Lactobacillus Bulgaricus Guide

Lactobacillus delbrueckii subspecies bulgaricus (until 1984 known as Lactobacillus bulgaricus) is one of several bacteria used for the production of yogurt. It is also found in other naturally fermented products. First identified in 1905 by the Bulgarian doctor Stamen Grigorov, it is named after Bulgaria. It is a Gram-positive rod that may appear long and filamentous. It is also non-motile, and it does not form spores. This bacterium is regarded as aciduric or acidophilic, since it requires a low pH (around 5.4-4.6) to grow effectively.

The bacterium has complex nutritional requirements, including the inability to ferment any sugar except lactose, from which it produces lactic acid, which gives yogurt its tart flavor, coagulates the milk proteins, and acts as a preservative. It is often helpful to sufferers of lactose intolerance, whose digestive systems lack the enzymes to break down lactose to simpler sugars. While fermenting milk, it produces acetaldehyde, which is one of the main yogurt aroma components.