Abstract
Arsenic (As) is a toxic semi-metallic element that is ubiquitous in the environment and poses serious human health risks. Phytoextraction by Pteris vittata is considered a low-cost and environmentally friendly approach to treat As-contaminated soil. P. vittata mainly absorbs arsenate thus the bioavailability of As to P. vittata depends on the chemical form of As. Microbial redox of As contributes to the biogeochemical cycling of As, and rhizobacterium-assisted phytoextraction by P. vittata was proposed. In this study, this microbe-assisted phytoextraction was applied to two fields, and the effectiveness of phytoextraction was evaluated. The results revealed that P. vittata was able to grow in temperate and subarctic climate zones. The biomass was influenced by the weather, and the As concentration in plants was dependent on the As content in the soil. The ratio of arsenite oxidase genes (aioA-like genes) to 16S rRNA genes was employed to evaluate the effect of As phytoextraction, and the results exhibited that the ratio was related to the As concentration in P. vittata. Our results showed that arsenite oxidation in the rhizosphere might not be achieved by single-strain inoculation, while this study provided empirical evidence that the rhizospheric aioA-like genes could be an indicator for evaluating the effectiveness of As phytoextraction.
Highlights
It is known that P. vittata prefers absorbing arsenate, As(V), than arsenite, As(III) [16], while As mobilization and transformation in the soil environment mainly occur through microorganisms [17]
For inoculation treatments (PvI), 5 mL of bacterial culture was added to the rhizoof each plant, and for control groups (PvN), 5 mL of 0.2× TSB medium was added instead sphere of each plant, and for control groups (PvN), 5 mL of 0.2× TSB medium was added of bacterial culture
The abundance of total bacteria and bacteriaderivative aioA-like genes was analyzed by quantitative real-time PCR targeted to 16S rRNA genes and aioA-like genes using a CFX ConnectTM Thermocycler (BioRad, Hercules, CA, USA) following the method described in the previous study [20]
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. A cost-efficient and environmentally friendly strategy is preferred to overcome these disadvantages of current remediation approaches. Phytoremediation is such a strategy which is low-cost and appropriate for widespread pollution [10]. Phytoextraction is a common subprocess of phytoremediation, in which plants remove the contaminant from the soil by uptake and accumulating it in their tissues [11]. It is known that P. vittata prefers absorbing arsenate, As(V), than arsenite, As(III) [16], while As mobilization and transformation in the soil environment mainly occur through microorganisms [17]. The effectiveness of microbe-assisted phytoextraction may readily be affected by other environmental factors, including soil composition and climate conditions. The progress of As phytoextraction was investigated, and an indicator accounting for microbe-assisted phytoextraction was determined
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