Persistence of biomarker ATP and ATP-generating capability in bacterial cells and spores contaminating spacecraft materials under earth conditions and in a simulated martian environment
Persistence of biomarker ATP and ATP-generating capability in bacterial cells and spores contaminating spacecraft materials under earth conditions and in a simulated martian environment
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DOI：
10.1128/aem.00891-08
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发表时间：
2008-08-01
影响因子：
4.4
通讯作者：
Nicholson, Wayne L.
中科院分区：
文献类型：
--
作者：
Fajardo-Cavazos, Patricia;Schuerger, Andrew C.;Nicholson, Wayne L.
大多数行星保护研究都集中在表征航天器表面的可行生物负荷、开发发射前减少生物负荷的技术以及研究模拟火星环境对微生物生存的影响。很少有研究检验模拟火星表面条件下航天器材料上生物特征分子的持久性。本研究研究了在 7.1 mbar 的模拟火星条件、校准为 4 W m(-2) UV-C（200 至 280 nm）、-10 摄氏度的全光谱模拟火星辐射以及 CO2 (95.54%)、N-2 (2.7%)、Ar (1.6%)、 O-2 (0.13%) 和 H2O (0.03%)。放射抗性不动杆菌、短小芽孢杆菌和枯草芽孢杆菌的细胞或孢子活力在几分钟到几小时内即可测量，而在暴露长达 21 天后可恢复高水平的内源 ATP。造成存活率暂时降低和 ATP 损失的主要因素是模拟的火星表面辐射。低压、低温和火星气体成分仅表现出轻微的影响。在短小芽孢杆菌和枯草芽孢杆菌孢子萌发过程中检测到的内源 ATP 的正常爆发分别在暴露于模拟火星条件 8 或 30 分钟后分别减少了 1 或 2 个数量级。结果支持这样的结论：内源性 ATP 将持续一段时间，可能会超出大多数火星表面任务的标称长度，并且发射前的行星保护协议可能需要额外的严格性，以进一步减少航天器表面生物特征分子的存在和丰度。
Most planetary protection research has concentrated on characterizing viable bioloads on spacecraft surfaces, developing techniques for bioload reduction prior to launch, and studying the effects of simulated martian environments on microbial survival. Little research has examined the persistence of biogenic signature molecules on spacecraft materials under simulated martian surface conditions. This study examined how endogenous adenosine-5'-triphosphate (ATP) would persist on aluminum coupons under simulated martian conditions of 7.1 mbar, full-spectrum simulated martian radiation calibrated to 4 W m(-2) of UV-C (200 to 280 nm), -10 degrees C, and a mars gas mix of CO2 (95.54%), N-2 (2.7%), Ar (1.6%), O-2 (0.13%), and H2O (0.03%). Cell or spore viabilities of Acinetobacter radioresistens, Bacillus pumilus, and B. subtilis were measured in minutes to hours, while high levels of endogenous ATP were recovered after exposures of up to 21 days. The dominant factor responsible for temporal reductions in viability and loss of ATP was the simulated Mars surface radiation; low pressure, low temperature, and the Mars gas composition exhibited only slight effects. The normal burst of endogenous ATP detected during spore germination in B. pumilus and B. subtilis was reduced by 1 or 2 orders of magnitude following, respectively, 8- or 30-min exposures to simulated martian conditions. The results support the conclusion that endogenous ATP will persist for time periods that are likely to extend beyond the nominal lengths of most surface missions on Mars, and planetary protection protocols prior to launch may require additional rigor to further reduce the presence and abundance of biosignature molecules on spacecraft surfaces.