Unravelling the killer activity of Lachancea species against the wine spoilage yeast Brettanomyces bruxellensis

Abstract

The wine industry faces many challenges including spoilage, mostly attributed to Brettanomyces bruxellensis as the main spoilage yeast. Its genetic diversity, persistence during vinification, and tolerance to various chemical preservatives (including sulfur dioxide), make it difficult to control. Killer toxins secreted by other yeast species could represent a promising biological alternative to chemical preservatives. Killer phenotype against B. bruxellensis has been described in various yeasts, but their application in industry remains limited. Such killer activity was recently reported in Lachancea thermotolerans but not fully investigated1. This study aimed to further explore and characterise killer phenotypes in the Lachancea genus against B. bruxellensis and other wine spoilage and beneficial yeasts. The killer phenotype of 17 Lachancea isolates was assessed against several target isolates: 29 B. bruxellensis strains representative of the six main genetic groups of this yeast species, as well as 25 strains belonging to beneficial or spoilage wine yeast species. The killer phenotype was assessed using a standard plate assay at pH 3.5. The zones of inhibition were measured in mm after 3-7 days incubation at 24 °C. Additionally, the impact of lactic acid (3 – 18 g/L) on the growth of spoilage yeasts was also assessed. Ten of the 17 Lachancea isolates screened displayed variable growth inhibition phenotypes against spoilage yeasts. Of these, L. thermotolerans A, L. thermotolerans B and L. waltii consistently displayed high permanent growth inhibitory effect against B. bruxellensis strains across the six genetic groups. Remarkably, these strains had no killer effect against all the nine commercial wine yeasts tested, highlighting them as promising biocontrol yeasts. All lactic acid concentration were ineffective at inhibiting the growth of target isolates suggesting that lactic acid was not involved in the killer phenotype. Although these results highlighted the three killer strains as potential biocontrol yeast in real winemaking, they pave a way to further exploring their efficacy under a wine-like liquid medium.

References

1. El Dana, F., David, V., Hallal, M. A., Tourdot-Maréchal, R., Hayar, S., Colosio, M.-C., & Alexandre, H. (2025). Metschnikowia pulcherrima and Lachancea thermotolerans killer toxins: Contribution to must bioprotection. Foods, 14(9), 1462. https://doi.org/10.3390/foods14091462