TRANSFORMATION OF RIFAMYCIN-B WITH SOLUBLE RIFAMYCIN OXIDASE FROM CURVULARIA-LUNATA

Transformation of rifamycin B to rifamycin S using soluble rifamycin o xidase from Curvularia lunata was carried out in shake flask and in a reactor. Optimum transformation temperature was found to be at 50-degr ees-C but, from the practical point of view, all the transformation re actions were carried out at 28-degrees-C. In non-stirring condition it took 50 h to transform the 1% (w/v) solution of rifamycin B, while in stirring condition (200 rpm) it took only 3 h. Five percent enzyme so lution (activity 11 IU ml-1) was found to be optimum for the transform ation reaction. An aeration rate of 1-1.5 vvm was maintained during tr ansformation reaction in a batch reactor. With higher substrate concen tration (3%, w/v) it took more time (7 h) to complete the transformati on than with 1% (w/v) rifamycin B (3 h). A few drops of antifoam (poly propylene glycol) was effective in suppressing the foam formed during aeration in the reactor and it did not interfere in the isolation of r ifamycin S.