Isolation and identification of dominant osmophilic Leuconostoc strains from traditional date product “Btana”

The current study aimed to isolate and identify dominant osmophilic bacteria associated with a traditional date product named “Btana”, produced in south region of Maghreb countries. Samples were randomly collected after two month of storage from tow villages (Mtarfat and Abani) in the Algerian southern department “Adrar”. A high osmotic pressure medium (MSE) was used for isolation of osmophilic bacteria, which were purified and examined for macroscopic and microscopic shape, Gram stain, catatalse, oxydase, acetoine and ADH production, reduction of nitrate, and motility. Isolates were then subculture on MRS medium for production of dextran, gas from glucose, growth in the presence of NaCl (3, 6.5 %) and sucrose (10, 20, 30, 40, and 50 %), pH tolerance (4.8, 6.5), growth temperature (10, 37, and 45°C) and thermo resistance (55°C for 15 min), enzymatic activity (proteolytic, lipolytic, hemolysis). Isolates were identified to specie’s level by sugar fermentation. Their growth and acidification kinetic were also studied. Results identified two species of Leuconostoc; Leuconostoc mesenteroides subsp. mesenteroides and Leuconostoc mesenteroides subsp. dextranicum. They show a high antibacterial activity against four indicator bacteria; Pseudomonas aeruginosa ATCC 27853, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922 and Staphylococcus aureus ATCC 25923.