Burzan Niels, Murad Lima Roberta, Frutschi Manon, Janowczyk Andrew, Reddy Bharti, Rance Andrew, Diomidis Nikitas, Bernier-Latmani Rizlan
Environmental Microbiology Laboratory, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland.
Bioinformatics Core Facility, Swiss Institute of Bioinformatics, Lausanne, Switzerland.
Front Microbiol. 2022 Apr 25;13:858324. doi: 10.3389/fmicb.2022.858324. eCollection 2022.
Microbial activity has the potential to enhance the corrosion of high-level radioactive waste disposal canisters, which, in the proposed Swiss deep geological repository, will be embedded in bentonite and placed in the Opalinus Clay (OPA) rock formation. A total of 12 stainless steel cylindrical vessels (referred to as modules) containing bentonite were deployed in an anoxic borehole in OPA for up to 5.5 years. Carbon steel coupons were embedded in the bentonite. Individual modules were retrieved after 1, 1.5, 2.5, and 5.5 years. Enumeration of aerobic and anaerobic heterotrophs and sulfate-reducing bacteria (SRB) revealed microbial growth for 1.5 years followed by a decline or stagnation in microbial viability. It was surprising to observe the growth of aerobic heterotrophs followed by their persistent viability in bentonite, despite the nominally anoxic conditions. In contrast, SRB numbers remained at very low levels. DNA-based amplicon sequencing confirmed the persistence of aerobes and the relatively low contribution of anaerobes to the bentonite microbiome. Bentonite dry density, exposure time, and bioavailable trapped oxygen are observed to shape the bentonite microbial community in the clay.
微生物活动有可能加剧高放废物处置罐的腐蚀，在瑞士拟建的深部地质处置库中，这些处置罐将嵌入膨润土并放置于奥帕林斯黏土（OPA）岩层中。总共12个装有膨润土的不锈钢圆柱形容器（称为模块）被部署在OPA的一个缺氧钻孔中长达5.5年。碳钢试片被嵌入膨润土中。在1年、1.5年、2.5年和5.5年后分别取出单个模块。对好氧和厌氧异养菌以及硫酸盐还原菌（SRB）的计数显示，微生物生长持续了1.5年，随后微生物活力下降或停滞。令人惊讶的是，尽管名义上处于缺氧条件，但在膨润土中仍观察到好氧异养菌的生长及其活力的持续存在。相比之下，SRB的数量一直处于非常低的水平。基于DNA的扩增子测序证实了需氧菌的持久性以及厌氧菌对膨润土微生物群落的贡献相对较低。观察到膨润土的干密度、暴露时间和生物可利用的 trapped oxygen 会影响黏土中的膨润土微生物群落。 （注：原文中“bioavailable trapped oxygen”表述不太准确，推测可能是“bioavailable trapped oxygen”，暂直译为“生物可利用的被困氧气”，具体需结合更多背景知识进一步确定准确含义）
