Behaviour of Yersinia enterocolitica and Aeromonas hydrophila in skim milk during fermentation by various lactobacilli.

In this study, behaviour of Yersinia enterocolitica and Aeromonas hydrophila in skim milk during fermentation by various Lactobacillus sp. were determined. pH values of the skim milk samples were also examined during fermentation. The amount of produced lactic acid and diacetyl/acetoin productions of the Lactobacillus sp. were estimated. Antimicrobial effects of the lactobacilli on Y. enterocolitica and A. hydrophila were also determined by an agar diffusion method. While Y. enterocolitica was not inhibited and grew during fermentation, A. hydrophila was inhibited, in part, and the growth was retarded. Results were supported by the agar diffusion method for Y. enterocolitica, whereas inhibition activity was not found for A. hydrophila. The highest lactic acid productions were estimated in L. bulgaricus (7.50 mg/ml) and L. acidophilus (5.63 mg/ml) and four out of six Lactobacillus sp. were found to be diacetyl/acetoin producers.