Penetrating the biofilm barrier: characterization of Escherichia Phage vB_EcoS-TPF103dw and harnessing depolymerase to combat Shiga toxin-producing Escherichia coli O103 Biofilm

Authors: Campos, David; Liao, Yen-Te; Harden, Leslie; Zhang, Yujie; Wu, Vivian

Submitted to: Frontiers in Microbiology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/11/2025
Publication Date: 11/27/2025
Citation: Campos, D., Liao, Y., Harden, L.A., Zhang, Y., Wu, V.C. 2025. Penetrating the biofilm barrier: characterization of Escherichia Phage vB_EcoS-TPF103dw and harnessing depolymerase to combat Shiga toxin-producing Escherichia coli O103 Biofilm. Frontiers in Microbiology. (16) Article.1715907. https://doi.org/10.3389/fmicb.2025.1715907.
DOI: https://doi.org/10.3389/fmicb.2025.1715907

Interpretive Summary: Shiga Toxin-producing E.coli (STEC) O157:H7 remains the most frequently studied serogroup; non-O157 strains, such as STEC O103, have gained attention for their involvement in outbreaks linked to contaminated meat, dairy products, and produce. In food-processing environments, some harmful E. coli, such as STEC O103, can attach tightly to stainless steel surfaces by forming a slimy coating containing sugars and other materials, known as biofilm. This biofilm makes it difficult for chemical disinfectants, like chlorine, to penetrate and kill the bacteria. We tested a natural virus that infects and kills bacteria, also known as a bacteriophage (phage), to see if it could infect a STEC O103 biofilm. The TPF103dw phage in this study was a newly isolated tailed phage with genetic features similar to the reference phage T5. Phage TPF103dw infected and lysed STEC O103 strains. Additionally, the phage contained genes likely to produce the enzyme (called depolymerase) that breaks down the external structure of biofilms. When applied to metal surfaces, the phage reduced the biofilm’s thickness dramatically within just 30 minutes, visually stripping away much of the protective coating. The phage reduced E. coil O103 counts by about 85%.

Technical Abstract: Introduction: Besides Shiga Toxin-producing E. coli (STEC) O157:H7, non-O157 STEC strains, such as O103, have been linked to outbreaks in meat, dairy, and produce. This study aimed to characterize and evaluate the lytic Siphovirus vB_EcoS-TPF103dw as an intervention against STEC O103 biofilm. Methods: Phage vB_EcoS-TPF103dw isolated from chicken feces, sequenced and biologically characterized. Antimicrobial activity was tested in vitro and against O103 biofilm on stainless steel. Biofilm disruption was examined by scanning electron microscopy (SEM). Results: TPF103dw, with a host range of (ATCC 13706, O103, and O26), and belonged to the Tequintavirus genus. TPF103dw has a latent period of approximately 50 minutes, with an estimated burst size of 232 PFU/cell, and is stable over a wide range of pH (pH 5 to pH 10) and temperature (4 to 60°C). Phage TPF103dw encoded four high-probability (>90%) depolymerase candidates. The results showed phage-free filtrates containing soluble depolymerases alone were sufficient to dismantle the extracellular polysaccharide layer, as confirmed by SEM. Phage application against STEC O103 biofilm on stainless-steel coupons for 30 minutes resulted in a significant STEC O103 reduction of 0.83 log10 CFU/coupon. Discussion: The findings of this study provide insights into a novel T5-like Siphoviridae phage, vB_EcoS-TPF103dw, and demonstrate its genomic diversity, predicted depolymerase-encoding potential, stability under variable conditions, and antimicrobial efficacy against STEC O103 biofilms in vitro.