PURIFICATION AND SOME PROPERTIES OF THE MANNANASES FROM THIELAVIA-TERRESTRIS

Thielavia terrestris NRRL 8126 cell free supernatants contained mannanase and beta-mannosidase when cultured on a complex media containing locust bean gum. Using acetone precipitation, SP-Sephadex C50 ion exchange chromatography and preparative gel electrophoresis, the crude enzyme was resolved into one-beta-D-mannosidase and four-beta-D-mannanase components. beta-D-mannosidase had a specific activity of 0.02 (U/mg) on p-nitrophenyl-beta-D-mannopyranoside substrate. Mannanase components M1, M2, M3 and M4 had specific activities of 28.2, 38.7, 52.8 and 4.17 (U/mg) respectively on purified locust bean galactomannan substrate. pH optima for the enzymes were in the range 4.5-5.5. Mannanase component M4 manifested the greatest thermostability, retaining full activity for 3 h at 60-degrees-C. Molecular weights determined by SDS-PAGE were 72000 for beta-mannosidase and 52 000, 30 000, 55 000 and 89 000 for M1, M2, M3 and M4 respectively. Carbohydrate contents of the enzymes ranged from 6-36%. Preliminary studies indicate that enzyme components hydrolyse the mannan substrate in a synergistic manner.