Genomic characterization and application on food samples of bacteriophage ETEC-S3 to control enterotoxigenic...

Enterotoxigenic Escherichia coli (ETEC) contamination remains a major global concern, including in Indonesia, where efforts to develop an ETEC vaccine to prevent foodborne diseases are currently underway. This study aimed to perform genomic characterization of bacteriophage φETEC-S3 and evaluate the efficacy of its application in food samples targeting Enterotoxigenic Escherichia coli. The phage exhibited a high lytic activity, reaching a titer of 3.8 ± 0.50 × 10¹⁰ PFU/mL and remained stable at both 4 °C and 37 °C based on the results of the thermal stability assays. Whole-genome bioinformatics analysis identified φETEC-S3 as a virulent double-stranded DNA phage belonging to the genus Phapecoctavirus within the class Caudoviricites. This genome contained structural and lytic genes, including those encoding the major capsid protein, tail fiber, and Rz-like spanin. Application studies demonstrated that phage φETEC-S3 significantly reduced the enterotoxigenic Escherichia coli population in all food samples from the initial day until the seventh day of incubation. The highest reduction percentages were for φETEC-S3 in soy milk on the initial day (93%) and in mashed potatoes on the seventh day (94%). Thus, φ ETEC-S3 is shown to be a promising candidate for a biocontrol agent against bacteria responsible for food spoilage.