Characterization of Novel Lactobacillus fermentum from Curd Samples of Indigenous Cows from Malnad Region, Karnataka, for their Aflatoxin B 1 Binding and Probiotic Properties

Thirty-four isolates of Lactobacillus spp. (LAB) from 34 curd samples were evaluated for their aflatoxin B (AFB ) binding and probiotic properties. Upon characterization, four LAB isolates (LC3/a, LC4/c, LC/5a, and LM13/b) were found to be effective in removing AFB from culture media with a capacity of above 75%. Staining reaction, biochemical tests, pattern of sugar utilization, and 16s rRNA gene sequence analysis revealed the identity of all the four isolates as L. fermentum. All of them could tolerate acidic pH, salt, and bile, which promise the use of these probiotic bacterial isolates for human applications. These isolates showed poor hydrophobicity and higher auto-aggregation properties. All L. fermentum isolates were found susceptible to gentamycin, chloramphenicol, cefoperazone, ampicillin, and resistant to ciprofloxacin and vancomycin. Results of hemolytic and DNase activity indicated their nonpathogenic nature. Though all L. fermentum isolates found inhibiting the growth of Salmonella ebony, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa, maximum inhibition was obtained with isolate LC5/a. Kinetic studies revealed that all four bacteria required a minimum of 2 h to reach stationary phase of AFB binding. AFB binding ability varied from 66 to 85.2% among these four isolates. Bile (0.4%) was significant (P ≤ 0.05) in reducing the AFB binding property of isolates LC3/a, LC4/c, and LM13/b, while increased AFB binding ability was recorded at acidic pH (2.0). AFB binding properties of isolate LC5/a were found least affected by acidic pH and bile. The findings of our study revealed the higher efficiency of L. fermentum isolate LC5/a in reducing the bioavailability of AFB1 in gut, and additionally, it improves the consumers' health by its various probiotic characters. These beneficial characters, L. fermentum isolates, promise them to use as probiotic formulations alone or in combinations with other beneficial probiotic-bacterial isolates.