Key Laboratory of Ecology and Environmental Science in Guangdong Higher Education and Guangdong Provincial Key Laboratory of Biotechnology for Plant Development, College of Life Sciences, South China Normal University, Guangzhou 510631, PR China.
State Key Laboratory for Bio-control and School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, PR China.
Chemosphere. 2014 May;103:99-104. doi: 10.1016/j.chemosphere.2013.11.040. Epub 2013 Dec 7.
Microbe-assisted phytoextraction shows a potential for the remediation of metal-contaminated soils. The aim of this study was to isolate, characterize, and evaluate the potential of endophytic bacteria in improving plant growth and metal uptake by Cd-hyperaccumulators-Amaranthus hypochondriacus and Amaranthus mangostanus. An endophytic bacterial strain JN27 isolated from roots of Zea mays displayed high tolerance and mobilization to Cd, and was identified as Rahnella sp. based on 16S rDNA sequencing. The strain also exhibited multiple plant growth beneficial features including the production of indole-3-acetic acid, siderophore, 1-aminocyclopropane-1-carboxylic acid deaminase and solubilization of insoluble phosphate. Subsequently, a pot trial was performed to elucidate the effects of inoculation with JN27 on plant growth and Cd uptake by A. hypochondriacus, A. mangostanus, Solanum nigrum and Z. mays grown in soils with different levels of Cd (25, 50, 100 mg Cd kg(-1)). The results revealed that inoculation with JN27 significantly increased the biomasses of all the tested plants and the Cd concentrations of all the tested plants except Z. mays in both above-ground and root tissues. Moreover, strain JN27 could successfully re-colonized in rhizosphere soils of all the tested plants and root interior of A. hypochondriacus and Z. mays. The present results indicated that the symbiont of A. hypochondriacus (or A. mangostanus) and strain JN27 can effectively improve the Cd uptake by plants and would be a new strategy in microbe-assisted phytoextraction for metal-contaminated soils.
微生物辅助植物提取技术在修复重金属污染土壤方面显示出巨大的潜力。本研究旨在从玉米根系中分离、鉴定和评价具有内生特性的细菌，研究其对超积累植物（反枝苋和刺苋菜）生长和金属吸收的潜在作用。从玉米根系中分离得到的一株内生细菌 JN27 对 Cd 具有较高的耐受性和迁移能力，根据 16S rDNA 测序结果鉴定其为 Rahnella sp.。该菌株还具有多种促进植物生长的特性，包括产生吲哚-3-乙酸、铁载体、1-氨基环丙烷-1-羧酸脱氨酶和溶解不溶性磷酸盐。随后，进行了盆栽试验，以阐明接种 JN27 对不同 Cd 水平（25、50、100mg Cd kg(-1))土壤中生长的反枝苋、刺苋菜、龙葵和玉米的生长和 Cd 吸收的影响。结果表明，接种 JN27 显著增加了所有测试植物的生物量，除玉米外，所有测试植物地上部和根部组织的 Cd 浓度也均有所增加。此外，JN27 菌株可以成功地再定殖到所有测试植物的根际土壤和反枝苋和玉米的根内部。本研究结果表明，反枝苋（或刺苋菜）的共生菌和菌株 JN27 可以有效提高植物对 Cd 的吸收，这将为受污染土壤的微生物辅助植物提取提供新策略。
