Figure 4

K-means clustering of S. meliloti 1021 genes differentially expressed after pH shift time-course. Six clusters (A-F), calculated by K-means clustering, were characterized by their specific transcriptomic profiling over 60 minutes following acidic pH shift. The graphics illustrate the expression profile based on the mean values; the X-axis represents time, whereas the Y-axis represents the log₂ ratio of gene expression (detailed view of the axes is shown in Figure 6). Tables below each graphic enlist genes distributed to the corresponding cluster.