Analysis of Different Design Approaches to Favor the Growth of Polyhydroxybutyrate (PHB) Producers in a Methane Utilizing Mixed Culture Community

Currently, petroleum-based plastic disposal and its subsequent accumulation in the environment have become a major concern in recent years. Hence, the industrialization of bioplastics, PHA biopolymer has gained broad interest in recent years. This thesis offers an efficient approach for maximizing PHB polymer production in methanotrophic bacteria through using the methane gas produced in the anaerobic digestion process in wastewater treatment plants (WWTPs). This is achieved through offering an innovative selection approach for PHB producers including type II methanotrophs whilst enabling other PHB accumulators to grow simultaneously. PHB accumulation reached around 60% accumulation in ammonia mineral salt (AMS) media and 55% in nitrate mineral salt (NMS), which is higher than what has been reached in the literature for both nitrogen sources. Furthermore, characterization of the PHB polymer with Sudan Black B dye and NMR. Lastly, an optimization of the operational parameters; using central composite design (CCD) have been performed.