title: Long-term cultivation of a stable Methylocystis-dominated methanotrophic enrichment enabling tailored production of poly(3-hydroxybutyrate-co-3-hydroxyvalerate).
abstract: Methane (CH4) is a readily available feedstock for production of polyhydroxyalkanoates (PHAs). The structure and PHA production capacity of a Methylocystis-dominated methanotrophic enrichment was stable in long-term operation (>175 days) when grown exponentially under non-aseptic conditions in fill-and-draw batch cultures with ammonium as nitrogen source. Cells harvested in the draw step were incubated in the absence of nitrogen with various combinations of CH4 and valerate to assess capacity for synthesis of poly(3-hydroxybutyrate) (P3HB) and poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV). When fed CH4 alone, only P3HB was produced. When fed CH4 plus valerate, PHBV was synthesized. The mol% of 3-hydroxyvalerate (3HV) increased with added valerate. Oxidation of CH4 was required for valerate assimilation, and the fraction of CH4 oxidized increased with increased mol% 3 HV. By separating PHA accumulation from cell replication, tailored PHA-rich biomass can be generated by addition of co-substrate, while retaining a large inoculum for the next cycle of cell division.
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA. Electronic address: jjaimyung@stanford.edu.
authors.forename: Jaewook
authors.initials: J
authors.lastname: Myung
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA. Electronic address: wakunamg@stanford.edu.
authors.forename: Wakuna M
authors.initials: WM
authors.lastname: Galega
authors.affiliation: Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma, Norman, OK 73019, USA. Electronic address: joy.vannostrand@ou.edu.
authors.forename: Joy D
authors.initials: JD
authors.lastname: Van Nostrand
authors.affiliation: Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma, Norman, OK 73019, USA. Electronic address: tyuan@ou.edu.
authors.forename: Tong
authors.initials: T
authors.lastname: Yuan
authors.affiliation: Institute for Environmental Genomics, Department of Microbiology and Plant Science, University of Oklahoma, Norman, OK 73019, USA. Electronic address: jzhou@ou.edu.
authors.forename: Jizhong
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Civil and Environmental Engineering, Stanford University, Stanford, CA 94305, USA; Woods Institute for the Environment, Stanford, CA 94305, USA; William and Cloy Codiga Resource Recovery Center, Stanford, CA 94305, USA. Electronic address: criddle@stanford.edu.
authors.forename: Craig S
authors.initials: CS
authors.lastname: Criddle
mesh_terms: D019149:Bioreactors / Q000382:microbiology*; D060847:Metabolic Engineering; D008697:Methane / Q000378:metabolism; D042083:Methylocystaceae / Q000378:metabolism*; D011091:Polyesters / Q000737:chemistry / Q000378:metabolism; D014631:Valerates / Q000378:metabolism; D000094122:Polyhydroxybutyrates
chemical_list: D008697:Methane; D011091:Polyesters; D014631:Valerates; C052620:poly(3-hydroxybutyrate)-co-(3-hydroxyvalerate); D000094122:Polyhydroxybutyrates
keywords: Copolymer; Methanotroph; PHB; PHBV; Polyhydroxyalkanoates