Previous work suggested M. xanthus contains an arginine kinase (ark) gene that was incorporated into its genome by horizontal gene transfer. This protein is a member of the phosphagen kinase family, which regulates the concentration of the energy‐carrier molecule ATP by catalyzing the reversible transfer a high‐energy phosphate from ATP to another molecule, in this case arginine. In response to starvation, Myxococcus xanthus cells aggregate to form mounds called fruiting bodies containing resistant spores that can survive until conditions improve. When ark is knocked out in M. xanthus the developmental pathway does not proceed normally. However, when M. xanthus cells with ark knocked‐out are exposed to osmotic stress during development, development is partially restored. The goal of this study is to determine whether this enzyme has evolved a novel function that makes it important for development. To test the effect of AK activity, I will insert genes for AKs of different activity into the M. xanthus DNA. These enzymes will provide AK activity, but not any novel functions that the M. xanthus AK may have. I will then observe whether development proceeds normally in these new strains. I am currently confirming the production of the plasmid that will be used to re‐insert the M. xanthus AK into its genome. This research is supported by the College of Wooster Biology department and Copeland Funding.