Fig. 1
Vector construction. Both pSIP409 and pSIP609 vectors were used for expression of B. licheniformis β-mannanase (BlManB) and B. subtilis chitosanase (BsCsnA). Enzyme expression was under the control of the Porfx promoter (also known as PsppQ) [32], which can be induced by the 19-residue peptide pheromone IP-673. The vectors contain an erythromycin resistance (erm R) or an alanine racemase (alr) gene as selection marker, for pSIP409 and pSIP609, respectively. Polyhistidine tags were incorporated C-terminally to facilitate one-step affinity purification. The 256rep replicon allows DNA replication in L. plantarum. Each enzyme was cloned in three forms, two of which contain a signal peptide for secretion (native or OmpA). The genes marked in red constitute the two-component system needed for peptide-pheromone driven induction; the grey areas marked with a T are terminator sequences