華中農業大學在國際期刊發表微生物修復稻田土壤銻污染的研究成果

近日，華中農業大學生命科學技術學院、農業微生物資源發掘與利用全國重點實驗室環境微生物課題組以“Toxic response of antimony in the Comamonas testosteroni and its application in soil antimony bioremediation”為題，在國際學術期刊Environment International上發表論文，闡明了微生物菌劑降低土壤銻毒性及銻生物有效性的機制，從而有效減少水稻銻積累。博士研究生羅雄為本文第一作者，李明順副教授為通訊作者，項目得到國家自然科學基金31970095的資助。

銻是一種劇毒的環境污染物，銻污染地區土壤銻含量遠高于正常的背景濃度。銻能通過食物鏈進入人體，導致癌變、心肌衰竭、肝壞死等疾病，嚴重威脅人類的健康。水稻可以過量富集銻，食用銻富集大米會嚴重威脅人類生命健康，尋找有效的銻修復方法成為亟待解決的問題，但水稻中銻氧化微生物驅動的銻修復機制及技術缺乏研究。國內外尚未報道微生物影響銻生物有效性和在水稻中驅動銻修復的機制。

該研究評估了Comamonas testosteroni JL40在銻污染生物修復中的應用潛力。發現菌株JL40通過細胞內積累/結合、胞外固定、Sb（III）氧化、ROS清除、Sb（III）外排和生物被膜產生等途徑響應銻的毒性。基于菌株JL40對Sb（III）的固定和氧化功能，采用盆栽試驗研究菌株JL40對銻的生物修復潛力。結果表明，在不同程度的銻污染土壤中，施加菌劑JL40后水稻糙米中銻積累量顯著降低，達到安全水平（<2.40 mg/kg）。此外，JL40菌株可以提高植物和土壤的健康，提高水稻產量。利用BCR和EDTA法對根際土壤中銻分級提取和單步提取，發現菌株JL40在土壤環境中可以起到鈍化和氧化銻的作用。在水稻盆栽過程中，菌株JL40接種30天后仍能保持在103 CFU/g以上。本研究為細菌在銻污染修復中的應用奠定了重要基礎。

該工作是課題組2020年和2021年在Science of the Total Environment和Molecular Microbiology發表論文之后又一與土壤銻污染修復相關的研究成果。

英文摘要：

Antimony（Sb）is toxic to ecosystems and potentially to public health via its accumulation in the food chain.Bioavailability and toxicity of Sb have been reduced using various methods for the remediation of Sb-contaminated soil in most studies.However,Sb-contaminated soil remediation by microbial agents has been rarely evaluated.In this study,we evaluated the potential for the use of Comamonas testosteroni JL40 in the bioremediation of Sb-contamination.Strain JL40 immobilized more than 30%of the Sb（III）in solution and oxidized over 18%to Sb（V）for detoxification.Meanwhile,strain JL40 responds to Sb toxicity through such as Sb efflux,intracellular accumulation,biofilm production,and scavenging of reactive oxygen species（ROS），etc.The results of the pot experiment showed the average Sb content of the brown rice was decreased by 59.1%,38.8%,and 48.4%,for 1.8,50,and 100 mg/kg Sb spiked soils,respectively.In addition,the results of plant,soil enzyme activity,and rice agronomic trait observations showed that the application of strain JL40 could maintain the health of plants and soil and improve rice production.The single-step and sequential extraction of Sb from rhizosphere soil showed that strain JL40 also plays a role in Sb immobilization and oxidation in the soil environment.During rice potted cultivation,bacterial community analysis and plate counting showed that the strain JL40 could still maintain 103 CFU/g after 30 days of inoculation.With phenotypic and differential proteomics analysis,strain JL40 conferred Sb（III）tolerance by a combination of immobilization,oxidation,efflux and scavenging of ROS,etc.Our study demonstrates the application of Sb-immobilizing and oxidizing bacteria to lower soil Sb and reduce accumulation of Sb in rice.Our results provide guidance for bacterial remediation of Sb-contaminated soil.

(關鍵字：銻 污染)