Scientists Figure Out How Microbes Make Wine Good

(Wired) - Yeast aren’t the only microbes that help turn boring grapes into the delicious, seductive, complex, confusing, subtle, and totally splendiferous tonic known as wine. In addition to those well-known fermenters, a type of bacteria called Oenococcus oeni (for reasons that will be obvious to oenophiles) is responsible for some of the flavorings and secondary fermentation in wine. Well, in virtually all red wines – from your magnificent Barolos to Two-buck Chuck — and in whites and sparklings to a lesser extent.

Now, scientists from (where else) Italy and Spain have studied the proteins O. oeni makes, and think they’re getting closer to figuring out how the bacteria add flavor and aroma to wine.

The team did this by analyzing the bacterial proteome – or, the population of proteins cells express. They looked specifically at the proteins present in the cell membranes and cytoplasm, the goop that fills a cell and contains all its organelles. Eventually, the team identified 152 different proteins involved in various metabolic pathways, and assembled a preliminary map connecting the components.

Then, they compared the O. oeni proteomic fingerprint to that of closely related bacterial strains. By looking for differences in the proteins each microbe makes, the team was able to identify proteins expressed by O. oeni that aren’t expressed by its less-boozy relatives. Not surprisingly, they report in the journal Open Biology, several of these proteins were enzymes involved in rearranging molecules to form diacetyls, acetoins, or esters, the compounds that give wine nutty, buttery, or fruity aromas.