Endoglucanase is widely used and of great interest in various industries, the present study was conducted to find new endoglu- canase with new properties from the bacterial flora in the gastrointestinal tract of Osphranteria coerulescens larvae. Bacillus safensis CF99 in the digestive tract of the larvae was identified by amplifying of 16S rRNA gene, which was able to produce endoglucanase. The isolated bacterium reached the maximum endoglucanase secretion at 37 °C in the presence of 0.25% (w/v) CMC as substrate, 1% (w/v) glucose as carbon source, and 1% (w/v) ammonium acetate as nitrogen source after 72 h. The endoglucanase had 91.20 unit/mg specific activity and purified 1.18 fold. SDS-PAGE and zymogram analyses confirmed a 44.5 kDa endoglucanase. The enzyme had the highest activity and stability at 50 °C and pH 8.5. Organic solvents reduced the enzyme activity negligibly, while metal ions increased the enzyme activity. The residual activity was 65%-95% at 2 mM and 5 mM of various enzyme inhibitors. SDS, CTAB, Triton X-100, H2O2, and Tween 80 lessened the endoglucanase activity. The half-life of the endoglucanase was estimated 90 min at optimum temperature. Substrate specificity showed that CMC was the best substrate with V max value of 53.88 ± 1.979 μmol/min and K m value of 0.4146 ± 0.1185 mg/mL. Disaccharide production was confirmed after 24 h by TLC analysis. Regarding the alkalophilic property of the endoglucanase and some practical properties such as high specific activity, the enzyme is suitable to use in different industries.

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