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Exposure to elevated nutrient load results in structural and functional changes to microbial communities associated with riparian wetland plants Phalaris arundinaceae and Veronica anagallis-aquatica
Rhizosphere ( IF 3.7 ) Pub Date : 2021-03-26 , DOI: 10.1016/j.rhisph.2021.100350
James W. Bannister , Lindsey K. Clairmont , Kevin J. Stevens , Robin M. Slawson

The goal of this study was to better understand the resilience of rhizosphere microbial communities located in riparian wetlands subjected to high nutrient loads following effluent or runoff exposure. Specifically, this research monitored functional profiles of mesocosm communities during an artificial high nitrogen load exposure following adaptation to high or low water quality conditions. Based on prior research, two species of wetland plants were chosen, Phalaris arundinaceae and Veronica anagallis-aquatica, both located in local riparian zones, and planted in wetland mesocosms. Rhizosphere bacterial community response was monitored for approximately three weeks after exposure to elevated nutrient loads, following prior adaptation for several months to either high or low (poor) water quality conditions. The impact of prior acclimation conditions was then assessed. Changes to rhizosphere bacterial community structure and function were monitored using PCR-denaturing gel gradient electrophoresis (DGGE) and Biolog™ Ecoplates, respectively. Plants were also sampled to assess any impact on mycorrhizal associations over the exposure period. As an additional indicator of functionality and nitrogen utilization within the mesocosm system, inorganic intermediate N species were monitored at the outflow. Significant differences were observed over time following elevated nutrient exposure in bacterial structural diversity and richness, as well as functional diversity and richness (p < 0.001). The effects of interactions between time, plant species and water quality exposure were also significant for both structural (p = 0.002) and functional (p = 0.05) community diversity. Elevated nutrient exposure resulted in changes to microbial carbon source utilization profiles, specifically, bacterial usage of amino acids (p = 0.032), polymers (p = 0.029) and carboxylic and ketonic acids (p = 0.042). Carboxylic and ketonic acid utilization by bacterial communities was positively correlated with the removal of nitrate and nitrite from experimental mesocosms. Mycorrhizal associations as measured by percent colonization also decreased significantly in P. arundinaceae following elevated nutrient exposure (p < 0.001). Furthermore, abundance of nitrogenous compounds in outflow water differed between plant species treatments, with V. anagallis-aquatica removing more nitrate from the outflow (p = 0.005) while P. arundinaceae removed higher levels of ammonia (p = 0.03). This study provides insight into how microbial communities respond to transient nutrient loads such as that experienced by overland runoff following a high rain event and will assist in the design and rehabilitation of wetlands or riparian buffer strips to manage higher nutrient loads resulting from increasing human activity impacting our freshwater systems.



中文翻译:

暴露于较高的营养负荷下会导致与河岸湿地植物plantsVeronica anagallis-aquatica相关的微生物群落的结构和功能发生变化

这项研究的目的是更好地了解位于污水或径流暴露后高营养负荷的河岸湿地上的根际微生物群落的复原力。具体而言,这项研究在适应高或低水质条件后,在人工高氮负荷暴露过程中监测了中观宇宙群落的功能概况。根据先前的研究,选择了两种湿地植物:a草Veronica anagallis-aquatica,都位于当地的河岸地区,并种植在湿地中观世界中。在暴露于高水平的营养物后,对根际细菌群落的响应进行了大约三周的监测,此前对高或低(差)水质条件进行了几个月的适应。然后评估先前适应条件的影响。分别使用PCR变性凝胶梯度电泳(DGGE)和Biolog™Ecoplates监测根际细菌群落结构和功能的变化。还对植物取样以评估在暴露期间对菌根协会的任何影响。作为介观体系内功能性和氮利用的另一个指标,在流出时监测了无机中间体N的种类。随着时间的推移,随着养分暴露量的增加,细菌的结构多样性和丰富度以及功能多样性和丰富度随时间的推移出现了显着差异(p <0.001)。时间,植物物种和水质暴露之间的相互作用对结构(p = 0.002)和功能(p = 0.05)社区多样性也很重要。营养物暴露的增加导致微生物碳源利用状况的变化,特别是细菌对氨基酸的使用(p = 0.032),聚合物的使用(p = 0.029)和羧酸和酮酸(p = 0.042)。细菌群落对羧酸和酮酸的利用与实验性中膜的硝酸盐和亚硝酸盐的去除呈正相关。以定植百分数衡量的菌根协会也显着下降。营养物暴露增加后的P. arundinaceae(p <0.001)。此外,在不同的植物物种处理之间,流出水中的含氮化合物含量也有所不同,V。anagallis-aquatica从流出物中去除了更多的硝酸盐(p = 0.005),而金莲花P. arundinaceae)去除了更高水平的氨(p = 0.03)。这项研究提供了关于微生物群落如何应对瞬态养分负荷的见解,例如高降雨事件后陆上径流所经历的瞬态养分负荷,并将有助于湿地或河岸缓冲带的设计和修复,以管理由于人类活动影响增加而产生的更高养分负荷我们的淡水系统。

更新日期:2021-03-31
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