You are here:
Corexit 9500 Enhances Oil Biodegradation and Changes Active Bacterial Community Structure of Oil-Enriched Microcosms
Citation:
Techtman, S., M. Zhuang, P. Campo-Moreno, E. Holder, R. Conmy, J. Santodomingo, T. Hazen, AND M. Elk. Corexit 9500 Enhances Oil Biodegradation and Changes Active Bacterial Community Structure of Oil-Enriched Microcosms. APPLIED AND ENVIRONMENTAL MICROBIOLOGY. American Society for Microbiology, Washington, DC, 83(10):e03462-16, (2017). https://doi.org/10.1128/AEM.03462-16
Impact/Purpose:
COREXIT 9500 is an oil dispersant that is widely used after an oil spill, however, not much is known about its effectiveness in degrading oil and its potential toxin effect on microbial communities. The purpose of this research is to better understand the impact of COREXIT 9500 on microbial communities by using gene sequencing on hydrocarbon enrichments. This work is important because it provides insights on microbial dynamics of hydrocarbon degrading bacteria and the effect of oil dispersants. The results of this work could be applied by private industry or the government when deciding which oil disperant to use.
Description:
While COREXIT 9500 is widely applied after oil spills for its reported dispersing activity, there is still a debate on the effectiveness on enhancing oil biodegradation and its potential toxic effect on microbial communities. To better understand the impact 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 cryophilic and mesophilic conditions and using both DNA and RNA extracts as sequencing templates. Oil biodegradation patterns in both cryophilic and mesophilic enrichments were consistent with those reported in the literature (i.e., aliphatics were degraded faster than aromatics). A slight increase in biodegradation was observed in the presence of COREXIT at both 25°C and 5°C experiments. Differences in community structure were observed between treatment conditions in the DNA-based libraries. The 25°C consortia was dominated by unclassified members of the Vibrio, Pseudoidiomarina, Marinobacter, Alcanivorax, and Thallassospira species, while the 5°C consortia were dominated by several genera of Flavobacteria, Alcanivorax and Oleispira. With the exception of Vibrio-like species, members of these genera have been linked to hydrocarbon degradation and have been observed after oil spills. Colwellia and Cycloclasticus, known aromatic degraders, was also found in these enrichments. RNA-based sequencing of 25°C enrichments showed that Vibrio spp. were less abundant than in the DNA libraries suggesting they were less active in degradation than Thallasospira, Marinobacter, and Pseudoidiomarina which were present at much higher relative abundance in the RNA libraries. RNA-based data of 5°C consortia indicated that Oleispira was greatly stimulated by the addition of oil. The addition of COREXIT did not have an effect on the active bacteria community structure of the 5°C consortia, while at 25°C a decrease in the relative abundance of Marinobacter was observed. OTU-level analysis indicates that several OTUs were inhibited by the addition of COREXIT. Conversely, a number of OTUs were stimulated by the addition of COREXIT. The results of this study provide some insights on the microbial dynamics of hydrocarbon degrading bacterial populations and the effect of dispersants on the relative activity levels of such bacterial groups.
URLs/Downloads:
DOI: Corexit 9500 Enhances Oil Biodegradation and Changes Active Bacterial Community Structure of Oil-Enriched Microcosms
COREXIT 9500 Enhances Oil Biodegrad & Chg Microbial Com
Free access through PubMed Central