he discovered that the shape of the yeast was different depending on the sample. If the wine was unspoiled, the yeast was round. If it was corrupted, the yeast was elongated and appeared alongside other, smaller, rod-shaped structures: bacteria. A biochemical analysis of the spoiled batches also revealed that under the wrong conditions, hydrogen attached itself to the nitrates in the beetroot, producing lactic acid, which gave off the fetid odor and made the wine taste sour.
