DEGRADATION OF PERENNIAL RYEGRASS LEAF AND STEM-CELL WALLS BY THE ANAEROBIC FUNGUS NEOCALLIMASTIX SP STRAIN CS3B

The degradation of cell walls isolated from stems and leaves of perenn ial ryegrass by the anaerobic fungus Neocallimastix sp. strain CS3b wa s studied in a defined medium, The combined cellulose and hemicellulos e fraction represented 53.1 (wt/wt) and 63.3% (wt/wt) of the dry weigh t of control grass leaf and stem cell walls, respectively, In both lea f and stern cell walls, glucose was the major neutral monosaccharide, followed by xylose, arabinose, and galactose. After 2 days of fermenta tion with Neocallimastix sp. strain CS3b, treated cell walls contained smaller amounts of neutral sugars compared with those of undigested c ell walls. These results were more evident for glucose, xylose, and ar abinose than for galactose, Furthermore, the sugar content of leaf cel l walls decreased before a decline in the sugar content of stem cell w alls was observed, Data from formate and hydrogen production indicated that the growth of Neocallimastix sp, strain CS3b was completed in 4 days in the culture system used, During this period, the fungus libera ted about 95% of the fermentable sugars in untreated material, On a pe rcentage basis, no significant differences were found in final extent of degradation of glucose, xylose, and arabinose, Galactose, however, was degraded to a lesser extent.