Optimization of the large-scale production for Erwinia amylovora bacteriophages.

Background: Fire blight, caused by Erwinia amylovora, poses a significant threat to global agriculture, with antibiotic-resistant strains necessitating alternative solutions such as phage therapy. Scaling phage therapy to an industrial level requires efficient mass-production methods, particularly in optimizing the seed culture process. In this study, we investigated large-scale E. amylovora phage production by optimizing media supplementation and fermenter conditions, focusing on minimizing seed phages and pathogenic strains to reduce risks and improve the seed culture process.

Results: We optimized the phage inoculum concentrations and media supplements to achieve higher phage yields comparable to or exceeding conventional methods. Laboratory-scale validation and refinement for fermenter-scale production allowed us to reduce bacterial and phage inoculum levels to 10⁵ CFU/mL and 10³ PFU/mL, respectively. Using fructose and sucrose supplements, the yields were comparable to conventional methods that use 10⁸ CFU/mL host bacteria and 10⁷ PFU/mL phages. Further pH adjustments in the fermenter increased yields by 16-303% across all phages tested.

Conclusions: We demonstrated the successful optimization and scale-up of E. amylovora phage production, emphasizing the potential for industrial bioprocessing with the reduced use of host cells and phage seeds. Overall, by refining key production parameters, we established a robust and scalable method for enhancing phage production efficiency.