Studies on Development of Bio-based Biodegradable Polymers and Their Efficacy as Biomaterials

Abstract

Exhaustion of non-renewable resources and increasing concern towards the non-biodegradability of conventional polymers demands research for alternative, bio-based and biodegradable polymers having comparable properties. Recently, research in the field of sustainable polymers is highly focused on the use of renewable wastes generated from agriculture, food, and the meat industry for the development of biodegradable biomaterials. The biomaterials prepared from these renewable wastes find their applications in the field of medicine and help to restore biological functions. Polyhydroxybutyrate (PHB) is a biodegradable biomaterial of bacterial origin produced intracellularly as an energy reserve in a stress-induced condition which has a potential application in drug delivery. Poly(latic acid) (PLA) is another class of bio-based polymer produced by the polymerization of lactide predominantly used in biomedical applications and packaging. Prodigiosin is a bacterial pigment used as a remedy for cancer treatment, and nanocellulose is a bionanomaterial suitable for high-performance applications. In this perspective, the current study extensively deals with the utilization of waste sorghum stalks consisting of fermentable sugars, cellulose, and hemicellulose for the production of biomaterials such as PHB and nanocellulose. Prodigiosin is produced from Serratia nematodiphila isolated from river water, and metal-free PLA is synthesized using prodigiosin as a metal-free catalyst. Over the assessment, the juice from agricultural waste sorghum stalks consisting of ~60 g/L of fermentable sugar is used as an inexpensive carbon source for the production of PHB. The minimal media supplemented with sorghum juice is used for the optimization and production of PHB. The optimized conditions yielded the maximum productivity of ~8.2 g/L of PHB within 24 h of cultivation. The fed-batch operation with dO2 controlled strategy maximized the productivity four-folds in comparison to the batch operation. It was able to obtain PHB with a molecular weight of ~400 KDa and recovery of ~94% using solvent extraction. The characterization of the produced