Collaborative Innovation Center of Water Security for the Water Source Region of Mid-line of the South-to-North Diversion Project of Henan Province, College of Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China; Henan Provincial Academician Workstation of Water Security for Water Source Region of Mid-line of South-to-North Diversion Project, Nanyang Normal University, Nanyang, 473061, China.
Collaborative Innovation Center of Water Security for the Water Source Region of Mid-line of the South-to-North Diversion Project of Henan Province, College of Agricultural Engineering, Nanyang Normal University, Nanyang, 473061, China.
Ecotoxicol Environ Saf. 2020 Jun 1;195:110375. doi: 10.1016/j.ecoenv.2020.110375. Epub 2020 Mar 20.
Microbial immobilization is a novel and environmentally friendly technology that uses microbes to reduce metal availability in soil and accumulation of heavy metals in plants. We used urea agar plates to isolate urease-producing bacteria from the rhizosphere soil of pakchoi in Cd- and Pb-contaminated farmland and investigated their effects on Cd and Pb accumulation in pakchoi and the underlying mechanisms. The results showed that two urease-producing bacteria, Bacillus megaterium N3 and Serratia liquefaciens H12, were identified by screening. They had higher ability to produce urease (57.5 ms cm min OD and 76.4 ms cm min OD, respectively). The two strains allowed for the immobilization of Cd and Pb by extracellular adsorption, bioprecipitation, and increasing the pH (from 6.94 to 7.05-7.09), NH content (69.1%-127%), and NH/NO ratio (from 1.37 to 1.67-2.11), thereby reducing the DTPA-extractable Cd (35.3%-58.8%) and Pb (37.8%-62.2%) contents in the pakchoi rhizosphere soils and the Cd (76.5%-79.7%) and Pb (76.3%-83.5%) contents in the leaves (edible tissue) of pakchoi. The strains were highly resistant to heavy metal toxicity; produced IAA, siderophores and abscisic acid; and increased the NH/NO ratio, which might be related to the two strains protectiing pakchoi against the toxic effect of Cd and Pb and increasing pakchoi biomass. Thus, the results were supposed to strain resources and a theoretical basis for the remediation of Cd- and Pb-contaminated farmlands for the safe production of vegetables.
微生物固定化是一种新颖的环保技术，它利用微生物减少土壤中金属的有效性并减少植物对重金属的积累。我们使用尿素琼脂平板从 Cd 和 Pb 污染农田的白菜根际土壤中分离产脲酶细菌，并研究了它们对白菜 Cd 和 Pb 积累的影响及其潜在机制。结果表明，通过筛选，鉴定出两株产脲酶细菌，即巨大芽孢杆菌 N3 和液化沙雷氏菌 H12，它们具有较高的产脲酶能力（分别为 57.5 ms cm min OD 和 76.4 ms cm min OD）。这两株菌通过细胞外吸附、生物沉淀和提高 pH 值（从 6.94 增加到 7.05-7.09）、NH 含量（增加 69.1%-127%）和 NH/NO 比值（从 1.37 增加到 1.67-2.11），从而减少了白菜根际土壤中 DTPA 可提取 Cd（35.3%-58.8%）和 Pb（37.8%-62.2%）的含量以及白菜叶片（可食用组织）中 Cd（76.5%-79.7%）和 Pb（76.3%-83.5%）的含量。这些菌株对重金属毒性具有高度抗性；产生 IAA、铁载体和脱落酸；并增加了 NH/NO 比值，这可能与这两株菌保护白菜免受 Cd 和 Pb 的毒性作用以及增加白菜生物量有关。因此，这些结果为菌株资源和受 Cd 和 Pb 污染农田的修复提供了理论依据，以便安全生产蔬菜。
