Relationship between growth conditions and gene expression profiles of the lux -type genes in R. rubrum. A: mRNA accumulation from selected genes in R. rubrum cultures grown under aerobic (white), microaerobic (grey) and phototrophic (black) conditions. B: PM levels and initial growth rates. C: AHL accumulation. All samples were harvested during exponential growth at an optical density of ~2. Genes associated with quorum sensing (I), the PM production (II), and metabolism (III) are indicated. D: Cluster analysis of growth condition dependent data shown in A, B and C. The red/gray pattern indicates the degree of structural identity; components with a high structural identity (R2 > 0.98) are clustered as indicated by the coloured groups (· · ··). Cluster analysis was performed using PermutMatrix version 1.9.3.