Enterobacter Sp. SM3Exhibits Run-and-Tumble Motility

Abstract

ABSTRACTThe recent discovery of the peritrichous, swarm-competent bacteriumEnterobacter sp. SM3has offered a new opportunity to elucidate the role of swarming motility in the gut microbiome. Here we present first findings of the run-and-tumble behavior ofSM3in both a control solution of motility buffer and upon bulk exposure to the chemoattractants serine and aspartate, drawing a comparison with the well-studied behavior ofE. coli. It was found thatSM3runs with an average speed of approximately 30 µm/s for an average duration of 0.77 s. Tumble events occur for an average duration of 0.11 s with a 69◦average tumble angle. Both values are similar to that ofE. coli. When exposed to serine,SM3suppresses the frequency of tumble events, which in turn increases the average run duration. In addition, the average tumble angle was found to decrease in response to serine. However, when exposed to up to a millimolar concentration of aspartate,SM3does not demonstrate a notable change in run-and-tumble parameters. These results suggest that run-and-tumble is the characteristic swimming behavior ofSM3in its planktonic state. These findings serve as a benchmark in a quest to determine the connection among swimming, swarming, and the complex dynamics of the gut microbiome.IMPORTANCEBacteria form the largest domain of living creatures on this planet. Our interactions with bacteria influence us in many ways, not the least of which being in regards to human health. A recently identified species of gut bacteria,Enterobacter sp. SM3, has been shown to reduce intestinal inflammation, suggesting that swarming could play a physiologically beneficial role. In this report, we study the motility of individualSM3bacteria This study is an essential step towards an overarching goal to understand the influence of bacterial motility on human health.