Baker Lory-Anne, Beauger Aude, Kolovi Sofia, Voldoire Olivier, Allain Elisabeth, Breton Vincent, Chardon Patrick, Miallier Didier, Bailly Céline, Montavon Gilles, Bouchez Agnès, Rimet Frédéric, Chardon Cécile, Vasselon Valentin, Ector Luc, Wetzel Carlos E, Biron David G
Université Clermont Auvergne, CNRS, LMGE, F-63000 Clermont-Ferrand, France; Université Clermont Auvergne, CNRS, GEOLAB, F-63000 Clermont-Ferrand, France; LTSER "Zone Atelier Territoires Uranifères", Clermont-Ferrand, France.
Université Clermont Auvergne, CNRS, GEOLAB, F-63000 Clermont-Ferrand, France; LTSER "Zone Atelier Territoires Uranifères", Clermont-Ferrand, France.
Sci Total Environ. 2023 May 15;873:162270. doi: 10.1016/j.scitotenv.2023.162270. Epub 2023 Feb 19.
Little is still known about the low dose effects of radiation on the microbial communities in the environment. Mineral springs are ecosystems than can be affected by natural radioactivity. These extreme environments are, therefore, observatories for studying the influence of chronic radioactivity on the natural biota. In these ecosystems we find diatoms, unicellular microalgae, playing an essential role in the food chain. The present study aimed to investigate, using DNA metabarcoding, the effect of natural radioactivity in two environmental compartments (i.e. spring sediments and water) on the genetic richness, diversity and structure of diatom communities in 16 mineral springs in the Massif Central, France. Diatom biofilms were collected during October 2019, and a 312 bp region of the chloroplast gene rbcL (coding for the Ribulose Bisphosphate Carboxylase) used as a barcode for taxonomic assignation. A total of 565 amplicon sequence variants (ASV) were found. The dominant ASV were associated with Navicula sanctamargaritae, Gedaniella sp., Planothidium frequentissimum, Navicula veneta, Diploneis vacillans, Amphora copulata, Pinnularia brebissonii, Halamphora coffeaeformis, Gomphonema saprophilum, and Nitzschia vitrea, but some of the ASVs could not be assigned at the species level. Pearson correlation failed to show a correlation between ASV' richness and radioactivity parameters. Non-parametric MANOVA analysis based on ASVs occurrence or abundances revealed that geographical location was the main factor influencing ASVs distribution. Interestingly, U was the second factor that explained diatom ASV structure. Among the ASVs in the mineral springs monitored, ASV associated with one of the genetic variants of Planothidium frequentissimum was well represented in the springs and with higher levels of U, suggesting its high tolerance to this particular radionuclide. This diatom species may therefore represent a bio-indicator of high natural levels of uranium.
关于辐射对环境中微生物群落的低剂量影响，目前仍知之甚少。矿泉是可能受到天然放射性影响的生态系统。因此，这些极端环境是研究慢性放射性对自然生物群影响的观测站。在这些生态系统中，我们发现硅藻这种单细胞微藻在食物链中起着至关重要的作用。本研究旨在利用DNA宏条形码技术，调查法国中央高原16个矿泉中两个环境隔室（即泉水沉积物和水）中的天然放射性对硅藻群落的遗传丰富度、多样性和结构的影响。2019年10月采集了硅藻生物膜，并使用叶绿体基因rbcL（编码核酮糖二磷酸羧化酶）的312bp区域作为分类鉴定的条形码。共发现565个扩增子序列变体（ASV）。优势ASV与圣洁舟形藻、格氏藻属、频繁平板藻、威尼斯舟形藻、波动双壁藻、交配双眉藻、布雷比松羽纹藻、咖啡形哈兰藻、嗜腐异极藻和玻璃菱形藻有关，但其中一些ASV无法在物种水平上进行鉴定。Pearson相关性未能显示ASV丰富度与放射性参数之间的相关性。基于ASV出现情况或丰度的非参数多变量方差分析表明，地理位置是影响ASV分布的主要因素。有趣的是，铀是解释硅藻ASV结构的第二个因素。在监测的矿泉中的ASV中，与频繁平板藻的一种遗传变体相关的ASV在含铀量较高的泉水中大量存在，表明其对这种特定放射性核素具有高度耐受性。因此，这种硅藻物种可能代表天然高铀水平的生物指示物。
