Fig. 6

Nitrogen cycling genes’ abundance, functional categories and bacterial correlations with environments. The relative abundance of the nitrogen cycling genes before and after enrichment as depicted by metagenome sequencing (a). Genes abundances were normalized into transcripts per million (TPM) counts. The dashed line indicated the undetected pathway. Pairwise Spearman’s correlation matrix summarized the relationships between bacteria and environmental factors (b). Correlations were shown as pie charts, which were determined by the Mantel tests