Fig. 6

Genetic potential of metagenome-assembled genomes (MAGs) with the same taxonomy as HRT bioindicators driving the catabolism of xylan and lactate to n-caproate and n-caprylate. These catabolic steps were categorised into four main functions of the anaerobic mixed culture fermentation. a Hydrolysis of xylan. b Xylose fermentation producing acetate and lactate. c Butyrate formation from lactate and acetate. d Chain elongation with lactate as electron donor producing n-butyrate, n-caproate and n-caprylate. Numbers represent the 18 different MAGs with similar phylogenies as the HRT bioindicators at the genus level (details in Table 1). The enzyme abbreviations are provided in red letters next to the pathways (solid lines). Dashed lines represent multi-enzyme reactions between the two indicated molecules. In (d), “cycle” refers to the reverse β-oxidation cycle. The complete metabolic pathways are depicted in Additional file 1: Fig. S12. un., unclassified; XL, xylanase (EC 3.2.1.8); XylT, xylose transporter (EC 7.5.2.10, EC 7.5.2.13); LacP, lactate permease (TC 2.A.14); CoAT, butyryl-CoA:acetate CoA-transferase (EC 2.8.3.-); PTB, phosphate butyryltransferase (EC 2.3.1.19); BUK, butyrate kinase (EC 2.7.2.7); ACT, acyl-CoA thioesterase (EC 3.1.2.20)