Effects of Soil Microbial Diversity on the Phosphate Fraction in the Rhizosphere of Phragmites communis in the Yeyahu Wetland in Beijing, China

Abstract

In this research, microorganisms in rhizosphere/non-rhizosphere soils of Phragmites communis in the Yeyahu Wetland were studied. A sequential extraction procedure was used to analyze the phosphorus (P) forms in the rhizosphere/non-rhizosphere soil with a variety of plant growth conditions (April, July, October). The soil bacteria community structure and the diversity was measured using the high-throughput of 16S rRNA amplicons. Furthermore, the complete crystallographic analysis (CCA) method was used to analyze the relationship between phosphate solubilizing microorganisms and P transformation in the soil samples. The results showed that the rank order of inorganic P (IP) fractions in the soil was generally as follows:Ca-bound P (Ca-P) > Occluded P (Oc-P) > Fe-bound P (Fe-P) > Exchangeable P (Ex-P) > Al-bound P (Al-P). The IP content was most affected by the growth of Phragmites communis. The minimum content of IP appeared in the vigorous growth period and the total IP content in the rhizosphere soil was generally lower than in the non-rhizosphere soil. The rank order of organic P (OP) fractions were highly resistant OP (HR-OP) > moderately resistant OP (MR-OP) > moderately labile OP (ML-OP) > labile OP (L-OP), and all the components of OP first decreased and then increased with the growth of plant. The major phylogenic groups in rhizosphere/non-rhizosphere soil of Phragmites communis, included Proteobacteria, Acidobacteria, Chloroflexi, and Actinobacteria among which, Proteobacteria was the majority group in the community composition. Furthermore, the rhizosphere/non-rhizosphere microbial community structure was significantly affected by seasonal changes and existing differences between the rhizosphere and non-rhizosphere soils. In addition, the main functional groups of the modal transformation of P bacteria genera were Bacillus, Enterobacter, Pseudomonas, Burkholderia, Acinetobacter, which can make use of most OP and IP, playing an important role in the transformation of P in wetland soils.