Mogul Rakesh, Miller Daniel R, Ramos Brian, Lalla Sidharth J
Chemistry and Biochemistry Department, California State Polytechnic University, Pomona, CA, United States.
Blue Marble Institute of Science, Seattle, WA, United States.
Front Microbiol. 2023 Mar 6;14:1090740. doi: 10.3389/fmicb.2023.1090740. eCollection 2023.
Stringent cleaning procedures during spacecraft assembly are critical to maintaining the integrity of life-detection missions. To ensure cleanliness, NASA spacecraft are assembled in cleanroom facilities, where floors are routinely cleansed with Kleenol 30 (K30), an alkaline detergent.
Through metabolomic and cultivation approaches, we show that cultures of spacecraft-associated Acinetobacter tolerate up to 1% v/v K30 and are fully inhibited at ≥2%; in comparison, NASA cleanrooms are cleansed with ~0.8-1.6% K30.
For A. johnsonii 2P08AA (isolated from a cleanroom floor), cultivations with 0.1% v/v K30 yield (1) no changes in cell density at late-log phase, (2) modest decreases in growth rate (~17%), (3) negligible lag phase times, (4) limited changes in the intracellular metabolome, and (5) increases in extracellular sugar acids, monosaccharides, organic acids, and fatty acids. For A. radioresistens 50v1 (isolated from a spacecraft surface), cultivations yield (1) ~50% survivals, (2) no changes in growth rate, (3) ~70% decreases in the lag phase time, (4) differential changes in intracellular amino acids, compatible solutes, nucleotide-related metabolites, dicarboxylic acids, and saturated fatty acids, and (5) substantial yet differential impacts to extracellular sugar acids, monosaccharides, and organic acids.
These combined results suggest that (1) K30 manifests strain-dependent impacts on the intracellular metabolomes, cultivation kinetics, and survivals, (2) K30 influences extracellular trace element acquisition in both strains, and (3) K30 is better tolerated by the floor-associated strain. Hence, this work lends support towards the hypothesis that repeated cleansing during spacecraft assembly serve as selective pressures that promote tolerances towards the cleaning conditions.
航天器组装过程中的严格清洁程序对于维持生命探测任务的完整性至关重要。为确保清洁，美国国家航空航天局（NASA）的航天器在洁净室设施中组装，洁净室的地板通常用碱性洗涤剂Kleenol 30（K30）进行清洁。
通过代谢组学和培养方法，我们发现与航天器相关的不动杆菌培养物能够耐受高达1%（v/v）的K30，而在≥2%时则被完全抑制；相比之下，NASA洁净室用约0.8 - 1.6%的K30进行清洁。
对于约翰逊不动杆菌2P08AA（从洁净室地板分离），用0.1%（v/v）K30培养产生以下结果：（1）对数后期细胞密度无变化；（2）生长速率适度降低（约17%）；（3）延迟期时间可忽略不计；（4）细胞内代谢组变化有限；（5）细胞外糖酸、单糖、有机酸和脂肪酸增加。对于抗辐射不动杆菌50v1（从航天器表面分离），培养产生以下结果：（1）约50%的存活率；（2）生长速率无变化；（3）延迟期时间减少约70%；（4）细胞内氨基酸、相容性溶质、核苷酸相关代谢物、二羧酸和饱和脂肪酸有差异变化；（5）对细胞外糖酸、单糖和有机酸有显著但有差异的影响。
这些综合结果表明：（1）K30对细胞内代谢组、培养动力学和存活率表现出菌株依赖性影响；（2）K30影响两种菌株对细胞外微量元素的获取；（3）与地板相关的菌株对K30的耐受性更好。因此，这项工作支持了以下假设：航天器组装过程中的反复清洁作为选择性压力，促进了对清洁条件的耐受性。
