Comparative Analysis of Rhizosphere and Endophytic Microbial Communities Between Root Rot and Healthy Root of Psammosilene tunicoides.

The wild resources of Psammosilene tunicoides have decreased sharply because of the long-term mining and excavation, which has led to the increased demand for its artificial cultivation. However, root rot represents a significant obstacle leading to a poor quality and product of P. tunicoides. Previous reports have not focused on root rot in P. tunicoides. Therefore, this study explores the rhizospheric and root endophytic microbial community structure and composition of healthy and root rot P. tunicoides to understand the mechanism underlying root rot. The properties of the rhizosphere soil were assessed using physiochemical methods, and the bacterial and fungal populations were studied through amplicon sequencing of the 16S rRNA genes and ITS regions in the root and soil. Compared to healthy samples, the pH, hydrolysis N, available P, and available K were significantly decreased in the diseased samples while the organic matter and total organic carbon were significantly increased in the diseased samples. Redundancy analysis (RDA) showed that soil environmental factors are related to changes in the root and rhizosphere soil microbial community of P. tunicoides indicating that the physiochemical properties of soil affect plant health. Alpha diversity analysis showed that the microbial communities of healthy and diseased samples were similar. Some bacterial and fungal genera were significantly increased or decreased (P < 0.05) in diseased P. tunicoides, and certain microbial factors that antagonized root rot were further explored. This study provides an abundant microbial resource for future studies and contributes to improving soil quality and P. tunicoides agricultural production.

Electrochemical heterogeneous catalytic degradation of wastewater containing phenol.

An electrochemical-heterogeneous catalytic process was applied to remove phenol from wastewater. Three key factors-applied potential, supporting electrolyte concentration, and pH-were tested for their effects on the phenol removal. The optimal condition was determined as an applied potential of 25 V, Na(2)SO(4) concentration of 500 mg L(-1), and a pH of 2.5. Under the optimal condition, the phenol and chemical oxygen demand (COD) removals were 83.7% and 42.9%, respectively. The apparent kinetics of phenol removal could be expressed as a pseudo first-order reaction. In addition, a possible mechanism of phenol degradation was proposed based on the intermediate products.