Corexit 9500 Enhances Oil Biodegradation and Changes Active Bacterial Community Structure of Oil-Enriched Microcosms

Journal Article · 09 March 2017 · Applied and Environmental Microbiology

DOI: https://doi.org/10.1128/AEM.03462-16 · OSTI ID:1474527

Techtmann, Stephen M.  ^[1]; Zhuang, Mobing ^[2]; Campo, Pablo ^[2]; Holder, Edith ^[3]; Elk, Michael ^[3]; Hazen, Terry C.  ^[4]; Conmy, Robyn ^[5]; Santo Domingo, Jorge W. ^[5]

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1. Michigan Technological Univ., Houghton, MI (United States)
2. Univ. of Cincinnati, OH (United States)
3. Pegasus, Inc., Cincinnati, OH (United States)
4. Univ. of Tennessee, Knoxville, TN (United States)
5. US Environmental Protection Agency (EPA), Cincinnati, OH (United States)

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, andOleispira. Most 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°CWhile 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.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1474527
• Alternate ID(s): OSTI ID: 1479312
• Journal Information: Applied and Environmental Microbiology, Journal Name: Applied and Environmental Microbiology Journal Issue: 10 Vol. 83; ISSN 0099-2240
• Publisher: American Society for MicrobiologyCopyright Statement
• Country of Publication: United States
• Language: English