Venkateswaran K, Satomi M, Chung S, Kern R, Koukol R, Basic C, White D
Planetary Protection Technologies, Jet Propulsion Laboratory, California Institute of Technology, Pasadena 91109, USA.
Syst Appl Microbiol. 2001 Jul;24(2):311-20. doi: 10.1078/0723-2020-00018.
In ongoing investigations to map and archive the microbial footprints in various components of the spacecraft and its accessories, we have examined the microbial populations of the Jet Propulsion Laboratory's Spacecraft Assembly Facility (JPL-SAF). Witness plates made up of spacecraft materials, some painted with spacecraft qualified paints, were exposed for approximately 7 to 9 months at JPL-SAF and examined the particulate materials collected for the incidence of total cultivable aerobic heterotrophs and heat-tolerant (80 degrees C for 15-min.) spore-formers. The results showed that the witness plates coated with spacecraft qualified paints attracted more dust particles than the non-coated stainless steel witness plates. Among the four paints tested, witness plates coated with NS43G accumulated the highest number of particles, and hence attracted more cultivable microbes. The conventional microbiological examination revealed that the JPL-SAF harbors mainly Gram-positive microbes and mostly spore-forming Bacillus species. Most of the isolated microbes were heat resistant to 80 degrees C and proliferate at 60 degrees C. The phylogenetic relationships among 23 cultivable heat-tolerant microbes were examined using a battery of morphological, physiological, molecular and chemotaxonomic characterizations. By 16S rDNA sequence analysis, the isolates fell into seven clades: Bacillus licheniformis, B. pumilus, B. cereus, B. circulans, Staphylococcus capitis, Planococcus sp. and Micrococcus lylae. In contrast to the cultivable approach, direct DNA isolation, cloning and 16S rDNA sequencing analysis revealed equal representation of both Gram-positive and Gram-negative microorganisms.
在正在进行的绘制和存档航天器及其配件各个部件中微生物足迹的调查中，我们检查了喷气推进实验室航天器装配设施（JPL-SAF）中的微生物群落。由航天器材料制成的见证板，有些涂有航天器合格涂料，在JPL-SAF暴露约7至9个月，并检查收集的颗粒材料中可培养需氧异养菌和耐热（80℃15分钟）芽孢形成菌的发生率。结果表明，涂有航天器合格涂料的见证板比未涂覆的不锈钢见证板吸引了更多的灰尘颗粒。在测试的四种涂料中，涂有NS43G的见证板积累的颗粒数量最多，因此吸引了更多可培养的微生物。传统的微生物学检查表明，JPL-SAF主要含有革兰氏阳性微生物，且大多是形成芽孢的芽孢杆菌属物种。大多数分离出的微生物耐热至80℃，并在60℃下增殖。使用一系列形态学、生理学、分子和化学分类学特征研究了23种可培养耐热微生物之间的系统发育关系。通过16S rDNA序列分析，分离物分为七个进化枝：地衣芽孢杆菌、短小芽孢杆菌、蜡样芽孢杆菌、环状芽孢杆菌、头葡萄球菌、动性球菌属和莱氏微球菌。与可培养方法不同，直接DNA分离、克隆和16S rDNA测序分析表明革兰氏阳性和革兰氏阴性微生物的比例相当。
