Abstract: Lactobacillus delbrueckii sub-species bulgaricus ATCC-55163, a strain of Lactobacillus delbrueckii sub-species bulgaricus that can produce essentially stereoisometrically pure L-(+)-lactic acid, and a process for producing essentially stereoisometrically pure L-(+)-lactic acid using the strain are disclosed. A method for producing a mutant strain of Lactobacillus that produces essentially stereoisometrically pure lactic acid is also disclosed.