Nitrite as agent selecting anaerobic phenol-degrading microflora in petroleum refining sediments

The degradation of phenol by microflora of petroleum refining sediments grown under conditions favouring denitrification was studied. Incubation of sediments at 30 and 55°C in medium with phenol and nitrate resulted in complete reduction of nitrate accompanied by accumulation of nitrite. When the sediments were incubated at 30°C in medium with nitrite, phenol was efficiently removed at nitrite concentrations not exceeding 185 mg NO2−-N l−1. Prolonged pressure of phenol (2.6 mM) and nitrite (8.2–20 mM) on the microflora of the sediments (three consecutive passages) resulted in gradual loss of denitrification activity with unaltered phenol activity. The microflora selected from the sediments demonstrated higher phenol activity in medium without external electron acceptor than in media with NO3−, NO2− or SO42−.