Enhanced Production of Cellulases by Cellulomonas Strains Grown on Different Cellulosic Residues

Cellulomonas strains consumed commercial cellulose, cellulosic residues, xylan, cellobiose and carboxymethyl cellulose (CMC) as carbon sources in liquid culture, the growth being the most on cellobiose medium. All three components of the cellulase complex of Cellulomonas were produced when the organisms utilized all substrates as sole carbon and energy sources. The filter-paper cellulase (FPase) and endo-glucanase (CMCase) activities were higher in media containing α-cellulose and cellulosic residues than in media containing CMC, cellobiose, and xylan. Cell-free supernatants of all organisms exhibited greater CMC hydrolyzing activity than filter paper and ß-glucoside hydrolyzing activities. All strains synthesized ß-glucosidase maximally on cellobiose followed by commercial cellulose and cellulosic residues. C. biazotea produced the highest FPase and CMCase activity during growth on α-cellulose. It was followed by C. flavigena, C. cellasea, and C. fimi. Endo-glucanase and FPase from all organisms were secreted into the medium; 10-13 % became adsorbed on the surface of the insoluble substrates and could be successfully eluted using Tween 80. ß-Glucosidase was located in cell extracts from all organisms. C. biazotea produced FPase and ß-glucosidase activities several-fold greater than those produced by many other strains of Cellulomonas and some other cellulolytic bacteria and fungi.