title: Selection of Type I and Type II methanotrophic proteobacteria in a fluidized bed reactor under non-sterile conditions.
abstract: Type II methanotrophs produce polyhydroxybutyrate (PHB), while Type I methanotrophs do not. A laboratory-scale fluidized bed reactor was initially inoculated with a Type II Methylocystis-like dominated culture. At elevated levels of dissolved oxygen (DO, 9 mg/L), pH of 6.2-6.5 with nitrate as the N-source, a Methylobacter-like Type I methanotroph became dominant within the biofilms which did not produce PHB. A shift to biofilms capable of PHB production was achieved by re-inoculating with Type II Methylosinus culture, providing dissolved N(2) as the N-source, and maintaining a low influent DO (2.0mg/L). The resulting biofilms contained both Types I and II methanotrophs. Batch tests indicated that biofilm samples grown with N(2) became dominated by Type II methanotrophs and produced PHB. Enrichments with nitrate or ammonium were dominated by Type I methanotrophs without PHB production capability. The key selection factors favoring Type II were N(2) as N-source and low DO.
authors: Department of Geography and Environmental Engineering, United States Military Academy, 745 Brewerton Road, West Point, NY 10996-1602, USA.
authors: Andrew R
authors: AR
authors: Pfluger
authors: Wei-Min
authors: WM
authors: Wu
authors: Allison J
authors: AJ
authors: Pieja
authors: Jonathan
authors: J
authors: Wan
authors: Katherine H
authors: KH
authors: Rostkowski
authors: Craig S
authors: CS
authors: Criddle
mesh_terms: D061249:Batch Cell Culture Techniques; D018441:Biofilms / Q000254:growth & development; D018533:Biomass; D019149:Bioreactors / Q000382:microbiology*; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000032:analysis; D042083:Methylocystaceae / Q000254:growth & development*; D020581:Methylosinus / Q000254:growth & development*; D009584:Nitrogen / Q000032:analysis; D010100:Oxygen / Q000032:analysis; D015203:Reproducibility of Results; D012995:Solubility; D013242:Sterilization
chemical_list: D009584:Nitrogen; D008697:Methane; D010100:Oxygen