The yeast Saccharomyces boulardii is well known for its probiotic effects such as treating or preventing gastrointestinal diseases. Due to its ability to survive in stomach and intestine, S. boulardii could be applied as a vehicle for producing and delivering bioactive substances of interest to human gut. In this study, we cloned the gene lecC encoding the antilisterial peptide leucocin C from lactic acid bacterium Leuconostoc carnosum in S. boulardii. The constructed S. boulardii strain secreted a peptide, which had molecular weight corresponding to leucocin C in SDS-PAGE. The peptide band inhibited Listeria monocytogenes in gel overlay assay. Likewise, concentrated S. boulardii culture supernatant inhibited the growth of L. monocytogenes. The growth profile and acid tolerance of the leucocin C secreting S. boulardii were similar as those of the strain carrying the empty vector. We further demonstrated that the cells of the leucocin C producing S. boulardii efficiently killed L. monocytogenes, also without antibiotic selection pressure. These results showed that antilisterial activity could be added to the arsenal of probiotic activities of S. boulardii, demonstrating its potential as a carrier for therapeutics delivery.

布拉氏酵母菌以其益生菌作用而闻名，例如治疗或预防胃肠道疾病。由于其能够在胃和肠中生存，布拉氏酵母菌可以用作生产和递送人类肠道感兴趣的生物活性物质的载体。在这项研究中，我们从布拉氏链球菌中的肉明串珠菌乳酸菌中克隆了编码抗李斯特菌肽白素C的基因lecC。构建的布拉氏酵母菌株分泌一种肽，其分子量与SDS-PAGE中的白素C相对应。在凝胶覆盖测定中，肽带抑制单核细胞增生李斯特氏菌。同样，浓缩的布拉氏酵母菌培养物上清液抑制了单核细胞增生李斯特菌的生长。分泌白素C的布拉氏酵母菌的生长概况和耐酸能力与携带空载体的菌株相似。我们进一步证明，产生白素C的布拉氏酵母菌细胞能够有效杀死单核细胞增生李斯特菌，而且没有抗生素选择压力。这些结果表明，抗李斯特菌活性可以添加到布拉氏酵母菌的益生菌活性库中，证明其作为治疗递送载体的潜力。