Co-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, China.
Co-Innovation Center for Sustainable Forestry in Southern China, College of Ecology and Environment, Nanjing Forestry University, Nanjing 210037, China.
Sci Total Environ. 2024 Nov 10;950:175225. doi: 10.1016/j.scitotenv.2024.175225. Epub 2024 Aug 3.
The present study was conducted to systematically explore the mechanisms underlying the impact of various surfactants (CTAB, SDBS, Tween 80 and rhamnolipid) at different doses (10, 100 and 1000 mg/kg) on the biodegradation of a model polycyclic aromatic hydrocarbon (PAH) by indigenous soil microorganisms, focusing on bioavailability and community responses. The cationic surfactant CTAB inhibited the biodegradation of phenanthrene within the whole tested dosage range by decreasing its bioavailability and adversely affecting soil microbial communities. Appropriate doses of SDBS (1000 mg/kg), Tween 80 (100, 1000 mg/kg) and rhamnolipid at all amendment levels promoted the transformation of phenanthrene from the very slow desorption fraction (F) to bioavailable fractions (rapid and slow desorption fractions, F and F), assessed via Tenax extraction. However, only Tween 80 and rhamnolipid at these doses significantly improved both the rates and extents of phenanthrene biodegradation by 22.1-204.3 and 38.4-76.7 %, respectively, while 1000 mg/kg SDBS had little effect on phenanthrene removal. This was because the inhibitory effects of anionic surfactant SDBS, especially at high doses, on the abundance, diversity and activity of soil microbial communities surpassed the bioavailability enhancement in dominating biodegradation. In contrast, the nonionic surfactant Tween 80 and biosurfactant rhamnolipid enhanced the bioavailability of phenanthrene for degradation and also that to specific degrading bacterial genera, which stimulated their growth and increased the abundance of the related nidA degradation gene. Moreover, they promoted the total microbial/bacterial biomass, community diversity and polyphenol oxidase activity by providing available substrates and nutrients. These findings contribute to the design of suitable surfactant types and dosages for mitigating the environmental risk of PAHs and simultaneously benefiting microbial ecology in soil through bioremediation.
本研究旨在系统地探讨不同剂量（10、100 和 1000 mg/kg）的各种表面活性剂（CTAB、SDBS、吐温 80 和鼠李糖脂）对土著土壤微生物降解模型多环芳烃（PAH）的影响机制，重点关注生物有效性和群落响应。阳离子表面活性剂 CTAB 通过降低生物有效性并对土壤微生物群落产生不利影响，从而抑制芘在整个测试剂量范围内的生物降解。适当剂量的 SDBS（1000 mg/kg）、吐温 80（100、1000 mg/kg）和鼠李糖脂在所有添加水平下均促进了芘从非常缓慢解吸的 F 部分（F）向生物可利用的 F 和 F 部分的转化，通过 Tenax 萃取进行评估。然而，只有在这些剂量下的吐温 80 和鼠李糖脂才能显著提高芘生物降解的速率和程度，分别提高了 22.1-204.3%和 38.4-76.7%，而 1000 mg/kg 的 SDBS 对芘的去除几乎没有影响。这是因为阴离子表面活性剂 SDBS 的抑制作用，尤其是在高剂量下，对土壤微生物群落的丰度、多样性和活性的影响超过了主导生物降解的生物有效性增强。相比之下，非离子表面活性剂吐温 80 和生物表面活性剂鼠李糖脂增强了芘的生物有效性，促进了特定降解细菌属的生长，增加了相关 nidA 降解基因的丰度。此外，它们通过提供可用的底物和营养物质，促进了总微生物/细菌生物量、群落多样性和多酚氧化酶活性。这些发现有助于设计合适的表面活性剂类型和剂量，以减轻 PAHs 的环境风险，同时通过生物修复有益于土壤中的微生物生态。
