In Vitro Screening of Bacterial Isolates From Dairy Products for Probiotic Properties and Other Health-Promoting...

The present research was aimed to isolate potential probiotic organisms from dairy products locally made in and around the Saurashtra region of Gujarat. A total of 224 colonies were screened for primary attributes. Based on the results, 70 isolates were carried further for secondary screening. Out of these, only 23 isolates were further tested for antioxidant activities. Only 6 potential probiotic strains were found to have all the probiotic attributes. These isolates demonstrated survivability up to 4 h at pH ≤ 3, bile concentration ≥ 1.5%, autoaggregation ability ≥ 81.08%, and cell surface hydrophobicity more than 70% while using toluene as the test hydrocarbon. The promising six isolates were subjected to 16S rRNA sequencing for species-level identification and found to be belonging to the genus Bacillus, Enterococcus, and Lactobacillus. The isolates demonstrated higher antioxidant potential as determined by ABTS, DPPH, and FRAP methods. For all three methods, L. rhamnosus was taken as a positive control that showed 85.61%, 39.56%, and 78.18% reduction of free radicals as determined by the ABTS, DPPH, and FRAP methods, respectively. Compared to this, Limosilactobacillus fermentum BAB 7912 demonstrated the highest reduction of ABTS radicals (83.45%), while Bacillus subtilis BAB 7918 reduced 29.95% DPPH free radicals and Bacillus spizizenii BAB 7915 reduced 80.93% ferric ions as determined by the FRAP method. Isolates were subjected to 16S rRNA sequencing for species-level identification and found to be belonging to genus Bacillus, Enterococcus, and Lactobacillus.