Etudes de l’activité antifongique des Bactéries lactiques vis-à-vis des champignons phytopatogènes d’Alternaria.sp.

Abstract

The control of phytopathogenic microorganisms by pesticides presents disadvantages for humans and the environment, to which is added the risk of the emergence of new resistant pathotypes. Certain microorganisms can serve as excellent biological control agents against fungal diseases. Food preservation is based primarily on the retardation or inhibition of the growth of contaminating microorganisms, and the antifungal activity of lactic acid bacteria is one of the sought-after technological properties. Bacteriocins are antimicrobial peptides produced by bacteria naturally immune to their own bacteriocins. This work has enabled the identification of many strains of lactic acid bacteria that produce antimicrobial peptides. The objective of our work is to test the antifungal activity of lactic acid bacteria against phytopathogenic fungi isolated from the leaves, stems and crowns, roots and fruits of two plants such as tomato and carrot presenting the Alternaria disease, the plants were collected from two different regions in Mostaganem. Isolation and purification of isolates were performed on MEA and PDA media. Isolation of the pathogen was performed (under the same previous conditions) for further work. Macroscopic and microscopic identification of strains represents the genus of Alternariaa sp. The antifungal effect was sought by the confrontation method, either direct or remote, in 2 strains of lactic acid bacteria isolated from raw camel and goat milk. About 100% of the isolates showed inhibitory activity against Alternaria sp, belonged to the genus Enterococcus faecium. And Lactobacillus plantarum produce antifungal compounds active against Alternaria sp, A change in the zones of inhibition was detected after the confrontation methods, An inhibition was observed.