Wild Yeast
Wild yeast is any mixture of the thousands of possible airborne yeast strains which may happen to appear and start their own fermentation in fermentable substance before you add your cultured yeast or in lieu of it altogether. Wild yeast can be unpredictable-– it can destroy the quality of a beverage or can carry out the fermentation in a more-or-less normal fashion. They are a favorite low-intervention winemakers, lambic brewers and many experimental fermenters.