Department of Biological & Environmental Engineering, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
Deparment of Microbiology, College of Agriculture and Life Sciences, Cornell University, Ithaca, New York, USA.
J Environ Qual. 2024 Sep-Oct;53(5):565-576. doi: 10.1002/jeq2.20600. Epub 2024 Jul 16.
Excessive amounts of nitrogen (N) and phosphorus (P) can lead to eutrophication in water sources. Woodchip bioreactors have shown success in removing N from agricultural runoff, but less is known regarding P removal. Woodchip bioreactors are subsurface basins filled with woodchips installed downgradient of agricultural land to collect and treat drainage runoff. Microorganisms use the woodchips as a carbon (C) source to transform N in the runoff, with unresolved biological impacts on P. This study aims to explore microbial communities present in the bioreactor and determine whether milling woodchips to probe the microbial communities within them reveals hidden microbial diversities or potential activities. Metagenomic sequencing and bioinformatic analyses were performed on six woodchip samples (i.e., three unmilled and three milled) collected from a 10-year-old woodchip bioreactor treating agricultural tile drainage. All samples had similar DNA purity, yield, quality, and microbial diversity regardless of milling. However, when sequences were aligned against various protein libraries, our results indicated greater relative abundance of denitrification and P transformation proteins on the outside of the woodchips (unmilled), while the interior of woodchips (milled) exhibited more functional gene abundance for carbohydrate breakdown. Thus, it may be important to characterize microbial communities both within woodchips, and on woodchip surfaces, to gain a more holistic understanding of coupled biogeochemical cycles on N, P, and C in woodchip bioreactors. Based on these findings, we advise that future microbial research on woodchips (and potentially other permeable organic materials) examine both the surface biofilm and the interior organic material during initial studies. Once researchers determine where specific proteins or enzymes of interest are most prevalent, subsequent studies may then focus on either one or both aspects, as needed.
过量的氮 (N) 和磷 (P) 会导致水源富营养化。木屑生物反应器已成功用于去除农业径流中的 N，但对 P 的去除知之甚少。木屑生物反应器是地下盆地，充满了木屑，安装在农业用地的下游，以收集和处理排水径流。微生物将木屑用作 C 源，将径流中的 N 转化，对 P 的生物影响尚未解决。本研究旨在探索生物反应器中存在的微生物群落，并确定是否将木屑磨碎以探测其中的微生物群落，以揭示隐藏的微生物多样性或潜在的活性。对来自一个 10 年历史的木屑生物反应器的六个木屑样本（即三个未磨碎和三个磨碎）进行了宏基因组测序和生物信息学分析，该生物反应器用于处理农业排水渠。所有样本的 DNA 纯度、产量、质量和微生物多样性都相似，无论是否进行磨碎。然而，当序列与各种蛋白质文库对齐时，我们的结果表明，在木屑的外部（未磨碎），反硝化和 P 转化蛋白的相对丰度更高，而木屑内部（磨碎）则表现出更多用于碳水化合物分解的功能基因丰度。因此，为了更全面地了解木屑生物反应器中 N、P 和 C 的耦合生物地球化学循环，可能需要对木屑内部和木屑表面的微生物群落进行特征描述。基于这些发现，我们建议未来对木屑（和可能的其他可渗透有机材料）的微生物研究在初始研究中同时检查表面生物膜和内部有机材料。一旦研究人员确定了最常见的特定蛋白质或酶的位置，随后的研究可能根据需要集中在一个或两个方面。
