The ecology of anaerobic degraders of BTEX hydrocarbons in aquifers

Abstract

The degradation of benzene, toluene, ethylbenzene and xylene (BTEX) contaminants in groundwater relies largely on anaerobic processes. While the physiology and biochemistry of selected relevant microbes have been intensively studied, research has now started to take the generated knowledge back to the field, in order to trace the populations truly responsible for the anaerobic degradation of BTEX hydrocarbons in situ and to unravel their ecology in contaminated aquifers. Here, recent advances in our knowledge of the identity, diversity and ecology of microbes involved in these important ecosystem services are discussed. At several sites, distinct lineages within the Desulfobulbaceae, the Rhodocyclaceae and the Gram-positive Peptococcaceae have been shown to dominate the degradation of different BTEX hydrocarbons. Especially for the functional guild of anaerobic toluene degraders, specific molecular detection systems have been developed, allowing researchers to trace their diversity and distribution in contaminated aquifers. Their populations appear enriched in hot spots of biodegradation in situ. 13C-labelling experiments have revealed unexpected pathways of carbon sharing and obligate syntrophic interactions to be relevant in degradation. Together with feedback mechanisms between abiotic and biotic habitat components, this promotes an enhanced ecological perspective of the anaerobic degradation of BTEX hydrocarbons, as well as its incorporation into updated concepts for site monitoring and bioremediation.

Geological gas‐storage shapes deep life

“…We can hypothesise that close to the reservoir of natural gas, dissolved hydrocarbons (i.e., short-chain alkanes, BTEX) may serve as exogenous nutrients and could be key factor shaping the composition of the communities. The literature on the topic is full of examples of the capacity of deltaproteobacteria and Firmicutes to grow on these organic molecules (Meckenstock et al, 2016;Lueders, 2017). Microbial communities populating subsurface environments have demonstrated such capacity for the biodegradation of hydrocarbons in the laboratory and in situ.…”

Spatial Pattern of Bacterial Community Diversity Formed in Different Groundwater Field Corresponding to Electron Donors and Acceptors Distributions at a Petroleum-Contaminated Site

“…The electron acceptors were consumed in a certain order, with O 2 consumed first, followed by NO reduction, and methane production, respectively [16]. Samples MW3 and MW17 were associated with high Fe 2+ and low SO 4 2− , which indicated that the electron acceptors Fe 3+ and SO 4 2− had been consumed, these two samples probably were in the methanogenesis stage.…”

“…Ai-xia Zhou researched the responses of microbial communities to seasonal fluctuations in groundwater level and found that groundwater-table fluctuations would affect the distribution, transport, and biodegradation of the contaminants [15]. Petroleum compounds can be transported from the source area in groundwater, with the result that the petroleum concentrations, redox conditions, biogeochemical processes, and bacterial communities would vary along the groundwater flow path [16]. This view can be supported by other related research, such as from Karolin Tischer, Etienne Yergeau and C.E.…”

Plant-bacteria synergism: An innovative approach for the remediation of crude oil-contaminated soils

“…A large variety of microorganisms (bacteria and archaea) have been identified with the capability to degrade hydrocarbon molecules anaerobically. These bacteria exploit anaerobic respiration via nitrate, nitrite, and metal ions or fermentation during substrate catabolism (Lueders, 2017;Portugal et al, 2017).…”

“…Likewise, this kind of biodegradation can happen beneath the surface of areas where aerobic biological activity has been ceased as all the oxygen is used. After oxygen exhaustion, there may be a consecutive employment of the electron acceptors (nitrate, ferric iron, sulphate, and hydrogen) to supply energy from the hydrocarbon mineralization (Aktas et al, 2017;Arulazhagan et al, 2017;Ghattas et al, 2017;Lueders, 2017).…”