[Expression and enzymatic characterization of a chitosanase with tolerance to a wide range of pH from ].

To screen and identify a chitosanase with high stability, we cloned the chitosanase gene from with a high protease yield from the barren saline-alkali soil and expressed this gene in . The expressed chitosanase of . (BA-CSN) was purified by nickel-affinity column chromatography. The properties including optimal temperature, optimal pH, substrate specificity, and kinetic parameters of BA-CSN were characterized. The results showed that BA-CSN had the molecular weight of 31.13 kDa, the optimal temperature of 55 ℃, the optimal pH 5.5, and good stability at temperatures below 45 ℃ and pH 4.0-9.0. BA-CSN also had good stability within 4 h of pH 3.0 and 10.0, be activated by K, Na, Mn, Ca, Mg, and Co, (especially by Mn), and be inhibited by Fe, Cu, and Ag. BA-CSN showcased the highest relative activity in the hydrolysis of colloidal chitosan, and it had good hydrolysis ability for colloidal chitin. Under the optimal catalytic conditions, BA-CSN demonstrated the Michaelis constant and maximum reaction rate of 9.94 mg/mL and 26.624 μmoL/(mL·min), respectively, for colloidal chitosan. In short, BA-CSN has strong tolerance to acids and alkali, possessing broad industrial application prospects.