Fig 1.
Treatment processes in the two PWWTPs and the shared ARGs.
(A) The flow charts and sampling sites of the treatment processes in two PWWTPs. The black points in oxidation ditch represent the sampling sites. HA: Hydrolytic Acidification; CASS: Cyclic Activated Sludge System; UBF: Up-flow Blanket Filter; (B) Number of shared ARG subtypes by adjacent treatment systems in two PWWTPs. (C) Percentage of the shared ARGs in the total ARGs.
Fig 2.
Abundance of ARGs in the PWWTP and STP sludge samples.
(A) Total abundance of ARGs in the PWWTP and STP sludge. (B) Percentage of the ARG types in the PWWTP and STP sludge. (C) Percentage of resistance mechanisms in the PWWTP and STP sludge.
Fig 3.
Percentage of the predominant ARG subtypes (≥1% in at least one sludge sample) in PWWTP and STP sludge.
Fig 4.
Principal coordinate analysis of 11 PWWTP and STP sludge samples based on the percentages of ARG subtypes.
Fig 5.
Bacterial community in the PWWTP sludge samples.
(A) Percentages of different phyla in the PWWTP sludge. “Others (1%)” refers to the phyla with abundance <1% in all samples. (B) Percentages of top 10 genera in the PWWTP sludge samples. The asterisks indicate the significant difference with p-value<0.05 between anaerobic and aerobic sludge samples.
Fig 6.
Redundancy analysis of the correlation between the percentages of 36 dominant genera with the percentages of eight ARG types in PWWTP sludge.
Arrows represent the seven genera significantly correlated with ARGs distribution (p<0.05).
Table 1.
The abundance and diversity of MGEs in PWWTP sludge.