CELLULOLYTIC ENZYMES OF RUMEN ANAEROBIC FUNGI ORPINOMYCES-JOYONII ANDCAECOMYCES-COMMUNIS

The rumen anaerobic fungi Orpinomyces joyonii A4 and Caecomyces commun is JB1 were grown on microcrystalline cellulose (MC) and alfalfa hay. The cellular distribution of cellulases produced by these organisms wa s monitored. Fungal cultures were separated into extracellular, intrac ellular and cell wall fractions and assayed for endoglucanase (EG) and beta-glucosidase activity. In both fungal isolates, EG activity was t he highest in the extracellular fraction regardless of the substrate u sed. The beta-glucosidase activity produced by O. joyonii was mainly f ound in the cell wall fraction, On the contrary, the same enzyme activ ity in C. communis predominated in the extracellular fraction. The pol ycentric isolate A4 more efficiently utilized both substrates, produce d more short chain fatty acids (up to 31 mmol/l) and showed higher tot al levels of EG (2744 nmol glucose/h/ml) than the monocentric strain J B1. On the other hand, beta-glucosidase (9033 nmol glucose/h/ml) activ ity was the highest in cultures of C, communis grown on cellulose. In cultures of O. joyonii grown on MC, the production of yellow affinity substance (YAS) with similar properties compared with yellow substance from Clostridium thermocellum was observed. This compound increased t he adsorption of fungal cellulases to MC the temperature and pH range tested.