Extracellular Enzyme Activity Profile in a Chemically Enhanced Water Accommodated Fraction of Surrogate Oil: Toward Understanding Microbial Activities After the Deepwater Horizon Oil Spill

“…The increase in leucine amino-peptidase activity also corresponded to an increase in alkaline phosphatase activity (S3 Fig), consistent with our previous findings [60]. Most of these isolates also showed an increase in the protein content of EPS by up to 5 and 20 folds (Fig 2) suggesting that the increased peptidase activity is related to the increase in the protein content of the EPS of most bacteria.…”

“…Microbial community analysis revealed an overall decrease in prokaryotic diversity in oil treatments compared with controls as observed in several mesocosm studies ( Kleindienst et al, 2015 ; Doyle et al, 2018 ). Furthermore, a higher relative abundance of eukaryotes such as Dinophyceae, Mediophyceae , and Diatomea members and prokaryotes such as oil-degrading Gammaproteobacteria members ( Oceanospirillales, Cellvibrionales , and Alteromonadales ) in the oil treatment are in line with the observations made in the field following the Deepwater Horizon oil spill ( Karthikeyan et al, 2019 ; Hancock et al, 2021 ; Quigg et al, 2021 ) and also by several other mesocosm studies ( Kimes et al, 2013 ; Kleindienst et al, 2015 ; Parsons et al, 2015 ; Almeda et al, 2018 ; Doyle et al, 2018 ; Kamalanathan et al, 2018 ; Bretherton et al, 2019 ; Gutierrez, 2019 ; Barbato and Scoma, 2020 ; Finkel et al, 2020 ). Assessment of co-occurrence of microbes to get insights of possible microbial interactions indicated severe effects of oil with ∼43% lower co-occurrences, which can be attributed to the observed slight decrease in microbial diversity.…”

“…Furthermore, the results of this study suggest that sinking MOS may supply a food source to populations of microbes that associate with and can alter petroleum oils. Parallel studies by our research collaborators certainly show microscopically a high-density population of microbes and enhanced lipase activity associated with microbe–oil aggregates, consistent with the chemical transformations observed here.…”