Isolation and identification of an oligotrophic and aerobic denitrification and its denitrification characteristics

The purpose was to characterize a newly isolated strain obtained from reservoir sediments and designated PY8,with respect to degrade nitrate.The strain was isolated by special domestication in liquid medium with nitrate as sole nitrogen source,which also had a desirable denitrification performance under aerobic and oligotrophic conditions.The phylogenetic tree of the strain was produced on the basis of morphology observation by SEM,experimental results of physiology and biochemistry and analysis of 16S rDNA sequence.The strain was identified as Rhizobium sp.The effects of initial pH,temperature,C/N ratio,initial sodium nitrate concentration and dosage on nitrate reduction activity as well as heterotrophic nitrification performance were investigated.The results indicated that the nitrate removal efficiency of PY8 strain could reach more than 95% after 72 h,under conditions of initial pH 6.0～10.0,temperature 25～30 ℃,C/N ratio 1.0～9.0,initial sodium nitrate concentration 0.01～0.50 g·L-1 and dosage 1%～15%.Also,the strain PY8 had a good ability of simultaneous nitrification and denitrification,and the ammonia removal efficiency could reach 58% during the culture.The study showed that strain PY8 had great potential in the biodenitrification of micro-polluted water.