Evaluation of biofilm formation by exopolysaccharide-producer strains of thermophilic lactic acid bacteria isolated from Algerian camel milk

Exploration of wild lactic acid bacteria from natural environments is the most suitable approach of search for the desired exopolysaccharide-phenotype. The significance of biofilm in food processing is a highly debated issue. The Biofilm represents the next major scientific challenge to microbiologists and food processors. A total of 30 thermophilic lactic acid bacteria strains were isolated from Algerian raw Camel milk. The isolation was carried on Chalmers agar, under aerobic and anaerobic conditions at 42 degrees C. The identification, based on the phenotypic characteristics showed high diversity of species and predominance of Lactobacillus and Enterococcus. Based on the mucoid type of the colonies, strains were screened for their ability to produce exopolysaccharides. The production of polymers was carried on modified MRS broth, then, the yields were quantified, using the colorimetric method. The results show that the tested strains produced large amounts of soluble exopolysaccharides, some strains have a potential to be used as culture starters for dairy products. These strains were examined for their ability to form biofilm, using the Biofilm Ring Test. The findings showed that all studied strains formed a biofilm. While, the Biofilm Ring Test with exopolysaccharide powder of different strains, showed positive result for only three Lactobacillus strains (La91, Lb116, La117) that Which suggest that there is no relationship between exopolysaccharide yield and biofilm formation.