Institute of Microbiology and Archaea Center, University of Regensburg, Germany.
Astrobiology. 2012 Jun;12(6):572-85. doi: 10.1089/ast.2011.0735.
The determination of the microbial load of a spacecraft en route to interesting extraterrestrial environments is mandatory and currently based on the culturable, heat-shock-surviving portion of microbial contaminants. Our study compared these classical bioburden measurements as required by NASA's and ESA's guidelines for the microbial examination of flight hardware, with molecular analysis methods (16S rRNA gene cloning and quantitative PCR) to further develop our understanding of the diversity and abundance of the microbial communities of spacecraft-associated clean rooms. Three samplings of the Herschel Space Observatory and its surrounding clean rooms were performed in two different European facilities. Molecular analyses detected a broad diversity of microbes typically found in the human microbiome with three bacterial genera (Staphylococcus, Propionibacterium, and Brevundimonas) common to all three locations. Bioburden measurements revealed a low, but heterogeneous, abundance of spore-forming and other heat-resistant microorganisms. Total cell numbers estimated by quantitative real-time PCR were typically 3 orders of magnitude greater than those determined by viable counts, which indicates a tendency for traditional methods to underestimate the extent of clean room bioburden. Furthermore, the molecular methods allowed the detection of a much broader diversity than traditional culture-based methods.
前往有趣的外星环境的航天器上的微生物负荷的测定是强制性的，目前基于可培养的、耐热存活的微生物污染物部分。我们的研究比较了这些经典的生物负荷测量，这些测量是 NASA 和 ESA 飞行硬件微生物检查指南所要求的，与分子分析方法（16S rRNA 基因克隆和定量 PCR）一起，进一步了解航天器相关清洁室微生物群落的多样性和丰度。在两个不同的欧洲设施中，对赫歇尔太空天文台及其周围的清洁室进行了三次采样。分子分析检测到了通常在人类微生物组中发现的广泛的微生物多样性，有三个细菌属（葡萄球菌、丙酸杆菌和短双歧杆菌）在所有三个地点都存在。生物负荷测量显示出低，但异质的，孢子形成和其他耐热微生物的丰度。通过定量实时 PCR 估计的总细胞数通常比通过活菌计数确定的细胞数高 3 个数量级，这表明传统方法倾向于低估清洁室生物负荷的程度。此外，分子方法允许检测到比传统基于培养的方法更广泛的多样性。
