Safety Evaluation of Bacillus Isolates From Fermented Tarhana With Probiotic Potential

ABSTRACT

Tarhana is a Turkish fermented food that has been widely consumed by Turkish people for hundreds of years. The main fermentation microorganisms are lactic acid bacteria; however, in this study, we aimed to isolate Bacillus strains from tarhana samples and to investigate some probiotic properties after identification. Various types of tarhana samples were collected, and after a preliminary screening test, 53 isolates were selected. The isolates were Gram‐positive, endospore‐forming, catalase‐positive, and motile. Biochemical pathogenicity tests, including lecithinase, DNase, and hemolytic activities, were performed, and all isolates were lecithinase‐negative and DNase‐negative. Hemolytic tests indicated that eight isolates were gamma‐hemolytic and the rest were alpha‐hemolytic. Ten virulence genes were investigated in all isolates, and none of them harbored any of these genes. The isolates exhibited strong tolerance to bile salts (78.3%–97.3%) and simulated gastric conditions (81.3%–99.5%). The hydrophobicity potential of the isolates was quite variable, ranging from 14.6% to 76.2%. Aggregation after 24 h ranged from 50.4% to 79.2%. Twenty of the isolates were strong biofilm formers and were susceptible to the antibiotics specific to Bacillus (according to EUCAST). This study revealed the potential of Turkish tarhana as a source of probiotic Bacillus strains.