Effects of Escherichia coli pollution on decomposition of aquatic plants: Variation due to microbial community composition and the release and cycling of nutrients.

ABSTRACT

Determination of the effects of Escherichia coli (E. coli) pollution on agricultural pond ecosystems with vegetation at different life stages is essential for the protection of ecological functions. However, no comprehensive study has yet shown the responses of epiphytic microbial communities to E. coli invasion during plant decay. Thus, this study was conducted to clarify variation in the decay of the following aquatic plants-Myriophyllum aquaticum, Nymphaea tetragona and Phragmites australis after E. coli pollution. Exogenous E. coli especially shifted the epiphytic microbial composition and distribution of P. australis. Stronger effects of E. coli on the archaeal community (edges/nodes = 0.818 < 1, modularity = 0.654; lower clustered structure, 0.389) were found than on the bacterial community (edges/nodes = 1.538 > 1, modularity = 1.291 > 0.654; higher clustered, 0.593). During plant decomposition, E. coli weakened methanogenesis by regulating the network of core genera Methanobacterium and Methanospirillum (spearman, P < 0.05), stimulated the accumulation of organic matters in water (P < 0.05). Similarly, nitrification and denitrification increased and decreased through network regulation in relative biomass of genera Devosia and Desulfovibrio (P < 0.05), respectively. The results provided theoretical supports for eutrophication management in pond ecosystems threatened by E. coli pollution.