Fig. 1

Alpha and beta diversities of the sputum microbiome in healthy controls (n = 10), AECOPD (n = 36), recovery (n = 18) and stable samples (n = 4): Community diversity (Shannon Index) and richness (number of observed OTUs) (a and b). The dark horizontal lines within the bar of A and B were the median values of each group. After the Kruskal–Wallis test is significant, a post-hoc analysis (Wilcoxon signed-rank test) was performed to determine which group of the independent variable differ from each other group. A and B indicated that either AECOPD or Recovery subjects is significantly less diverse and richness than the healthy control. Principal Coordinate Analysis of the sputum microbiome membership based on the Jaccard distance matrix (c). Each point represents 1 subject with Health Control as green circle, AECOPD as red triangle and Stable as blue square. Regarding beta diversity measures, significant differences in community membership between AECOPD vs healthy controls (ANOSIM, R = 0.43, P < 0.05), AECOPD vs stable (ANOSIM, R = 0.29, P < 0.05), healthy control vs recovery (R = 0.47, P < 0.05) and healthy control vs stable (R = 0.38, P < 0.05) were detected. Health Control: subjects without any clinical signs; AECOPD: acute exacerbations of chronic obstructive pulmonary disease; Recovery: the patient recovering from exacerbation treatment; Stable: stable period over 8 weeks free of an AECOPD