Heavy metal-immobilizing bacteria increase the biomass and reduce the Cd and Pb uptake by pakchoi (Brassica chinensis L.) in heavy metal-contaminated soil
Heavy metal-immobilizing bacteria increase the biomass and reduce the Cd and Pb uptake by pakchoi (Brassica chinensis L.) in heavy metal-contaminated soil
复制标题
重金属固定菌可增加重金属污染土壤中小白菜 (Brassica chinensis L.) 的生物量并减少 Cd 和 Pb 的吸收
DOI：
10.1016/j.ecoenv.2020.110375
复制
发表时间：
2020-06-01
影响因子：
6.8
通讯作者：
Yao, Lunguang
中科院分区：
文献类型：
--
作者：
Han, Hui;Cai, Hong;Yao, Lunguang
微生物固定化是一种新型的环境友好技术，它利用微生物来减少土壤中金属的有效性和植物中重金属的积累。采用尿素琼脂平板分离镉、铅污染农田小白菜根际土壤中的产尿素酶细菌，研究其对小白菜体内镉、铅积累的影响及其机制。结果表明，通过筛选鉴定出两株产尿素酶细菌：巨大芽孢杆菌N3和液化沙雷氏菌H12。产酶能力较强，分别为57.5ms cm(-1)min(-1)OD600-1和76.4ms cm(-1)min(-1)OD600-1。通过胞外吸附、生物沉淀和提高pH(从6.94升至7.05~7.09)、NH4+含量(69.1%~127%)、NH4+/NO3-比(从1.37升至1.67~2.11)，两株菌株都能固定化Cd和Pb.从而降低了小白菜根际土壤中DTPA可提取态Cd(35.3%-58.8%)和铅(37.8%-62.2%)的含量，降低了小白菜叶片(可食组织)中Cd(76.5%-79.7%)和Pb76.3%-83.5%的含量。菌株对重金属毒害的抗性较强，产生IAA、铁载体和脱落酸，提高了NH4+/NO3-的比值，这可能与两株菌株保护小白菜免受Cd、Pb的毒害，提高小白菜的生物量有关。本研究结果为Cd、Pb2+污染农田的安全生产提供了理论依据。
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(-1) min(-1) OD600-1 and 76.4 ms cm(-1) min(-1) OD600-1, 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), NH4+ content (69.1%-127%), and NH4+/NO3- 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 NH4+/NO3- ratio, which might be related to the two strains protecting 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.