Fig. 4

Metaproteomic functional analysis of potential psychobiotics. a Heatmap of Spearman’s correlation for key protein groups and psychological factor scores. The protein groups whose correlation coefficient |R| was ≥ 0.35 (P < 0.001) in more than 50% of the psychological factors are shown here. The scaling of correlation coefficient is represented by color depth—a positive correlation is expressed in red and a negative correlation in blue. *P ≤ 0.05, **P ≤ 0.01, ***P ≤ 0.001. The taxonomic assignment and KO ID corresponding to each proteome are displayed in (b). b KEGG functional enrichment analysis based on the key protein groups (P-adjusted = 0.05). c Taxon-function-coupled enrichment analysis of the key protein groups. Matching taxon and function by using Ultra-deep Metaproteomics established by Daniel Figeys laboratory [19]