45] Sodium-driven flagellar motors of alkalophilic Bacillus

Abstract

Publisher Summary This chapter describes the method to measure the motility and bioenergetic parameters of alkalophilic Bacillus. Although the flagellar motors of these bacteria require Na + for their rotation and the rotation speed is optimal under alkaline conditions, the swimming pattern and swimming speed of these bacteria are indistinguishable from those of neutrophilic Bacillus such as B. subtilis. Hence, most methods for the motility measurements of neutrophilic bacteria are also utilizable for alkalophilic Bacillus. Bacteria swim by rotating their flagella, and each flagellum is driven at its base by a rotary motor embedded in the cell wall and cytoplasmic membrane. In the case of bacteria such as Escherichia coli and Bacillus subtilis , which are living in moderate conditions, the energy for rotation of their flagellar motors is supplied by the electrochemical potential gradient of protons across the membrane—namely, the protonmotive force. Recent studies indicate that the presence of the electrochemical potential gradient of Na + is essential for rotation of these flagellar motors. Thus, these alkalophilic Bacillus strains are considered to have the Na + -driven flagellar motors.