In assessing the bacterial populations present in spacecraft assembly, spacecraft test, and launch preparation facilities, extremophilic bacteria (requiring severe conditions for growth) and extremotolerant bacteria (tolerant to extreme conditions) were isolated. Several cultivation approaches were employed to select for and identify bacteria that not only survive the nutrient-limiting conditions of clean room environments but can also withstand even more inhospitable environmental stresses. Due to their proximity to spacefaring objects, these bacteria pose a considerable risk for forward contamination of extraterrestrial sites. Samples collected from four geographically distinct National Aeronautics and Space Administration clean rooms were challenged with UV-C irradiation, 5% hydrogen peroxide, heat shock, pH extremes (pH 3.0 and 11.0), temperature extremes (4°C to 65°C), and hypersalinity (25% NaCl) prior to and/or during cultivation as a means of selecting for extremotolerant bacteria. Culture-independent approaches were employed to measure viable microbial (ATPbased) and total bacterial (quantitative PCR-based) burdens. Intracellular ATP concentrations suggested a viable microbial presence ranging from below detection limits to 10 6 cells/m 2 . However, only 0.1 to 55% of these viable cells were able to grow on defined culture medium. Isolated members of the Bacillaceae family were more physiologically diverse than those reported in previous studies, including thermophiles (Geobacillus), obligate anaerobes (Paenibacillus), and halotolerant, alkalophilic species (Oceanobacillus and Exiguobacterium). Nonspore-forming microbes (␣-and ␤-proteobacteria and actinobacteria) exhibiting tolerance to the selected stresses were also encountered. The multiassay cultivation approach employed herein enhances the current understanding of the physiological diversity of bacteria housed in these clean rooms and leads us to ponder the origin and means of translocation of thermophiles, anaerobes, and halotolerant alkalophiles into these environments.

SummaryProteinaceous, hair-like appendages known as fimbriae or pili commonly extend from the surface of prokaryotic cells and serve important functions such as cell adhesion, biofilm formation, motility and DNA transfer. Here we show that a novel group of archaea from cold, sulphidic springs has developed cell surface appendages of an unexpectedly high complexity with a well-defined base-to-top organization. It represents a new class of filamentous cell appendages, for which the term 'hamus' is proposed. Each archaeal cell is surrounded by a halo of about 100 hami, which mediate strong adhesion of the cells to surfaces of different chemical composition. The hami are mainly composed of 120 kDa subunits and remained stable in a broad temperature and pH range (0-70 ∞ ∞ ∞ ∞ C; 0.5-11.5). Electron microscopy and cryo-electron tomography revealed that the hamus filament possesses a helical basic structure. At periodic distances, three prickles emanate from the filament, giving it the character of industrially produced barbwire. At its distal end the hami carry a tripartite, barbed grappling hook (60 nm in diameter). The architecture of this molecular hook is reminiscent of man-made fishhooks, grapples and anchors. It appears that nature has developed a perfect mechanical nano-tool in the course of biological evolution, which also might prove useful in the field of nanobiotechnology.

Recently, a unique microbial community, growing in a whitish, macroscopically visible strings-of-pearls-like structure was discovered in the cold, sulfidic marsh water of the Sippenauer Moor near Regensburg, Bavaria, Germany. The pearls interior is predominated by microcolonies of the non-methanogenic SM1 euryarchaeon; the outer part of the pearls is mainly composed of Thiothrix. To screen sulfidic ecosystems for the distribution of such unique microbial communities, comparative microbial and geochemical analyses of cold, sulfidic springs of three geographically distinct locations in Bavaria, Germany, and Dalyan, Turkey, were performed. Here, we report on the discovery and study of another type of strings-of-pearls revealing a new microbial community structure. While the SM1 euryarchaeon is again the predominant archaeal constituent, the bacterial partner is the so-called IMB1 eta-proteobacterium. Due to the predominance of the IMB1 eta-proteobacterium, the strings-of-pearls reveal a fluffy and greyish macroscopical appearance. The phylogenetic survey revealed SM1 euryarchaeal relatives, designated as SM1 group, in all sites studied, indicating a widespread distribution of these archaea in terrestrial ecosystems.

No abstract

Halorhabdus tiamatea sp. nov., a non-pigmented, extremely halophilic archaeon from a deep-sea, hypersaline anoxic basin of the Red Sea, and emended description of the genus Halorhabdus ). An emended description of the genus Halorhabdus is also proposed.An ever increasing diversity of extremely halophilic archaea is being uncovered from practically every type of hypersaline biotope, but no strain has ever been described from a deep-sea, hypersaline, anoxic basin. These deep-sea brines are unusual athalassohaline environments created by the evaporation, and subsequent exposure and flooding, of ancient seas, and are relatively stable as a result of their higher density (DasSarma & Arora, 2001). All of the known deep-sea brines are associated with tectonic activity, though found in regions around the world that represent entirely different geodynamic environments, namely divergent and convergent plate boundary settings (Red Sea and Mediterranean Sea, respectively) and the salt tectonics of the Gulf of Mexico (Degens & Ross, 1969; Scientific Staff of Cruise Bannock 1984-12, 1985Wiesenburg et al., 1985).The first deep-sea brines to be discovered were in the Red Sea, but only a few microbiological studies have been performed on these brines and, consequently, only a few micro-organisms (all of which are bacteria) have been isolated from these unusual biotopes (Antunes et al., , 2007Eder et al., 2001;Fiala et al., 1990; Trüper, 1969). Nonetheless, data from phylogenetic and biochemical studies have shown that a diverse archaeal population exists in these deep-sea brines (Eder et al., 1999(Eder et al., , 2001(Eder et al., , 2002Michaelis et al., 1990).New samples for microbiological studies were retrieved from the northern-most brine-filled depths of the Red Sea during Cruise 52/3 of RV Meteor in 2002(Antunes, 2003. Strain SARL4BT was isolated from the brine-sediment interface of the Shaban Deep as the result of a subsequent microbial diversity assessment study that relied on phylogenetic targeting of members of the Archaea. A phylogenetic analysis based on 16S rRNA gene sequencing revealed a close relationship between strain SARL4BT and Halorhabdus utahensis, the sole recognized species of the genus Halorhabdus. We propose that, on the basis of The GenBank/EMBL/DDBJ accession number for the 16S rRNA gene sequence of strain SARL4BT is EF127229.Polar lipid profiles of Halorhabdus utahensis and strain SARL4B T , separated by mono-dimensional TLC, are shown in a supplementary figure available with the online version of this paper.