Abstract:

Soil petroleum hydrocarbon contamination has become one of the global environmental issues. Bioremediation technology has significant advantages of being green, low-carbon, and cost-effective. Harnessing the synergistic effects of plants and microorganisms is an important approach to enhance the efficiency of organic-contaminated soil remediation. In order to enhance the survival rate of plants in contaminated soil and maintain the activity of microorganisms, Impatiens balsamina L. was used as the remediation plant. The seed coating technology and microbial immobilization technology were combined. The encapsulation-crosslinking method was employed to coat the seeds of Impatiens balsamina with the aforementioned materials, including sodium alginate 10.0 g•L⁻¹, bentonite 35.0 g•L⁻¹, and biochar 8.00 g•L⁻¹, along with the cross-linking agent, calcium chloride 50.0 g•L⁻¹. The coated seeds were used to immobilize highly efficient petroleum hydrocarbon-degrading bacterium, Acinetobacter junii. A pot experiment was conducted to investigate the influence of the immobilization of microorganisms on Impatiens balsamina seeds in a seed coating carrier on TPHs removal under the condition of a total petroleum hydrocarbon (TPHs) mass fraction of 10.4 g•kg⁻¹ in the soil. The results indicated that after a 40 days pot experiment, the seed-coated Impatiens balsamina exhibited better growth than the uncoated ones. By comparing the soil dehydrogenase, hydrogen peroxide, urease, polyphenol oxidase activities, microbial community diversity, and TPHs removal rate of different treatment groups (control (CK), T1- addition of free microorganisms, T2- bare-seeded Impatiens balsamina, T3- seed-coated Impatiens balsamina, T4- seed-coated Impatiens balsamina with added free microorganisms, T5- seed-coated Impatiens balsamina with immobilized microorganisms), T5 exhibited significant increases in soil dehydrogenase (85.8%), hydrogen peroxide (8.72%), urease (56.1%), and polyphenol oxidase activities (62.1%). T5 showed the highest Shannon index, indicating the most even distribution of soil species. Moreover, the abundance of Chloroflexi phylum was increased by 54.8% in T5, indicating an improved microbial community diversity. Notably, T5 achieved the highest TPHs removal rate of 45.1%, which was 1.53 to 3.53 times higher than other treatment groups. The study demonstrated that the immobilization of microorganisms on seed coating carriers of Impatiens balsamina could enhance the plant-microbe remediation capacity. These findings provide evidence for the use of seed coating carriers with immobilized microorganisms in the remediation of petroleum hydrocarbon-contaminated soil.

Key words: petroleum hydrocarbon, bioremediation, Impatiens balsamina L., seed coating, microbial community, immobilized microorganisms

摘要：

土壤石油烃污染已成为全球环境问题之一。生物修复技术具有绿色、低碳、低成本的显著优点，发挥植物和微生物的协同作用是提高有机污染土壤修复效率的重要途径。为了提高植物在污染土壤中的存活率以及保持微生物的活性，以观赏园艺植物凤仙花（Impatiens balsamina L.）作为修复植物，结合种子包衣技术和微生物固定化技术，使用包衣材料海藻酸钠10.0 g•L⁻¹膨润土35.0 g•L⁻¹以及生物炭8.00 g•L⁻¹，交联剂氯化钙50.0 g•L⁻¹，采用包埋-交联法先对凤仙花种子包衣处理，然后以凤仙花种子包衣为载体固定化石油烃高效降解菌琼氏不动杆菌（Acinetobacter junii，Hsr2a），通过盆栽试验，研究在总石油烃（Total petroleum hydrocarbons，TPHs）质量分数为10.4 g•kg⁻¹的条件下，凤仙花种子包衣载体固定化微生物对土壤TPHs去除率的影响。结果表明，经过40 d盆栽修复，包衣处理的凤仙花较裸种凤仙花植物长势更好。通过对比不同处理组（CK空白对照，T1添加游离微生物，T2裸种凤仙花，T3凤仙花包衣种，T4凤仙花包衣种并添加游离微生物，T5凤仙花种子包衣载体固定化微生物）的土壤脱氢酶、过氧化氢酶、脲酶、多酚氧化酶活性、微生物群落多样性以及TPHs去除率，发现T5的土壤脱氢酶、过氧化氢酶、脲酶、多酚氧化酶活性分别增加了85.8%、8.72%、56.1%、62.1%；T5的Shannon指数最高，土壤物种分布最均匀；同时T5的绿弯菌门（Chloroflexi）占比增加了54.8%，土壤的微生物群落多样性提高；T5的TPHs去除率最高达到45.1%，是其他处理组的1.53－3.53倍。综上，凤仙花种子包衣载体固定化微生物能强化植物-微生物修复能力。研究结果可为种子包衣载体固定化微生物修复石油烃污染土壤提供依据。

关键词: 石油烃, 生物修复, 凤仙花, 种子包衣, 微生物群落, 固定化微生物