ABSTRACT
The ability of lactic acid bacteria (LAB) to produce antimicrobial substances has historically
long been used to preserve foods. Preservation ofmilk by fermentation has been used early in
history, Sumerian writings about dairying go back to about 6000 B.C. Procedures for the
fermentation of meat were developed as early as the fifteenth century B.C. in Babylon and
China. Methods for the fermentation of vegetables were known in China in the third century
B.C.[1] Since the days ofMetchnikoff, lactic acid bacteria have also been used as probiotics to
improve the composition and activity normal microbiota of the intestine.[2]
Fermentation reduces the amount of available carbohydrates and results in a range of
small molecular mass organic molecules that exhibit antimicrobial activity, the most com-
mon being lactic, acetic, and propionic acids.[3] In addition to the production of these
inhibitory primary metabolites, many other antimicrobial components can be formed by
different lactic acid bacteria. One should bear in mind that antimicrobial substances are
not produced for human convenience. The biological significance is thought to be that
of amensalism, a means of one bacterium gaining advantage over another competing
microbe. This can be achieved by changing the environment, e.g., acidification, or pro-
duction of toxins against competitors.[4,5]
The aim of this chapter is to discuss the formation, spectrum of activity, and mode of
action of the various antimicrobial substances produced by lactic acid bacteria.
