Isolation of urease-producing bacteria and their effects on reducing Cd and Pb accumulation in lettuce (Lactuca sativa L.).
Isolation of urease-producing bacteria and their effects on reducing Cd and Pb accumulation in lettuce (Lactuca sativa L.).
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产脲酶细菌的分离及其对减少生菜 (Lactuca sativa L.) 中镉和铅积累的影响。
DOI：
10.1007/s11356-019-06957-3
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发表时间：
2020
期刊：
影响因子：
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通讯作者：
Han Hui
中科院分区：
文献类型：
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作者：
Wang Tiejun;Wang Shilin;Tang Xingchun;Fan Xianpeng;Yang Sheng;Yao Lunguang;Li Yadong;Han Hui
农业土壤中过量的镉和铅进入食物链并对所有生物产生不利影响。因此，寻找一种环保的方式来减少蔬菜中的重金属积累是很重要的。利用尿素琼脂板从镉、铅污染农田莴苣根际土壤中分离出产脲酶细菌，研究其产脲酶和固定重金属的能力。研究了这些菌株对生菜生物量、品质和Cd、Pb积累量的影响。结果表明，从莴苣根际土壤中筛选到2种产脲酶细菌：布甘肠杆菌（Enterobacter bugandensisTJ6）和巨芽孢杆菌（bacillus megateriumHD8）。它们产生脲酶（分别为44.5 mS cm−1min−1OD600−1和54.2 mS cm−1min−1OD600−1）和IAA（分别为303 mg L−1和387 mg L−1）的能力很强。与对照相比，接种菌株TJ6和HD8降低了培养液中Cd（75.3 ~ 85.8%）和Pb（74.8 ~ 87.2%）浓度，提高了培养液pH（6.92 ~ 8.13 ~ 8.53）。水培试验结果表明，两株菌株分别提高了生菜芽（可食组织）生物量（31.3 ~ 55.2%）、品质（可溶性蛋白含量28.6 ~ 52.6%、维生素C （Vc）含量34.8 ~ 88.4%）、Cd（25.6 ~ 68.9%）和Pb（48.7 ~ 78.8%）含量。此外，菌株HD8比菌株TJ6更能降低莴苣对Cd和Pb的吸收以及溶液中水溶性Cd和Pb的含量。这些数据表明，产脲菌通过胞外吸附、固定化Cd和Pb、提高ph来保护生菜免受Cd和Pb的毒害。这两种菌株的重金属固定化效果可以为重金属污染农田的生物修复提供原位蔬菜安全保障。
Excess Cd and Pb in agricultural soils enter the food chain and adversely affect all organisms. Therefore, it is important to find an eco-friendly way to reduce heavy metal accumulation in vegetables. We used urea agar plates to isolate urease-producing bacteria from the rhizosphere soil of lettuce in Cd- and Pb-contaminated farmland and investigated their ability to produce urease and immobilize heavy metals. The effects of these strains on the biomass, quality, and Cd and Pb accumulation of lettuce were also studied. The results showed that two urease-producing bacteria,Enterobacter bugandensisTJ6 andBacillus megateriumHD8, were screened from the rhizosphere soil of lettuce. They had a high ability to produce urease (44.5 mS cm−1min−1OD600−1and 54.2 mS cm−1min−1OD600−1, respectively) and IAA (303 mg L−1and 387 mg L−1, respectively). Compared with the control, inoculation with strains TJ6 and HD8 reduced the Cd (75.3–85.8%) and Pb (74.8–87.2%) concentrations and increased the pH (from 6.92 to 8.13–8.53) in solution. A hydroponic experiment showed that the two strains increased the biomass (31.3–55.2%), improved the quality (28.6–52.6% for the soluble protein content and 34.8–88.4% for the vitamin C (Vc) content), and reduced the Cd (25.6–68.9%) and Pb (48.7–78.8%) contents of lettuce shoots (edible tissue). In addition, strain HD8 had a greater ability than strain TJ6 to reduce lettuce Cd and Pb uptake and water-soluble Cd and Pb levels in solution. These data show that the urease-producing bacteria protect lettuce against Cd and Pb toxicity by extracellular adsorption, Cd and Pb immobilization, and increased pH. The effects of heavy metal immobilization by the two strains can guarantee vegetable safety in situ for the bioremediation of heavy metal–polluted farmland.