Enrichment of Methylosinus-dominant consortia from mangroves for polyhydroxybutyrate (PHB) production

Oil-based plastics’ unrestrained production associated with their non-biodegradability and inappropriate discharge altogether with the sharp increase in greenhouse gas (GHGs) emissions represent two of the main environmental problems faced by humankind. In this scenario, this work comes up with an alternative to solve both environmental problems: the bioconversion of methane into polyhydroxybutyrate (PHB), a biodegradable polymer produced by methanotrophic bacteria that could substitute plastics and sequester GHGs from the atmosphere. In this work, samples from distinguished mangrove areas unrevealed Methylosinus-dominant consortia capable of producing PHB and thrive under methane concentrations of up to 70 % (v/v). Copper and methane concentrations besides cultivation time were assessed to find the most suitable condition for PHB production. The best results were obtained by a consortium predominant by 54 % of Methylosinus, reaching 183 mg L−1 of PHB in a two-stage PHB process after 12 days using 12.3 % (v/v) of methane in air atmosphere and 10 µM Cu2+ in NMS medium. The results obtained in this work indicate the consortium’s potential in methane bioconversion into a product of interest and further elucidates microbial interactions in mangrove microbial communities.