Archaeal diversity analysis of spacecraft assembly clean rooms

Abstract

One of the main tasks of NASA's planetary protection program is to prevent the forward contamination of extraterrestrial environments with Earth life, and in turn preserve other planets and the integrity of future life detection missions. Despite information regarding bacterial diversity in NASA's clean rooms, little is known about the presence of Archaea. Archaeal community analysis of spacecraft-associated surfaces is important, as they are considered by some to represent terrestrial life most capable of surviving on Mars. The first insights into the archaeal diversity of clean rooms where spacecraft assembled are attempted. Nucleic acid sequences clustering with uncultivable Archaea within the Eury-and Crenarchaeota were retrieved from 8 of 26 samples collected from several spacecraft assembly clean rooms. Due to their potential capability to survive and proliferate in Martian conditions, screening for Archaea on spacecraft surfaces and instruments that are associated with future life detection missions may be necessary.

Archaea in artificial environments: Their presence in global spacecraft clean rooms and impact on planetary protection

“…The majority of sequences obtained, clustered with mainly uncultivated Crenarchaeota from very diverse biotopes like soil, sediments, deserts or plant roots (Figure 1). Interestingly, the US American clean room sequences (Moissl et al, 2008) clustered within this group of Archaea as well (crenarchaeal soil group 1b; DeLong, 1998), and were closely related to the newly retrieved clone Archaea in global spacecraft assembly clean rooms C Moissl-Eichinger sequences. The closest cultivated neighbor to these sequences was the thermophilic ammonia oxidizer candidatus Nitrososphaera gargensis (Hatzenpichler et al, 2008), showing up to 96% similarity in the 16S rRNA gene with the sequences from this study.…”

“…A previous study showed that because of low microbial biomass observed in spacecraft-assembly clean rooms, and the even lower abundance of Archaea, parallel samples taken in one clean room led to 2/3 negative results when screened for archaeal 16S rRNA genes (Moissl et al, 2008). Therefore, samples from larger surface areas were taken and pooled in order to detect archaeal signatures more effectively.…”

“…These analyses (calculation of coverage of clone libraries, chimera check, ARB) were carried out as given previously (Moissl et al, 2008).…”

“…Very recently, we reported the molecular detection of Archaea in two US American NASA spacecraft assembly facilities (Moissl et al, 2008). Overall, 30 different crenarchaeal and euryarchaeal 16S rRNA gene sequences were derived from these American clean rooms, however the physiological status and quantity of associated cells were unknown.…”

“…For more than 20 years Archaea were considered to be extremophiles that were ecologically restricted, and highly adapted to specific and often hostile biotopes (for example, Pyrodictium, Picrophilus; Woese and Fox, 1977;Moissl et al, 2008). However, new molecular methodologies have revealed an omnipresence of Archaea in almost any 'normal' natural biotope, like marine and freshwater environments, or soil (Bintrim et al, 1997;Karner et al, 2001;Rudolph et al, 2004).…”