Comparative Proteomics of Marinobacter sp. TT1 Reveals Corexit Impacts on Hydrocarbon Metabolism, Chemotactic Motility, and Biofilm Formation.

Saskia Rughöft,Sara Kleindienst,Tony Gutierrez,Nico Jehmlich

doi:10.3390/microorganisms9010003

Abstract

The application of chemical dispersants during marine oil spills can affect the community composition and activity of marine microorganisms. Several studies have indicated that certain marine hydrocarbon-degrading bacteria, such as Marinobacter spp., can be inhibited by chemical dispersants, resulting in lower abundances and/or reduced biodegradation rates. However, a major knowledge gap exists regarding the mechanisms underlying these physiological effects. Here, we performed comparative proteomics of the Deepwater Horizon isolate Marinobacter sp. TT1 grown under different conditions. Strain TT1 received different carbon sources (pyruvate vs. n-hexadecane) with and without added dispersant (Corexit EC9500A). Additional treatments contained crude oil in the form of a water-accommodated fraction (WAF) or chemically-enhanced WAF (CEWAF; with Corexit). For the first time, we identified the proteins associated with alkane metabolism and alginate biosynthesis in strain TT1, report on its potential for aromatic hydrocarbon biodegradation and present a protein-based proposed metabolism of Corexit components as carbon substrates. Our findings revealed that Corexit exposure affects hydrocarbon metabolism, chemotactic motility, biofilm formation, and induces solvent tolerance mechanisms, like efflux pumps, in strain TT1. This study provides novel insights into dispersant impacts on microbial hydrocarbon degraders that should be taken into consideration for future oil spill response actions.

Highlights

Chemical dispersants are routinely applied during major marine oil spills to break up surface slicks and disperse oil in the water column
Different macroscopic growth patterns were observed between these treatments with a classical homogeneous increase in optical density in pyruvate-containing cultures and growth in differently sized aggregates in the other three treatments (Corexit: barely visible aggregates; n-hexadecane: thin biofilm at water-HC interface and approximately 1-mm-sized aggregates in medium; n-hexadecane + Corexit: large, thin aggregates ranging from 1–1.5 cm size; Figure S2)
Gates in medium; n-hexadecane + Corexit: large, thin aggregates ranging from 1–1.5 cm size; Figure S2)

Summary

Introduction

Chemical dispersants are routinely applied during major marine oil spills to break up surface slicks and disperse oil in the water column. Following the Deepwater Horizon (DWH) oil spill in the Gulf of Mexico in 2010, for instance, seven million liters of dispersants (Corexit EC9500A and EC9527A) were applied in response to the release of an estimated. Members of the genus Marinobacter, in particular, have been shown to become negatively affected by chemical dispersant exposure [3,4,7,13,15]. This genus includes several ubiquitous marine HC degraders that often represent alkane-degrading key players responding to oil spillage in the marine environment [4,8,16]. Recent work in our group with Marinobacter sp. strain TT1 has demonstrated that this strain is able to grow on Corexit EC9500A as sole carbon and energy source [17], similar to other marine

Methods

Results

Conclusion