Fungal pectinases, efficient in enhancing the digestion of raw starch from cassava tuber
1993
Lerluck Chitradon | Polson Mahakhan | Vichian Kitpreechavanich (Kasetsart Univ., Bangkok (Thailand). Faculty of Science. Dept. of Microbiology)
Crude enzyme of Rhizopus sp. 26R, high in pectinase activity was produced using solid substrate cultivation. Substrate composed of wheat bran, rice bran and rice husk in a ratio of 6:12:2 at 58 % initial moisture content, pH 5.7 and incubation temperature at 32 deg C were found to be the optimal culture conditions. Cultivation under these conditions for 6 days gave the highest pectinase activity of ca. 700 units per gram wet substrate. Partial purification of the enzymes was performed and some properties of the enzymes were reported. One of the interesting characteristics of the crude enzyme from Rhizopus sp. 26R was that it showed high potential in enhancing the activity of glucoamylase of Aspergillus niger J8 in the digestion of raw starch from whole cassava tuber when hydrolyzation was carried out using mixed crude enzymes of the two microorganisms. At the 1st hour of thereaction, the mixed enzymes gave the most efficient digestibility with hydrolyzation rate twice faster than that when glucoamylase was used alone and about 3 times faster than when pectinases were applied. Rate of hydrolyzation, however, decreased upon further incubation that at the end of 8 hour the mixed enzymes gave 1.3 times faster rate than that by glucoamylase and twice of that by the pectinases. Moreover, activity of the glucoamylase in digestion of raw ground cassava tuber that enhanced by the enzyme of Rhizopus sp. 26R was higher than that enhanced by the commercial pectinase.
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