Simultaneous production of endoglucanase and β-glucosidase using synthetic two cistron genes

Simultaneous production of endoglucanase and β-glucosidase by using a synthetic two cistron system in Escherichia coli was attempted as a possible way of reducing production cost. The first cistron in this system we constructed is an endoglucanase gene fused to a tac promoter that provides for efficient expression. The second cistron is a β-glucosidase structural gene. A ribosome binding site sequence of 33-base was inserted between the two cistron genes. E. coli cells transformed with the system produced 12.4 units/mg protein of endoglucanase and 327 units/mg protein of β-glucosidase, which represent 15% and 22% of total cellular protein, respectively, in L medium within three hours after induction with IPTG.