Role of trace elements as cofactor: An efficient strategy towards enhanced biobutanol production

Metabolic engineering has potential to steadily enhance product titers by inducing changes in metabolism. Especially, availability of cofactors plays a crucial role in improving efficacy of product conversion. Hence, the effect of certain trace elements was studied individually or in combinations, to enhance butanol flux during its biological production. Interestingly, nickel chloride (100 mg L-1) and sodium selenite (1 mg L-1) showed nearly two-fold increase in solvent titer, achieving 16.13±0.24 and 12.88±0.36 g L-1 total solvents with yield of 0.30 and 0.33 g g-1, respectively. Subsequently, addition time (screened entities) was optimized (8 h) to further increase solvent production up to 18.17±0.19 and 15.5±0.13 g L-1 by using nickel and selenite, respectively. A significant upsurge in butanol dehydrogenase (BDH) levels was observed, which reflected in improved solvent productions. Additionally, a three-dimensional structure of BDH was also constructed using homology modeling and subsequently docked with substrate, cofactor and metal ion to investigate proper orientation and molecular interactions.