Fig. 4: Microbial community profiling.

a Principal coordinate analysis (PCoA) based on a Bray-Curtis matrix at the species level. b Analysis of functional genes related to biofilm formation and QS using PICRUSt based on the KEGG database. Co-occurrence network for (c) the non-QQ GD-MBR (GD-MBR 1) and (d) the QQ GD-MBR (GD-MBR 2). The size of each yellow node indicates the number of connections it has, while the nodes themselves reflect the class level. Positive and negative correlations are shown by blue and red lines, respectively (p < 0.05). Each correlation has a strong Spearman’s coefficient of > 0.75 or < –0.75.