Jet Propulsion Laboratory, California Institute of Technology, Biotechnology and Planetary Protection Group, Pasadena, CA, 91109, USA.
Center for Research in Infectious Diseases, School of Chemical and Biotechnology, SASTRA Deemed to be University, Thanjavur, 613 401, India.
Sci Rep. 2019 Oct 3;9(1):14251. doi: 10.1038/s41598-019-50782-0.
NASA cleanrooms are certified by particle counts and are humidity-controlled, temperature-regulated, and oligotrophic in nature for assembling spacecraft subsystems. Microorganisms, which are not part of the cleanroom certification metrics, should not be overlooked when assessing the cleanliness of the facility since they can enter through soil or air, shed from humans, adapt to the oligotrophic conditions, and subsequently could contaminate spacecraft. These biogenic particles need to be identified to extend our knowledge of biological contamination for future NASA mission use. This study collected particles from the cleanroom and estimated the distribution of fallout microbial cell and inert dust particles using microscopy and molecular techniques. Aluminum coupon-based polycarbonate filter assemblies were deployed in the spacecraft assembly cleanroom facility to collect fallout particles. Epifluorescence and electron microscopy showed that particles varied in size and structure, and displayed live/dead biological and inert particle signatures from sources that include spores and fungal hyphae. Additionally, correlative epifluorescence and field emission scanning electron microscopy, combined with energy-dispersive X-ray analysis (for elemental compositions) methods, differentiated whether microbes adhering to particles were live/dead cells or inert particles. This visualization approach allowed for the classification of microorganisms as being standalone (free-living) or associated with a particle, as well as its characteristic size. Furthermore, time-course microscopy was used to determine the microbial cell growth and confirm the biological/molecular identification. Routine investigation of cleanroom biological and inert fallout particles will help to determine the biological load of spacecraft components and will also have direct relevance to the pharmaceutical and medical industries. One of the main objectives for NASA's current and future missions is to prevent forward and back contamination of exploring planets. The goal of this study is to determine the association of microorganisms with the inert, natural cleanroom fallout particles and to ascertain whether microorganisms prefer to adhere to a particle size. A novel microscopy technique was developed, and by utilizing various molecular techniques, particles and associated microbial phylogeny were characterized. An accurate assessment of the microbes associated with cleanroom particles is necessary to protect the health of the people who occupy the room for long duration for aeronautical, medical, and pharmaceutical industries.
美国国家航空航天局（NASA）的洁净室通过粒子计数进行认证，并具有湿度控制、温度调节和贫营养特性，可用于组装航天器子系统。在评估设施的清洁度时，不应忽视微生物，因为它们可能通过土壤或空气进入，从人类身上脱落，适应贫营养条件，随后可能污染航天器。为了扩展我们对未来 NASA 任务使用的生物污染的了解，需要识别这些生物源颗粒。本研究从洁净室中收集颗粒，并使用显微镜和分子技术估计沉降微生物细胞和惰性尘埃颗粒的分布。基于铝制优惠券的聚碳酸酯过滤器组件被部署在航天器组装洁净室设施中，以收集沉降颗粒。荧光和电子显微镜显示，颗粒的大小和结构各不相同，并显示出来自包括孢子和真菌菌丝体在内的来源的死活生物和惰性颗粒特征。此外，相关的荧光和场发射扫描电子显微镜，结合能量色散 X 射线分析（用于元素组成）方法，区分了附着在颗粒上的微生物是死活细胞还是惰性颗粒。这种可视化方法允许对微生物进行分类，确定其是独立存在（自由生活）还是与颗粒相关，以及其特征大小。此外，还使用时程显微镜来确定微生物细胞的生长并确认生物/分子鉴定。对洁净室生物和惰性沉降颗粒的常规调查将有助于确定航天器部件的生物负荷，并且还将与制药和医疗行业直接相关。美国国家航空航天局（NASA）当前和未来任务的主要目标之一是防止探索行星的前后污染。本研究的目的是确定微生物与惰性、自然洁净室沉降颗粒的关联，并确定微生物是否更喜欢附着在一定大小的颗粒上。开发了一种新的显微镜技术，并通过利用各种分子技术，对颗粒和相关微生物系统发育进行了表征。准确评估与洁净室颗粒相关的微生物对于保护在航空、医疗和制药等行业中长时间占用房间的人员的健康是必要的。
