耐镉促生缺陷短波单胞菌Y01Z的分离与表征

Isolation and characterization of a cadmium-tolerant and plant growth-promoting bacterium, Brevundimonas diminuta Y01Z

摘要:

【目的】本研究旨在从湖北地区镉污染严重的水稻根际土壤中，分离并鉴定能耐受高浓度的镉离子，同时具有镉去除能力和促进植物生长的细菌。【方法】采用稀释涂布平板和镉浓度梯度驯化的方法，成功分离出一株最高可耐受700 mg/L CdCl₂且稳定生长的菌株，命名为Y01Z，并结合形态学、生理生化和分子生物学等方法对其进行鉴定。【结果】结果显示该菌株属于缺陷短波单胞菌(Brevundimonas diminuta)，其最适生长条件为pH值7.0、温度30 °C、NaCl浓度0.5%。扫描电镜和透射电镜分析显示，Y01Z通过拉长细胞尺寸以确保在高浓度镉处理下的生存和繁殖，同时能吸附镉离子，并将其输送到细胞内沉积。傅里叶变换红外光谱分析显示，Cd²⁺与细菌表面羧基、羟基、羰基和酰胺等官能团结合。经过104 h的培养，Y01Z菌株能够去除高达75%的总添加镉，从300 mg/L降至74.73 mg/L。此外，该菌株还具有促进植物生长的功能，如溶解磷，产生铵态氮和吲哚乙酸，并含有嗜铁载体等物质。【结论】本研究探讨了缺陷短波单胞菌Y01Z在耐镉、植物促生方面的性质，以及在修复镉污染土壤方面的应用前景。本研究为深入探究根际微生物与植物之间的互作关系，并开发高效的镉修复菌剂和绿色农业提供了理论依据。

Abstract:

[Objective] This study aims to isolate and characterize the bacteria with tolerance to cadmium ions and the abilities to remove cadmium and promote plant growth from the rice rhizosphere soil in Hubei province, China. [Methods] Using the dilution-plate spreading and gradient domestication methods with cadmium concentration gradients, we isolated a bacterial strain named Y01Z, which demonstrated stable growth and could tolerate 700 mg/L CdCl₂. The strain was then identified based on morphological, physiological, biochemical, and molecular biological characteristics. [Results] Y01Z was identified as Brevundimonas diminuta, with the optimal growth conditions of pH 7.0, 30 °C, and 0.5% NaCl. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that Y01Z elongated its cells under high cadmium concentrations to ensure survival and reproduction. Moreover, it accumulated cadmium ions and transported them intracellularly. Fourier transform infrared spectroscopy indicated that Cd²⁺ bound to carboxyl, hydroxyl, carbonyl, and amide functional groups on the cell surface. After 104 hours of cultivation, B. diminuta Y01Z removed 75% of the total added cadmium, reducing the cadmium concentration from 300 mg/L to 74.73 mg/L. Additionally, the bacterium exhibited plant growth-promoting properties, including solubilization of phosphorus, production of amino nitrogen and indole-3-acetic acid, and possession of iron-chelating agents. [Conclusion] The findings suggest that B. diminuta Y01Z has significant potential for rhizobacteria-mediated remediation of cadmium-contaminated soils and the promotion of sustainable agriculture practices.