Swimming speed and chemokinetic response of Rhodobacter sphaeroides investigated by natural manipulation of the membrane potential

Publisher Website
Google Scholar
Abstract
The ΔΨ of R. sphaeroides, grown under high light to reduce the levels of light‐harvesting bacteriochlorophyll, was naturally manipulated using light intensity. The relationship between ΔΨ and the swimming speed of free swimming populations of cells was investigated. After de‐energisation by incubation in the dark there was an apparent threshold of about −13 mV which had to be overcome before functional motor rotation could resume and at −45 mV the motor saturated. Further increases in ΔΨ over −45 mV did not increase the free swimming velocity. However, when a chemokinetic effector was added there was an increase in swimming speed, even though the ΔΨ was well above saturation, indicating that the chemokinetic response is independent of normal relationship between motor rotation and ΔΨ.