Elucidating the Physiological Role of Guanidinium (Gdm+) in Bacteria

Abstract

Until recently, guanidinium (Gdm+) was not known to be physiologically relevant in bacteria. Gdm+ is most commonly known for industrials purposes in production of explosives, rubber, plastics and as a chaotropic agent for protein denaturation. However, it has recently been shown that diverse bacteria have mechanisms to sense Gdm+, use Gdm+ as a nitrogen source, and export Gdm+ using guanidinium exporters (Gdx), establishing Gdm+ homeostasis as important to bacterial physiology. Here, we examine the effects of exogenous guanidinium ion on bacteria in context of planktonic growth and biofilm formation. We further investigate how and why bacteria endogenously produce Gdm+. Using flow cytometry, we test the competitive fitness of bacteria that are deficient in guanidinium exporter under conditions of varying carbon and nitrogen. These experiments begin to reveal the biological role of a metabolite that was once overlooked.