Characterization of antibacterial activity of lytic bacteriophage PE-1 for biological control of Escherichia coli K88 in vitro

In recent years, antibiotic-resistant pathogens have placed tremendous pressure on pathogen control within the livestock industry. Consequently, we have turned our attention to phages, a unique type of virus that has co-evolved with bacteria for an extended period. PE-1 is a bacteriophage strain capable of effectively controlling target pathogens and was isolated from samples collected from dead piglets suffering from intestinal disease and their living environment. Enterotoxigenic Escherichia coli (ETEC) K88 was employed as an inhibitory target to characterize the growth characteristics and in vitro antibacterial effects of bacteriophage PE-1. Morphological analysis tentatively classified phage PE-1 as belonging to the Podoviridae family. The one-step growth curve revealed that phage PE-1 had a short latent period of 10 min, a rise period of 20 min, and a burst size of 13 PFU/cell. The optimal multiplicity of infection (MOI) for phage PE-1 is 10, and the phage maintained normal activity at pH levels between 4−11 and temperatures no higher than 55 °C. Through two in vitro simulated test experiments, we evaluated the antibacterial efficacy of the bacteriophage. Our findings indicated that bacteriophage PE-1 delayed the growth activity of ETEC K88 by more than 2 h and reduced the proliferation rate of the host bacteria under infection conditions. Moreover, the bacteriophage decreased the concentration of host bacteria that reached the stationary phase. After inoculating the host bacteria with the optimal MOI, the host bacteria concentration dropped by nearly three orders of magnitude after 4 h. In conclusion, bacteriophage PE-1 demonstrates potential as an antibacterial agent for ETEC K88.