ABSTRACT
Human civilizations throughout history have placed great practical and economic value on methodologies to improve keeping qualities of foods. One of the most ancient of these practices involves fermentation by lactic acid bacteria (LAB) that are indigenous to raw milk, meat, vegetables, and cereal grains. The LAB are a diverse group of gram-positive (gram+) cocci, coccobacilli, and bacilli whose defining characteristics are that they (1) have a low «55 mol%) G + C content; (2) are acid tolerant; (3) are nonsporing; (4) are nutritionally fastidious; (5) are aerotolerant but not aerobic; (6) are unable to synthesize porphyrins; and (7) have a strictly fermentative metabolism with lactic acid as the major metabolic endproduct.
