Screening of dextranase-producing fungi and the effect of medium composition on dextranase production
2001
Supachai Samappito (Mahasarakham Univ., Maha Sarakham (Thailand). Faculty of Technology. Dept. of Biotechnology)
Screening method was developed for detection of dextranase-producing fungi from various agricultural sites of Mahasarakham Province. The method involved 2 steps of primary and secondary screening using agar medium A and liquid medium B, respectively, for the selection. The agar medium A containing (w/v) : 1.0 percent dextran T2000, 0.2 percent NaNO3, 0.2 percent KH2PO4, 0.2 percent yeast extract, 2.0 percent agar, pH 5.5 was used successfully to select four isolates which showed a clear zone appearing around colonies. These positive isolates were further checked for dextranase production in liquid medium B containing 1.5 percent dextran T2000 and the same other components as the basal medium A. Among the four isolates (A1, A2, A3, B1), B1 appeared to exhibit highest dextranase activity with 5.5 unit/ml after 5 days of cultivation. Manipulation of medium composition in shaken flasks showed that B1 could produce up to 22.2 units/ml after 5 days of cultivation (4 times higher) in liquid medium containing (w/v): 1.5 percent dextran T2000, 0.3 percent NaNO3, 0.2 percent KH2PO4, 0.2 percent yeast extract and 0.3 percent soybean meal, pH 5.5. In a five-liter fermentor using the same medium, B1 also showed similar dextranase activity (21 units/ml) after 5 days of cultivation as the shaken flasks.
显示更多 [+] 显示较少 [-]