An isolated fungal extra-cellular enzyme disintegrates the polysaccharide encapsulating a marine unicellular alga

摘要

A strain of Ref-1 was isolated from contaminant of micro-alga polysaccharide kept in a refrigerator and Strain of Ref-1 was identified as Homobasidiomycete. sp. It produced extra-cellular enzyme, the yield of which was enhanced more than 9.5 fold after selecting nutritional parameters. The maximum enzyme production was obtained at pH 3.5, 15℃, 5% (w/v) haptose as carbon source and 0.5% yeast extract as nitrogen source, and enzyme activity value obtained in liquid culture was 75 U/ml after 5 days of cultivation. The enzyme was optimally active at pH 5.0-5.5 and pH 7.5- 8.0, respectively, and stable over pH range 3.7-5.7 and 7.5-9.5. The enzyme optimally active at 55-75℃, remained at 91.9% and 60.8% of its original activity when incubated for 2 hours and 8 hours at 45℃, while it lost 55% of its original activity after 30 min at 50-70℃, PH5.5. Ca<'2+> of 10mM increased the activity by 2.0-folds, while Zn<'2+> and Co<'2+> of 10mM completely inhibited the enzyme activity. The specificity of substrates showed the enzyme from Ref- 1 had 94.1% activity towards xylan, while no activity towards CMC, FP and starch.