Microbial community composition and activity controls phosphorus transformation in rhizosphere soils of the Yeyahu Wetland in Beijing, China

Zedong Teng,Yunyun Zhu,Min Li,Michael J Whelan

doi:10.1016/j.scitotenv.2018.02.115

Zedong Teng, Yunyun Zhu + Show 2 more

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https://doi.org/10.1016/j.scitotenv.2018.02.115

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Abstract

Microorganisms in the rhizosphere of wetland plants can have a significant impact on phosphorus (P) interception. We investigated the seasonal pattern of microbial community structure and its relationship with different P forms in the rhizosphere of three plants Scirpus planiculmis, Zizania latifolia, and Phragmites australis from the Yeyahu Wetland, China. Chloroform fumigation-extraction was used to determine the soil microbial biomass P (SMBP) and phospholipid fatty acids (PLFA) were used to characterize microbial community composition. P fractions in rhizosphere soil samples were also observed using sequential chemical fractionation. Results showed that the average total PLFA (TPLFA) contents of rhizosphere soils ranged from 34.9 to 40.7nmol·g−1 and were highest in summer. Bacteria were predominant in the rhizospheres of all three plants, accounting for >63% of TPLFA. Aerobic bacteria, represented by 16:0 PLFA, were most abundant. Both organic P (OP) and inorganic P (IP) accumulated in the rhizosphere during the winter die-back phase. Furthermore, both TPLFA and bacterial PLFA decreased with increases in highly resistant OP (HR-OP), occluded P (Oc-P) and Calcium-bound P (Ca-P). This suggests that bacteria play an important role in P transformation and can make use of various P forms. We also found that SMBP was significantly negatively correlated with labile OP (L-OP), moderately labile OP (ML-OP) and HR-OP, reflecting a high degree of cross correlation between SMBP and the PLFA indices.

Highlights

Phosphorus (P) is a key limiting nutrient in both aquatic and terrestrial ecosystems
The seasonal pattern in microbial biomass which peaked in July or August can be explained in a number of ways, including the seasonal development of the wetland vegetation which is widely believed to have a symbiotic relationship with the microbial community in the rhizosphere
Consistent and systematic seasonal patterns in different P fractions and in indicators of the size and composition of the microbial biomass were observed in the rhizosphere soils associated with three wetland plants

Summary

Introduction

Phosphorus (P) is a key limiting nutrient in both aquatic and terrestrial ecosystems. Replenishment of soil P reserves through fertilization is common in agriculture, but the long-term sustainability of this practice is questionable, because the main source of fertilizer P is rock phosphate which is mined from non-renewable reserves. P can be lost from soils via the erosion of particles and via leaching of soil pore water (Haygarth et al.,1998; Heckrath et al, 1995), leading to eutrophication of freshwater (Correll et al, 1998) and marine ecosystems (Philippart et al, 2007) and elevated P concentrations in groundwater (Holman et al, 2008). P can accumulate in sediment and be periodically released into overlying water under suitable environmental conditions, making remediation difficult (Ribeiro et al, 2008)

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