Influence of p-Coumaric Acid and Micronutrients on Growth and 4-Ethylphenol Production by Brettanomyces bruxellensis
The wine spoilage caused by Brettanomyces bruxellensis is one of the global concerns for winemakers. Detecting the presence of B. bruxellensis using routine laboratory culture techniques becomes challenging when cells enter the viable but not culturable (VBNC) state. This study aims to investigate the impact of p-coumaric acid (a volatile phenol precursor) and micronutrients on B. bruxellensis’ culturability, viability, and volatile phenol production under sulfite stress. In red wine, exposure to a high sulfite dose (100.00 mg L-1 potassium metabisulfite) resulted in immediate cell death, followed by a recovery of culturability after two weeks. Surprisingly, such “dead” or non-culturable cells continued to produce 4-ethylphenol (4-EP). However, in the model wine medium, a death phase was observed at only 50.00 mg L-1 potassium metabisulfite (PMB), without any signs of growth recovery or 4-EP production. Nevertheless, when the model wine medium was supplemented with minerals and vitamins, growth recovery and 4-EP production were observed, indicating that the survival of sulfite-stressed state cells is dependent on the micronutrient’s availability. It has been reported by removing important micronutrients such as trace vitamins like biotin can lead to prevent the growth of B. bruxellensis (3). Moreover, we observed that B. bruxellensis can utilize p-coumaric acid (p-CA) as an energy source in the model wine, with a specific growth rate of 0.0134 and 0.0142 h-1 when supplied with 0.10 and 1.00 mM of p-CA, respectively. Additionally, sulfite-stressed yeast cells could synthesize ATP through proton efflux while utilizing p-CA. The p-CA, a constituent of both grapes and wine not only serves as a carbon source but also enables the cell to survive and produce 4-EP under sulfite stress. Our findings lay the foundation for future research on the importance of p-CA in managing yeast survival under sulfite stress.
Acknowledgements: The authors thank FCT, Portugal, for funding through DL 57/2016/CP1382/CT0012 to Mahesh Chandra, and strategic project UID/AGR/04129/2020 (LEAF).
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Issue: ICGWS 2023
1 Laboratório de Microbiologia, Linking Landscape Environment Agriculture and Food Research Center (LEAF), Instituto Superior de Agronomia, University of Lisbon, Tapada da Ajuda, 1349–017 Lisboa, Portugal
2 School of Engineering, Lusófona University, 1749-024 Lisboa, Portugal
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wine spoilage, sulfur dioxide, Brettanomyces bruxellensis, p-coumaric acid, VBNC, 4-ethylphenol, wine micronutrients, volatile phenols