A strategic media engineering and fed-batch approach enhances violacein production by Chromobacterium violaceum MTCC2656

Abstract

Violacein, a therapeutic pigment synthesised naturally in specific bacterial systems, is commercially unexplored owing to low titers. The current study aimed to formulate a suitable medium and to develop a fed-batch strategy for improving the violacein productivity in a natural producer—Chromobacterium violaceum MTCC2656. The carbon and the nitrogen sources were extensively screened and their levels were optimised for maximal violacein production. The micronutrients in the medium were subjected to a two-level statistical optimisation using design of experiment approach and the final media formulation was validated. As a fed-batch approach, a combination of pulse feeding of glucose and tryptophan with optimised broth harvest of 60% (v/v) was attempted that achieved a titer of 1046 ± 16 mg/L with productivity of 26.12 ± 0.64 mg/L/h in each progressive cycle of fed-batch. The strategic sequential step of media formulation and fed-batch fermentation improved the violacein titer by ~ 5 folds. Kinetic modelling was used to understand the enhancement in fermentation performance in both the batch and fed-batch processes. The findings from the current study would enable to understand and correlate the patterns of substrate uptake and violacein formation to establish strategies for enhancing overall productivity in the fermentation processes.

Funding

All India Council for Technical Education,