Co-metabolism of substrates by Bacillus thuringiensis regulates polyhydroxyalkanoate co-polymer composition

Polyhydroxyalkanoate PHA) production by Bacillus thuringiensis EGU45 was studied by co-metabolism of crude glycerol CG) 1%, v/ v), glucose 0.05-0.5%, w/ v) and propionic acid 0.05-0.5%, v/ v) under batch shake flask) culture conditions. Glycerol + PA combination resulted in 15-100 mg/ L PHA co-polymers with a HV content of 33-81 mol%. The addition of NH4Cl 0.5%, w/ v) to CG + PA enhanced PHA production by 1.55-fold, with a HV content of 58-70 mol%. The time period of incubation of PA to the feed: CG + glucose was optimized to be 3 h after initiation of fermentation. The PHA contents were found to be stable at 1900-2050 mg/ L up scaling from 0.4 to 2.0 L feed material. Biochemical characterization through GC-MS of PHA co-polymer revealed the presence of 3-hydroxydecanoate 3-HDD), 3-hydroxyoctadecanoate 3HOD), 3-hydroxyhexadecanoate 3HHD). (C) 2016 Elsevier Ltd. All rights reserved.