Dutta Avishek, Sar Pinaki, Sarkar Jayeeta, Dutta Gupta Srimanti, Gupta Abhishek, Bose Himadri, Mukherjee Abhijit, Roy Sukanta
Environmental Microbiology and Genomics Laboratory, Department of Biotechnology, Indian Institute of Technology Kharagpur, Kharagpur, India.
School of Bioscience, Indian Institute of Technology Kharagpur, Kharagpur, India.
Front Microbiol. 2019 Jul 16;10:1362. doi: 10.3389/fmicb.2019.01362. eCollection 2019.
Archaeal community structure and potential functions within the deep, aphotic, oligotrophic, hot, igneous provinces of ∼65 Myr old basalt and its Archean granitic basement was explored through archaeal 16S rRNA gene amplicon sequencing from extracted environmental DNA of rocks. Rock core samples from three distinct horizons, basaltic (BS), transition (weathered granites) (TZ) and granitic (GR) showed limited organic carbon (4-48 mg/kg) and varied concentrations (<1.0-5000 mg/kg) of sulfate, nitrate, nitrite, iron and metal oxides. Quantitative PCR estimated the presence of nearly 10-10 archaeal cells per gram of rock. Archaeal communities within BS and GR horizons were distinct. The absence of any common OTU across the samples indicated restricted dispersal of archaeal cells. Younger, relatively organic carbon- and FeO-rich BS rocks harbor , along with varied proportions of and . Extreme acid loving, thermotolerant sulfur respiring , heterotrophic, ferrous-/H-sulfide oxidizing and were more abundant and closely interrelated within BS rocks. Samples from the GR horizon represent a unique composition with higher proportions of and uneven distribution of and affiliated to , SAGMCG-1, FHMa11 terrestrial group, AK59 and unclassified taxa. Acetoclastic methanogenic , autotrophic SAGMCG-1 and MCG of could be identified as the signature groups within the organic carbon lean GR horizon. Sulfur-oxidizing was relatively more abundant in sulfate-rich amygdaloidal basalt and migmatitic gneiss samples. Methane-oxidizing ANME-3 populations were found to be ubiquitous, but their abundance varied greatly between the analyzed samples. Changes in diversity pattern among the BS and GR horizons highlighted the significance of local rock geochemistry, particularly the availability of organic carbon, FeO and other nutrients as well as physical constraints (temperature and pressure) in a niche-specific colonization of extremophilic archaeal communities. The study provided the first deep sequencing-based illustration of an intricate association between diverse extremophilic groups (acidophile-halophile-methanogenic), capable of sulfur/iron/methane metabolism and thus shed new light on their potential role in biogeochemical cycles and energy flow in deep biosphere hosted by hot, oligotrophic igneous crust.
通过对从岩石提取的环境DNA进行古菌16S rRNA基因扩增子测序，探索了年龄约6500万年的玄武岩及其太古宙花岗岩基底深部、无光、贫营养、高温火成岩省中的古菌群落结构和潜在功能。来自三个不同层位的岩芯样本，玄武岩层（BS）、过渡层（风化花岗岩）（TZ）和花岗岩层（GR）显示有机碳含量有限（4 - 48毫克/千克），硫酸盐、硝酸盐、亚硝酸盐、铁和金属氧化物的浓度各不相同（<1.0 - 5000毫克/千克）。定量PCR估计每克岩石中存在近10 - 10个古菌细胞。BS层和GR层内的古菌群落不同。样本中没有任何共同的操作分类单元，表明古菌细胞的扩散受限。较年轻、相对富含有机碳和FeO的BS岩石中，除了不同比例的[具体微生物名称缺失]和[具体微生物名称缺失]外，还含有[具体微生物名称缺失]。极端嗜酸、耐热的硫呼吸[具体微生物名称缺失]、异养、亚铁/硫化氢氧化[具体微生物名称缺失]和[具体微生物名称缺失]在BS岩石中更为丰富且密切相关。GR层的样本代表了一种独特的组成，[具体微生物名称缺失]和[具体微生物名称缺失]隶属于[具体微生物类群名称缺失]、SAGMCG - 1、FHMa11陆地类群、AK59和未分类类群，其比例较高且分布不均。产乙酸甲烷菌[具体微生物名称缺失]、自养的SAGMCG - 1和[具体微生物名称缺失]的MCG可被确定为贫有机碳GR层中的标志性类群。硫氧化[具体微生物名称缺失]在富含硫酸盐的杏仁状玄武岩和混合片麻岩样本中相对更为丰富。发现甲烷氧化ANME - 3种群普遍存在，但在分析样本中的丰度差异很大。BS层和GR层之间多样性模式的变化突出了当地岩石地球化学的重要性，特别是有机碳、FeO和其他养分的可用性以及物理限制（温度和压力）对极端嗜热古菌群落特定生态位定殖的影响。该研究首次基于深度测序展示了能够进行硫/铁/甲烷代谢的不同极端嗜热类群（嗜酸菌 - 嗜盐菌 - 产甲烷菌）之间的复杂关联，从而为它们在由高温、贫营养火成岩地壳承载 的深部生物圈中的生物地球化学循环和能量流动中的潜在作用提供了新的见解。
