Evaluación de un bacteriófago con actividad lítica contra Escherichia coli mediante ensayos fisicoquímicos, genéticos y fenotípicos.

Abstract

Environmental dissemination is a global concern, and bacteriophages represent a promising alternative for controlling antibiotic-resistant bacteria due to their high specificity, ability to self-replicate, and coevolution with the host. The objective of this research was to evaluate a bacteriophage with lytic activity against Escherichia coli through physicochemical, genetic, and phenotypic tests. Bacteriophages from lytic genera such as Felixunavirus, Dhillonvirus, and Justusliebigvirus were isolated from water and sediment samples from the Estero Salado, Guayaquil- Ecuador. However, only phage BME3, belonging to the last genus, managed to lyse E. coli strains with different antibiotic susceptibility phenotypes: 57.14% (8/14) resistant, 12.5% (1/8) intermediate, and 80% (4/5) sensitive. Likewise, BME3 infected strains of E. coli ATCC 25922 and Salmonella typhimurium ATCC 14028, and did not react with Bacillus sp., Vibrio sp., and Pseudomonas sp. BME3 demonstrated stability at temperatures below 60°C and in pH ranges between 3 to 11 and lacks sensitivity to chloroform. Through transmission electron microscopy, it was verified that BME3 belongs to the Caudoviricetes class, with the length of the icosahedral head and the contractile tail was 102.64±11.57 nm and 105.00±9.00 nm, respectively. The genome of phage BME3 consists of double-stranded DNA with a length of 147,371 bp, a GC content of 37.5%, and 15 tRNA genes. Furthermore, BME3 lacks lysogenic genes, antibiotic resistance, and virulence factors, indicating that this bacteriophage is safe for phage therapy.