ABSTRACT
The fermentation broth of one actinomycete strain ACMA006 strongly inhibited growth of many tumor cells and some microorganisms, but its cytotoxicity to human normal cells were weak. Strain ACMA006 grow well on most tested media, producing exuberant vegetative hyphae and aerial hyphae. Its optimization temperature is 28?C. Phyloge-netic analysis based on 16S rDNA sequence showed that strain ACMA006 was closely related to one of the genus Streptomycetes (S.cavourensis subsp. washingtonensis) with 16S rDNA sequence similarity values of 100%, but had many differences in other features including its morphology, physiological and biochemical characteristics. The pre-liminary study supported the view that the strain ACMA006 represented a new strain of the S.cavourensis subsp. wash-ingtonensis.