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, 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 oilmore » 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.« less

Authors:

Techtmann, Stephen M.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-8702-9329"
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Zhuang, Mobing ^[2]; Campo, Pablo ^[2]; Holder, Edith ^[3]; Elk, Michael ^[3]; Hazen, Terry C.  ^[4];

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• Search DOE PAGES for ORCID "0000-0002-2536-9993"
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Conmy, Robyn ^[5]; Santo Domingo, Jorge W. ^[5]

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+ Show Author Affiliations

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)

Publication Date:

2017-03-10

Research Org.:

Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1474527

Alternate Identifier(s):

OSTI ID: 1479312

Grant/Contract Number:  

AC05-00OR22725; AC02-05CH11231

Resource Type:

Accepted Manuscript

Journal Name:

Applied and Environmental Microbiology

Additional Journal Information:

Journal Volume: 83; Journal Issue: 10; Journal ID: ISSN 0099-2240

Publisher:

American Society for Microbiology

Country of Publication:

United States

Language:

English

Subject:

59 BASIC BIOLOGICAL SCIENCES