Key Laboratory of Yangtze River Water Environment of the Ministry of Education, Tongji University, Shanghai 200092, China.
Key Laboratory of Yangtze River Water Environment of the Ministry of Education, Tongji University, Shanghai 200092, China; Shanghai BaoSen Environmental Technology Co., Ltd., Shanghai 200439, China.
J Environ Sci (China). 2020 Dec;98:39-46. doi: 10.1016/j.jes.2020.05.023. Epub 2020 Jun 11.
Lacustrine sediment played important roles in migration and transformation of its water soluble organic matter (WSOM), and the source and composition of WSOM would affect water trophic status and the fate of pollutants. However, we know little about the pathway of WSOM transformation and its driving bacterial communities in lacustrine sediment. In the present study, we investigated the spatial distribution patterns of sediment WSOM and its fluorescent fractions across Lake Chaohu using fluorescence spectroscopy, and explored WSOM compositional structure through our proposed calculated ratios. In addition, we also analyzed sediment bacterial community using Illumina sequencing technology, and probed the possible pathway of sediment WSOM transformation under the mediate of indigenous bacteria. Our results showed that the inflowing rivers affected the spatial distribution patterns of WSOM and its five fractions (including tyrosine-, tryptophan-, fulvic acid-, humic acid-like substances and soluble microbial productions), and sediment WSOM originated from fresh algae detritus or bacterial sources. In parallel, we also found that Proteobacteria (mainly γ-Proteobacteria and δ-Proteobacteria), Firmicutes (mainly Bacilli), Chloroflexi, Acidobacteria, Planctomycetes and Actinobacteria dominate sediment bacterial community. Furthermore, these dominant bacteria triggered sediment WSOM transformation, specifically, the humic acid-like substances could be converted into fulvic acid-like substances, and further degraded into aromatic protein-like and SMP substances. In addition, our proposed ratios (P-L:H-L, Ar-P:SMP and H-L ratio), as supplementary tool, were effective to reveal WSOM composition structure. These results figured out possible pathway of WSOM transformation, and revealed its microbial mechanism in lacustrine sediment.
湖泊沉积物在其水溶性有机物（WSOM）的迁移和转化中起着重要作用，而 WSOM 的来源和组成会影响水的营养状态和污染物的归宿。然而，我们对 WSOM 转化的途径及其在湖泊沉积物中的驱动细菌群落知之甚少。本研究采用荧光光谱法研究了巢湖沉积物中 WSOM 及其荧光组分的空间分布模式，并通过提出的计算比值法探讨了 WSOM 的组成结构。此外，还利用 Illumina 测序技术分析了沉积物细菌群落，并探讨了在土著细菌介导下 WSOM 转化的可能途径。结果表明，入湖河流影响了 WSOM 及其五个荧光组分（酪氨酸、色氨酸、富里酸、腐殖酸和可溶性微生物产物）的空间分布模式，而沉积物 WSOM 来源于新鲜藻类碎屑或细菌源。同时，还发现变形菌门（主要为γ-变形菌门和δ-变形菌门）、厚壁菌门（主要为芽孢杆菌）、绿弯菌门、酸杆菌门、浮霉菌门和放线菌门是沉积物细菌群落的优势菌门。此外，这些优势细菌触发了沉积物 WSOM 的转化，具体表现为腐殖酸类物质可转化为富里酸类物质，进一步降解为芳香蛋白类和 SMP 类物质。此外，我们提出的比值（P-L：H-L、Ar-P：SMP 和 H-L 比值）作为补充工具，有效地揭示了 WSOM 的组成结构。这些结果阐明了 WSOM 转化的可能途径，并揭示了其在湖泊沉积物中的微生物机制。
