The resting cells of a 2-deoxystreptamine idiotrophic mutant of Micromonosporasagamiensis were found to transform sisomicin into gentamicin Cla and sagamicin. The biotransformation products were isolated by a combination of ion exchange and carbon column chromatographic procedures, and properly identified. Antibiotic G-52 (G'-A^methylsisomicin) was not detected in the transformation products. Gentamicin Cla was formed at an early stage of the biotransformation, followed by sagamicin formation. The (4',50-reduction of sisomicin mayoccur first, followed by 6'-iV-methylation.By use of a similar procedure, it was demonstrated that verdamicin was transformed into gentamicin C2a (the 6'-C epimer ofgentamicin C2), C2, and then Q. Carbon TLC clearly separated gentamicin C2a, C2, and verdamicin. In this biotransformation, the (4/,5/)-reduction of verdamicin occurred first, followed by 6/-C-epimerization, and then 6/-7V-methylation. In contrast with M. sagamiensis, M. zionensis NRRL5466and M. inyoensis NRRL3292did not possess any detectable activity of the (4',5 ')-re(iiiction of sisomicin or verdamicin. Alternatively, NRRL5466transformed sisomicin into antibiotic G-52, and verdamicin into a new antibiotic, VF3-1. The antibiotic VF3-1 was suggested as 6/-7V-methylverdamicin by chromatographic and mass spectrum data. The implications of these findings were discussed in relation to sagamicin biosynthesis in M. sagamiensis.In a previous report,1} it was demonstrated that resting cells of a 2-deoxystreptamine (DOS) idiotrophic mutant of Micromonospora sagamiensis transformed gentamicin minor components into sagamicin and gentamicin C. During these studies, transformation of sisomicin-group antibiotics was examined. As shown in Fig. 1 Sagamicin biosynthesis was discussed on the basis of these findings. MATERIALS AND METHODSMicroorgan isms. Micromonospora sagam iens is KYI1525 (a DOS idiotroph derived from a sagamicin producer, KY1 1505),5) M. inyoensis NRRL3292, and M. zionensis NRRL5466were used.Media and culture condition. The compositions of the seed and fermentation media and culture condition were described in a previous paper.1)

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