Approved Abstracts

Effect of crude oil WAF and WAF+ Dispersant on benthic active bacterial communities from cold environment

Author(s): University of the Basque country; University of Pau; University of the Basque country;
Presenter: Tamer Abdelaziz

Oil spill pollution is an emerging problem facing cold environments. Due to the harsh environmental condition, microbial biodegradation is the most cost effective method for oil spill remediation. However, low temperature yields slow biodegradation processes, therefore, dispersant is usually added to stimulate degradation rates. In this study, we investigated the effects of Water Accommodated Fraction (WAF), with and without the addition of dispersant, on the sediment resident and active microbial communities using ribosomal RNA and DNA microbial sequences. We conducted a 21 days microcosm experiment at 4 °C with WAF and WAF+ Dispersant, using sediment from two contrasted environments: pristine and contaminated sediments. Results have shown that both sediments had different microbial communities with different behavior in response to the addition of WAF or WAF+ Dispersant. Compared to pristine sediment, contaminated sediment had more taxa responsive to the addition of WAF or WAF+ Dispersant. Such result suggested that microbial community inhabiting contaminated sediment were adapted to the presence of hydrocarbon, containing hydrocarbon degraders and/or taxa that are responsive to dispersant. During the experiment, the decrease of PAHs concentrations was consistent with the patterns of abundances of microbial predicted functions, showing that the microbial communities inhabiting both sediments were able to degrade low molecular weight (LMW) PAHs faster than high molecular weight (>3 rings; HMW) PAHs, further enhanced by the presence of dispersant. Our study demonstrates that WAF biodegradation was efficient under cold conditions, particularly in PAH-adapted microbial communities inhabiting contaminated sediments. Such capacity relies on the legacy effect representing an “immunization” to the presence of hydrocarbons, possible even in cold environment.
Funded: Basque Government (IT810-13), UPV/EHU (cotutelle predoctoral grant to TH), EU (GRACE project, grant No 679266).

Keywords: Water Accommodated Fraction; Microbial communities; Dispersant




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