Stabilization of rifamycin-B oxidase fromCurvularia lunata

The present investigation deals with the stabilization of rifamycin-B oxidase activity in the culture filtrate ofCurvularia lunata using various methods. It was found that rifamycin-B oxidase activity in the culture filtrate was stable up to 5 days at 5°C, degrading thereafter due to microbial contamination. The stabilization of enzyme activity was carried out by (i) concentration of culture filtrate and (ii) lyophilization, the activity remaining intact for 24 and 75 days, respectively. In another method, the enzyme activity was preserved by addition of 25–30% glycerol to the culture filtrate and the storability of enzyme activity then increased up to 90 days at 5°C. The conversion of rifamycin-B to rifamycin-S using the stabilized rifamycin-B oxidase and fresh culture filtrate were comparable when run under similar conditions. The recovery of rifamycin-S powder from these experiments was not affected in any way in the presence of glycerol. Therefore, the present method of preservation of rifamycin-B oxidase may find industrial application for commerical production of rifamycin-S, which is an important intermediate for the synthesis of an antituberculosis drug, rifamycin.