Different synthetic chemical dispersants elicit distinct bacterial community responses to crude oil (2017)

Dispersants are commonly used worldwide as a primary response tool to treat oil spills at sea, yet their use is debated due to their toxicological effects and potential to affect oil biodegradation rates. Here, we examined the effect of three globally-stockpiled synthetic chemical dispersants (Superdispersant 25, Slickgone EW, Slickgone NS) on the microbial response to crude oil and its biodegradation in a subarctic marine environment during the winter of 2015 and fall of 2017. Using 16S rRNA gene amplicon sequencing, the communities were found to be rich in oil-degrading taxa, such as Alcanivorax, Thalassospira, and Alteromonas. Discriminating ASVs were differentially increased in the dispersant-amended 2015 studies, represented by members of Sulfitibacter, Thalassospira, Hyphomonadaceae, Alteromonas, Pseudoalteromonas and Celeribacter. In the 2017 studies, members of Alteromonas, Alcanivorax, Zhongshania, Methylophilaceae and Arenicellaceae became predominantly enriched. The distinction between treatments was much greater for the 2015 than the 2017 studies. Notably, Superdispersant 25 enriched for Dokdonia, Formosa, Acinetobacter, Marinobacter, Halomonas, Oceanicaulis, Thalassospira, Sedimentitalea, Oleibacter and Roseobacter. The communities exposed to Slickgone ES or Slickgone NS had Marinomonas and Colwellia as part of their core microbiome. Slickgone ES enriched for Psychromonas and Alcanivorax, while the addition of oil enriched for members of Caulobacteraceae, Methylophilaceae and Sphingomonadaceae. In the 2017 studies, we quantified the degradation of various hydrocarbon species in the oil treatments using GC-MS, and applied Data Integration Analysis for Biomarker discovery using Latent variable approaches for Omics studies (DIABLO) to integrate hydrocarbon degradation data with the microbial populations. This showed a number of taxa were negatively correlated to hydrocarbons – i.e. they increased when the hydrocarbon was reduced – and included Aquibacter, Hyphomonas, Thalassospira, Alteromonas, Sphingopyxis, and Paralucidibaca.