Exploring novel inducers of phage tail-like particle expression using a fluorescent reporter bacterium.

R-tailocins are phage tail-like particles produced by diverse bacterial species, playing crucial roles in interbacterial competition and microbial community dynamics. While their production is typically triggered by DNA damage through the bacterial SOS response, the full range of potential inducers remains largely unexplored. This study aimed at identifying novel chemical compounds capable of triggering R-tailocin gene expression. A fluorescent reporter bacterial strain was employed to monitor R-tailocin gene cluster activity, and over 1,500 compounds were screened using Biolog Phenotype MicroArray plates. This screen identified several previously unreported inducers of R-tailocin expression. Among the strongest inducers identified were pipemidic acid and urea, although their induction levels did not exceed those observed with the commonly used inducer mitomycin C. The identified compounds exhibited distinct temporal induction patterns, suggesting variation in their underlying regulatory mechanisms. Several also displayed clear dose-response patterns, providing further insights into their potency and potential modes of action. Notably, R-tailocin induction did not necessarily lead to complete population lysis, as a subset of cells consistently survived the induction process. Collectively, these findings expand the current understanding of R-tailocin induction and production in bacterial populations, uncovering novel chemical triggers and revealing diverse expression dynamics. These insights offer potential implications for microbial community ecology and the development of targeted antimicrobial strategies.