In listening to American distillers and brewers, one gets a sense that the yeast used to ferment sugars into alcohol is important to the process of creating flavorful whiskeys. The best example I can give off the top of my head is Four Roses Bourbon, which employs at least 5 different types of yeast in creating its 10 different recipes for bourbons. Having done a tasting of the full flight of all 10, I found I was partial to the bourbons made with lower rye percentages in the mash that were fermented with the more floral strain of yeast.
In Scotland, the general sense appears to have been that yeast is the least important component in the creation of whisky, with the grain, water and wood being the true flavor influences. That historical notion has come under question in recent years (see, e.g., the article linked below) https://www.drinks-insight-network.com/features/featurefeeling-fruity-using-new-yeasts-to-develop-alternative-scotch-flavours-5835010/ and we now have a new whisky released by Glenmorangie that looks to explore the influence of yeast on a sprit. https://www.glenmorangie.com/en-us/news
Dr. Bill Lumsden, the master distiller at Glenmorangie (and a pretty smart science guy having a PhD in chemistry) determined to make a whisky with the natural strain of yeast growing on the distillery’s cadboll barley. The spirit has been matured in first fill and refill ex-bourbon casks for an indeterminate number of years (yes, as with all the Glenmorangie Private Edition whiskies, it is not age stated). I look forward to getting a bottle or 2 of this 51.2% ABV, non-chill filtered whisky to taste and see if there is anything notably different from other Glenmorangie expressions that I may trace to the yeast. One never knows….