Microbial oil-degradation under mild hydrostatic pressure (10 MPa): which pathways are impacted in piezosensitive hydrocarbonoclastic bacteria?

Alberto Scoma,Nico Boon,Sara Borin,Francesca Mapelli,Marta Barbato,Emma Hernandez-Sanabria,Daniele Daffonchio

doi:10.1038/srep23526

Alberto Scoma, Nico Boon + Show 5 more

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https://doi.org/10.1038/srep23526

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Abstract

Oil spills represent an overwhelming carbon input to the marine environment that immediately impacts the sea surface ecosystem. Microbial communities degrading the oil fraction that eventually sinks to the seafloor must also deal with hydrostatic pressure, which linearly increases with depth. Piezosensitive hydrocarbonoclastic bacteria are ideal candidates to elucidate impaired pathways following oil spills at low depth. In the present paper, we tested two strains of the ubiquitous Alcanivorax genus, namely A. jadensis KS_339 and A. dieselolei KS_293, which is known to rapidly grow after oil spills. Strains were subjected to atmospheric and mild pressure (0.1, 5 and 10 MPa, corresponding to a depth of 0, 500 and 1000 m, respectively) providing n-dodecane as sole carbon source. Pressures equal to 5 and 10 MPa significantly lowered growth yields of both strains. However, in strain KS_293 grown at 10 MPa CO2 production per cell was not affected, cell integrity was preserved and PO43− uptake increased. Analysis of its transcriptome revealed that 95% of its genes were downregulated. Increased transcription involved protein synthesis, energy generation and respiration pathways. Interplay between these factors may play a key role in shaping the structure of microbial communities developed after oil spills at low depth and limit their bioremediation potential.

Highlights

Oil spills represent an overwhelming carbon input to the marine environment that immediately impacts the sea surface ecosystem
We focused on the effects exerted by mild pressure increases (0.1, 5 and 10 MPa, corresponding to 0, 500 and 1000 m depth) on two strains belonging to different species of the genus Alcanivorax, namely A. jadensis KS_339 and A. dieselolei KS_293, which were isolated from surface waters of the Mediterranean Sea
When cells were incubated under the highest pressure (10 MPa) net growth was comparable between the two strains and lower than that observed at 0.1 MPa (P < 0.05) (Fig. 1a)

Summary

Introduction

Oil spills represent an overwhelming carbon input to the marine environment that immediately impacts the sea surface ecosystem. Increased transcription involved protein synthesis, energy generation and respiration pathways Interplay between these factors may play a key role in shaping the structure of microbial communities developed after oil spills at low depth and limit their bioremediation potential. Temperature, pH, nutrient and O2 availability are known to affect the structure of seawater microbial communities[3] along with the alkane profile of the spilled oil, thereby determining the long-term impact of oil spills. Another critical factor for oil biodegradation at sea is hydrostatic pressure. Other critical factors such as pH and salinity are not as remarkably affected by depth as pressure, while temperature varies significantly in this zone to a lower extent with respect to pressure and depending on latitude and season[14]

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