Fig. 4
Association of strain NCT- 2 colonization with soil bacterial communities and nitrate reductase and effects on enriched biomarkers and metabolic profiles in rhizosphere soil. a Correlations between bacterial community and ASV_20544 abundance (n = 8). The statistical significance of comparisons is assessed using Mantel test based on Pearson’s product moment correlation using 9999 permutations. RS, rhizosphere soil; RE, root endosphere. b Ordinary least squares (OLS) linear regression between the soil nitrate reductase (S-NR) and the abundance of ASV_20544 (n = 8). The fitted lines are regression lines from OLS regression, and the shaded areas indicate 95% confidence interval of the fit. The statistical test used is F-test. c Based on the random forest model prediction biomarkers of rhizosphere soil bacterial community. d Linear discriminant analysis (LDA) effect size cladogram of the rhizosphere soil bacterial community. The taxon from the inner circle to the outer circle is phylum to genus, and the node size corresponds to the average relative abundance of the taxon, in which hollow and solid nodes represent insignificant and significant differences between groups, respectively. CRS, control group rhizosphere soil; BRS, treatment group rhizosphere soil. e KEGG pathway enrichment analysis of differentially expressed metabolites (DEMs) in rhizosphere soil under strain NCT- 2 inoculation. DA Score reflects the overall changes of all metabolites in the metabolic pathway, with a score of 1 indicating an upregulation of the expression trend of all annotated DEMs in the pathway, and − 1 indicating a downregulation of the expression trend of all annotated DEMs in the pathway. The size of the dots indicates the number of DEMs annotated in the pathway. The dots are distributed on the right side of the central axis, and the longer the line segment, the more inclined the overall expression of the pathway is to be upregulated; On the contrary, it indicates that the overall expression of the pathway tends to be downregulated. Enrichment analysis was performed using Fisher’s exact test, and P values were corrected by the BH method (**P < 0.01, ***P < 0.001)