Toward an intensive understanding of sewer sediment prokaryotic community assembly and function

Abstract

Prokaryotic communities play important roles in sewer sediment ecosystems, but the community composition, functional potential, and assembly mechanisms of sewer sediment prokaryotic communities are still poorly understood. Here, we studied the sediment prokaryotic communities in different urban functional areas (multifunctional, commercial, and residential areas) through 16S rRNA gene amplicon sequencing. Our results suggested that the compositions of prokaryotic communities varied significantly among functional areas. Desulfomicrobium, Desulfovibrio, and Desulfobacter involved in the sulfur cycle and some hydrolytic fermentation bacteria were enriched in multifunctional area, while Methanospirillum and Methanoregulaceae, which were related to methane metabolism were significantly discriminant taxa in the commercial area. Physicochemical properties were closely related to overall community changes (p < 0.001), especially the nutrient levels of sediments (i.e., total nitrogen and total phosphorus) and sediment pH. Network analysis revealed that the prokaryotic community network of the residential area sediment was more complex than the other functional areas, suggesting higher stability of the prokaryotic community in the residential area. Stochastic processes dominated the construction of the prokaryotic community. These results expand our understanding of the characteristics of prokaryotic communities in sewer sediment, providing a new perspective for studying sewer sediment prokaryotic community structure.

Keywords: assembly mechanism; co-occurrence pattern; prokaryotic community function; sewer sediment; sulfur cycle.

FIGURE 1

(A) Differences of Shannon and Richness indices in sediment from different functional areas. Significance of differences is indicated by “a, b, c” (p < 0.05; multiple comparison with ANOVA tests); (B) Principal coordinate analysis (PCoA) based on Bray-Curtis dissimilarity and PERMANOVA tests showing the variation of sediment prokaryotic communities from different functional areas. ***p < 0.001.

FIGURE 2

Circos plot showing the distribution of sewer sediment prokaryotic community composition at phylum level in different functional areas.

FIGURE 3

Heatmap representing major differences in predicted functions among sewer sediments from different functional areas based on Functional annotation of prokaryotic taxa (FAPROTAX).

FIGURE 4

Redundancy analysis (RDA) of sewer sediment prokaryotic communities with physicochemical properties. TP, total phosphorus; TN, total nitrogen; AS, available sulfur; TS, total solid; TOC, total organic carbon; VS, volatile solid; NO₃^–-N, nitrate- nitrogen; NH₄⁺-N, ammonium-nitrogen; pH, sediment pH; physical texture (sand, and silt contents).

FIGURE 5

Two-way correlation network analysis between prokaryotic genera and sediment physicochemical properties. Different colors of nodes were classified into various phyla. TOC, total organic carbon; pH, sediment pH; TP, total phosphorus; TN, total nitrogen; TS, total solid; VS, volatile solid; AS, available sulfur; NH₄⁺-N, ammonium-nitrogen; physical texture (sand, and silt contents).

FIGURE 6

Co-occurrence network analysis of the sewer sediment prokaryotic communities from different functional areas. (A) Co-occurrence networks in different functional areas. (B) keystone species analysis.

FIGURE 7

The assembly process of sewer sediment prokaryotic communities from different functional area. (A) The neutral community model. The Blue dashed line indicates 95% confidence intervals for the prediction of neutral model. R² values indicate the goodness of fit. The Nm parameter reflects immigration times metacommunity size. (B) The contributions of different ecological processes in assembling the prokaryotic community. HeS, heterogeneous selection; HoS, homogeneous selection; HD, homogenizing dispersal; DL, dispersal limitation; DR, drift.