Recently, the Innovation Team of Remediation of Degraded and Contaminated Farmland from the Institute of Environment and Sustainable Development in Agriculture, Chinese Academy of Agricultural Sciences has made new progress, revealing the molecular mechanisms of microbial arsenic resistance and accumulation. The related findings have been published as a cover paper in the Environmental Science & Technology .

Arsenic in flooded paddy soils mainly takes the form of the more toxic arsenite (As^III) and methylarsenite (MAs^III). Rice rhizosphere is a hotspot for As uptake, and an active zone for various microorganisms. Yet little is known about how eukaryotic microorganisms in the rhizospheres of rice respond to As toxicity in paddy soils, and how to develop green remediation technologies by using As-resistant microorganisms needs to be further studied.

This study discovered a new metal-binding protein TaGlo1, derived from Trichoderma asperellum SM-12F1, which could effectively mitigate As^III and MAs^III toxicity to fungi. Compared with the existing binding proteins, TaGlo1 had a stronger arsenic binding strength and stability, and recombinant Escherichia coli carrying Taglo1 could better resist environmental arsenic toxicity and increase intracellular arsenic accumulation. Three cysteines within TaGlo1, Cys13, Cys18 and Cys71, mainly participated in binding with As^III, while Cys13 and Cys18 mainly participated in binding with MAs^III. In addition, the study also found that Taglo1 was widely distributed in the paddy soils of China's 14 typical farming areas, and its gene abundance increased significantly with pore water As. The results further demonstrated the potential of the fungi-derived Taglo1 for alleviating As toxicity in the soil-rice system, which can be helpful for future application to the green remediation of As-contaminated paddy soils through bioengineered bacteria, amplification of functional genes in rhizospheres and other methods.

This research was funded by the National Natural Science Foundation of China and the Agricultural Science and Technology Innovation Program of the Chinese Academy of Agricultural Sciences.

Linkage: https://pubs.acs.org/doi/10.1021/acs.est.3c11043