Flea-borne transmission is a recent evolutionary adaptation that distinguishes the deadly Yersinia pestis from its progenitor Y.pseudotuberculosis,a mild pathogen transmitted via the food-borne route.Y.pestis synthesizes biofilms in the flea gut,which is important for fleaborne transmission.Yersinia biofilms are bacterial colonies surrounded by extracellular matrix primarily containing a homopolymer of N-acetyl-D-glucosamine that are synthesized by a set of specific enzymes.Yersinia biofilm production is tightly regulated at both transcriptional and post-transcriptional levels.All the known structural genes responsible for biofilm production are harbored in both Y.pseudotuberculosis and Y.pestis,but Y.pestis has evolved changes in the regulation of biofilm development,thereby acquiring efficient arthropod-borne transmission.
