Fig. 7

Proposed model of interactions between the worm and its associated microbiome. The active form of bacterial vitamin B6, pyridoxal-5P (PLP), is a required cofactor of cysteine synthases (cysl) of the worm for the enzyme activity. Identification of multiple homologs (serC_1–4 and pdxA2_1–3) in the specific route of vitamin B6 de novo pathway (conversion of D-erythrose 4-P to 3-amino-1-hydroxyacetone 1-P4) in the native bacterial isolates, as determined by nanopore sequencing, and identification of multiple isomers (cysl-1-4) for cysteine synthesis in the host, as determined by RNAseq, demonstrate the critical importance of the interspecies relationship. In this proposed model, vitamin B6 is linked to cellular detoxication through GSTs, which is accompanied with the regulation of TGF-beta and Wnt signaling pathways, where C. elegans genes, with human homologs, are regulated. Bacterial genes are highlighted with bold and italic to indicate the relation to Chryseobacterium sp. CHNTR56 MYb120 and Comamonas sp. 12022 MYb131, respectively. The sequential order for the enzymatic steps is indicated with super script in parenthesis. Red arrow indicates up regulation and blue arrow indicates down-regulation. *: confirmed by RNAseq. ^: reverse gene expression (compared to the other enriched genes in the indicated pathway). ǂ: supported by the downregulation of hsp-16.2 (detected by RNAseq)