title: Corexit 9500 Enhances Oil Biodegradation and Changes Active Bacterial Community Structure of Oil-Enriched Microcosms.
abstract: To better understand the impacts of Corexit 9500 on the structure and activity levels of hydrocarbon-degrading microbial communities, we analyzed next-generation 16S rRNA gene sequencing libraries of hydrocarbon enrichments grown at 5 and 25°C using both DNA and RNA extracts as the sequencing templates. Oil biodegradation patterns in both 5 and 25°C enrichments were consistent with those reported in the literature (i.e., aliphatics were degraded faster than aromatics). Slight increases in biodegradation were observed in the presence of Corexit at both temperatures. Differences in community structure were observed between treatment conditions in the DNA-based libraries. The 25°C consortia were dominated byVibrio,Idiomarina,Marinobacter,Alcanivorax, andThalassospiraspecies, while the 5°C consortia were dominated by several species of the generaFlavobacterium,Alcanivorax, andOleispiraMost of these genera have been linked to hydrocarbon degradation and have been observed after oil spills.ColwelliaandCycloclasticus, known aromatic degraders, were also found in these enrichments. The addition of Corexit did not have an effect on the active bacterial community structure of the 5°C consortia, while at 25°C, a decrease in the relative abundance ofMarinobacterwas observed. At 25°C,Thalassospira,Marinobacter, andIdiomarinawere present at higher relative abundances in the RNA than DNA libraries, suggesting that they were active in degradation. Similarly,Oleispirawas greatly stimulated by the addition of oil at 5°C.IMPORTANCEWhile dispersants such as Corexit 9500 can be used to treat oil spills, there is still debate on the effectiveness on enhancing oil biodegradation and its potential toxic effect on oil-degrading microbial communities. The results of this study provide some insights on the microbial dynamics of hydrocarbon-degrading bacterial populations in the presence of Corexit 9500. Operational taxonomic unit (OTU) analyses indicated that several OTUs were inhibited by the addition of Corexit. Conversely, a number of OTUs were stimulated by the addition of the dispersant, many of which were identified as known hydrocarbon-degrading bacteria. The results highlight the value of using RNA-based methods to further understand the impact of dispersant on the overall activity of different hydrocarbon-degrading bacterial groups.
authors.affiliation: Department of Biological Sciences, Michigan Technological University, Houghton, Michigan, USA.
authors.forename: Stephen M
authors.identifier: http://orcid.org/0000-0002-8702-9329
authors.initials: SM
authors.lastname: Techtmann
authors.affiliation: Department of Biomedical, Chemical and Environmental Engineering, University of Cincinnati, Cincinnati, Ohio, USA.
authors.forename: Mobing
authors.initials: M
authors.lastname: Zhuang
authors.affiliation: Cranfield Water Science Institute, Cranfield University, Cranfield, United Kingdom.
authors.forename: Pablo
authors.initials: P
authors.lastname: Campo
authors.affiliation: Pegasus, Inc., Cincinnati, Ohio, USA.
authors.forename: Edith
authors.initials: E
authors.lastname: Holder
authors.affiliation: Pegasus, Inc., Cincinnati, Ohio, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: Elk
authors.affiliation: Department of Civil and Environmental Engineering, University of Tennessee, Knoxville, Tennessee, USA.|Center for Environmental Biotechnology, University of Tennessee, Knoxville, Tennessee, USA.
authors.forename: Terry C
authors.identifier: http://orcid.org/0000-0002-2536-9993
authors.initials: TC
authors.lastname: Hazen
authors.affiliation: U.S. Environmental Protection Agency, Cincinnati, Ohio, USA.
authors.forename: Robyn
authors.initials: R
authors.lastname: Conmy
authors.affiliation: U.S. Environmental Protection Agency, Cincinnati, Ohio, USA santodomingo.jorge@epa.gov.
authors.forename: Jorge W
authors.initials: JW
authors.lastname: Santo Domingo
mesh_terms: D001419:Bacteria / Q000145:classification / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D001673:Biodegradation, Environmental; D006838:Hydrocarbons / Q000378:metabolism; D008055:Lipids / Q000494:pharmacology*; D010578:Petroleum / Q000378:metabolism; D059392:Petroleum Pollution / Q000032:analysis; D010802:Phylogeny
chemical_list: D006838:Hydrocarbons; D008055:Lipids; D010578:Petroleum; C470995:corexit 9500
keywords: 16S RNA; Corexit 9500; Gulf of Mexico; dispersant; hydrocarbon; microbial community; oil biodegradation