A new strain, named SYF26, was isolated from the Hei He oligotrophic drinking-water reservoir in China. Based on its phenotypic and phylogenetic characteristics, the isolate was identified as a species of genus Acinetobacter. Strain SYF26 was able to grow at low NH 4 + -N concentrations (5.46 mg l "1 ), and the nitrification rate was 0.064 mg NH 4