Exposure to Crude Oil and Chemical Dispersant may Impact Marine Microbial Biofilm Composition and Steel Corrosion
Journal Article - Open Access
NAVAL RESEARCH LAB WASHINGTON DC WASHINGTON United States
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The release of hydrocarbons and chemical dispersant in marine environments may disrupt benthic ecosystems, including artificial reefs, formed by historic steel shipwrecks, and their associated organisms. Experiments were performed to determine the impacts of crude oil, dispersed crude oil, and dispersant on the community structure and function of microorganisms in seawater SW and biofilms formed on carbon steel, a common ship hull construction material. Steel corrosion was also monitored to illustrate how oil spills may impact preservation of steel shipwrecks. Microcosms were filled with seawater SW and incubated at 4 degrees C. Carbon steel disks CSDs were placed in each tank, and tanks were amended with crude oil andor dispersant or no treatment. SW and CSD biofilms were sampled biweekly for genetic analysis using Illumina sequencing of 16S ribosomal RNA gene amplicons. Predicted and sequenced bacterial metagenomes were analyzed to examine impacts of oil and dispersant on metabolic function. Gammaproteobacteria, Alphaproteobacteria, and Flavobacteriia dominated SW and biofilms. Bacterial community structure differed significantly between treatments for SW and biofilms. OTUs affiliated with known Pseudomonas and potential Marinomonas hydrocarbon-degraders were roughly twice as abundant in biofilms treated with oil and dispersed oil, and steel corrosion of CSDs in these treatments was higher compared to control and dispersant treatments. OTUs affiliated with the Rhodobacteraceae family biofilm formers and potential oil degraders were less abundant in the dispersant treatment compared to other treatments in biofilm and SW samples, but OTUs affiliated with the Pseudoalteromonas genus biofilm formers and proposed hydrocarbon degraders were more abundant in dispersant-treated biofilms.