A Novel Approach to Overcoming Antibiotic Resistance: Exploring the Future Role of Bacteriophages

Overview

The rapid rise of antibiotic-resistant bacteria has created an urgent need for alternative antimicrobial strategies. Bacteriophages, or phages, are viruses that infect and destroy bacteria with high specificity and minimal impact on beneficial microbes. As the most abundant biological entities on Earth, phages play a critical role in regulating bacterial populations and are increasingly studied for applications in medicine, agriculture, and food safety. This project examined how varying concentrations of bacteriophages affect bacterial lysis in Escherichia coli B and sought to identify the minimum effective phage dose (MED) required to produce significant bacterial destruction. The guiding research question was: How does phage concentration, measured as plaque-forming units per milliliter (PFU/mL), influence bacterial lawn lysis and inform the minimum effective dose analogous to a therapeutic level in phage therapy? It was hypothesized that higher phage concentrations would result in increased plaque formation and greater bacterial lysis due to a higher frequency of successful phage infections. To test this hypothesis, a standard plaque assay was performed using T4r bacteriophages and E. coli B as the host bacterium. A series of tenfold serial dilutions (10⁻⁶ to 10⁻¹⁰) was prepared from a phage stock solution. Each dilution was mixed with actively growing E. coli in molten soft agar and poured onto nutrient agar plates. A control plate containing bacteria without phages was included to confirm normal bacterial growth. Plates were incubated at 37°C for 12–24 hours, after which plaques were counted. Each dilution series was repeated across three independent trials to ensure reproducibility. Phage concentration was calculated using the formula PFU/mL = (number of plaques × dilution factor) ÷ volume plated, with only plates containing 30–300 plaques used for reliable quantification. Results showed a strong, consistent dose-dependent relationship between phage concentration and bacterial lysis. The highest concentration (10⁻⁶) produced complete lysis with too numerous to count plaques, while the control plates showed intact bacterial lawns with no plaques. The 10⁻⁷ dilution consistently resulted in near-complete bacterial lysis and plaque counts within the optimal range, identifying it as the minimum effective phage dose. Lower concentrations (10⁻⁸ to 10⁻¹⁰) produced progressively fewer plaques and partial or no lysis, demonstrating insufficient phage activity at low doses. These findings demonstrate that effective bacterial control using bacteriophages depends on achieving a minimum concentration threshold. This research supports the potential of phage therapy as a targeted alternative to antibiotics and emphasizes the importance of accurate phage quantification for therapeutic, environmental, and food safety applications. Future research could refine dose thresholds, test additional bacterial strains, and examine infection kinetics to further support real-world phage-based treatments.

Competition history

• CSEF 2026 Microbiology (Senior Division) · Entry S-16-02

Related projects

Closest projects by meaning, across every fair and year in the corpus.

Browse more like this

• All Microbiology projects
• CSEF Microbiology projects
• Every CSEF 2026 project