest crude violacein produced to date using agro-industrial–based waste as a substrate with minimal supplementation in a shake flask. Conclusions: The study signifies the potentiality of soybean meal as a cost-effective growth medium for the production of violacein. Optimization of the fermentation parameters clearly demonstrated a surge in violacein production. Significance and Impact of the Study: Utilization of soybean meal as an alternative to the expensive commercial media would surely promote the large-scale synthesis of this multifaceted compound.