title: Production of medium-chain-length polyhydroxyalkanoates by activated sludge enriched under periodic feeding with nonanoic acid.
abstract: The potential use of activated sludge for the production of medium-chain-length polyhydroxyalkanoates (MCL-PHAs) was investigated. The enrichment of bacterial populations capable of producing MCL-PHAs was achieved by periodic feeding with nonanoic acid in a sequencing batch reactor (SBR). Denaturing gradient gel electrophoresis analysis revealed Pseudomonas aeruginosa strains to be predominant in the bacterial community during the SBR process. The composition of PHA synthesized by the enriched biomass from nonanoic acid consisted of a large concentration (>89 mol%) of MCL monomer units and a small amount of short-chain-length monomer units. Under fed-batch fermentation with continuous feeding of nonanoic acid at a flow rate of 0.225 g/L/h and a C/N ratio of 40, a maximum PHA content of 48.6% dry cell weight and a conversion yield (Y(p/s)) of 0.94 g/g were achieved. These results indicate that MCL-PHA production by activated sludge is a promising alternative to typical pure culture approaches.
authors.affiliation: Department of Microbiology and Molecular Biology, Chungnam National University, Daejeon 305-764, Republic of Korea.
authors.forename: Sun Hee
authors.initials: SH
authors.lastname: Lee
authors.forename: Jae Hee
authors.initials: JH
authors.lastname: Kim
authors.forename: Debaraj
authors.initials: D
authors.lastname: Mishra
authors.forename: Yu-Yang
authors.initials: YY
authors.lastname: Ni
authors.forename: Young Ha
authors.initials: YH
authors.lastname: Rhee
mesh_terms: D004591:Electrophoresis, Polyacrylamide Gel; D005227:Fatty Acids / Q000378:metabolism*; D054813:Polyhydroxyalkanoates / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000378:metabolism; D012722:Sewage
chemical_list: D005227:Fatty Acids; D054813:Polyhydroxyalkanoates; D012722:Sewage; C008776:pelargonic acid