Lactic acid bacteria pathogen reduction

The mechanism(s) by which lactic acid bacteria inhibit or inactivate other bacteria is not totally clear. Daly et al. (1972), Speck (1972), and Gilliland and Speck (1972) have cited evidence which suggests that the following may be involved (1) production of antibiotics such as nisin, diplococcin, acidophilin, lactocidin, lactolin, and perhaps others (2) production of hydrogen peroxide by some lactic acid bacteria (3) depletion of nutrients by lactic acid bacteria, which makes growth of pathogens difficult or impossible (4) production of volatile acids (5) production of acid and reduction in pH (6) production of D-leucine and (7) lowering the oxidation-reduction potential of the substrate. 

V. Use of Lactic Acid Bacteria for In Vivo Reduction of Food-Borne Pathogens... 

V. USE OF LACTIC ACID BACTERIA FOR IN VIVO REDUCTION OF FOOD-BORNE PATHOGENS... 

The inoculation of chickens with non-pathogenic cultures of bacteria has been reported to reduce Salmonella populations in chickens (Nurmi and Rantala, 1973 Wierup et al, 1988 Rehe, 1991). Probiotic administration is quite similar in approach to competitive exclusion in that a specific bacterial culture, often lactic acid bacteria, is administered to live birds. The two procedures may also accomplish the same goals with respect to pathogen reduction. However, a tenet of probiotic administration has been that it improves animal growth (Jernigan et al., 1985). 

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