title: Characterization of wastewater treatment plant microbial communities and the effects of carbon sources on diversity in laboratory models.
abstract: We are developing a laboratory-scale model to improve our understanding and capacity to assess the biological risks of genetically engineered bacteria and their genetic elements in the natural environment. Our hypothetical scenario concerns an industrial bioreactor failure resulting in the introduction of genetically engineered bacteria to a downstream municipal wastewater treatment plant (MWWTP). As the first step towards developing a model for this scenario, we sampled microbial communities from the aeration basin of a MWWTP at three seasonal time points. Having established a baseline for community composition, we investigated how the community changed when propagated in the laboratory, including cell culture media conditions that could provide selective pressure in future studies. Specifically, using PhyloChip 16S-rRNA-gene targeting microarrays, we compared the compositions of sampled communities to those of inocula propagated in the laboratory in simulated wastewater conditionally amended with various carbon sources (glucose, chloroacetate, D-threonine) or the ionic liquid 1-ethyl-3-methylimidazolium chloride ([C2mim]Cl). Proteobacteria, Bacteroidetes, and Actinobacteria were predominant in both aeration basin and laboratory-cultured communities. Laboratory-cultured communities were enriched in γ-Proteobacteria. Enterobacteriaceae, and Aeromonadaceae were enriched by glucose, Pseudomonadaceae by chloroacetate and D-threonine, and Burkholderiacea by high (50 mM) concentrations of chloroacetate. Microbial communities cultured with chloroacetate and D-threonine were more similar to sampled field communities than those cultured with glucose or [C2mim]Cl. Although observed relative richness in operational taxonomic units (OTUs) was lower for laboratory cultures than for field communities, both flask and reactor systems supported phylogenetically diverse communities. These results importantly provide a foundation for laboratory models of industrial bioreactor failure scenarios.
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Sangwon
authors.initials: S
authors.lastname: Lee
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Jil T
authors.initials: JT
authors.lastname: Geller
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Tamas
authors.initials: T
authors.lastname: Torok
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Cindy H
authors.initials: CH
authors.lastname: Wu
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Mary
authors.initials: M
authors.lastname: Singer
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Francine C
authors.initials: FC
authors.lastname: Reid
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Tarjan
authors.affiliation: Earth Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Terry C
authors.initials: TC
authors.lastname: Hazen
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Adam P
authors.initials: AP
authors.lastname: Arkin
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California, United States of America.
authors.forename: Nathan J
authors.initials: NJ
authors.lastname: Hillson
mesh_terms: D001419:Bacteria / Q000235:genetics / Q000254:growth & development; D002244:Carbon / Q000378:metabolism*; D059013:Microbial Consortia / Q000235:genetics; D010944:Plants / Q000382:microbiology*; D062065:Wastewater / Q000382:microbiology*; D014871:Water Microbiology; D018508:Water Purification
chemical_list: D002244:Carbon; D062065:Wastewater