Metabolism and Biodegradation of Spacecraft Cleaning Reagents by Strains of Spacecraft-Associated Acinetobacter

Spacecraft assembly facilities are oligotrophic and low-humidity environments, which are routinely cleaned using alcohol wipes for benchtops and spacecraft materials, and alkaline detergents for floors. Despite these cleaning protocols, spacecraft assembly facilities possess a persistent, diverse, d...

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Bibliographic Details
Published in:	Astrobiology Vol. 18; no. 12; p. 1517
Main Authors:	Mogul, Rakesh, Barding, Jr, Gregory A, Lalla, Sidharth, Lee, Sooji, Madrid, Steve, Baki, Ryan, Ahmed, Mahjabeen, Brasali, Hania, Cepeda, Ivonne, Gornick, Trevor, Gunadi, Shawn, Hearn, Nicole, Jain, Chirag, Kim, Eun Jin, Nguyen, Thi, Nguyen, Vinh Bao, Oei, Alex, Perkins, Nicole, Rodriguez, Joseph, Rodriguez, Veronica, Savla, Gautam, Schmitz, Megan, Tedjakesuma, Nicholas, Walker, Jillian
Format:	Journal Article
Language:	English
Published:	United States 01-12-2018
Subjects:	2-Propanol - metabolism Acinetobacter - drug effects Acinetobacter - enzymology Alcohol Dehydrogenase - metabolism Bacterial Proteins - metabolism Biodegradation, Environmental Detergents - metabolism Equipment Contamination - prevention & control Ethanol - metabolism Hydrogen Peroxide - pharmacology Microbial Viability - drug effects Spacecraft Bioburden Spacecraft Acinetobacter Cleaning Planetary protection Extreme survival Metabolism
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Summary:	Spacecraft assembly facilities are oligotrophic and low-humidity environments, which are routinely cleaned using alcohol wipes for benchtops and spacecraft materials, and alkaline detergents for floors. Despite these cleaning protocols, spacecraft assembly facilities possess a persistent, diverse, dynamic, and low abundant core microbiome, where the are among the dominant members of the community. In this report, we show that several spacecraft-associated metabolize or biodegrade the spacecraft cleaning reagents of ethanol (ethyl alcohol), 2-propanol (isopropyl alcohol), and Kleenol 30 (floor detergent) under ultraminimal conditions. Using cultivation and stable isotope labeling studies, we show that ethanol is a sole carbon source when cultivating in 0.2 × M9 minimal medium containing 26 μM Fe(NH ) (SO ) . Although cultures expectedly did not grow solely on 2-propanol, cultivations on mixtures of ethanol and 2-propanol exhibited enhanced plate counts at mole ratios of ≤0.50. In support, enzymology experiments on cellular extracts were consistent with oxidation of ethanol and 2-propanol by a membrane-bound alcohol dehydrogenase. In the presence of Kleenol 30, untargeted metabolite profiling on ultraminimal cultures of 50v1 indicated (1) biodegradation of Kleenol 30 into products including ethylene glycols, (2) the potential metabolism of decanoate (formed during incubation of Kleenol 30 in 0.2 × M9), and (3) decreases in the abundances of several hydroxy- and ketoacids in the extracellular metabolome. In ultraminimal medium (when using ethanol as a sole carbon source), 50v1 also exhibits a remarkable survival against hydrogen peroxide (∼1.5-log loss, ∼10 colony forming units (cfu)/mL, 10 mM H O ), indicating a considerable tolerance toward oxidative stress under nutrient-restricted conditions. Together, these results suggest that the spacecraft cleaning reagents may (1) serve as nutrient sources under oligotrophic conditions and (2) sustain extremotolerances against the oxidative stresses associated with low-humidity environments. In perspective, this study provides a plausible biochemical rationale to the observed microbial ecology dynamics of spacecraft-associated environments.
ISSN:	1557-8070
DOI:	10.1089/ast.2017.1814