Abstract

Leuconostoc species are lactic acid bacteria widely used in milk fermentation. Based on morphological, physiological and biochemical analysis, 18 strains of Leuconostoc mesenteroides were isolated and identified from 10 samples of goat's milk and camel's milk. Strains were identified as follows 09 strains of L. mesenteroides subsp.mesenteroides and 09 strains of L. mesenteroides subsp. dextranicum. The results of technological tests of the strains showed that strains produced dextran, carbon dioxide, and resist to 55°C for 15 min, which promote their industrial use. The growth kinetic, acidification evolution and carbon dioxide production of L. mesenteroides subsp.dextranicum strain in skim milk at 30°C were slightly higher than L. mesenteroides subsp.mesenteroides. Addition of yeast extract to skim milk stimulates the development of L. mesenteroides subsp. mesenteroides by increasing its growth, acidification activity and evolved CO₂. Susceptibility to antibiotics was also evaluated on 33 antibiotics and strains of L. mesenteroides showed resistance to 42.4% of antibiotics used.

Key words: Technological, Leuconostoc, milk, growth kinetic, carbon dioxide, yeast extract, antibiotics