Isolation and characterization of gluten-degrading Enterococcus mundtii and Wickerhamomyces anomalus, potential probiotic strains from indigenously fermented sourdough (Khamir)

The present study was undertaken to isolate and characterize gluten hydrolyzing microbiota from locally fermented sourdoughs (Khamir) to evaluate their potential as a candidate for probiotics. Sixty autochthonous sourdough samples were collected from different areas of Pakistan. Nineteen bacterial and three yeast isolates were screened for the presence of gluten-degrading ability from sourdough samples. These isolates were sub-cultured on different media for presumptive pre-selection by biochemical assays. Five bacterial isolates were lactic acid bacteria and two were Bacillus sp among 19 bacterial isolates which were further characterized based on auto-aggregation, β-galactosidase activity, antibiotic susceptibility, anti-pathogenic activity, bile salts tolerance, pH tolerance, surface hydrophobicity and cholesterol assimilation. In this study Lactobacillus plantarum ATCC 14917 was used as control strain to compare the probiotic potential of isolated strains. Idetnfication based on 16S and 28S rRNA sequencing revealed the presence of four Enterococcus faecalis strains along with Enterococcus mundtii, Bacillus cereus and Bacillus megaterium strains. All yeast strains were identified as Wickerhamomyces anomalus. Among all microbial strains, E. mundtii QAUSD01 and W. anomalus QAUWA03 had the ability to tolerate low pH, bile salt properties and hydrophobicity compared to other gluten-degrading strains. These two strains exhibited the potential to be used as probiotic for sourdough fermentation.