Fifty actinomycete strains isolated from 19 acid soil samples collected from Hunan and Yunnan provinces could grow on media at pH4.5 and pH7.0. Thirty-eight actinomycete strains isolated from 14 alkaline soil samples collected from Xinjiang, Qinghai and Yunnan provinces could grow on media at pH10.0 and pH7.0. Thus, they were moderately acidophilic or moderately alkalophilic actinomycetes. Twelve linear plasmids and 3 circular plasmids were detected among the 88 strains by the pulsed-field gel electrophoresis and standard alkaline-denaturation procedure, respectively.