Efficient secretory expression of gene encoding a broad pH-stable maltose-forming amylase from Lactobacillus plantarum S21 in food-grade lactobacilli host

Abstract

The native and the N-terminal signal peptide sequence deleted gene encoding for α-amylase from Lactobacillus plantarum S21 were cloned into the inducible lactobacilli expression vectors pSIP409 and pSIP609 and expressed in L. plantarum WCFS1 and food-grade L. plantarum TGL02, respectively. Only the native amylase gene was expressed and secreted extracellular amylase at a level of approximately 2000 U/L with 90 % secretion efficiency from both hosts. The purified extracellular amylase from the L. plantarum TGL02 retained unique properties of the wild-type enzyme, particularly the broad pH stability (4.0–8.0) and maltose-forming activity. The results indicate high compatibility of L. plantarum S21 signal peptide sequence to both recombinant lactobacilli hosts. The recombinant lactobacilli exhibited high efficiency for direct lactic acid production from starch as found with L. plantarum S21. The efficient compatible signal peptide is also expected to be applied in secretory expression for production of valuable proteins in food-grade lactobacilli host.