Figure 4.
Different trends of functional modules and metabolites from the faecal microbiomes of gastrectomy and control groups. Relative abundance and linear discriminant analysis (LDA) score (log10) of Kyoto Encyclopedia of Genes and Genomes (KEGG) modules annotated by the Human Microbiome Project Unified Metabolic Analysis Network 2 (HUMAnN2) and overlapping with those annotated by our in-house pipeline (linear discriminant analysis effect size (LEfSe): p<0.05, q<0.1, LDA>2.0) (A). Richness (Chao1) and alpha-diversity (Shannon-Wiener) of contributor species were estimated. Three modules (marked by an asterisk (*) in A) contributed by significantly more diverse and richer microbes (two-sided Mann-Whitney U test (MWU): p<0.001) in the gastrectomy group, in spite of their enrichment in the control group (B). The modules were M00196, M00535 and M00122 (two-sided MWU: p=5.31×10−4, 3.17×10−5, 7.14×10−6, for richness, respectively, and p=1.12×10−4, 2.22×10−4, 6.10×10−4, for alpha-diversity, respectively). KEGG modules’ relative abundance is represented by the top value of each stack of bars. Samples were subsequently sorted according to the dominant contributor to a module and then grouped as either gastrectomy or control (sample order differs between panels). Different trends in metabolites were also observed between the two groups (LEfSe: p<0.05, q<0.1, LDA>3.0) (C). Bile acid reaction consisted of deconjugation of conjugated bile acids (glycocholate and taurocholate) into their primary form (cholate) and amino acids (glycine and taurine) followed by 7-α/β-dehydroxylation to form secondary bile acids (deoxycholic acid (DCA)). The colours highlight enrichment in the control (blue) and gastrectomy (orange) groups (D).