Regulation of butanol biosynthesis in Clostridium acetobutylicum ATCC 824 under the influence of zinc supplementation and magnesium starvation.

Present study reports modulation in butanol biosynthesis in Clostridium acetobutylicum ATCC 824 under the influence of zinc supplementation or magnesium starvation either individually or in combination. An improvement in butanol titer from 11.83 g L in control to 13.72 g L, 15.79 g L, and 19.18 g L was achieved when organism was grown on magnesium starved, zinc supplemented and combined zinc supplemented-magnesium starved fermentation medium, respectively. The elevation in butanol biosynthesis was associated with raised glucose utilization, reduced ethanol production and early induction of solventogenesis. Change in these phenotypic traits of the organism may be attributed to multi-level modulation in central carbon metabolism e.g., upregulation of glycolytic pathway; upregulation in thiolase activity; key intermediate enzyme for biosynthesis of acids and solvent; upregulation in the activity of butyrylaldehyde dehydrogenase & butanol dehydrogenase, the enzymes responsible for butanol biosynthesis and downregulation in alcohol dehydrogenase, redirecting carbon flux from ethanol to butanol.