Shifts in the bacterial-community dynamics, bioavailability, and biodegradation of polycyclic aromatic hydrocarbons (PAHs) of chronically contaminated soil were analyzed in Triton X-100–treated microcosms at the critical micelle concentration (T-CMC) and at two sub-CMC doses. Only the sub-CMC-dose microcosms reached sorbed-PAH concentrations significantly lower than the control: 166 ± 32 and 135 ± 4 mg kg⁻¹ dry soil versus 266 ± 51 mg kg⁻¹; consequently an increase in high- and low-molecular-weight PAHs biodegradation was observed. After 63 days of incubation pyrosequencing data evidenced differences in diversity and composition between the surfactant-modified microcosms and the control, with those with sub-CMC doses containing a predominance of the orders Sphingomonadales, Acidobacteriales, and Gemmatimonadales (groups of known PAHs-degrading capability). The T-CMC microcosm exhibited a lower richness and diversity index with a marked predominance of the order Xanthomonadales, mainly represented by the Stenotrophomonas genus, a PAHs- and Triton X-100–degrading bacterium. In the T-CMC microcosm, whereas the initial surface tension was 35 mN m⁻¹, after 63 days of incubation an increase up to 40 mN m⁻¹ was registered. The previous observation and the gas-chromatography data indicated that the surfactant may have been degraded at the CMC by a highly selective bacterial community with a consequent negative impact on PAHs biodegradation. This work obtained strong evidence for the involvement of physicochemical and biologic influences determining the different behaviors of the studied microcosms. The results reported here contribute significantly to an optimization of, surfactant-enhanced bioremediation strategies for chronically contaminated soil since the application of doses below the CMC would reduce the overall costs.

在临界胶束浓度（T-CMC）和两个亚CMC剂量下，在Triton X-100处理的微观世界中分析了慢性污染土壤的细菌群落动力学，生物利用度和多环芳烃（PAH）的生物降解变化。 。只有亚CMC剂量的微观世界达到的吸附PAH浓度显着低于对照：166±32和135±4 mg kg ^-1干燥土壤，而266±51 mg kg ^-1; 因此，观察到高分子量和低分子量PAHs的生物降解增加。孵育63天后，焦磷酸测序数据证明表面活性剂修饰的微观世界与对照之间的多样性和组成存在差异，其中亚CMC剂量主要包含鞘氨醇，酸性细菌和芽孢杆菌（已知的PAHs降解能力组） ）。T-CMC缩影显示出较低的丰富度和多样性指数，并以Xanthomonadales阶显着优势，主要由嗜麦芽单胞菌属，PAHs和Triton X-100降解细菌代表。在T-CMC微观世界中，初始表面张力为35 mN m ^-1，在孵育63天后增加至40 mN m ^-1已注册。先前的观察和气相色谱数据表明，表面活性剂可能已在CMC处被高度选择性的细菌群落降解，从而对PAHs的生物降解产生负面影响。这项工作为确定所研究的微观世界的不同行为的物理化学和生物学影响的参与提供了有力的证据。此处报道的结果极大地有助于优化针对慢性污染土壤的表面活性剂增强的生物修复策略，因为在CMC以下施用剂量将降低总体成本。