Expression and optimization of alginate lyase in recombinant Escherichia coli induced by lactose

The feasibility of expression of alginate lyase in recombinant Escherichia coli induced by lactose instead of IPTG was studied.The main factors of induction such as terminal concentration of lactose, inducing temperature, the optimal time of induction, the duration were analyzed. The response surface was used to improve the design and to fabricate pure enzyme by refining crude enzyme with Ni-NTA affinity column. The results showed that the optimal condition was adding 22 mmol/L ( terminal concentration) lactose, 29 ℃ and inducing 22 h.The activity of 8.552 U/m L induced by lactose was basically the same with IPTG.The research demonstrated the lactose could be used as an efficient inducer of genetically engineered strain.