Microbially-driven sulfur cycling microbial communities in different mangrove sediments

Microbially-driven sulfur cycling is a vital biogeochemical process in the sulfur-rich mangrove ecosystem. It is critical to evaluate the potential impact of sulfur transformation in mangrove ecosystems. To reveal the diversity, composition, and structure of sulfur-oxidizing bacteria (SOB) and sulfate-reducing bacteria (SRB) and underlying mechanisms, we analyzed the physicochemical properties and sediment microbial communities from an introduced mangrove species (Sonneratia apetala), a native mangrove species (Kandelia obovata) and the mudflat in Hanjiang River Estuary in Guangdong (23.27 degrees N, 116.52 degrees E), China. The results indicated that SOB was dominated by autotrophic Thiohalophilus and chemoautotrophy Chromatium in S. apetala and K. obovata, respectively, while Desulfatibacillum was the dominant genus of SRB in K. obovata sediments. Also, the redundancy analysis indicated that temperature, redox potential (ORP), and SO42- were the significant factors influencing the sulfur cycling microbial communities with elemental sulfur (ES) as the key factor driver for SOB and total carbon (TC) for SRB in mangrove sediments. Additionally, the morphological transformation of ES, acid volatile sulfide (AVS) and SO42- explained the variation of sulfur cycling microbial communities under sulfur-rich conditions, and we found mangrove species-specific dominant Thiohalobacter, Chromatium and Desulfatibacillum, which could well use ES and SO42-, thus promoting the sulfur cycling in mangrove sediments. Meanwhile, the change of nutrient substances (TN, TC) explained why SOB were more susceptible to environmental changes than SRB. Sulfate reducing bacteria produces sulfide in anoxic sediments at depth that then migrate upward, toward fewer reducing conditions, where it's oxidized by sulfur oxidizing bacteria. This study indicates the high ability of SOB and SRB in ES, SO42-,S-2(-) and S2- generation and transformation in sulfur-rich mangrove ecosystems, and provides novel insights into sulfur cycling in other wetland ecosystems from a microbial perspective. (C) 2020 Elsevier Ltd. All rights reserved.

微生物驱动的硫循环是富硫红树林生态系统中一项至关重要的生物地球化学过程。评估红树林生态系统中硫转化的潜在影响至关重要。为了揭示硫氧化细菌（SOB）和硫酸盐还原细菌（SRB）的多样性、组成和结构以及潜在机制，我们分析了中国广东韩江河口（北纬23.27度，东经116.52度）的一种引进红树林物种（无瓣海桑）、一种本地红树林物种（秋茄）以及滩涂的理化性质和沉积物微生物群落。结果表明，在无瓣海桑和秋茄中，硫氧化细菌分别以自养型的嗜硫盐菌属和化能自养型的着色菌属为主，而脱硫杆菌属是秋茄沉积物中硫酸盐还原细菌的优势属。此外，冗余分析表明，温度、氧化还原电位（ORP）和硫酸根（SO₄²⁻）是影响硫循环微生物群落的重要因素，其中元素硫（ES）是红树林沉积物中硫氧化细菌的关键驱动因子，总碳（TC）是硫酸盐还原细菌的关键驱动因子。另外，元素硫、酸可挥发性硫化物（AVS）和硫酸根的形态转化解释了富硫条件下硫循环微生物群落的变化，并且我们发现了红树林物种特异性的优势嗜硫杆菌属、着色菌属和脱硫杆菌属，它们能够很好地利用元素硫和硫酸根，从而促进红树林沉积物中的硫循环。同时，营养物质（总氮、总碳）的变化解释了为什么硫氧化细菌比硫酸盐还原细菌更容易受到环境变化的影响。硫酸盐还原细菌在深层缺氧沉积物中产生硫化物，然后向上迁移，朝着氧化性更强的环境移动，在那里被硫氧化细菌氧化。这项研究表明了硫氧化细菌和硫酸盐还原细菌在富硫红树林生态系统中产生和转化元素硫、硫酸根、硫离子（S⁻²）和二价硫离子（S²⁻）的高能力，并从微生物角度为其他湿地生态系统中的硫循环提供了新的见解。（C）2020爱思唯尔有限公司。保留所有权利。