An actinomycete isolate designated as TS-1980 with multiple resistance to aminoglycoside antibiotics was found to produce novel antibiotics. The strain showed taxonomic features identical to the type strain of Nocardiopsis mutabilis except for the temperature range for growth and the utilization of mannitol and raffinose. Based on the capability of growing at lower temperature range, the strain was named N. mutabilis subsp. cryophilis subsp. nov. Physico-chemical and biological characterization of a purified antibiotic revealed its novel polyamine-type nature with a broad antimicrobial activity. The antibiotic was named dopsisamine.As reported previously1,2), naturally-occurring actinomycete strains with multiple resistance to wide ranges of aminoglycoside (AG) antibiotics show a high probability of antibiotic production.