School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin 300072, China.
School of Environmental Science and Engineering, Tianjin University, 92 Weijin Road, Tianjin 300072, China.
Ecotoxicol Environ Saf. 2024 Oct 15;285:117138. doi: 10.1016/j.ecoenv.2024.117138. Epub 2024 Sep 30.
The problem of potentially toxic metal pollution is increasingly acute with the development of human society. In this study, we investigated the remediation of nickel (Ni) and cadmium (Cd) co-contamination through inoculating rice with three new-isolated Ni- and Cd-resistant plant growth-promoting rhizobacteria (PGPR) Y3, Y4, and Y5. These three strains possessed growth-promoting properties, including 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase activity, the ability of indoleacetic acid (IAA) production, phosphate solubilization, siderophores production, and exopolysaccharide (EPS) development. According to 16S rDNA sequence homology, strains Y3, Y4, and Y5 were identified as Pseudomonas sp., Chryseobacterium sp., and Enterobacter sp., respectively. Based on the results of rice germination experiments conducted under combined toxicity, we set the contamination concentrations for Ni at 20 μg mL and Cd at 40 μg mL. Then we conducted potting experiments at these concentration levels to study the effects of strains Y3, Y4, and Y5 on rice growth under synergistic Ni and Cd stress. The results indicated that the inoculated strains Y3, Y4, and Y5 were effective in promoting the growth of rice seedlings under the combined stress of Ni and Cd, and conferring tolerance to Ni and Cd by increasing the antioxidant enzyme activities of the seedlings. Among them, strain Y3 exhibited stronger ACC deaminase activity, IAA production capacity, and EPS production capacity, showing the most pronounced growth-promoting effect on rice. It was demonstrated that after inoculation with strain Y3, the germination rate of rice seeds increased by 43 %, the fresh weight of stems improved by 35 %, and the chlorophyll content enhanced by 70 % and other growth-promoting phenomena. Additionally, under Ni and Cd stress, strain Y5 performed better than strain Y4 in terms of IAA production capacity and its influence on rice root growth, suggesting that IAA production might play a specifically essential role in root growth under Ni and Cd stress.
随着人类社会的发展，潜在有毒金属污染问题日益严重。在本研究中，我们通过接种三种新分离的耐镍（Ni）和镉（Cd）植物促生根际细菌（PGPR）Y3、Y4 和 Y5 来研究修复 Ni 和 Cd 的复合污染。这三种菌株具有促生长特性，包括 1-氨基环丙烷-1-羧酸（ACC）脱氨酶活性、吲哚乙酸（IAA）生产能力、溶磷能力、产铁载体和胞外多糖（EPS）能力。根据 16S rDNA 序列同源性，菌株 Y3、Y4 和 Y5 分别被鉴定为假单胞菌、黄杆菌和肠杆菌。基于联合毒性下水稻萌发实验的结果，我们将 Ni 的污染浓度设定为 20μg mL，Cd 的污染浓度设定为 40μg mL。然后，我们在这些浓度水平下进行盆栽实验，研究菌株 Y3、Y4 和 Y5 在协同 Ni 和 Cd 胁迫下对水稻生长的影响。结果表明，接种的菌株 Y3、Y4 和 Y5 在 Ni 和 Cd 的复合胁迫下有效促进了水稻幼苗的生长，并通过提高幼苗的抗氧化酶活性赋予其对 Ni 和 Cd 的耐受性。其中，菌株 Y3 表现出更强的 ACC 脱氨酶活性、IAA 生产能力和 EPS 生产能力，对水稻的促生效果最为显著。研究表明，接种菌株 Y3 后，水稻种子的发芽率提高了 43%，茎的鲜重提高了 35%，叶绿素含量提高了 70%等促生现象。此外，在 Ni 和 Cd 胁迫下，菌株 Y5 在 IAA 生产能力及其对水稻根生长的影响方面优于菌株 Y4，表明 IAA 生产可能在 Ni 和 Cd 胁迫下对根生长起着特别重要的作用。
