Figure 6.
Tethered cell responses to d-glc withdrawal. Transition times, tr (±SE), on addition (+) or withdrawal (−) are shown. Positive and negative values denote CCW and CW responses, respectively. Results obtained with a single experimental culture split into two halves, one energized by dl-lactate and the other not. Tethered cells lacking lactate were partially deenergized because they responded positively to its addition and negatively to its withdrawal. Similar results were obtained in additional experiments (n > 5 for each condition). Responses to addition or withdrawal of the attractant aspartate (0.5 μM) or the repellent leucine (10 mM), periplasmic ligands for the MCPs Tar and Tsr, respectively, measured in separate experiments, are also shown. These responses were insensitive to the presence of lactate. In each case, 20–50 cell populations were analyzed.