Evaluation of probiotic and antifungal properties of the predominant LAB isolated from fermented acorn (Quercus persica)

Characterization of lactic acid bacteria (LAB) isolated from rarely studied fermentation substrates can lead to isolate unique microorganisms. In the present study, predominant LAB was isolated from fermented acorn using repeat of back-slopping process, and then the isolate was identified by PCR. Subsequently, probiotic properties of the isolate (including resistance to acid and bile, antibacterial, auto and co-aggregations, antibiotic susceptibility and blood hemolysis), as well as its antifungal effect were studied. Sequencing results of the PCR products led to the identification of Pediococcus acidilactis as predominant LAB isolate. The survival percentage of the isolate in continuous acid and bile treatment was equal to 72%. The inhibitory effect of the isolate on Bacillus cereus was also significantly (P<0.05) higher than the other foodborne indicator bacteria. Furthermore, crude cell free supernatant (CFS) obtained from LAB culture completely inhibit the growth of B. cereus; meanwhile, its naturalized CFS had no inhibitory effect on Salmonella enterica. LAB isolate had also proper auto and co-aggregation (with E. coli) potentials and had no hemolytic activity. Antifungal activity of the isolate against Aspergillus niger was also verified. By considering the proper probiotic and antifungal potentials of the P. acidilactis isolated from fermented acorn it is possible to use the isolate as microbial starter, adjunct, probiotic and or protective culture in fermentation industries.