Hybrid yeast strains that have a traditional wine yeast as one parent and a non-traditional yeast as the other parent are an important part of the AWRI’s yeast strain development research and can bring interesting new characters and behaviours to wine, without any genetic modification. As part of this work, AWRI researchers have developed a new method to isolate hybrid yeast strains with improved fermentation kinetics. The approach uses ‘adaptive evolution’, similar to that described by Charles Darwin as ‘survival of the fittest’, in a fermentation environment and has been recently published in the high-impact journal Frontiers in Microbiology.

Initially, an interspecific hybrid strain was generated (through traditional breeding techniques) which it was hoped would reduce the volatile acidity generated in high-sugar fermentations. However, the new hybrid strain showed reduced fermentation robustness compared to the wine yeast parent strain. To understand this further, the hybrid was placed in a fermentation environment, and progressively evolving cells were screened for loss of chromosomal material and evaluated for fermentation fitness. While a number of chromosomal alterations were identified, by the end of the experiment all the ‘fittest’ hybrid yeast cells were found to have lost Chromosome 14 from the non-S. cerevisiae parent. Evaluating the evolved hybrids that had lost Chromosome 14 from the non-S. cerevisiae parent showed they retained the targeted trait of reduced volatile acidity production while also exhibiting improved fermentation kinetics. This highlighted chromosomal mutations as a potential new method for screening hybrid yeast.

The full paper detailing these results is available at: https://doi.org/10.3389/fmicb.2018.01442

Bellon, J.R., Ford, C.M., Borneman, A.R., Chambers, P.J. 2018. A Novel Approach to Isolating Improved Industrial Interspecific Wine Yeasts Using Chromosomal Mutations as Potential Markers for Increased Fitness. Front. Microbiol. 9 (1442): 1-12.

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