Selection and Evaluation of Anti-Listerial Activity of Leuconostoc Mesenteroides Wild Strains Isolated from Algerian Raw Dromedary Milk

Abstract

Camel milk is a key food in arid and semi-arid regions for their nutritional needs qualitative and quantitative. Beneficial microflora of camel milk represented by lactic acid bacteria is a potential source of biological material used in food technology. A total of five samples of individual dromedary raw milks were collected from three camels nomad herd in south Algeria and were analysed for bacterial load. A total of sixty different colonies characterized as Lactic acid bacteria, they were classified by phenotypic and biochemical analysis as Leuconostoc mesenteroides subsp mesenteroides and Leuconostoc mesenteroides subsp dextranicum. Then, they were tested for antimicrobial compounds production. Out of these, twenty two strains were determined to be able to inhibit the growth of the indicator pathogens strains Listeria innocua ATCC 33090 by the agar spot test. Two strains were selected by the large and clear zones of inhibition when tested by the well diffusion assay. The two strains Y44 and Y46 show a high antimicrobial activity against Listeria innocua ATCC 33090 by inhibitory substances with proteinaceous nature confirmed after treatment with proteases and Urea, it was proved by kinetics growth in mixed culture. This fact suggests that bacteriocin-like produced by the both Leuconostoc strains are specific against Listeria sp and may find application as biopreservatives in food products. Therefore, the bio-protective cultures technology would be an ideal solution for enhanced the microbiological safety of food products.