CIMAR/CIIMAR-Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal.
CIMAR/CIIMAR-Centro Interdisciplinar de Investigação Marinha e Ambiental, Universidade do Porto, Terminal de Cruzeiros do Porto de Leixões, Av. General Norton de Matos s/n, 4450-208, Matosinhos, Portugal; Department of Microbiology, Goa University, Taleigao Plateau, Goa, 403206, India.
Chemosphere. 2018 May;199:54-67. doi: 10.1016/j.chemosphere.2018.01.171. Epub 2018 Feb 1.
This study investigates the potential of an indigenous estuarine microbial consortium to degrade two polycyclic aromatic hydrocarbons (PAHs), naphthalene and fluoranthene, under nitrate-reducing conditions. Two physicochemically diverse sediment samples from the Lima Estuary (Portugal) were spiked individually with 25 mg L of each PAH in laboratory designed microcosms. Sediments without PAHs and autoclaved sediments spiked with PAHs were run in parallel. Destructive sampling at the beginning and after 3, 6, 12, 30 and 63 weeks incubation was performed. Naphthalene and fluoranthene levels decreased over time with distinct degradation dynamics varying with sediment type. Next-generation sequencing (NGS) of 16 S rRNA gene amplicons revealed that the sediment type and incubation time were the main drivers influencing the microbial community structure rather than the impact of PAH amendments. Predicted microbial functional analyses revealed clear shifts and interrelationships between genes involved in anaerobic and aerobic degradation of PAHs and in the dissimilatory nitrate-reducing pathways (denitrification and dissimilatory nitrate reduction to ammonium - DNRA). These findings reinforced by clear biogeochemical denitrification signals (NO consumption, and NH increased during the incubation period), suggest that naphthalene and fluoranthene degradation may be coupled with denitrification and DNRA metabolism. The results of this study contribute to the understanding of the dissimilatory nitrate-reducing pathways and help uncover their involvement in degradation of PAHs, which will be crucial for directing remediation strategies of PAH-contaminated anoxic sediments.
本研究调查了本土河口微生物群落在硝酸盐还原条件下降解两种多环芳烃（PAHs），萘和荧蒽的潜力。从葡萄牙利马河口采集了两个物理化学性质不同的沉积物样品，在实验室设计的微宇宙中分别单独添加 25mg/L 的每种 PAH。同时还平行运行了未添加 PAH 的沉积物和添加了 PAH 的灭菌沉积物。在孵育 3、6、12、30 和 63 周时进行了破坏性采样。萘和荧蒽的水平随时间下降，降解动力学因沉积物类型而异。16S rRNA 基因扩增子的下一代测序（NGS）显示，沉积物类型和孵育时间是影响微生物群落结构的主要驱动因素，而不是 PAH 添加剂的影响。预测微生物功能分析显示，参与 PAHs 厌氧和需氧降解以及异化硝酸盐还原途径（反硝化和异化硝酸盐还原为铵-DNRA）的基因之间存在明显的转变和相互关系。通过明确的生物地球化学反硝化信号（NO 消耗和 NH 在孵育期间增加）得到了强化，表明萘和荧蒽的降解可能与反硝化和 DNRA 代谢相关。本研究的结果有助于理解异化硝酸盐还原途径，并有助于揭示它们在 PAHs 降解中的作用，这对于指导受 PAH 污染的缺氧沉积物的修复策略至关重要。
