Pachiadaki Maria G, Rédou Vanessa, Beaudoin David J, Burgaud Gaëtan, Edgcomb Virginia P
Department of Geology and Geophysics, Woods Hole Oceanographic Institution Woods Hole, MA, USA.
Laboratoire Universitaire de Biodiversité et Ecologie Microbienne, EA 3882, ESIAB, Technopôle de Brest Iroise, Université de Brest Plouzané, France.
Front Microbiol. 2016 Jun 9;7:846. doi: 10.3389/fmicb.2016.00846. eCollection 2016.
The deep sedimentary biosphere, extending 100s of meters below the seafloor harbors unexpected diversity of Bacteria, Archaea, and microbial eukaryotes. Far less is known about microbial eukaryotes in subsurface habitats, albeit several studies have indicated that fungi dominate microbial eukaryotic communities and fungal molecular signatures (of both yeasts and filamentous forms) have been detected in samples as deep as 1740 mbsf. Here, we compare and contrast fungal ribosomal RNA gene signatures and whole community metatranscriptomes present in sediment core samples from 6 and 95 mbsf from Peru Margin site 1229A and from samples from 12 and 345 mbsf from Canterbury Basin site U1352. The metatranscriptome analyses reveal higher relative expression of amino acid and peptide transporters in the less nutrient rich Canterbury Basin sediments compared to the nutrient rich Peru Margin, and higher expression of motility genes in the Peru Margin samples. Higher expression of genes associated with metals transporters and antibiotic resistance and production was detected in Canterbury Basin sediments. A poly-A focused metatranscriptome produced for the Canterbury Basin sample from 345 mbsf provides further evidence for active fungal communities in the subsurface in the form of fungal-associated transcripts for metabolic and cellular processes, cell and membrane functions, and catalytic activities. Fungal communities at comparable depths at the two geographically separated locations appear dominated by distinct taxa. Differences in taxonomic composition and expression of genes associated with particular metabolic activities may be a function of sediment organic content as well as oceanic province. Microscopic analysis of Canterbury Basin sediment samples from 4 and 403 mbsf produced visualizations of septate fungal filaments, branching fungi, conidiogenesis, and spores. These images provide another important line of evidence supporting the occurrence and activity of fungi in the deep subseafloor biosphere.
深海沉积生物圈位于海底以下数百米深处，蕴藏着细菌、古菌和微生物真核生物的意外多样性。尽管有几项研究表明真菌在地下生境的微生物真核生物群落中占主导地位，并且在深达1740米海底以下的样本中检测到了酵母和丝状形态的真菌分子特征，但人们对地下生境中的微生物真核生物了解较少。在这里，我们比较并对比了来自秘鲁边缘1229A站点6米和95米海底以下沉积物岩芯样本以及坎特伯雷盆地U1352站点12米和345米海底以下样本中的真菌核糖体RNA基因特征和整个群落的元转录组。元转录组分析显示，与营养丰富的秘鲁边缘相比，营养较不丰富的坎特伯雷盆地沉积物中氨基酸和肽转运蛋白的相对表达更高，而秘鲁边缘样本中运动基因的表达更高。在坎特伯雷盆地沉积物中检测到与金属转运蛋白以及抗生素抗性和产生相关的基因表达更高。对来自345米海底以下的坎特伯雷盆地样本进行的聚腺苷酸聚焦元转录组分析，以真菌相关转录本的形式为地下活跃的真菌群落提供了进一步证据，这些转录本涉及代谢和细胞过程、细胞和膜功能以及催化活性。在这两个地理上分离的位置，相当深度处的真菌群落似乎由不同的分类群主导。分类组成以及与特定代谢活动相关基因的表达差异可能是沉积物有机含量以及海洋区域的函数。对来自4米和403米海底以下的坎特伯雷盆地沉积物样本进行的显微镜分析产生了有隔真菌丝、分支真菌、分生孢子形成和孢子的可视化图像。这些图像提供了另一重要证据，支持真菌在深海海底生物圈中的存在和活动。
