Purpose

Oil hydrocarbons are widespread pollutants in soil which pose serious threats to ecological environment. Thus, this study carried out the bioremediation of oil-contaminated soil by using the efficient petroleum-degrading bacteria and soil conditioner, to investigate the changes of physicochemical properties of contaminated soil during bioremediation, reveal the relationship among the exogenous degradation strains and indigenous microbe, and finally illuminate the effects of soil conditioner and microbe on the bioremediation of oil-contaminated soil.

Materials and methods

A PAH-degrading strain named Stenotrophomonas maltophilia was used in this study, which was isolated from an e-waste dismantling area. The soil conditioner in this present study was developed previously by using agricultural wastes, which was in a powdered form and rich in N, P, and K. The simulated experiments were conducted under the control environmental conditions of greenhouse, to study the effects of inoculation and soil conditioner on bioremediation of oil-contaminated soil. Then, the physicochemical properties of soil and the degradation rates of oil were measured at different set times to evaluate the bioremediation effect.

Results and discussion

Adding 1% soil conditioner could significantly improve the soil conditions and offer microorganism enough N, P, and K, which would promote microbial growth and played a key role on bioremediation of oil-contaminated soil. Although in polluted soil, the microorganism could maintain metabolic activity and use the petroleum as carbon source. The soil indigenous microbe was more easily to adapt to the contaminated surrounding. However, when both of them co-existed in soil, they would restrain each other, and go against the oil decomposition. Thus, making two types of microorganisms work to achieve synergy was the key to gain much better remediation effect. Because the indigenous microbe was good at decomposing low molecular compounds and saturated hydrocarbons, while the oil-degrading strains can effectively decompose high molecular weight aromatics.

Conclusions

The soil nutrient and microorganism, including the exogenous oil-degrading strains and the soil indigenous microbe, had an important effect on degradation of petroleum. The addition of soil conditioner, presence of indigenous microbe, and inoculation of oil-degrading strains all were conducive to bioremediation of oil-contaminated site, but the key was to control the proportion and relationship of the three.

Graphical abstract

中文翻译：

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土壤改良剂与微生物结合对油污土壤的生物修复

目的

石油烃是土壤中广泛的污染物，对生态环境构成严重威胁。因此，本研究利用高效的石油降解细菌和土壤改良剂对油污土壤进行了生物修复，研究了生物修复过程中被污染土壤的理化性质变化，揭示了外源降解菌株与本地微生物之间的关系，最后阐明了土壤改良剂和微生物对油污土壤生物修复的影响。

材料和方法

在这项研究中使用了一种降解PAH的菌株，称为麦芽嗜麦芽单胞菌，该菌株是从电子废物拆解区域分离出来的。本研究中的土壤改良剂以前是通过使用农业废料开发的，该农业废料为粉末状且富含N，P和K。在温室的控制环境条件下进行了模拟实验，以研究接种的影响和土壤改良剂对油污土壤的生物修复。然后，在不同的设定时间测量土壤的理化性质和油脂的降解率，以评估生物修复效果。

结果和讨论

添加1％的土壤改良剂可以显着改善土壤状况，并为微生物提供足够的N，P和K，这将促进微生物的生长，并在油污土壤的生物修复中发挥关键作用。尽管在受污染的土壤中，微生物仍可以维持代谢活性并使用石油作为碳源。土壤土著微生物更容易适应被污染的环境。但是，当它们在土壤中共存时，它们会相互约束，并会阻止油的分解。因此，使两种微生物共同发挥协同作用是获得更好的修复效果的关键。因为土著微生物擅长分解低分子化合物和饱和烃，而油降解菌株可以有效分解高分子量芳烃。

结论

土壤养分和微生物，包括外源降解油脂的菌株和土壤原生微生物，对石油的降解具有重要影响。添加土壤改良剂，存在土著微生物和接种降解石油的菌株均有助于对受石油污染的地点进行生物修复，但关键是控制这三个地点的比例和关系。

图形概要