一株耐镉促生细菌Achromobacter sp.A81的分离鉴定及特性

Isolation, identification, and characterization of a cadmium-tolerant bacterium Achromobactersp. A81 with plant growth-promoting effect

摘要:

【目的】从广西某矿区污染土中筛选并鉴定耐镉(cadmium,Cd)促生细菌，评估其耐Cd、去Cd²⁺效率、促生特性及对Cd胁迫下水稻生长的影响，展现其在植物促长与土壤修复中的潜力。【方法】通过稀释涂布和Cd²⁺浓度梯度驯化分离耐Cd细菌，进一步通过形态学、生理生化及16S rRNA基因系统发育树法进行鉴定；再运用微量稀释法、电感耦合等离子体质谱法、比色法测定菌株的耐Cd能力、去Cd²⁺效率和植物促生特性；最后通过盆栽试验考察施加菌株后对Cd胁迫下水稻生长的影响。【结果】从重金属污染土壤中分离得到12株对Cd²⁺表现较好抗性的细菌，其中对Cd耐受最好的一株细菌鉴定并命名为无色杆菌属(Achromobacter sp.) A81，其对Cd²⁺的耐受浓度高达800 mg/L，在10 mg/L Cd²⁺浓度下培养7 d，其最大Cd²⁺去除率为44.66%；菌株A81的上清液和菌体可共同吸附Cd²⁺；在Cd胁迫下分泌大量胞外聚合物(extracellular polymeric substance,EPS)，主要成分为不溶性和可溶性蛋白。此外，该菌株具有固氮、溶磷、产铁载体、吲哚乙酸(indole-3-acetic acid,IAA)和1-氨基环丙烷-1-羧酸(1-aminocyclopropane-1-carboxylic acid,ACC)脱氨酶等植物促生活性，展现出显著的促生潜力。盆栽试验结果表明，与Cd胁迫组的对照相比，接种菌株A81后水稻的株高、根长、茎粗和鲜重分别增加了9.08%、39.59%、41.94%和73.58%。【结论】本研究探究了Achromobacter sp.A81在耐Cd、除Cd与植物促生方面的特性，以及其在Cd污染土壤修复中的应用潜力，为微生物治理重金属污染与农业绿色发展提供科学依据与优质菌株资源。

关键词:耐镉;无色杆菌属;植物促生;镉胁迫;水稻盆栽

Abstract:

[Objective] To screen and identify cadmium (Cd)-tolerant bacteria with plant growth-promoting effect from contaminated soil of a mining area in Guangxi, characterize the strain screened out in terms of the Cd tolerance, Cd²⁺ removal efficiency, plant growth-promoting effect, and influence on rice growth under Cd stress, and demonstrate the potential of the strain in plant growth and soil remediation. [Methods] Cd-tolerant bacteria were isolated by the dilution coating method and Cd²⁺ concentration gradient acclimation and further identified based on the morphological, physiological, biochemical characteristics and the 16S rRNA gene phylogenetic tree. The Cd tolerance, Cd²⁺ removal efficiency, and plant growth-promoting effect of the target strain were measured by microdilution, inductively coupled plasma mass spectrometry, and colorimetry. Finally, the effect of the strain on the growth of rice plants under Cd stress was investigated by a pot experiment. [Results] Twelve strains of bacteria with good tolerance to Cd²⁺ were isolated from heavy metal-contaminated soil, and one strain with the best tolerance to Cd was identified as Achromobacter sp. A81, which could grow in the presence of 800 mg/L Cd²⁺. Strain A81 cultured with 10 mg/L Cd²⁺ for 7 days showed the maximum Cd²⁺ removal rate of 44.66%. Both the supernatant and cells of strain A81 demonstrated the ability to adsorb Cd²⁺. Under Cd stress, the strain secreted a large amount of extracellular polymeric substances (EPS) primarily composed of insoluble and soluble proteins. Furthermore, this strain was capable of fixing nitrogen, solubilizing phosphorus, and secreting siderophores, indole-3-acetic acid (IAA), and 1-aminocyclopropane-l-carboxylate (ACC) deaminase, demonstrating remarkable plant growth-promoting effect. Pot experiment results revealed that compared with the group subjected to Cd stress, the rice plants inoculated with strain A81 showed increases of 9.08%, 39.59%, 41.94%, and 73.58% in plant height, root length, stem diameter, and fresh weight, respectively. [Conclusion] This study investigated the Cd tolerance, Cd removal efficiency, and plant growth-promoting effect of Achromobacter sp. A81 and assessed the application potential of this strain in Cd-contaminated soil remediation, providing a scientific basis and high-quality strain resources for the microbial remediation of heavy metal pollution and green agricultural development.

Key words:cadmium tolerance;Achromobacter sp.;plant growth-promoting;cadmium stress;potted rice plant