Microorganisms involved in anaerobic benzene degradation

Benzene is a highly toxic compound. Moreover, benzene-contaminated groundwater is a widespread problem caused mainly by the lack of oxygen in the subsurface. Longterm exposure may cause leukaemia. However, pure cultures of microorganisms with the ability to degrade benzene anaerobically have recently been isolated from novel enrichment cultures. The novel pure cultures include the hyperthermophilic archaeon Ferroglobus placidus and the Geobacter strains Ben and metallireducens which degrade benzene anaerobically coupled to the reduction of Fe(III). Syntrophic interactions have been suggested in enrichments where members of the Peptococcaceae within the class Clostridia are the dominant organisms and suggested as being responsible for the first attack on the benzene ring. Laboratory enrichment studies have also resulted in the development of consortia which degrade benzene, with different terminal electron acceptors supporting the syntrophy. Other benzene-degrading microorganisms have been identified under methanogenic conditions, involving the reduction of humic acids by, for example, the deltaproteobacterium Hasda-A and members of the Betaproteobacteria, Gammaproteobacteria and Deltaproteobacteria, respectively. This review focuses on the microorganisms involved in anaerobic benzene degradation under conditions involving several electron acceptors in recent years. Information related to the anaerobic degradation of benzene is critical to understanding and predicting the fate of this contaminant in groundwater.