Hall Steven J, Huang Wenjuan, Napieralski Stephanie A, Roden Eric
Department of Ecology, Evolution and Organismal Biology, Iowa State University, Ames, IA, United States.
Department of Geoscience, University of Wisconsin-Madison, Madison, WI, United States.
Front Microbiol. 2022 Jun 2;13:866828. doi: 10.3389/fmicb.2022.866828. eCollection 2022.
Periodic oxygen (O) limitation in humid terrestrial soils likely influences microbial composition, but whether communities share similar responses in disparate environments remains unclear. To test if specific microbial taxa share consistent responses to anoxia in radically different soils, we incubated a rainforest Oxisol and cropland Mollisol under cyclic, time-varying anoxic/oxic cycles in the laboratory. Both soils are known to experience anoxic periods of days to weeks under field conditions; our incubation treatments consisted of anoxic periods of 0, 2, 4, 8, or 12 d followed by 4 d of oxic conditions, repeated for a total of 384 d. Taxa measured by 16S rRNA gene sequences after 48 d and 384 d of experimental treatments varied strongly with increasing anoxic period duration, and responses to anoxia often differed between soils at multiple taxonomic levels. Only 19% of the 30,356 operational taxonomic units (OTUs) occurred in both soils, and most OTUs did not respond consistently to O treatments. However, the OTUs present in both soils were disproportionally abundant, comprising 50% of sequences, and they often had a similar response to anoxic period duration in both soils ( < 0.0001). Overall, 67 OTUs, 36 families, 15 orders, 10 classes, and two phyla had significant and directionally consistent (positive or negative) responses to anoxic period duration in both soils. Prominent OTUs and taxonomic groups increasing with anoxic period duration in both soils included actinomycetes (), numerous , possible metal reducers () or oxidizers ( Koribacter), methanogens (), and methanotrophs (). OTUs decreasing with anoxic duration in both soils included nitrifiers () and ubiquitous unidentified and . Even within the same genus, different OTUs occasionally showed strong positive or negative responses to anoxic duration (e.g., in the ), highlighting a potential for adaptation or niche partitioning in variable-O environments. Overall, brief anoxic periods impacted the abundance of certain microbial taxa in predictable ways, suggesting that microbial community data may partially reflect and integrate spatiotemporal differences in O availability within and among soils.
潮湿陆地土壤中周期性的氧气（O）限制可能会影响微生物组成，但不同环境中的群落是否有相似的反应仍不清楚。为了测试特定的微生物分类群在截然不同的土壤中对缺氧是否有一致的反应，我们在实验室中对雨林氧化土和农田软土进行了周期性、随时间变化的缺氧/有氧循环培养。已知这两种土壤在田间条件下都会经历数天至数周的缺氧期；我们的培养处理包括0、2、4、8或12天的缺氧期，随后是4天的有氧条件，总共重复384天。在实验处理48天和384天后，通过16S rRNA基因序列测量的分类群随缺氧期持续时间的增加而有很大变化，并且在多个分类水平上，两种土壤对缺氧的反应通常不同。在这两种土壤中出现的30356个操作分类单元（OTU）中，只有19%，并且大多数OTU对氧气处理的反应不一致。然而，在两种土壤中都存在的OTU数量过多，占序列的50%，并且它们对缺氧期持续时间的反应在两种土壤中通常相似（P<0.0001）。总体而言，67个OTU、36个科、15个目、10个纲和两个门在两种土壤中对缺氧期持续时间都有显著且方向一致（正或负）的反应。在两种土壤中，随着缺氧期持续时间增加而显著的OTU和分类群包括放线菌（）、许多、可能的金属还原剂（）或氧化剂（科里杆菌）、产甲烷菌（）和甲烷氧化菌（）。在两种土壤中随着缺氧持续时间减少的OTU包括硝化菌（）以及无处不在的未鉴定和。即使在同一属内，不同的OTU偶尔也会对缺氧持续时间表现出强烈的正或负反应（例如，在中的），这突出了在可变氧气环境中适应或生态位划分的潜力。总体而言，短暂的缺氧期以可预测的方式影响了某些微生物分类群的丰度，这表明微生物群落数据可能部分反映并整合了土壤内部和土壤之间氧气有效性的时空差异。
