Biopolymers

Polyhydroxyalkanoates (PHAs) have drawn attention due to its similarity to plastics. Its global demand is 34,000 MT, although their large scale production is limited by costly feed and recovery process. Crude glycerol (CG), generated at the rate of 10% of the total biodiesel produced may serve as a cheap raw material for PHAs production. Here, we report the potential of Bacillus thuringiensis to utilize high CG as feed, for PHA co-polymers production at high N containing medium. PHA production by B. thuringiensis EGU45 was studied on three different media: NB, GM2, and M-9 supplemented with various inorganic nitrogen (N) sources. CG (1 -10%) was supplemented with different components of NB as N sources. The PHA was later analyzed by TEM, GC, GPC, NMR and FTIR. B. thuringiensis EGU45 was found to produce 1.5-3.5 g PHA/L from feed containing 1-10% CG and NB without any acclimatization. Here, the PHA yields were 56-72% of the total biomass. B. thuringiensis EGU45 could produce PHA at the rate of 1.5-1.8 g/L, from 1% CG on media having high N contents. B. thuringiensis EGU45 was able to produce co-polymer of P(87% 3HB-co-13% 3HV) on high N containing feed supplemented with propionic acid. B. thuringiensis EGU45 grown on peptone+YE supplemented with 1% CG showed large PHA inclusions (0.75-1.25 μm) within the cells. The PHA produced on CG was found to have a Mw of 3.85 × 105 Da with a polydispersity index of 2.1. The use of B. thuringiensis EGU45 towards efficient conversion of CG to PHA without the necessity of limited amount of N and pH controls could improve its feasibility at large scale with a flexible harvesting time. Further, integration of H2 and PHA production processes by exploiting functional consortium of Bacillus can increase the process efficiency.