Effects of Dispersants and Biosurfactants on Crude-Oil Biodegradation and Bacterial Community Succession

Abstract

This study evaluated the effects of three commercial dispersants (Finasol OSR 52, Slickgone NS, Superdispersant 25) and three biosurfactants (rhamnolipid, trehalolipid, sophorolipid) in crude-oil seawater microcosms. We analysed the crucial early bacterial response (1 and 3 days). In contrast, most analyses miss this key period and instead focus on later time points after oil and dispersant addition. By focusing on the early stage, we show that dispersants and biosurfactants, which reduce the interfacial surface tension of oil and water, significantly increase the abundance of hydrocarbon-degrading bacteria, and the rate of hydrocarbon biodegradation, within 24 h. A succession of obligate hydrocarbonoclastic bacteria (OHCB), driven by metabolite niche partitioning, is demonstrated. Importantly, this succession has revealed how the OHCB Oleispira, hitherto considered to be a psychrophile, can dominate in the early stages of oil-spill response (1 and 3 days), outcompeting all other OHCB, at the relatively high temperature of 16 °C. Additionally, we demonstrate how some dispersants or biosurfactants can select for specific bacterial genera, especially the biosurfactant rhamnolipid, which appears to provide an advantageous compatibility with Pseudomonas, a genus in which some species synthesize rhamnolipid in the presence of hydrocarbons.

Exploration of marine bacterioplankton community assembly mechanisms during chemical dispersant and surfactant‐assisted oil biodegradation

“…Although having a similar community composition initially, the community dynamics in the biosurfactant‐dispersed oil microcosms became very distinct from that amended with chemically dispersed oil over time, suggesting that biosurfactants and dispersants select for different species. A similar outcome was observed in a more recent work comparing multiple chemical dispersants to rhamnolipid (Thomas et al., 2021 ). However, most studies investigating the effects of dispersant on microbial community have only relied on metagenomic and/or proteomic analyses to describe and measure the effect of dispersants on individual taxonomic groups (e.g., obligate hydrocarbon‐degrading species) and not on a community level in terms of assembly.…”

Assessment of Hydrocarbon Degradation Potential in Microbial Communities in Arctic Sea Ice

“…Therefore, bioremediation techniques, such as harnessing the potential of oil compound degradation by indigenous microbes, have been suggested to be more suitable for such regions due to their relatively easy implementation, cost-effectiveness, and smaller impact on the environment [11,12]. In natural marine environments, the biodegradation of crude oil involves a succession of species in microbial consortia [13]. Microorganisms in the sea, free-living or associated with others, have been studied in laboratories by applying culturing techniques [14,15].…”

Response and oil degradation activities of a northeast Atlantic bacterial community to biogenic and synthetic surfactants

“…Similar results were found in a more recent study in which rhamnolipid, trehalose, and sophorolipid biosurfactants were compared to three commercial dispersants in oiled microcosms with marine coastal water. Although the biosurfactants caused differential microbial responses, the rate of alkane biodegradation was similar to the microcosms amended with dispersants [ 19 ].…”