Identification of Chemotaxis Protein Substrates in Thiomicrospira crunogena

Introduction
Thiomicrospira crunogena is a
Gram negative, aquatic, colorless sulfur oxidizing, chemolithoautotrophic bacterium. Cells are spiral shaped 0.2-0.3 µm in diameter and 1-2µm long, some individual cells can reach up to 30 µm long (3). T. crunogena is motile via a singular polar flagellum. It is the first deep-sea autotrophic hydrothermal vent bacterium to have its genome fully sequenced and annotated (1). Originally isolated from the East Pacific Rise, it is commonly isolated from deep-sea hydrothermal vent communities where warm, CO2 rich hydrothermal fluid that surges from cracks in the basal crust mixes with cold, oxic bottom water (1). This mixture creates eddies, or whirling of water similar to a vortex where the dilute hydrothermal fluid causes a dynamic habitat with respect to time and nutrient concentrations. The warm hydrothermal fluid emitted from the fissures contains CO2 concentrations between 0.02 mM to >1 mM where as the bottom water is around 2°C and contains CO2 concentrations less than 0.02 mM (1). This difference in CO2 concentration, temperature and oxygen concentration causes T. crunogena to be just as dynamic metabolically in order to survive in an ever-changing environment. As previously mentioned, T. crunogena is a chemolithoautotrophic bacterium deriving it’s energy from inorganic compounds such as hydrogen sulfide, thiosulfate, elemental sulfur and sulfide minerals (pyrite and chalcopyrite) (1). It uses theses compounds as its electron donors, oxygen as its sole electron acceptor and CO2 as its only carbon source (5). Genome analysis has revealed that T. crunogena contains all of the genes necessary for sulfur oxidizing multienzyme system or Sox system where sulfite, thiosulfate, sulfur and hydrogen sulfide dependent-cytochrome c