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

Abstract

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.

Prospect of metabolic engineering in enhanced microbial lipid production: review

“…Along with a high growth rate that is capable of reaching critical biomass level within 12-24 h and easy culture method, bacteria has the capability to achieve remarkable grounds in industrial lipid production; however, low average oil content and accumulation of most of the lipids in the outer membrane of the cells has reduced their significance as microbial lipid producers [76]. Most of the lipid-producing bacteria belong to the actinomycetes group and includes the most studied Rhodococcus sp., Streptomyces sp., Nocardia sp., Mycobacterium sp., and Dietzia sp., all capable of producing lipids and synthesising TAGs under nitrogen-limiting growth conditions and excess availability of carbon source [77]. R.opacus and R. jostii are the most frequently studied oleaginous bacteria and are therefore considered the model organisms.…”