Syntrophic Hydrocarbon Degradation in a Decommissioned Off-Shore Subsea Oil Storage Structure

Area of Science:

• Microbiology
• Environmental Science
• Genomics

Background:

• Oil production significantly impacts petroleum reservoir microbial ecology.
• Microbial communities in oil infrastructure are vital for bioremediation, biocorrosion, and H2S production but remain understudied.
• Understanding these microbiomes is critical for environmental risk mitigation, especially during decommissioning.

Purpose of the Study:

• To analyze the planktonic microbial community in the aqueous phase of a subsea oil storage structure.
• To identify dominant microbial lineages and their metabolic potential for hydrocarbon degradation.
• To inform decommissioning strategies for marine infrastructure.

Main Methods:

• Quantification and sequencing of microbial 16S rRNA genes.
• Metagenomic analysis.
• Reconstruction of metagenome-assembled genomes (MAGs).

Main Results:

• A unique microbiome dominated by organisms related to Dethiosulfatibacter and Cloacimonadetes was identified.
• The community exhibited a strong potential for degrading low molecular weight aromatic hydrocarbons.
• Genes involved in interspecies electron transfer and formate/acetate metabolism were widespread, suggesting syntrophic degradation.

Conclusions:

• Genomic data is essential for informing decommissioning strategies in marine environments.
• Hydrocarbon-degrading microbial communities in man-made structures can differ significantly from those in natural marine environments.
• The study expands the known repertoire of hydrocarbon degraders and highlights potential syntrophic processes.