一株产耐热纤维素酶菌株的筛选及酶学性质

采用纤维素刚果红平板法从大田蘑菇种植场建堆的稻草样中分离得到了1株能产具有较好温度耐受性和pH稳定性的纤维素酶的放线菌DY3.综合形态、生理生化特征以及16S rDNA序列分析,将其初步鉴定为嗜热裂孢菌(Thermobifida fusca).对该菌所产纤维素酶的性质研究表明:最适催化温度为65℃,在70℃保温60 min后仍有75%以上的活力;最适催化pH为7.5,在pH 5.5～10.0之间该酶的稳定性较好,pH 10.0的条件下仍有80%的活力;最适作用底物是羧甲基纤维素钠.研究可为木质纤维素的生物预处理提供一定参考价值.

Screening of a Thermostable Cellulase-producing Strain and Its Enzymatic Properties

Using CMC Congo Red agar plate method,an actinomycetic strain producing cellulase with high temperature tolerance and pH stability was isolated from the sample collected from mushroom plantation.The strain was identified and named as Thermobifida fusca DY3 by morphological,physiological and biochemical characteristics,and 16S rDNA gene sequence analysis.The study on the cellulase showed that the extracellular thermostable cellualse exhibited the maximum activity at 65 ℃ and retained more than 75% of its maximum activity after incubation for 60 minutes at 70 ℃.The enzyme also showed its pH stability between pH 5.5 and 10.0,and retained 80% of its maximum enzymatic activity after treated at pH 10.0.The sodium carboxymethylcellulose was its best zymolyte.All the characteristics of the enzyme provide reference value for its application in biological pretreatment of lignocellulose.