Production of Bioplastic (Polyhydroxybutyrate) with Local Bacillus megaterium Isolated from Petrochemical Wastewater

Iran J Biotechnol. 2021 Jul 1;19(3):e2849. doi: 10.30498/ijb.2021.244756.2849. eCollection 2021 Jul.


Background: Polyhydroxybutyrate is a biodegradable plastic produced by some bacteria and can completely be replaced with petroleum based non-degradable plastics.

Objectives: This study was done to isolate and identify one local strain with a high-production ability for industrial purposes.

Material and methods: The sampling from petrochemical wastewater was done. The existence of polyhydroxybutyrate in isolates was studied with Sudan Black staining. Using the Sudan Black B plate assay method and estimating produced PHB amount, the most potent isolate was chosen. This isolate was distinguished by morphological and biochemical methods and determining 16S rRNA gene sequencing. The final confirmation of polyhydroxybutyrate synthesis was done by FTIR and 1H NMR. To increase more production of polyhydroxybutyrate, the effect of different factors including carbon, nitrogen, pH, and temperature were assessed.

Results: Six bacterial isolates producing polyhydroxybutyrate were separated, which among them, one new strain of Bacillus megaterium named saba.zh was selected as better isolation. 16S rRNA nucleotide sequence of bacterium was assigned accession number: MN519999 in the NCBI database. The optimal conditions to increase the production of polyhydroxybutyrate, are using glucose as a carbon source, ammonium sulfate as the nitrogen source, in the condition with having pH 7 and temperature 30 °C. After optimizing, the production of PHB increased from 56.51% to 85.41%.

Conclusions: This research indicated that Bacillus megaterium saba.zh, due to better polymer yield, is a potent PHB producer which can be used for PHB industrial production.

Keywords: Bioplastic; Petrochemical Wastewater; Polyhydroxybutyrate; Bacillus megaterium.