In vivo expression technology and signature-tagged mutagenesis screens for identifying mechanisms of survival of zoonotic foodborne pathogens.

High-throughput genetic screens provide great insights into the biochemistry and molecular biology of how bacteria sense, respond to, and propagate within their environments. Genomics era techniques such as microarrays and proteomics have great potential to increase our understanding of how foodborne pathogens grow and survive within animal and human hosts, in the environment and foods, and during thermal and nonthermal inactivation protocols. While these techniques are incredibly useful for studying gene expression in simplified in vitro conditions, it is much more challenging to pursue similar studies within more complex experimental models such as in vivo, within the food matrix, or within heterogeneous microbial populations. Techniques such as in vivo expression technology (IVET) and signature-tagged mutagenesis (STM) provide alternatives for studying bacterial gene expression and growth requirements within these settings. These techniques are used extensively by the medical, veterinary, and plant research communities for identifying genes promoting the colonization and disease process, factors mediating commensalism between bacteria and their host, and genes that promote survival of environmental bacteria within natural settings. Research into the transmission and survival of foodborne pathogens from farm-to-fork would likely benefit from these techniques, however there are few reports describing their use for such purposes. This review will briefly cover the methods of IVET and STM, discuss how these techniques improved our understanding of the interactions between zoonotic foodborne pathogens and their animal hosts, and ask whether these techniques could be further exploited to better understand the survival of foodborne pathogens within the environment, within food matrices, and during inactivation protocols.