特异腐质霉纤维素酶的研究

由腐植土中分离到一株嗜热真菌,经鉴定为特异腐质霉(Humicola insolens Cooney etEmerson)。研究了这株菌纤维素酶的产生条件和一般性质。菌在含麦麸5％、NaNO0.3％的液体培养基(灭菌前pH7.5,灭菌后pH7.2)中,于45℃培养4天,以羧甲基纤维素钠为底物,每ml滤液酶活力为20个单位。酶作用的最适条件为:pH6.0,温度为65—70℃。该纤维素酶是一种耐热酶,热稳定性较强,70℃保温5分钟后,酶活力剩余88％。底物对该酶的热钝化有较强的保护作用,无底物存在条件下,70℃保温6小时后,酶活力仅剩余1％,而在同样的处理温度和时间,在有底物存在条件下,酶活力可剩余30％。该酶在45℃保温15小时的条件下,pH稳定范围为6.0—9.0。

STUDIES ON CELLULASE FROM HUMICOLA INSOLENS

A thermophilic fungus, Humicola insolens was isolated from humus in Beijing. The conditions of production and properties of eellulase of the fungus have been investigated. After growing in shaking flasks containing 5% wheat bran and 0.3% NaNO_3 (pH 7.5 before and 7.2 after sterilization) at 45℃ for 4 days, the potency of the crude culture filtrate acting on carboxymethylcellulose (sodium salt) was 20 units per ml. The optimal pH and optimal temperature for enzyme action was 6.0 and 65—70℃ Thermal stability of the enzyme was good, after incubating at 70℃ for 5 minutes, 88% of the cellulase activity remained. Substrate had protective action on the enzyme, when incubated together with CMC-Na at 70℃ for 6 hours, 30% of the cellulase activity remained, but only 1% remained in the absence of CMC-Na. The enzyme was stable at pH 6.0—9.0 at 45℃ for 15 hours.