Total mineralization of 2-ethylhexyl nitrate by bacterial cocultures

2-Ethylhexyl nitrate (2-EHN) is a widely-used chemical which is commonly added to diesel oil to boost its cetane index. The 2-EHN molecule is recalcitrant to biodegradation but still utilized as sole carbon source by Mycobacterium austroafricanum IFP 2173. The incomplete degradation of 2-EHN by this strain results in the accumulation of an intermediary metabolite i.e. 4-ethyldihydrofuran-2(3H)-one (4-EDF). The study aimed at isolating 4-EDF degraders in order to achieve total mineralization of 2-EHN in cocultures with M. austroafricanum IFP 2173. Bacterial isolates were obtained from diesel-contaminated soil by enrichment in serial cultures supplemented with 4-EDF, the degradation of which was monitored by CO₂ measurements. Two strains were isolated and identified as Bacillus cereus and Burkholderia sp., respectively. Complete mineralization of 2-EHN was achieved by associating M. austroafricanum IFP 2173 with either bacterial isolate in cocultures. In the context of environmental acceptability, efficient degradation of a potentially persistent pollutant by a bacterial consortium is demonstrated.