Multi-objective optimization for biomass and lipid production by oleaginous bacteria using vegetable waste as feedstock

In this study, pretreated organic wastes such as waste paper cups, cardboard waste, and vegetable waste were screened for the growth and lipid production of oleaginous bacteria DS-7 (isolated from the dairy effluent scum). The pretreated vegetable waste was found to be the best feedstock for biomass and lipid production by the DS-7. Further, process parameters such as inoculation time, substrate concentration (w/v) (amount of pretreated vegetable waste), pH, and inoculum size were optimized using a multi-objective optimization technique to enhance the biomass and lipid productions. The optimization study successfully enhanced the biomass concentration (g/L) and lipid content (%) by 47.9% and 15.84%, respectively in comparison with the unoptimized state. The biomass and lipid productivities were 42% (1.449 g/L/d) and 51% (1.267 g/L/d) greater than unoptimized conditions. The characteristics of the biodiesel obtained from the valorization of vegetable waste were comparable to the standard. Thus, the vegetable waste can be utilized as a potential feedstock for microbial biodiesel production.