Despite the continuous advances in the understanding of the mechanisms related to the bioremediation of soils contaminated with hydrocarbons, there are gaps regarding the assessment of the production of biosurfactants in situ. The objective of this work was to verify the effects of biostimulation (ammonium sulfate or whey) and bioaugmentation (B. methylotrophicus) on the in situ production of biosurfactants in soil, evaluated by the determination of surface tension, during the bioremediation of diesel oil. Biostimulation (ammonium sulfate/whey) achieved a total removal of the contaminant of 40%. The application of biostimulation and bioaugmentation together resulted in the removal of 61.64% of the contaminant, 28.04% higher in relation to natural attenuation. For bioaugmentation and biostimulated soils, a decrease in surface tension was observed, indicating the production of biosurfactants in the soil (44.33 mN/m), which was not observed in natural attenuation (61.49 mN/m) or control treatment (64.45 mN/m). In sterile soil, the sorption values were around 20%, showing that there were no different rates of adsorption of the contaminant. Thus, it was found that the joint application of biostimulation and bioaugmentation techniques helped in the production of biosurfactants directly in the soil and increased the biodegradation of diesel oil in the soil.

Graphic abstract

中文翻译：

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粘土中柴油生物修复过程中生物表面活性剂原位生产的生物刺激

尽管对碳氢化合物污染土壤生物修复相关机制的理解不断取得进展，但在原位生物表面活性剂生产评估方面仍存在差距。这项工作的目的是验证生物刺激（硫酸铵或乳清）和生物强化（甲基营养芽孢杆菌）的效果) 在柴油生物修复过程中，通过测定表面张力来评估土壤中生物表面活性剂的原位生产。生物刺激（硫酸铵/乳清）使污染物的总去除率达到 40%。生物刺激和生物强化的应用共同导致去除了 61.64% 的污染物，比自然衰减高 28.04%。对于生物强化和生物刺激土壤，观察到表面张力降低，表明土壤中生物表面活性剂的产生 (44.33 mN/m)，这在自然衰减 (61.49 mN/m) 或对照处理 (64.45 mN/m) 中未观察到）。在无菌土壤中，吸附值约为 20%，表明污染物的吸附速率没有差异。因此，

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