Effective bioremediation strategy for rapid in situ cleanup of anoxic marine sediments in mesocosm oil spill simulation

Abstract

The purpose of present study was the simulation of an oil spill accompanied by burial of significant amount of petroleum hydrocarbons (PHs) in coastal sediments. Approximately 1000 kg of sediments collected in Messina harbor were spiked with Bunker C furnace fuel oil (6500 ppm). The rapid consumption of oxygen by aerobic heterotrophs created highly reduced conditions in the sediments with subsequent recession of biodegradation rates. As follows, after 3 months of ageing, the anaerobic sediments did not exhibit any significant levels of biodegradation and more than 80% of added Bunker C fuel oil remained buried. Anaerobic microbial community exhibited a strong enrichment in sulfate-reducing PHs-degrading and PHs-associated Deltaproteobacteria. As an effective bioremediation strategy to clean up these contaminated sediments, we applied a Modular Slurry System (MSS) allowing the containment of sediments and their physical–chemical treatment, e.g., aeration. Aeration for 3 months has increased the removal of main PHs contaminants up to 98%. As revealed by CARD-FISH, qPCR, and 16S rRNA gene clone library analyses, addition of Bunker C fuel oil initially affected the activity of autochthonous aerobic obligate marine hydrocarbonoclastic bacteria (OMHCB), and after 1 month more than the third of microbial population was represented by Alcanivorax-, Cycloclasticus-, and Marinobacter-related organisms. In the end of the experiment, the microbial community composition has returned to a status typically observed in pristine marine ecosystems with no detectable OMHCB present. Eco-toxicological bioassay revealed that the toxicity of sediments after treatment was substantially decreased. Thus, our studies demonstrated that petroleum-contaminated anaerobic marine sediments could efficiently be cleaned through an in situ oxygenation which stimulates their self-cleaning potential due to reawakening of allochtonous aerobic OMHCB.

Substrates specialization in lipid compounds and hydrocarbons of Marinobacter genus

“…This value is higher than the twofold increase observed in anaerobic mesocosm with a CARD-FISH probe exploring only 26 % of Marinobacter sequence (Genovese et al 2014) but are in agreement with augmentation of Marinobacter ribosomal sequences found by pyrosequencing before and after oil pollution in mangrove (dos Santos et al 2011). In our study, Marinobacter reached about 0.3 % of the bacterial community in mesocosms containing hydrocarbon which is lower than the value found with less specific probe in anaerobic mesocosm by Genovese et al (2014). However, comparison between different studies should be taken with caution since other factors could be involved such as sensitivity to the load of petroleum or the selection of some species not detected by qPCR or CAR-FISH or a kinetic effect.…”

“…In a study on the Deep Horizon spill, Marinobacter aquaolei strain VT8 genome (now affiliated with Marinobacter hydrocarbonoclasticus) was the closest match to metatranscriptomes (Lamendella et al 2014). Moreover, in anoxic mesocosm, Marinobacter strain alkB cDNA, coding for a hydroxylase involved in degradation of short-chain alkanes, has been quantitatively detected by qPCR (Genovese et al 2014). These results led some authors to propose the use of sequences of the genus Marinobacter as one of the proxies for oil pollution monitoring (dos Santos et al 2011;Genovese et al 2014;Gray et al 2011).…”

“…Moreover, in anoxic mesocosm, Marinobacter strain alkB cDNA, coding for a hydroxylase involved in degradation of short-chain alkanes, has been quantitatively detected by qPCR (Genovese et al 2014). These results led some authors to propose the use of sequences of the genus Marinobacter as one of the proxies for oil pollution monitoring (dos Santos et al 2011;Genovese et al 2014;Gray et al 2011). Molecular approaches alone are, however, unable to establish a relationship between the presence of a genus and its real ecophysiological role in the studied ecosystem.…”

Dinámica De Poblaciones Bacterianas Y Actividad Deshidrogenasa Durante La Biorremediación De Suelo Recién Contaminado E Intemperizado Con Hidrocarburos

“…En general, los suelos contaminados-intemperizados presentaron una riqueza de especies menor, comparados con los suelos recién contaminados, siendo notoria la disminución en la riqueza a través del tiempo de muestreo. Genovese et al (2014), atribuyeron este comportamiento a la presión de selección ejercida por los contaminantes sobre una comunidad microbiana en SNC, hacia una comunidad formada por microorganismos degradadores y/o resistentes a los hidrocarburos.…”

The metabolic pathways and environmental controls of hydrocarbon biodegradation in marine ecosystems

“…Sherry et al (2014) show that the composition of the crude oil itself may play a critical role as volatile hydrocarbons inhibit biodegradation under methanogenic conditions. Capping and in situ aeration are shown to effectively remediate and detoxify buried oil in anaerobic marine sediments by Genovese et al (2014). Torlapati and Boufadel (2014) present a numerical model that employs genetic algorithms to predict biodegradation kinetics for oil entrapped in sediments.…”