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

Abstract

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.