Central Role of Dynamic Tidal Biofilms Dominated by Aerobic Hydrocarbonoclastic Bacteria and Diatoms in the Biodegradation of Hydrocarbons in Coastal Mudflats

Abstract

<jats:title>ABSTRACT</jats:title><jats:p>Mudflats and salt marshes are habitats at the interface of aquatic and terrestrial systems that provide valuable services to ecosystems. Therefore, it is important to determine how catastrophic incidents, such as oil spills, influence the microbial communities in sediment that are pivotal to the function of the ecosystem and to identify the oil-degrading microbes that mitigate damage to the ecosystem. In this study, an oil spill was simulated by use of a tidal chamber containing intact diatom-dominated sediment cores from a temperate mudflat. Changes in the composition of bacteria and diatoms from both the sediment and tidal biofilms that had detached from the sediment surface were monitored as a function of hydrocarbon removal. The hydrocarbon concentration in the upper 1.5 cm of sediments decreased by 78% over 21 days, with at least 60% being attributed to biodegradation. Most phylotypes were minimally perturbed by the addition of oil, but at day 21, there was a 10-fold increase in the amount of cyanobacteria in the oiled sediment. Throughout the experiment, phylotypes associated with the aerobic degradation of hydrocarbons, including polycyclic aromatic hydrocarbons (PAHs) (<jats:named-content content-type="genus-species">Cycloclasticus</jats:named-content>) and alkanes (<jats:named-content content-type="genus-species">Alcanivorax</jats:named-content>,<jats:named-content content-type="genus-species">Oleibacter</jats:named-content>, and<jats:named-content content-type="genus-species">Oceanospirillales</jats:named-content>strain ME113), substantively increased in oiled mesocosms, collectively representing 2% of the pyrosequences in the oiled sediments at day 21. Tidal biofilms from oiled cores at day 22, however, consisted mostly of phylotypes related to<jats:named-content content-type="genus-species">Alcanivorax borkumensis</jats:named-content>(49% of clones),<jats:named-content content-type="genus-species">Oceanospirillales</jats:named-content>strain ME113 (11% of clones), and diatoms (14% of clones). Thus, aerobic hydrocarbon biodegradation is most likely to be the main mechanism of attenuation of crude oil in the early weeks of an oil spill, with tidal biofilms representing zones of high hydrocarbon-degrading activity.</jats:p>

Estuarine sediment hydrocarbon-degrading microbial communities demonstrate resilience to nanosilver

“…Like Coulon et al (2012), we generally observed high overall rates of crude oil biodegradation in Colne estuary sediments. Furthermore, hydrocarbon biodegradation followed a classical pathway whereby the breakdown of short chain alkanes exceeded that of long chain alkanes and branched alkanes by day 7, and the biodegradation of low ring-number PAHs was greater than that of high ring-number PAHs (Atlas, 1981).…”

“…The present study focused on the Colne estuary, UK, as a model system from which to measure the effect of AgNPs on estuarine microbial communities, due to its susceptibility to oil pollution (Coulon et al, 2012) and the presence of a large wastewater treatment works which is a potential release site for AgNPs (Fig. 1).…”

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

“…2009; Bayen 2012), salt marshes (Duran and Goñi Urriza 2010; Coulon et al. 2012; Chronopoulou et al. 2013), coral reefs (Burns 2014; Ko, Chang and Cheng 2014; Guigue et al.…”

How to Improve Toxicity Assessment? From Single-Species Tests to Mesocosms and Field Studies

“…The characteristics that allow the assessment of exposure of living organisms to contaminants have been highlighted for many different chemicals such as metals and metalloids (Muller et al, 2003;Smolyakov et al, 2010a,b;Bennett et al, 2012;Correia et al, 2013a;Lagauzère et al, 2013), metal-based nanoparticles (Cleveland et al, 2012;Lowry et al, 2012;Buffet et al, 2013Buffet et al, , 2014, veterinary drug ivermectin (Sanderson et al, 2007), algicide Irgarol (Sapozhnikova et al, 2009), many different pesticides (Bromilow et al, 2006;Pablo et al, 2008), brominated flame retardants (de Jourdan et al, 2013), and petroleum hydrocarbons and polyaromatic hydrocarbons (Yamada et al, 2003;Coulon et al, 2012). Studies of behavior and fate of chemicals and oils, in particular in the event of real spills at sea, have been carried out using flume tanks, the most recent of which allow the reproduction of the height and frequency of waves, the exposure of surface slicks to the recreated spectrum of natural light, and air circulation at the water surface (Centre of Documentation, Research and Experimentation on Accidental Water Pollution, http://www.cedre.…”