Research Projects

The research aims to develop an efficient lignocellulose feedstock (~hydrolysate)-based microbial platform to produce 1,4 butanediol (BDO), an important industrial raw material for manufacturing biodegradable polymers. BDO is primarily manufactured from petroleum-based feedstocks and cannot be produced naturally from any micro-organism. However, the biosynthesis of BDO can be achieved through metabolic engineering of microbial hosts. The BDO biosynthesis pathway was constituted in Escherichia coli with heterologous expression of four enzymes from anaerobic bacteria. The biological precursor of BDO, ketoglutarate (KG), was achieved by the oxidative TCA cycle, followed by conversion to BDO by reductive enzymes of carbon metabolism. E. coli was extensively engineered to achieve anaerobic operation of the TCA cycle in the oxidative direction, producing approximately 18g/l of BDO from glucose, xylose, sucrose, and mixed sugar streams derived from biomass hydrolysis. With surplus lignocellulosic biomass availability in India at about 230 million tonnes per annum, there is significant potential for bio-manufacturing valuable chemicals like BDO from lignocellulosic feedstocks. The proposed two-step BDO biosynthesis microbial model would reduce the need for massive engineering steps involved in equipping E. coli to grow on different sugars. If the objective is reached, bio-based production of BDO will be an economically attractive option over petroleum feedstock-based production.