TRANSFORMATION OF RIFAMYCIN-B WITH GROWING AND RESTING CELLS OF CURVULARIA-LUNATA

Growing and resting cell systems of Curvularia lunata were used for th e transformation of rifamycin B to rifamycin S. In the case of growing cells, rifamycin B was added at the time of inoculation and at the di fferent phases of growth. Interestingly, it was found that C. lunata c ould grow in the presence of rifamycin B and could convert rifamycin B to rifamycin S. Growing cells 24 and 48 h of age were capable of tran sforming rifamycin B. Resting cells, cultivated at the exponential or early stationary phase, were found to be very active, and the resting cells of different ages were repeatedly used for the transformation re action. Growing cells of 72 and 96 h were not capable of transforming rifamycin B, whereas resting cells of similar ages were very active. D ue to the adsorption of rifamycins by the growing and resting cells of C. lunata, the stoichiometric yield of rifamycin S was not obtained.