Screening and optimization of cyanobacteria cultivated on palm oil mill effluent (POME) to produce polyhydroxybutyrate

The use of cyanobacteria for intracellular polyhydroxybutyrate (PHB) accumulation for bioplastic production offers a cost-saving opportunity. Because of their short generation cycles, cyanobacteria have a high potential as a source of PHB. This research aimed to screen the best cyanobacteria strain growing on palm oil mill effluent (POME) and optimize the environmental and nutritional factors by using Box-Behnken RSM. Results showed that Synechocystis sp. produced the highest PHB compared to Nostoc sp., Synechococcus sp., and Chroococcus sp. Further optimization revealed that the interaction of glycerol and UV-C irradiation, or glycerol and iron addition increased PHB production of Synechocystis sp.. The highest PHB production was found at 670 mg L-1 glycerol, 70 min UV-C irradiation time, and 20 mg L-1 iron. It was confirmed by FT-IR, GC-MS and NMR H-1 that PHB was dominated by butyric esters with 284 degrees C thermal stability.