ETUDE DE L’ACTIVITE ANTIBACTERIENNE DE LA NISINE CONTRE Pseudomonas fluorescens

Abstract

In this research, we are interested in the study of antibacterial activity of lactic strain (Lactococcus lactis ssp. Lactis) isolated from camel cheese against a psychrotrophic strain (Pseudomonas fluorescens). The nisin producer strain was isolated from a camel cheese prepared with fresh yield significant, equal to 35.5%. The test strain is a psychrotrophic strain isolated from a sample of raw camel milk, stored at 4 ° C for more than 3 days. The culture medium of Lactococcus lactis ssp. Lactis in M17 medium was centrifuged (8000 g, 20 min at 4 ° C). Thus, the supernatant was neutralized and tested against Pseudomonas fluorescens strain with three gel diffusion techniques; spots, shafts and discs. The neutralized supernatant presented antibacterial activity which is manifested by the appearance of inhibition zones diameter differs depending on the type of test used. Diameters varying between 9 and 18 mm and between 12 and 29 mm respectively were recorded with the wells and the discs. The technique of spots gave less conclusive results.