Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, College of Environment, Hohai University, Nanjing, 210098, China.
Ministry of Education Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes, College of Environment, Hohai University, Nanjing, 210098, China.
Chemosphere. 2019 Dec;236:124253. doi: 10.1016/j.chemosphere.2019.06.223. Epub 2019 Jul 1.
Epiphytic bacteria on submerged macrophytes play important roles in the nutrient cycle in freshwater ecosystems. However, little is known about the composition and role of epiphytic bacteria during the decomposition of submerged macrophytes. In this study, the alterations in epiphytic bacterial composition, abundances of nitrogen cycle-related genes and nutrient release were investigated in a 56-day decomposition process of Potamogeton malaianus. The total reduced biomass was positively related to the contents of carbon, nitrogen and phosphorus released from plant residues. Nutrient released from plant litter showed a positively effect on the concentrations of carbon, nitrogen and phosphorus in the overlying water (p < 0.01). The carbon, phosphorus and nitrogen decreased with decomposition process in both plant debris and overlying water. Humic acid-like substances were the main component of dissolved organic matter in the conditioning stage, whereas fulvic acid-like substances dominated in the fragmentation stage. Results from network analysis and canonical correspondence analysis showed dominant bacterial clades changed with decomposition process. Bacteroidetes was the most abundant phylum in the leaching stage and Spirochaetes, Chlorobi, and Bacteroidetes dominated in the conditioning stage, while Chlorobi dominated in the fragmentation stage. The highest abundance of cnorB and nosZ were detected in the leaching and fragmentation stage, respectively. Bacterial denitrification contributed to nitrogen removal and might be promoted by high ORP and DOC concentration. Our results indicate that epiphytic bacterial community shift drived the metabolism of nutrients C, N, and S during the decomposition of P. malaianus.
沉水植物附生细菌在淡水生态系统的养分循环中发挥着重要作用。然而，人们对沉水植物分解过程中附生细菌的组成和作用知之甚少。在这项研究中，我们调查了 56 天的菹草分解过程中附生细菌组成、氮循环相关基因丰度和养分释放的变化。总还原生物量与植物残体释放的碳、氮和磷含量呈正相关。植物残体释放的养分对水层中碳、氮和磷的浓度有正效应（p < 0.01）。在植物碎屑和上覆水中，碳、磷和氮随着分解过程而减少。在调理阶段，腐殖酸类物质是溶解有机物质的主要成分，而在碎裂阶段，富里酸类物质占主导地位。网络分析和典范对应分析的结果表明，随着分解过程的进行，优势细菌类群发生了变化。在淋溶阶段，拟杆菌门是最丰富的门，在调理阶段，螺旋体门、绿菌门和拟杆菌门占主导地位，而在碎裂阶段，绿菌门占主导地位。cnorB 和 nosZ 的丰度在淋溶和碎裂阶段最高。细菌反硝化作用有助于氮的去除，并且可能受到高氧化还原电位和 DOC 浓度的促进。我们的研究结果表明，沉水植物菹草分解过程中，附生细菌群落的变化驱动了 C、N 和 S 等营养物质的代谢。
