Influence of PAHs among other coastal environmental variables on total and PAH-degrading bacterial communities

Abstract

We evaluated the relative impact of anthropogenic polycyclic aromatic hydrocarbons (PAHs) among biogeochemical variables on total, metabolically active, and PAH bacterial communities in summer and winter in surface microlayer (SML) and subsurface seawaters (SSW) across short transects along the NW Mediterranean coast from three harbors, one wastewater effluent, and one nearshore observatory reference site. At both seasons, significant correlations were found between dissolved total PAH concentrations and PAH-degrading bacteria that formed a gradient from the shore to nearshore waters. Accumulation of PAH degraders was particularly high in the SML, where PAHs accumulated. Harbors and wastewater outfalls influenced drastically and in a different way the total and active bacterial community structure, but they only impacted the communities from the nearshore zone (<2 km from the shore). By using direct multivariate statistical analysis, we confirmed the significant effect of PAH concentrations on the spatial and temporal dynamic of total and active communities in this area, but this effect was putted in perspective by the importance of other biogeochemical variables.

Biogeochemical cycling and phyto- and bacterioplankton communities in a large and shallow tropical lagoon (Términos Lagoon, Mexico) under 2009–2010 El Niño Modoki drought conditions

“…The sensor was calibrated in the laboratory before the cruises following Tedetti et al (2010) and Sauret et al (2016). In this work, the mean dissolved total PAH concentrations derived from the sensor are given in ng L −1 with a mean coefficient of variation of 10 %.…”

“…A total of 100 µL of each sample was introduced in triplicate into a 48-well microplate with 900 µL of sterile minimum medium, as previously described (Rodríguez-Blanco et al, 2010;Sauret et al, 2016). A mixture of six PAHs from two to five rings (naphthalene, fluorene, phenanthrene, fluoranthene, pyrene, and benzo[a]pyrene) prepared in dichloromethane in equimolar concentration was introduced into each well at a final concentration of 10 µg mL −1 as previously described by Sauret et al (2016). This corresponds to a very high concentration of PAH in nature, i.e.…”

“…Nitrogen fertilization from allochthonous inputs from the Palizada River may be crucial for PAH degradation potential in the Términos Lagoon. Indeed, it is well accepted that bacterial degradation of hydrocarbons (carbon source for bacteria) is dependent on nutrients to re-equilibrate the C : N : P ratio (Sauret et al, 2015(Sauret et al, , 2016. Some halotolerant bacteria such as Marinobacter hydrocarbonoclasticus sp.…”

“…17 (Grimaud et al, 2012) may have the capability to degrade PAHs and survive in rivers, lagoons, and seawater. Further studies using PAH-stable isotopes coupled with pyrosequencing (Dombrowski et al, 2016;Sauret et al, 2016) are necessary to identify the dynamics of these functional communities in the Términos Lagoon. Using similar approaches, previous reports have shown that the pollutant content and PAHs, in particular, were responsible for the bacterial community structure dynamic in the sediment of the Bizerte Lagoon, Tunisia (Ben Said et al, 2010).…”

Effect of Aloe Vera wastes on physico-chemical properties and microbiological activity in soils

“…Among toxic substances contained in aloin, polycyclic aromatic hydrocarbons (PAHs) are known by their harmful effect once in the ecosystem; they are one of the most common groups with known or potential toxic properties [8]. PAHs are a substantial threat to ecological function and soil biodiversity [9].The response of microbial communities to chronic inputs of PAHs [10,11,12] has received little attention compared to the effect of acute contaminations [13,14,15]. Indeed, previous studies demonstrated that PAH change bacterial communities structure and diversity [16,17,18].…”