重金属固定植物促生细菌的筛选及其阻控小麦富集重金属效应

由于工业和采矿业等人类的活动造成农田土壤Cd和Pb污染日益严重,并可通过食物链严重影响人类健康,必须采取有效措施阻控农作物对重金属的吸收.本研究依据细菌的重金属抗性和植物促生特性筛选功能菌株,并通过摇瓶吸附实验和小麦砂培实验验证其对小麦生长和阻控小麦吸收Cd和Pb的影响.结果显示,从狗尾草根际土壤中共分离到具有固定重金属和促生能力的菌株18株,其中巨大芽孢杆菌N3和液质沙雷氏菌H12效果最好,均能抵抗高质量浓度的Cd(650mg·L~(-1))和Pb(2 700 mg·L~(-1)),分泌吲哚乙酸(IAA)(56. 6 mg·L~(-1)和69. 1 mg·L~(-1))、铁载体和1-氨基环丙烷羧酸(ACC)脱氨酶.静置培养实验表明,菌株N3和H12显著提高溶液中NH4+的质量浓度和p H值,降低溶液中Cd(63. 1%～73. 8%)和Pb(69. 1%～81. 8%)的质量浓度.砂培条件下,与不接菌相比,菌株N3和H12不仅能够显著增加小麦根(47. 2%～97. 4%)和地上部(65. 3%～153%)的干重,还能够显著降低小麦根和地上部中Cd(49. 2%～68. 3%)和Pb(27. 4%～84. 5%)的含量.本研究结果为Cd、Pb污染农田的修复和农作物的安全生产提供菌种资源和理论依据.

Isolation of Heavy Metal Immobilizing and Plant Growth-Promoting Bacteria and Its Effects on Reducing Heavy Metal Accumulation in Wheat

The effects of heavy metal contamination on farmland continues to worsen progressively with an increase in anthropogenic activities such as industrial pollution and mining. Excess Cd and Pb in agricultural soils enter the food chain and adversely affect all organisms. Therefore, it is important to find an eco-friendly way to reduce heavy metal accumulation in crops. Based on their heavy metal resistance and growth-promoting characteristics, functional bacterial strains were screened and their effects on growth and heavy metal accumulation in wheat were verified via shaking flask adsorption and sand culture tests. Eighteen functional strains were isolated from the rhizospheric soil of Salvia setaria. Among them, Bacillus megaterium N3 and Serratia liquefaciens H12 were most effective at resisting high Cd (650 mg·L^-1) and Pb (2700 mg·L^-1) concentrations, and at producing indole-3-acetic acid (IAA) (56.6 mg·L^-1and 69.1 mg·L^-1, respectively), siderophores, and 1-Amino-1-cyclopropanecarboxylic acid (ACC) deaminase. Static incubation experiments showed that strains N3 and H12 significantly increased the NH₄⁺ concentration and pH, and decreased the Cd (63.1%-73.8%) and Pb (69.1%-81.8%) concentration in solution. In sand cultures, strains N3 and H12 not only increased the dry weight of wheat roots (47.2%-97.4%) and shoots (65.3%-153%) significantly, but also significantly reduced the Cd (49.2%-68.3%) and Pb (27.4%-84.5%) content in wheat roots and shoots. Thus, the results provide strain resources and a theoretical basis for the remediation of Cd- and Pb-contaminated farmlands for the safer production of crops.