Water Properties Influencing the Abundance and Diversity of Denitrifiers on Eichhornia crassipes Roots: A Comparative Study from Different Effluents around Dianchi Lake, China.

Neng Yi,Zhenhua Zhang,Yan Gao,Hongbo Shao,Shaohua Yan

doi:10.1155/2015/142197

Neng Yi, Zhenhua Zhang + Show 3 more

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https://doi.org/10.1155/2015/142197

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Abstract

To evaluate effects of environmental conditions on the abundance and communities of three denitrifying genes coding for nitrite (nirK, nirS) reductase and nitrous oxide (nosZ) reductase on the roots of Eichhornia crassipes from 11 rivers flowing into the northern part of Dianchi Lake. The results showed that the abundance and community composition of denitrifying genes on E. crassipes root varied with different rivers. The nirK gene copies abundance was always greater than that of nirS gene on the roots of E. crassipes, suggesting that the surface of E. crassipes roots growth in Dianchi Lake was more suitable for the growth of nirK-type denitrifying bacteria. The DGGE results showed significant differences in diversity of denitrifying genes on the roots of E. crassipes among the 11 rivers. Using redundancy analysis (RDA), the correlations of denitrifying microbial community compositions with environmental factors revealed that water temperature (T), dissolved oxygen (DO), and pH were relatively important environmental factors to modifying the community structure of the denitrifying genes attached to the root of E. crassipes. The results indicated that the specific environmental conditions related to different source of rivers would have a stronger impact on the development of denitrifier communities on E. crassipes roots.

Highlights

Phytoremediation technology using floating macrophytes (Eichhornia crassipes) performed very well in remediation eutrophic water body since E. crassipes is capable of assimilating large amount of nutrients efficiently [1,2,3]
There are more than 31 rivers, which carried wastewater discharged from different types of sewage treatment plants (STPs), agriculture, and domestic source, flowing into the lake
The water from STP sites was characterized by relatively high concentrations of nitrate (4.79–12 mg L−1) and low concentrations of ammonia nitrogen (0.06–1.98 mg L−1) and organic matter, which had contrary properties comparing to those rivers receiving raw sewage from industrial, domestic, and agricultural sources

Summary

Introduction

Phytoremediation technology using floating macrophytes (Eichhornia crassipes) performed very well in remediation eutrophic water body since E. crassipes is capable of assimilating large amount of nutrients efficiently [1,2,3]. During 2010– 2012, large-scale confined growth of E. crassipes was used to remove pollutants (mainly N and P) from Dianchi Lake as well as the rivers connecting to the lake. To evaluate the contributions of water hyacinth to the removal of nitrogen from the lake, both assimilation and stimulated denitrification by the macrophyte are important since N-15 tracing experiment in labs indicated that the values of N-15 at.% excess of N2-N production were significantly (p < 0.05) higher with the growth of E. crassipes than that without [5, 6]. Previous studies suggested that the root system of floating macrophyte could support the attachment of microorganism and enhance the growth and activity of bacteria for removing organic matter and nutrients [8]

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