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Isolation and structural characterization of levan produced by probiotic Bacillus tequilensis-GM from Tunisian fermented goat milk
- Abid, Yousra, Azabou, Samia, Casillo, Angela, Gharsallah, Houda, Jemil, Nawel, Lanzetta, Rosa, Attia, Hamadi, Corsaro, Maria Michela
- International journal of biological macromolecules 2019 v.133 pp. 786-794
- Enterococcus, Escherichia coli, Listeria monocytogenes, amylases, antibiotics, beta-galactosidase, bile salts, biofilm, fermented dairy products, gastric juice, goat milk, hemolysis, hydrophobicity, levan, molecular weight, probiotics, proteinases, saliva, skim milk, starter cultures
- The probiotic features of strain GM newly isolated from Tunisian spontaneously fermented goat milk and identified as Bacillus tequilensis-GM were assessed. Strain GM showed high resistance to saliva (90.64%), gastric juice (88.55%), intestinal juice (72.83%) and resistance to bile salts (65.22%), was able to act against Listeria monocytogenes ATCC 15313, Escherichia coli ATCC 25922 and Enterococcus feacalis ATCC 25912, showed high surface hydrophobicity (77.3%) and was sensitive to most of the studied antibiotics. Strain GM did not exhibit any hemolytic activity whereas it was able to produce protease, amylase and β-galactosidase. Moreover, results showed that strain GM produced high molecular weight β-(2 → 6)-levan with high ability to inhibit and to disrupt pathogenic biofilms and with high ability to reduce syneresis of sucrose-supplemented skimmed milk. B. tequilensis-GM can therefore be suitable to be used as starter culture in fermented dairy products, since it possesses desirable probiotic properties in addition to its ability to produce levan.