Competitive Exclusion means two species which are competing for the same sources cannot live in together. If one of these species has a little bit more advantage or has a higher population than the other, transcend one will command the environment. In any case, the population of one species will be dominating the other. The low populated side will be lost the competition. Great numbers of beneficial bacteria compete with pathogen microorganisms for cling on the host (organism).
ANTIMICROBIAL MATERIAL PRODUCTION
Antimicrobial material production from lactic acid bacteria may be classified as compounds which have low molecular mass (as H2O2, CO2, diacetyl) and compounds which have high molecular mass (as bacteriocin). These produced antimicrobial materials inhibit pathogen and spoilage bacteria.
EFFECTS of pH and BACTERIOCINS
Lactic acid bacteria produce organic acid that provides the antibacterial effect by reducing the pH of the environment. We know that less pH increases the influence of other antimicrobial metabolites. Bacteriocins influence on only specific pathogens causing no harm on the useful microbiota. None of the thermal manipulations causes lack of bacteriocin activation. At the same time, many of study shows that more acidic bacteriocins are more active than the others.