PHYSICO CHEMICAL CHARACTERIZATION OF A T5-LIKE SALMONELLA PHAGE ΦSP-3

Abstract

Antimicrobial resistance is a problem faced by humanity for quite some time now. Search for an intelligent alterative to antibiotics led the scientific community to join hands with an age old foe of pathogenic bacteria - bacteriophages. The present study elaborates the potential of a previously isolated phage with biocontrol capability, to survive and adsorb in various physicochemical environments . ΦSP-3, a Salmonella specific lytic phage capable of infecting host in nutrient deprived states with an added advantage of high host specificity and absence of virulence genes as previously reported was chosen for the study. Salmonella Enteritidis was used as host. Basic growth parameters like time taken for phage adsorption, optimal multiplicity of infection (MOI) and one step growth curve, were determined, followed by physicochemical characterization. Various parameters studied include temperature, pH, salinity and presence of sugars and CaCl2. 25 minutes of exposure time was required for 100% adsorption and optimal MOI was calculated as one. The latent period and the rise period was 30 minutes each with a subsequent burst size of 60 phages per bacterium. ΦSP-3 could survive upto 70ºC. 1M NaCl was optimal for phage viability while 0.25M favored maximal adsorption. The optimum pH for ΦSP-3 viability and adsorption was 8. Among the sugars,Arabinose was most influential in inactivating ΦSP-3. 100% adsorption was achieved at both 37ºC and at 40ºC. 10mM of CaCl2 to be optimum for ΦSP-3. Thus the present study substantiates the candidature of ΦSP-3 as a sturdy biocontrol agent capable of thriving well in diverse physicochemical environments.