Abstract
SummaryWe describe the impact of two propeptides and PedC on the production yield and the potency of recombinant pediocins produced in L actococcus lactis. On the one hand, the sequences encoding the propeptides SD or LEISSTCDA were inserted between the sequence encoding the signal peptide of Usp45 and the structural gene of the mature pediocin PA‐1. On the other hand, the putative thiol‐disulfide oxidoreductase PedC was coexpressed with pediocin. The concentration of recombinant pediocins produced in supernatants was determined by enzyme‐linked immunosorbent assay. The potency of recombinant pediocins was investigated by measuring the minimal inhibitory concentration by agar well diffusion assay. The results show that propeptides SD or LEISSTCDA lead to an improved secretion of recombinant pediocins with apparently no effect on the antibacterial potency and that PedC increases the potency of recombinant pediocin. To our knowledge, this study reveals for the first time that pediocin tolerates fusions at the N‐terminal end. Furthermore, it reveals that only expressing the pediocin structural gene in a heterologous host is not sufficient to get an optimal potency and requires the accessory protein PedC. In addition, it can be speculated that PedC catalyses the correct formation of disulfide bonds in pediocin.
Highlights
Bacteriocins from lactic acid bacteria are defined as antimicrobial proteinaceous compounds synthesized by ribosomes (Riley, 2009)
This study reveals for the first time that pediocin tolerates fusions at the N-terminal end
In the plasmids pSec::s-rped and pSec::lrped, the sequences encoding the propeptides SD and LEISSTCDA, respectively, were inserted between spusp45 and Δsp::pedA. These plasmids theoretically lead to the secretion of recombinant fusion pediocins PA-1, named S-Rpediocin and L-Rpediocin, that would exhibit the peptide SD and LEISSTCDA at the N-terminus respectively
Summary
Bacteriocins from lactic acid bacteria are defined as antimicrobial proteinaceous compounds synthesized by ribosomes (Riley, 2009). They are used in food as biopreservatives and were lately suggested as drug candidates and probiotic promoting factors (Dobson et al, 2012). As bio-preservatives, they can be added to food following three different strategies: in situ into fermented food by bacterial culture which constitutes the starter culture, directly in a purified or semi-purified form (e.g. nisin A, nisaplin, Danisco) and as an ingredient based on a fermentation of a bacteriocin-producing strain (pediocin PA-1, ALTA 2431, Quest International) (Cotter et al, 2013). Low production rate by natural bacterial producers can dramatically impair further application of bacteriocins (Jack et al, 1996; Guyonnet et al, 2000; Jasniewski et al, 2008)
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