Isolation and identification of bacteria responsible for simultaneous anaerobic ammonium and sulfate removal

Sulfate-dependent anaerobic ammonium oxidation is a novel biological reaction, in which ammonium is oxidized with sulfate as the electron acceptor under anoxic conditions. Ammonium and sulfate are cosmopolitan chemical species which are an integral part of the global nitrogen and sulfur cycles. A detailed exploration of sulfate-dependent anaerobic ammonium oxidation is quite practical. In this work, a bacterial strain named ASR has been isolated from an anaerobic ammonia and sulfate removing reactor working under steady-state. On the basis of electron microscopy, physiological tests and 16S rDNA phylogenetic sequence analysis, the strain ASR is found to be related to Bacillus benzoevorans. According to the biological carbon source utilization test, the strain ASR could use many carbon sources. Its optimum pH value and temperature were 8.5 and 30 degrees C, respectively. The test proves that the strain ASR is able to use sulfate to oxidize ammonia anaerobically. The maximum ammonia and sulfate removal rates were 44.4% and 40.0%, respectively. The present study provided biological evidence for the confirmation and development of sulfate-dependent anaerobic ammonium oxidation and brought new insights into the global nitrogen and sulfur cycles.