School of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia, USA.
Center for Environmental Biotechnology, Department of Microbiology, Department of Civil and Environmental Engineering, Department of Biosystems Engineering and Soil Science, University of Tennessee, Knoxville, Tennessee, USA.
Appl Environ Microbiol. 2021 May 26;87(12):e0054621. doi: 10.1128/AEM.00546-21.
The phylogenetic and functional diversities of microbial communities in tropical rainforests and how these differ from those of temperate communities remain poorly described but are directly related to the increased fluxes of greenhouse gases such as nitrous oxide (NO) from the tropics. Toward closing these knowledge gaps, we analyzed replicated shotgun metagenomes representing distinct life zones and an elevation gradient from four locations in the Luquillo Experimental Forest (LEF), Puerto Rico. These soils had a distinct microbial community composition and lower species diversity compared to those of temperate grasslands or agricultural soils. In contrast to the overall distinct community composition, the relative abundances and nucleotide sequences of NO reductases () were highly similar between tropical forest and temperate soils. However, respiratory NO reductase () was 2-fold more abundant in the tropical soils, which might be relatable to their greater NO emissions. Nitrogen fixation () also showed higher relative abundance in rainforest than in temperate soils, i.e., 20% versus 0.1 to 0.3% of bacterial genomes in each soil type harbored the gene, respectively. Finally, unlike temperate soils, LEF soils showed little stratification with depth in the first 0 to 30 cm, with ∼45% of community composition differences explained solely by location. Collectively, these results advance our understanding of spatial diversity and metabolic repertoire of tropical rainforest soil communities and should facilitate future ecological studies of these ecosystems. Tropical rainforests are the largest terrestrial sinks of atmospheric CO and the largest natural source of NO emissions, two greenhouse gases that are critical for the climate. The microbial communities of rainforest soils that directly or indirectly, through affecting plant growth, contribute to these fluxes remain poorly described by cultured-independent methods. To close this knowledge gap, the present study applied shotgun metagenomics to samples selected from three distinct life zones within the Puerto Rico rainforest. The results advance our understanding of microbial community diversity in rainforest soils and should facilitate future studies of natural or manipulated perturbations of these critical ecosystems.
热带雨林中微生物群落的系统发育和功能多样性，以及这些多样性与热带地区温室气体（如氧化亚氮 (NO)）通量增加的关系，仍描述不足，但与温室气体的增加直接相关。为了弥补这些知识空白，我们分析了来自波多黎各 Luquillo 实验森林 (LEF) 四个地点不同生命带和海拔梯度的具有代表性的 shotgun 宏基因组。与温带草原或农业土壤相比，这些土壤具有独特的微生物群落组成和较低的物种多样性。与整体独特的群落组成形成鲜明对比的是，NO 还原酶 () 的相对丰度和核苷酸序列在热带森林和温带土壤之间非常相似。然而，呼吸型 NO 还原酶 () 在热带土壤中的丰度是温带土壤的两倍，这可能与它们更高的 NO 排放有关。固氮 () 在雨林中的相对丰度也高于温带土壤，即在每个土壤类型中，分别有 20%和 0.1%至 0.3%的细菌基因组携带该基因。最后，与温带土壤不同的是，LEF 土壤在 0 到 30 厘米的深度范围内几乎没有分层，仅通过位置就可以解释 45%的群落组成差异。总的来说，这些结果提高了我们对热带雨林土壤微生物群落空间多样性和代谢组成的理解，并应该有助于未来对这些生态系统的生态研究。热带雨林是大气 CO 的最大陆地汇和 NO 排放的最大天然源，这两种温室气体对气候至关重要。直接或通过影响植物生长间接影响这些通量的雨林土壤微生物群落仍未被培养依赖方法充分描述。为了弥补这一知识空白，本研究应用 shotgun 宏基因组学对从波多黎各雨林的三个不同生命带中选择的样本进行了研究。研究结果提高了我们对雨林土壤微生物群落多样性的理解，并应该有助于未来对这些关键生态系统进行自然或人为干扰的研究。
