Skip to main content



Two central paradigms are currently understood to control biodegradation of hydrocarbons in groundwater and sediments: (i) Redox gradients and interphases between compartments are ‘hot-spots’ of for contaminant breakdown, and (ii) biodegradation is primarily limited by local electron acceptor availability, in particular that of oxygen (Lueders, 2017). The POLLOX project now aims to question these established paradigms and to elaborate a ground-breaking new perspective of the role of molecular oxygen in what is currently considered as pollutant degradation in anoxic compartments. POLLOX postulates that oxygen-dependent degradation of pollutants in anaerobic compartments is possible by several emerging physiological adaptations of microbes. During the first 2.5 years of its lifetime, the POLLOX project has embarked successfully on tackling its two central hypotheses, i.e. that (i) long-distance electron transfer by filamentous “cable bacteria” can play a role in biodegradation processes at contaminated sites, and that (ii) NO-dismutating microbes, potentially capable of utilizing oxygen-dependent catabolic pathways under absence of external oxygen can be found in contaminated groundwater.

In a interdisciplinary research endeavour, we have now demonstrated that cable bacteria within the Desulfobulbaceae capable of long-distance electron transfer across redox gradients to oxygen as an electron acceptor can actually be found in contaminated aquifers (Müller et al. 2016). Moreover, we have developed a molecular assay specifically targeting putative NO dismutase genes, revealing a wide diversity and surprising abundance of respective populations in contaminated aquifers and wastewater treatment systems. This discovery suggests that NO dismutation could be a physiology much more widespread than currently perceived. We are currently following up on the ecophysiological and sequencing-based characterisation of these novel populations, using innovative column cultivation systems and cutting-edge labelling-assisted transcriptomics.

The POLLOX project aims to revolutionise the current perception of the role and relevance of molecular oxygen as an agent in contaminant degradation at redox gradients in groundwater, and of how microbes can circumvent physical habitat constraints by limited mixing in porous media. Understanding the controls of these emergent microbial capacities may open new routes for optimized pollutant removal and nitrogen elimination in natural and engineered water systems.