Isolation and characterization of bacteriophages with lytic activity against common bacterial pathogens

Aim: Present investigation was conducted to isolate and characterize bacteriophages with lytic activity against common bacterial pathogens. Materials and Methods: A total of 60 samples of animal waste disposal from cattle (42) and buffalo (18) farms were collected from three different strata, i.e., top, mid, and bottom of collection tank. Samples were primarily subjected to rapid detection methods, and then isolation of phage was done by double agar layer method using Bacillus subtilis (BsH) and Escherichia coli (EH) as host system. Phages were characterized on the basis of plaque morphology, temperature, pH susceptibility, and host range. Results: Recovery of phages was higher from dairy cattle farm waste (78.57%) as compared to buffalo farm waste (72.22%) and bottom layer of tank showed maximum recovery. Bacillus subtilis (91%) supported the growth of more phages as compared to E. coli (9%). Three different phage morphotypes were observed each against Bacillus subtilis (BsHR(1), BsHR(2), and BsHR(3)) and E. coli (EHR1, EHR2, and EHR3). Mean phage titer of above six phage isolates ranged between 3x10(10) and 5x10(12) plaque forming units/ml. Viability of phages was by, and large unaffected at 70 degrees C within 2-3 min, and phage isolates were completely inactivated below pH 3 and above 11. Coliphage EHR1 had widest host range followed by BsHR(1) and BsHR(2) while EHR2, EHR3, and BsHR(3) had low lytic activity. Conclusion: It could be concluded from the present study that the Bacillus and Coli phage has wide host range and thus exhibits the potential to be used as drug substitute tool against common bacterial pathogens.