16S rRNA amplicon study of archaeal community on 0.45-0.8 micron and >8 micron particles in the Broadkill River in Lewes, DE.. Archaeal Community Patterns on Size-Fractioned Particles in the Broadkill River

Particulate matter in estuarine systems has been shown to host microbial communities that can impact nutrient cycling. Salinity and oxygen have been implicated as environmental stressors that dictate the community composition of particle-associated microbes. More studies, however, have focused on bacterial populations than archaeal. Here we investigate bacterial and archaeal community compositions on size-fractioned suspended particles along a salinity gradient of the Broadkill River in coastal Delaware. We examine the effects of stressors on communities of bacteria and archaea, including the analysis of shifts in diatoms. We found that environmental stressors varied by size of particle and by the domain under investigation. Bacteria associated with smaller particles were influenced by salinity, but bacterial on large particles were potentially responding to geochemistry and direct competition with eukaryotes for habitat space, particularly for photosynthesis. We found that archaea are affected by salinity stress to a lower degree than bacteria, but a greater environmental pressure may be anoxic habitat space on larger particles, which results in a higher species richness, particularly of anaerobic groups of archaea, on these large particles.

河口系统中的颗粒物已被证实可栖息着影响养分循环的微生物群落。盐度与溶解氧已被证实为调控颗粒附着微生物群落组成的关键环境胁迫因子。然而，现有研究对细菌（Bacteria）种群的关注程度远高于古菌（Archaea）。本研究以特拉华州沿海布罗德基尔河的盐度梯度带为研究对象，针对不同粒径分级的悬浮颗粒物上的细菌与古菌群落组成展开调查，探究环境胁迫因子对两类微生物群落的影响，其中涵盖硅藻群落动态变化的相关分析。研究结果显示，环境胁迫因子的作用效果随颗粒物粒径以及所研究的微生物域而异：附着于小粒径颗粒物的细菌群落主要受盐度调控，而大粒径颗粒物上的细菌群落则可能响应于地球化学条件，以及与真核生物就栖息空间（尤其是光合作用所需生境）产生的直接竞争。本研究发现，古菌群落受盐度胁迫的程度低于细菌，但大粒径颗粒物上的缺氧栖息环境可能构成更强的环境压力，进而使得此类大颗粒物上的物种丰富度更高，尤以厌氧古菌类群为甚。