Ahmed Mir Alvee, Campbell Barbara J
Department of Biological Sciences, Clemson University, Clemson, South Carolina, USA.
Appl Environ Microbiol. 2025 Feb 19;91(2):e0235724. doi: 10.1128/aem.02357-24. Epub 2025 Jan 8.
The abundant and metabolically versatile aquatic bacterial order, , influences marine biogeochemical cycles. We assessed metagenome-assembled genome (MAG) abundance, estimated growth rates, and potential and expressed functions in the Chesapeake and Delaware Bays, two important US estuaries. Phylogenomics of draft and draft/closed genomes from this study and others placed 46 nearly complete MAGs from these bays into 11 genera, many were not well characterized. Their abundances varied between the bays and were influenced by temperature, salinity, and silicate and phosphate concentrations. genera possessed unique and shared genes for transporters, photoheterotrophy, complex carbon degradation, nitrogen, and sulfur metabolism reflecting their seasonal differences in abundance and activity. genomospecies were more ubiquitous than the more niche specialists, HIMB11, CPC320, LFER01, and MED-G52. Their estimated growth rates were correlated to various factors including phosphate and silicate concentrations, cell density, and light. Metatranscriptomic analysis of four abundant genomospecies commonly revealed that aerobic anoxygenic photoheterotrophy-associated transcripts were highly abundant at night. These also differentially expressed genes for CO oxidation and nutrient transport and use between different environmental conditions. Phosphate concentrations and light penetration in the Chesapeake Bay likely contributed to higher estimated growth rates of HIMB11 and LFER01, respectively, in summer where they maintained higher ribosome concentrations and prevented physiological gene expression constraints by downregulating transporter genes compared to the Delaware Bay. Our study highlights the spatial and temporal shifts in estuarine within and between these bays reflected through their abundance, unique metabolisms, estimated growth rates, and activity changes.
In the complex web of global biogeochemical nutrient cycling, the emerge as key players, exerting a profound influence through their abundance and dynamic activity. While previous studies have primarily investigated these organisms within marine ecosystems, this study delves into their roles within estuarine environments using a combination of metagenomic and metatranscriptomic analyses. We uncovered a range of genera, from generalists to specialists, each exhibiting distinct abundance patterns and gene expression profiles. This diversity equips them with the capacity to thrive amidst the varying environmental conditions encountered within dynamic estuarine habitats. Crucially, our findings illuminate the adaptable nature of estuarine , revealing their various energy production pathways and diverse resource management, especially during phytoplankton or algal blooms. Whether adopting a free-living or particle-attached existence, these organisms demonstrate remarkable flexibility in their metabolic strategies, underscoring their pivotal role in driving ecosystem dynamics within estuarine ecosystems.
丰富且代谢多样的水生细菌目——[具体目名未给出]，影响着海洋生物地球化学循环。我们评估了美国两个重要河口切萨皮克湾和特拉华湾中宏基因组组装基因组（MAG）的丰度、估计生长速率以及潜在和表达的功能。本研究及其他研究中草图和草图/完成基因组的系统发育基因组学将来自这些海湾的46个近乎完整的MAG归入11个属，其中许多属尚未得到充分表征。它们在不同海湾的丰度有所不同，并受温度、盐度以及硅酸盐和磷酸盐浓度的影响。[具体属名未给出]属拥有独特且共享的转运蛋白、光异养、复杂碳降解、氮和硫代谢相关基因，反映了它们在丰度和活性上的季节性差异。[具体属名未给出]基因组种比更具生态位特异性的HIMB11、CPC320、LFER01和MED - G52更为普遍。它们的估计生长速率与多种因素相关，包括磷酸盐和硅酸盐浓度、细胞密度和光照。对四种丰富的基因组种的宏转录组分析通常表明，与好氧不产氧光异养相关的转录本在夜间高度丰富。这些[具体属名未给出]在不同环境条件下还差异表达了一氧化碳氧化以及营养物质转运和利用相关的基因。切萨皮克湾的磷酸盐浓度和光穿透率可能分别导致了夏季HIMB11和LFER01较高的估计生长速率，与特拉华湾相比，它们在夏季维持了更高的核糖体浓度，并通过下调转运蛋白基因防止了生理基因表达受限。我们的研究突出了这些海湾内部和之间河口[具体属名未给出]在丰度、独特代谢、估计生长速率和活性变化方面所反映出的时空变化。
在全球生物地球化学营养循环的复杂网络中，[具体目名未给出]作为关键参与者出现，通过其丰富度和动态活性发挥着深远影响。虽然先前的研究主要在海洋生态系统中研究这些生物，但本研究通过宏基因组学和宏转录组学分析相结合的方法深入探究了它们在河口环境中的作用。我们发现了一系列[具体属名未给出]属，从泛化种到特化种，每个属都表现出独特的丰度模式和基因表达谱。这种多样性使它们有能力在动态河口栖息地遇到的不同环境条件下茁壮成长。至关重要的是，我们的发现揭示了河口[具体属名未给出]的适应性本质，揭示了它们各种能量产生途径和多样的资源管理方式，特别是在浮游植物或藻类大量繁殖期间。无论采取自由生活还是附着于颗粒的生存方式，这些生物在代谢策略上都表现出显著的灵活性，强调了它们在驱动河口生态系统内生态系统动态方面的关键作用。
