Optimal conditions for alpha-mannosidase production from mold isolate AD-3S on solid culture
Chanikarn Koomnok, Chiang Mai Univ., Chiang Mai (Thailand). Faculty of Science. Dept. of Biology. Microbiology Section
Solid state fermentation of the mold isolate AD-3S for the production of alpha-mannosidase was evaluated under various conditions. For each set of experiments, the completely randomized design statistic was followed for analysis of the results. Among those investigations were the moisture content of 45, 50, 55, 58, 62, 64, 66, 68 and 70 percent, the nitrogen sources of (NH4)2SO4, NH4NO3 or urea, the carbon sources of glutinous rice bran, rice bran, wheat bran, glutinous rice fluor, rice fluor, wheat fluor, cassava fluor, glucose, sucrose or manitol, cultured at 30, 45, 50 and 55 deg C for 0 to 10 days. The enzyme produced by the mold was extracted for 1, 5 and 24 hours and the amount determined by measuring the absorbance at 400 nm of the p-nitrophenol released from the p-nitrophenyl-alpha-D-mannopyranoside substrate on the basis of total protein content as measured by the method of Lowry. The growth temperature of 45 deg C at the moisture content of 64 percent using 0.6 percent of glutinous rice bran as carbon source and 2 percent of (NH4)2SO4 as nitrogen source over 5 days gave the highest enzyme activity of 32.564 munit/ml and specific activity of 104.707 munit/mg protein when extracted with distilled water for one hour in an ice bath. The enzyme was stable at 4-60 deg C and between pH 5.5 to 8.0 with the optimal temperature and pH being 55 deg C and 6.0, respectively.
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