School of Environmental Science and Engineering, Marine Synthetic Ecology Research Center, Southern Marine Science and Engineering Guangdong Laboratory (Zhuhai), State Key Laboratory of Biocontrol, Sun Yat-Sen University, Guangzhou 510006, China.
Institute of Marine Science and Technology, Shandong University, Qingdao 266237, China.
Sci Total Environ. 2024 Sep 20;944:173961. doi: 10.1016/j.scitotenv.2024.173961. Epub 2024 Jun 13.
The sulfur (S) cycle is an important biogeochemical cycle with profound implications for both cellular- and ecosystem-level processes by diverse microorganisms. Mangrove sediments are a hotspot of biogeochemical cycling, especially for the S cycle with high concentrations of S compounds. Previous studies have mainly focused on some specific inorganic S cycling processes without paying specific attention to the overall S-cycling communities and processes as well as organic S metabolism. In this study, we comprehensively analyzed the distribution, ecological network and assembly mechanisms of S cycling microbial communities and their changes with sediment depths using metagenome sequencing data. The results showed that the abundance of gene families involved in sulfur oxidation, assimilatory sulfate reduction, and dimethylsulfoniopropionate (DMSP) cleavage and demethylation decreased with sediment depths, while those involved in S reduction and dimethyl sulfide (DMS) transformation showed an opposite trend. Specifically, glpE, responsible for converting SO to SO, showed the highest abundance in the surface sediment and decreased with sediment depths; in contrast, high abundances of dmsA, responsible for converting dimethyl sulfoxide (DMSO) to DMS, were identified and increased with sediment depths. We identified Pseudomonas and Streptomyces as the main S-cycling microorganisms, while Thermococcus could play an import role in microbial network connections in the S-cycling microbial community. Our statistical analysis showed that both taxonomical and functional compositions were generally shaped by stochastic processes, while the functional composition of organic S metabolism showed a transition from stochastic to deterministic processes. This study provides a novel perspective of diversity distribution of S-cycling functions and taxa as well as their potential assembly mechanisms, which has important implications for maintaining mangrove ecosystem functions.
硫（S）循环是一个重要的生物地球化学循环，对各种微生物的细胞和生态系统水平过程都有深远的影响。红树林沉积物是生物地球化学循环的热点，特别是对于 S 循环，其 S 化合物浓度很高。以前的研究主要集中在一些特定的无机 S 循环过程上，而没有特别关注整体 S 循环群落和过程以及有机 S 代谢。在这项研究中，我们使用宏基因组测序数据全面分析了 S 循环微生物群落的分布、生态网络和组装机制及其随沉积物深度的变化。结果表明，参与硫氧化、同化硫酸盐还原和二甲基硫丙酸（DMSP）裂解和去甲基化的基因家族的丰度随着沉积物深度的增加而降低，而参与 S 还原和二甲基硫（DMS）转化的基因家族则呈现相反的趋势。具体来说，glpE 基因家族负责将 SO 转化为 SO，其丰度在表层沉积物中最高，随着沉积物深度的增加而降低；相反，dmsA 基因家族负责将二甲基亚砜（DMSO）转化为 DMS，其丰度较高，且随着沉积物深度的增加而增加。我们确定假单胞菌和链霉菌是主要的 S 循环微生物，而 Thermococcus 可能在 S 循环微生物群落的微生物网络连接中发挥重要作用。我们的统计分析表明，分类组成和功能组成通常受到随机过程的影响，而有机 S 代谢的功能组成则从随机过程向确定性过程转变。本研究提供了一个新的视角，即 S 循环功能和分类群的多样性分布及其潜在的组装机制，这对维持红树林生态系统功能具有重要意义。
