Characterization of the inhibitory power of Lactobacillus of meat origin.

In this study we have tried to characterize the inhibitory power of Lactobacilli of meat origin. We selected 28 Lactobacillus strains isolated at various stages of sausage manufacture (mixed, baked, dried). These strains were tested for their inhibitive activity on gram negative bacteria (Pseudomonas fluorescens; Ps. aeruginosa, Escherichia coli B 41 enteropathogenic). It appears that the Lactobacillus strains synthetize one or more inhibitive substances instable in cold or heat, sensitive to the enzyme activity of peroxidase and to certain proteolytic enzymes (protease isolated from Bacillus subtilis and pepsin). Moreover, this inhibitive activity is associated with the bacterial walls. The instability of these inhibitors leads us to think of peroxide type substances; our results show that it is not hydrogen peroxide but, without doubt, far more complex peroxides associated to a proteinic structure which conditions their activity.