Listeria decontamination of chicken meat with beer brewed with bacteriocin producing Saccharomyces boulardii

In this work, we studied the control of Listeria monocytogenes in raw chicken meat by marinating breast strips with beer containing bacteriocin leucocin C. An URA3 auxotrophic strain of probiotic yeast Saccharomyces boulardii CNCM I-745 was used as a host to express the gene lecC encoding the bacteriocin leucocin C. Secretion of leucocin C was confirmed by the inhibition against L. monocytogenes using agar well diffusion assay. The new auxotrophic host secreted leucocin C better than previously constructed wild-type strain, and therefore it was used to brew anti-listerial beer. The beer was shown to maintain its anti-listerial activity for 38 days. Chicken breast strips spiked with L. monocytogenes were then marinated with the anti-listerial beer for overnight, and the killing of L. monocytogenes was analysed. Marination with beer containing leucocin C reduced the viable cells of L. monocytogenes by about 1.6 log from (2.2 +/- 0.6) x 10(7) CFU/g on day 24, and 2.2 log from (1.8 +/- 0.3) x 10(5) CFU/g on day 38. In conclusion, the URA3 auxotrophic S. boulardii efficiently secreted the bacteriocin leucocin C, and brewing beer with this strain resulted in anti-listerial beer. Such beer is effective as a marinade in reducing the Listeria risk in chicken breast strips.