Cd-Resistant Plant Growth-Promoting Rhizobacteria Bacillus siamensis R27 Absorbed Cd and Reduced Cd Accumulation in Lettuce (Lactuca sativa L.)

作者：Shaofang Liu, Yu‐Shan Huang, Qinyuan Zheng, Mengting Zhan, Zhihong Hu, Hongjie Ji, Du Zhu, Xia Zhao · 发表于：Microorganisms · 年份：2024 · DOI：10.3390/microorganisms12112321 · 被引用次数：16 · 研究领域：Plant-Microbe Interactions and Immunity、Plant Stress Responses and Tolerance、Legume Nitrogen Fixing Symbiosis

The use of plant growth-promoting rhizobacteria (PGPR) for the bioremediation of heavy metal cadmium (Cd) and for enhancing plant growth in Cd-polluted soil is widely recognized as an effective approach. This study aimed to isolate Cd-resistant bacteria with plant growth-promoting (PGP) traits from the rhizosphere of vegetables subjected to metal contamination and to investigate the mechanisms associated with Cd adsorption as well as its impact on Cd uptake in lettuce. Six Cd-resistant bacterial strains were isolated from rhizosphere soil, among which the R27 strain exhibited the highest tolerance to Cd (minimum inhibitory concentration of 2000 mg/L) along with PGP traits, including phosphate solubilization (385.11 mg/L), the production of indole-3-acetic acid (IAA) (35.92 mg/L), and siderophore production (3.34 mg/L). Through a range of physiological, biochemical, and molecular assessments, the R27 strain was classified as Bacillus siamensis. This strain demonstrated notable efficiency in removing Cd2+ from the growth medium, achieving an efficacy of 80.1%. This removal was facilitated by cell surface adsorption through functional groups such as O–H, C=O, –CO–NH–, and C–O, alongside intracellular Cd accumulation, as evidenced by SEM, TEM, EDX, and FTIR analyses. Pot culture experiments indicated that R27 significantly promoted lettuce seedling growth and helped plants tolerate Cd stress, with the underlying mechanisms likely involving increased antioxidant activities for sca...