INTERACTIONS BETWEEN LACTIC AND PSYCHROTROPHIC GRAM-NEGATIVE FLORA IN MILK

Lactic acid and psychrotrophic bacteria in raw milk are basically determined by sources of contamination and storage temperatures. Besides, reciprocal interactions exist between both bacterial populations. Lactic acid bacteria develop different types of antagonistic actions (production of organic acids, H2O2, bacteriocins, etc.) whereas psychrotrophic bacteria do promote cooperation (comensalism) increasing available nitrogen degrading of H2O2. These interactions tend to occur sequentially, following variations in storage temperature.