从土壤中筛选出1株产外切型异麦芽三糖水解酶的黄绿青霉,可特异性地水解右旋糖酐只产生异麦芽三糖。该菌株产酶最优条件为:培养液中淀粉、葡聚糖、NH4Cl、酵母膏的质量分数分别为1%、1%、0.1%、0.1%,pH 6.0,接种量1%,装液量50 mL/250 mL,转速120 r/min。25℃培养13 d酶活达到176.80 U/mL。酶的最适作用温度为55℃,在50℃半衰期为3 h,最适作用pH为6.5,在pH 4.0～pH 6.5范围内稳定;金属离子K+、Ba2+显著促进酶活,Ca2+、Fe2+强烈抑制酶活;150 mmol/L NaCl所产生的离子强度促进酶活。

A strain of Penicillium citreoviride was screened from soil to produce exo-isomaltotriodextranase,which specifically released isomaltotriose as main products from dextran T70.The optimum condition for Isomaltotriodextranase production consisted of 1 % starch,1 % dextran,0.1 % NH4Cl and 0.1 % yeast extract,the initial pH for 6.0,1 % inoculating quantity,rate of shaking flask with 50 mL liquid in a 250 mL flask was 120 r/min.After fermentation for 13 days at 25℃,the enzyme activity was 176.80 U/mL.The enzyme displayed maximum activity at 55℃.The half-life of the enzyme was 3 h at 50℃.The optimum pH was pH 6.5,and the enzyme activity was stable from pH4.0～6.5.The enzyme was enhanced by K + and Ba2 +,but was inhibited by Ca2 +,Fe2 +.The enzyme activity could be improved by the ionic strength of NaCl at 150 mmol/L.