A novel manganese starvation-inducible expression system for Lactobacillus plantarum

A novel expression system for Lactobacillus plantarum was developed. This system is based on the manganese starvation-inducible promoter from specific manganese transporter of L. plantarum NC8, which was cloned for the first time. The expression of a β-glucosidase from Pyrococcus furiosus (CelB) was achieved by cultivating L. plantarum NC8 at low manganese concentrations with MRS medium and the pmntH2-CelB expression vector. A CelB activity of 8.52 μkatoNPGal L(-1) was produced in a bioreactor (4 L). The advantages of the novel expression system are that no addition of an external inducing agent was required, and additionally, no further introduction of regulatory genes was necessary. The new promoter meets the general demands of a food-grade expression system.