Engineering broad-spectrum phage-resistant <i>Escherichia coli</i> via adaptive and programmable defense strategies

Phage contamination is a significant challenge in industrial fermentation and severely impacts product quality and production efficiency. We systematically compared spontaneous mutation and CRISPR/Cas9-mediated immunity as two strategies for engineering phage-resistant <i>E. coli</i> strains. Both approaches effectively protected bacterial cultures from phage infection without compromising recombinant protein production, underscoring their potential for industrial applications. Notably, spontaneous mutation conferred broad-spectrum resistance but was associated with fitness costs and limited evolutionary stability. In contrast, CRISPR/Cas9-based immunity offered long-term, programmable protection with minimal growth impairment. By delineating the trade-offs between these two strategies, our work provides a framework for selecting tailored phage resistance solutions suited to diverse biomanufacturing scenarios.