Lactic Acid Bacteria: An Introduction to Taxonomy, Physiology and Molecular Biology

At the turn of the 20th century, the term “lactic acid bacteria” (LAB) was used to refer to “milk-souring organisms”. While similarities between milk-souring organisms and other bacteria producing lactic acid were soon observed, the monograph by Orla-Jensen (1919) formed the basis of the present classification of LAB. The criteria used by Orla-Jensen (cellular morphology, mode of glucose fermentation, temperature ranges of growth, and sugar utilization patterns) are still very important for the classification of LAB, although the advent of more modern taxonomic tools, especially molecular biological methods, has considerably increased the number of LAB genera from the four originally recognized by Orla-Jensen (Lactobacillus, Leuconostoc, Pediococcus, and Streptococcus).