DEGRADATION AND UTILIZATION OF GRASS CELL-WALLS BY ANAEROBIC FUNGI ISOLATED FROM YAK, LLAMA AND SHEEP

Anaerobic fungi were isolated from the rumen fluid of sheep and from t he faeces of llama and yak. Based on morphology and growth characteris tics, five isolates were identified as Neocallimastix species. One spe cies, isolated from rumen fluid, showed properties characteristic for Piromyces. Ah the isolates were able to grow on cell walls isolated fr om perennial rye-grass. Neocallimastix species degraded the cell walls to a very high extent (89%) and were more efficient in cell wall degr adation than Piromyces (64%). The major cell wall monosaccharides, glu cose, xylose and arabinose were almost completely removed from the wal ls. Formate, acetate and hydrogen were the major end-products of ferme ntation, with lesser amounts of ethanol and lactate and only minor amo unts of succinate being produced. All strains secreted cell wall degra ding enzymes, including exoglucanase, endoglucanase, beta-glucosidase, xylanase and beta-xylosidase. Cellulolytic enzyme activities were hig hest in Neocallimastix species while xylanolytic enzyme activities wer e relatively high in the Piromyces culture.