A comparative study of β-1, 4-endoglucanase (possessing β-1, 4-exoglucanase activity) from Bacillus subtilis LH expressed in Pichia pastoris GS115 and Escherichia coli Rosetta (DE3)

摘要

β-1, 4-Endoglucanase (EG) from Bacillus subtilis LH was expressed in Escherichia coli Rosetta (DE3) and Pichia pastoris GS115, respectively. The CMCase activity of EG (EGE) from the cell lysate of DE3 reached 20,010. U/ml, and that of EG (EGP) from the supernatant of GS115 was only 2008. U/ml. EGE and EGP were bifunctional cellulases excluding β-1, 4-glucosidase (BGL). The CMCases of them, optimally active at 65. °C and pH 6.8, exhibited more than 80% residual activity at pH 5-10 and 60% activity at 40-70. °C and pH 5-9. EGE (EGP) mixed with BGL had more than 1.5-fold higher CMCase and filter paperase activities compared to EGE (EGP). N-glycosylation protected EGP from immobilized-papain attack and accounted for 30. kDa and a higher thermostability, whereas EGE was decomposed into a 33. kDa active truncated EG (EGT) and two 18. kDa fragments. EGE and EGP performed much better than EGT in denim biostoning.