Not much is known about the history of Lactobacillus Acidophilus. However, we do know that the process began a long time ago before refrigerators, when they had to preserve milk. Lactobacillus helped them do that. It formed long chains of Lactobacillus where made that naturally preserved the milk. In the 19th century when the idea for the production of natural diary cultures was invented, the process of converting lactose into Lactic acid was invented. This fermentation process is what the bacteria had done naturally for roughly five thousand years. It is thought that yogurt a dairy that was fermented long ago, was cultured by lactobacillus acidophilus in skin sacks used to store dairy.