Evaluation of Amycolatopsis mediterranei VA18 for production of rifamycin-B

Comparative studies were performed to develop a fermentation process for th e production of rifamycin-B using Amycolatopsis mediterranei VA18. Wheat br an as substrate in solid state fermentation (SSF), and peanut meal and soyb ean with glucose were used as substrate for submerged fermentation (SmF). V arious process parameters including moisture and pH of the substrate, inocu lum size, temperature and period of incubation were optimised for rifamycin -B production. For SmF, the optimal conditions were 10% (v/v) inoculum, pH 7.2, incubation temperature 30 degreesC with a fermentation period of 6 day s. When SmF was carried out in fermenter with controlled aeration (1.5 vvm) and dissolved oxygen level (80%), rifamycin production increased to about 1.5-fold greater than the flasks. SSF was, in general, superior to SmF cond ucted in flasks or fermenter. Optimal conditions for SSF were 7.2 substrate pH, 30% (v/v) inoculum size and incubation at 32 degreesC for 9 days. As t he content of substrate moisture increased in SSF, rifamycin production als o increased and highest yields were obtained when fermentation was carried out using 90% moisture which led practically to semi-solid-to-slurry condit ions of fermentation. With 70% substrate moisture (SSF conditions), rifamyc in production was about 15 g/kg which was about 31 g/kg with 80% moisture. Maximum production (rifamycin-B, 39 g/kg substrate) was obtained with 90% s ubstrate moisture, which was almost 16-fold higher than that obtained in th e fermenter (SmF). Ethyl acetate appeared as the most suitable organic solv ent for the extraction of the antibiotic from the fermented material. (C) 2 000 Published by Elsevier Science Ltd. All rights reserved.