THE BIOCHEMISTRY OF RUMEN PROTOZOA. 7. THE CARBOHYDRASES OF POLYPLASTRON MULTIVESICULATUM (DOGIEL & FEDOROWA)

Abstract

P. multivesiculatum has been established as the sole large protozoon in the rumen of a sheep. Suspensions of the organism, substantially free from bacteria and other ciliates, have been obtained from the rumen liquor of this sheep. Cell-free extracts obtained from disintegrated cells of P. multivesiculatum hydrolyse a number of poly- and oligo-saccharides. A high [alpha]-amylase activity is present in the extracts. This enzyme has maximum activity at pH-5.0, and yields maltose as the main product of hydrolysis of amylose. The extracts also hydrolyse maltose, but not methyl [alpha]-D-glucoside or [alpha][alpha] [image]-trehalose. The extracts slowly hydrolyse cellulose, yielding glucose as the main product. Cellobiose is also hydrolysed. Extracts of mixed rumen bacteria, prepared in the same way as the protozoal extracts, do not hydrolyse cellulose. Wheat-flour pentosan and xylobiose are hydrolysed by the extracts. The former is most readily decomposed at pH 6.3, and the main products are arabinose and xylose. The extracts hydrolyse pectin and sodium polypectate. Galacturonic acid is the main product from both substrates. Pectin-esterase activity is greatest at pH 7.2. Sucrose, melibiose, raffinose, inulin and lactose are also hydrolysed by the extracts.