Dynamics and distribution of bacterial and archaeal communities in oil-contaminated temperate coastal mudflat mesocosms

Abstract

Mudflats are ecologically important habitats that are susceptible to oil pollution, but intervention is difficult in these fine-grained sediments, and so clean-up usually relies on natural attenuation. Therefore, we investigated the impact of crude oil on the bacterial, diatom and archaeal communities within the upper parts of the diatom-dominated sediment and the biofilm that detached from the surface at high tide. Biodegradation of petroleum hydrocarbons was rapid, with a 50% decrease in concentration in the 0-2 mm section of sediment by 3 days, indicating the presence of a primed hydrocarbon-degrading community.The biggest oil-induced change was in the biofilm that detached from the sediment, with increased relative abundance of several types of diatom and of the obligately hydrocarbonoclastic Oleibacter sp., which constituted 5% of the pyrosequences in the oiled floating biofilm on day-3 compared to 0.6% in the non-oiled biofilm. Differences in bacterial community composition between oiled and non-oiled samples from the 0-2 mm section of sediment were only significant at days 12 to 28, and the 2-4 mm-sediment bacterial communities were not significantly affected by oil. However, specific members of the Chromatiales were detected (1% of sequences in the 2-4 mm section) only in the oiled sediment, supporting other work that implicates them in anaerobic hydrocarbon degradation.Unlike the Bacteria, the archaeal communities were not significantly affected by oil. In fact, changes in community composition over time, perhaps caused by decreased nutrient concentration and changes in grazing pressure, overshadowed the effect of oil for both Bacteria and Archaea. Many obligate hydrocarbonoclastic and generalist oil-degrading bacteria were isolated, and there was little correspondence between the isolates and the main taxa detected by pyrosequencing of sediment-extracted DNA, except for Alcanivorax, Thalassolituus, Cycloclasticus and Roseobacter spp., which were detected by both methods.

Role of environmental factors and microorganisms in determining the fate of polycyclic aromatic hydrocarbons in the marine environment

“…2011; Andrei, Banciu and Oren 2012) as shown by Bertrand et al. (1990), who isolated the first halophilic strain able to degrade PAHs (to a lesser extent than aliphatic hydrocarbons) from a salt marsh, a marine coastal ecosystem where Archaea represent an important component (Sanni, Coulon and McGenity 2015). PAH biodegradation has also been observed under methanogenic conditions (Chang, Um and Holoman 2006).…”

“…2010; Stauffert et al. 2014; Sanni, Coulon and McGenity 2015). Modifications in the composition of archaeal communities have been described during oil spills (Newell et al.…”

Effects of Pollution on Marine Organisms

“…Forties crude oil (a light North Sea crude) to sediments collected from the Colne Estuary, U.K., Sanni et al (2015) observed a 50% decrease in total petroleum hydrocarbon (TPH) (start= 1472.2 µg g-1) in the 0-2 mm sediment interval. The bacterial population was significantly different in the 0-2mm sediment interval in oiled versus non-oiled sediments by day 12, but the archaeal communities did not change.…”

Biosurfactant Production in Sub-Oxic Conditions Detected in Hydrocarbon-Degrading Isolates from Marine and Estuarine Sediments

“…Sediment deposition and bioturbation can contribute to trap PHs in microaerobic or anaerobic sediment layers [34] in which the presence of PHs further enhances the lowering of the redox potential in sediments [35]. So the presence of PH in estuarine sediments is often associated with microaerobic or anaerobic conditions [36] and estuarine sediments are rich in hydrocarbon-degrading bacteria, especially in contaminated areas [37][38][39].Due to the difficult access to submerged sediments and the material and time constraints involved in anaerobic cultivation of bacteria, isolation and characterization of culturable anaerobic bacteria from these sediments if often overlooked. The aim of this work is to isolate and identify bacteria with PH-remediation potential from sub-seafloor sediments, in particular from deep-sea and estuarine sites containing PHs.…”