ABSTRACT
A class of bacteria that has been associated with fermented foods is the lactic acid bacteria (LAB). LAB are generally associated with habitats rich in nutrients, such as various food commodities (vegetables, milk, meat), but some are also habitants of the normal ora of the oral cavity and the gastrointestinal and genitourinary tracts of animals and humans (Axelsson 1998). The genera of interest to fermented foods are Lactobacillus, Leuconostoc, Pediococcus, Lactococcus, and Streptococcus. Lactococci are used as starter cultures for various types of dairy products, and pediococci are used for sausage-making and as silage inoculants (Hammes et al. 1990; Hammes and Vogel 1995). Leuconostoc species have been used in dairy fermentation to produce the avor compound diacetyl from citric acid and are often important in spontaneous vegetable fermentations, for example, sauerkraut (Daeschel et al. 1987). The only Streptococcus species that is associated with food technology is Streptococcus thermophilus, which is used as a starter culture in combination with Lactobacillus delbrueckii subspecies bulgaricus in the production of yogurt. The genus Lactobacillus is the largest in the LAB group. Lactobacilli are widespread in nature and have found applications in many areas of the food industry, such as fermented meats and vegetables, dairy products, wine, and cider production (Fleming et al. 1985; Hammes et al. 1990; Buckenhuskes 1993; Oberman and Libudzisz 1998; Salovaara 1998). In addition, certain species are members of the indigenous human microora (Mikelsaar et al. 1998) and have been postulated to exert probiotic activities, making them ideal candidates for probiotic food products.
