Increasing of activity and thermostability of cold active butanol-tolerant endoglucanase from a marine Rhodococcus sp. under high concentrations of butanol condition.

Optimum pH and temperature of the endoglucanase from Rhodococcus sp. was 5.0 and 40 °C. The endoglcuanase activity was 1.18 folds higher in 5% butanol solution than that in butanol-free solution. Melt point temperature was 2.5 °C higher in 5% butanol solution (50.0 °C) than that in butanol-free solution (47.5 °C). At 45-60 °C, Gbbs-free energy change, ∆G, was higher in 5% butanol solution than that in butanol-free solution. The content of α-helix and β-sheet increased in 5% butanol solution. The increasing of α-helix and β-sheet content led to higher activity and better thermostability in butanol solution. The cold active butanol-tolerant endoglucanase was valuable for biobutanol production by a simultaneous saccharification and fermentation process.