Figure 4From: Environmental transcriptome analysis reveals physiological differences between biofilm and planktonic modes of life of the iron oxidizing bacteria Leptospirillum spp. in their natural microbial communityTranscriptional evidence for metabolic differences between sessile (biofilm) and swimming (planktonic) modes of life. Genes encoding mixed acid fermentation enzymes are up-regulated in the biofilm (bottom part). As a result, two metabolites can be produced: acetyl-phosphate (acP) and acetate. The former can be used as a phospho-donor intermediate, while the later can be transformed to acetyl-CoA or released to the medium. They could be produced by fermentation of sugars via the Embden-Meyerhof-Parnas pathway to pyruvate, then to acetyl phosphate (acP) by pyruvate oxidase (PoxB), and finally to acetate by AckA. In contrast, genes encoding key TCA cycle enzymes are up-regulated in the swimming (planktonic) cells (top part; see also text for explanations). Circles indicate the name of the enzymes whose genes are being expressed in the Río Tinto samples (red, preferentially induced in biofilm; green, in planktonic cells; and yellow transcribed in both places). All of them have been identified in the L. ferrooxidans genome sequence draft (to be published elsewhere; see Additional file 1 Table S2, and Additional file 2). POR, pyruvate oxidoreductase system; Pta, phosphotransacetylase; Idh, NAD+ dependent isocitrate dehydrogenase; Acn, Aconitase; Mdh, Malate dehydrogenase; FumC, fumarate hydratase component C; SdhA, succinate dehydrogenase component A; SucCD, Succinate dehydrogenase; PpsA, phosphoenolpyruvate synthase; AccACD, acetyl-CoA carboxylase.Back to article page