Tomer, it is best IMHO to think of this not as bread or fermenting yeast. It is sereviciae, but a special strain. It follows normal glucose fermentation pathways, but will also help to hydrolize as casein, adding flavor. In raw milk blue cheese, this kind of strain is often found naturally in established ecosystems. The origin I think is not in a practice... it's modern... isolated yeast added back to pasteurized milk in a recipe to achieve specific properties.