Nisin-selectable food-grade secretion vector for Lactococcus lactis

Abstract

A nisin-resistant Lactococcus lactis strain TML01 was isolated from crude milk. A gene with 99% homology to the nisin-resistance gene, nsr, was identified. The food-grade secretion plasmid, pLEB690 (3746 bp), was constructed based on this novel nsr gene enabling primary selection with up to 5 μg nisin/ml. The functionality of pLEB690 as a secretion vector was shown by expressing and secreting the pediocin AcH gene papA in L. lactis. pLEB690 is therefore, a functional food-grade secretion vector potentially useful for the food industry.

Genetic characterisation and heterologous expression of leucocin C, a class IIa bacteriocin from Leuconostoc carnosum 4010

“…As a result, bioactive pediocin was produced by Lc. lactis with and without nisin induction, though the production level was higher with nisin induction (Li et al 2011).…”

“…In order to secrete antilisterial bacteriocins in Lc. lactis strains, the usp45 lactococcal secretion signal has been used to replace the original signal sequences of these bacteriocins Li et al 2011). In previous study, mature enterocin P gene was fused with SSusp45 into a lactococcal expression vector.…”

“…Similar principle was applied for producing pediocin by Lc. lactis using a food-grade secretion vector with nisin selection (Li et al 2011). The papA gene encoding mature pediocin was fused to usp45 signal sequence carried by the food-grade vector pLEB690.…”

“…Construction of plasmids derived from the food-grade vector pLEB690 (I) and plasmid pLEB730 carrying lecI gene (II). pLEB690 was derived from pLEB688 with the insertion of nisin inducible promotor P nisZ and the lactococcal SSusp45 (Li et al 2011). The vector plasmid pLEB690 (Ia) was restricted with NaeI and ligated with PCR fragments of lecC (Ib) or lecCI (Ic) without lecC signal sequence.…”

“…However, the co-expressed lecI did not improve the production (Figure 11). Previously papA encoding mature pediocin was cloned into the same plasmid in the same way (Li et al 2011). In this study, that plasmid was used to compare the production and antilisterial activity of pediocin and LecC.…”