Spore UV and acceleration resistance of endolithic Bacillus pumilus and Bacillus subtilis isolates obtained from Sonoran desert basalt: implications for lithopanspermia

Bacterial spores have been used as model systems for studying the theory of interplanetary transport of life by natural processes such as asteroidal or cometary impacts (i.e., lithopanspermia). Because current spallation theory predicts that near-surface rocks are ideal candidates for planetary ejection and surface basalts are widely distributed throughout the rocky planets, we isolated spore-forming bacteria from the interior of near-subsurface basalt rocks collected in the Sonoran desert near Tucson, Arizona. Spores were found to inhabit basalt at very low concentrations (相似文献   

Leadership issues with multicultural crews on the international space station: lessons learned from Shuttle/Mir

In isolated and confined environments, two important leadership roles have been identified: the task/instrumental role (which focuses on work goals and operational needs), and the supportive/expressive role (which focuses on morale goals and emotional needs). On the International Space Station, the mission commander should be familiar with both of these aspects of leadership. In previous research involving a 135-day Mir space station simulation in Moscow and a series of on-orbit Mir space station missions during the Shuttle/Mir program, both these leadership roles were studied. In new analyses of the Shuttle/Mir data, we found that for crewmembers, the supportive role of the commander (but not the task role) related positively with crew cohesion. For mission control personnel on the ground, both the task and supportive roles of their leader were related positively to mission control cohesion. The implications of these findings are discussed in terms of leadership on board the International Space Station.     

Recurrent isolation of hydrogen peroxide-resistant spores of Bacillus pumilus from a spacecraft assembly facility

While the microbial diversity of a spacecraft assembly facility at the Jet Propulsion Laboratory (Pasadena, CA) was being monitored, H2O2-resistant bacterial strains were repeatedly isolated from various surface locations. H2O2 is a possible sterilant for spacecraft hardware because it is a low-temperature process and compatible with various modern-day spacecraft materials, electronics, and components. Both conventional biochemical testing and molecular analyses identified these strains as Bacillus pumilus. This Bacillus species was found in both unclassified (entrance floors, anteroom, and air-lock) and classified (floors, cabinet tops, and air) locations. Both vegetative cells and spores of several B. pumilus isolates were exposed to 5% liquid H2O2 for 60 min. Spores of each strain exhibited higher resistance than their respective vegetative cells to liquid H2O2. Results indicate that the H2O2 resistance observed in both vegetative cells and spores is strain-specific, as certain B. pumilus strains were two to three times more resistant than a standard Bacillus subtilis dosimetry strain. An example of this trend was observed when the type strain of B. pumilus, ATCC 7061, proved sensitive, whereas several environmental strains exhibited varying degrees of resistance, to H2O2. Repeated isolation of H2O2-resistant strains of B. pumilus in a clean-room is a concern because their persistence might potentially compromise life-detection missions, which have very strict cleanliness and sterility requirements for spacecraft hardware.     

The benefits and dilemmas of an international space station

Serious recommendations have been made about the development and mutual manning of an international space station. The achievements of ESA show that such international organizations can work successfully in high technology projects, although with problems. However, other work on isolated and confined environments suggests that sustained cooperation in the unique quarters of a space station for long durations may have special inter-cultural difficulties that need to be examined before any long term commitment is made. Also, a careful look at international activities in general suggests that in spite of the fact that there are many potential benefits for cooperative activities, there are also many international obstacles. If such an effort is to be embarked upon, it is important to look candidly at the problems that can be generated from the multi-national social, economic, and cultural systems in order to do serious and direct analyses. Such a project might be strangled by unanticipated and complex problems of a socio-cultural nature.     

Control of Lunar and Martian dust--experimental insights from artificial and natural cyanobacterial and algal crusts in the desert of Inner Mongolia, China

Studies on the colonization of environmentally extreme ground surfaces were conducted in a Mars-like desert area of Inner Mongolia, People's Republic of China, with microalgae and cyanobacteria. We collected and mass-cultured cyanobacterial strains from these regions and investigated their ability to form desert crusts artificially. These crusts had the capacity to resist sand wind erosion after just 15 days of growth. Similar to the surface of some Chinese deserts, the surface of Mars is characterized by a layer of fine dust, which will challenge future human exploration activities, particularly in confined spaces that will include greenhouses and habitats. We discuss the use of such crusts for the local control of desert sands in enclosed spaces on Mars. These experiments suggest innovative new directions in the applied use of microbe-mineral interactions to advance the human exploration and settlement of space.     

Resistance of bacterial endospores to outer space for planetary protection purposes--experiment PROTECT of the EXPOSE-E mission

Spore-forming bacteria are of particular concern in the context of planetary protection because their tough endospores may withstand certain sterilization procedures as well as the harsh environments of outer space or planetary surfaces. To test their hardiness on a hypothetical mission to Mars, spores of Bacillus subtilis 168 and Bacillus pumilus SAFR-032 were exposed for 1.5 years to selected parameters of space in the experiment PROTECT during the EXPOSE-E mission on board the International Space Station. Mounted as dry layers on spacecraft-qualified aluminum coupons, the "trip to Mars" spores experienced space vacuum, cosmic and extraterrestrial solar radiation, and temperature fluctuations, whereas the "stay on Mars" spores were subjected to a simulated martian environment that included atmospheric pressure and composition, and UV and cosmic radiation. The survival of spores from both assays was determined after retrieval. It was clearly shown that solar extraterrestrial UV radiation (λ≥110?nm) as well as the martian UV spectrum (λ≥200?nm) was the most deleterious factor applied; in some samples only a few survivors were recovered from spores exposed in monolayers. Spores in multilayers survived better by several orders of magnitude. All other environmental parameters encountered by the "trip to Mars" or "stay on Mars" spores did little harm to the spores, which showed about 50% survival or more. The data demonstrate the high chance of survival of spores on a Mars mission, if protected against solar irradiation. These results will have implications for planetary protection considerations.     

Bacillus subtilis spore survival and expression of germination-induced bioluminescence after prolonged incubation under simulated Mars atmospheric pressure and composition: implications for planetary protection and lithopanspermia

Bacterial endospores in the genus Bacillus are considered good models for studying interplanetary transfer of microbes by natural or human processes. Although spore survival during transfer itself has been the subject of considerable study, the fate of spores in extraterrestrial environments has received less attention. In this report we subjected spores of a strain of Bacillus subtilis, containing luciferase resulting from expression of an sspB-luxAB gene fusion, to simulated martian atmospheric pressure (7-18 mbar) and composition (100% CO(2)) for up to 19 days in a Mars simulation chamber. We report here that survival was similar between spores exposed to Earth conditions and spores exposed up to 19 days to simulated martian conditions. However, germination-induced bioluminescence was lower in spores exposed to simulated martian atmosphere, which suggests sublethal impairment of some endogenous spore germination processes.     

Molecular identification of cyanobacteria associated with stromatolites from distinct geographical locations

Modern stromatolites represent a significant resource for studying microbial ecology and evolution. A preliminary investigation was undertaken employing specific genetic probes to characterize the cyanobacteria responsible for stromatolite construction in a range of environments, including microbial mats found in Australia not previously examined with molecular methods. Isolates of cyanobacteria were collected from stromatolites in thermal springs, hypersaline lakes, and oceanic fringes on two continents. A polymerase chain reaction specific for DNA of cyanobacterial 16S rRNA was developed, the resulting products of the DNA amplification reaction were sequenced, and the data were used to infer relatedness between the isolates studied and other members of the cyanobacterial radiation. Complete sequence was generated for the region from position 27 to 408 for 13 strains of cyanobacteria associated with stromatolites. All stromatolite-derived sequences were most closely related to cyanobacteria, as indicated by local sequence alignment. It was possible to correlate genetic identity with morphological nomenclatures and to expand the phylogeny of benthic cyanobacteria. These inferences were also expanded to temporal variation in the dominant resident cyanobacterial species based on sampling of surface and core sinter laminations. Under the methods employed, only one cyanobacterial strain was detected in each sample, suggesting the possible dominance of a specific clonal population of cyanobacteria at any one time in the biota of the samples tested. The data indicate that internal core samples of a stromatolite at least 10 years old can be successfully analyzed by DNA-based methods to identify preserved cyanobacteria.     

Separation of bacterial cells by free flow electrophoresis under microgravity: a result of the SpaceLab-Japan project on Space Shuttle flight STS-47

We demonstrated free flow electrophoresis (FFE) of charged cells under microgravity, where gravitational effects are almost eliminated. Separation of a mixture of three bacterial strains (mutants of Salmonella typhimurium LT2) by FFE was conducted on NASA Space Shuttle flight STS-47 (September 1992). The experiment was designed to differentiate three strains having different lipopolysaccharide core structures in the cell membrane. The results were compared to those of ground experiments, in order to examine whether or not FFE in a weightless environment provides distinct advantages. Smooth strain SL1027 and rough strain SL3749 migrated to two separated fractions. The quality (viability) and the yields of the separated samples were sufficient to show the advantage of microgravity. Another rough strain, SL1102, exhibited unexpected electrophoretic behavior, which prevented the complete resolution of the three strains. All the strains were recovered as viable cells after 8 days of flight. The present study suggests that electrophoretic separation of bacterial cells is much more effective under microgravity conditions with relatively good resolution in comparison with the ground operation.     

用指向性真空规进行空间站结构泄漏监测的设想

文章提出利用指向性真空规扫描监测空间站舱体漏率的设想:在空间站舱体外壁上实验舱和服务舱的连接处、实验舱底和对接装置的连接处、服务舱底和对接装置的连接处分别设计供指向性真空规运动的轨道,形成3个环行圈,指向性真空规在步进电机的作用下在各自的运动轨道上旋转,对空间站的外部结构进行扫描。初步分析了指向性真空规泄漏监测的灵敏度和定位精度。     

Survival of Bacillus subtilis endospores on ultraviolet-irradiated rover wheels and Mars regolith under simulated Martian conditions

Endospores of Bacillus subtilis HA101 were applied to a simulated Mars Exploration Rover (MER) wheel and exposed to Mars-normal UV irradiation for 1, 3, or 6 h. The experiment was designed to simulate a contaminated rover wheel sitting on its landing platform before rolling off onto the martian terrain, as was encountered during the Spirit and Opportunity missions. When exposed to 1 h of Mars UV, a reduction of 81% of viable endospores was observed compared to the non-UV irradiated controls. When exposed for 3 or 6 h, reductions of 94.6% and 96.6%, respectively, were observed compared to controls. In a second experiment, the contaminated rover wheel was rolled over a bed of heat-sterilized Mars analog soil; then the analog soil was exposed to full martian conditions of UV irradiation, low pressure (6.9 mbar), low temperature (-10°C), and an anaerobic CO(2) martian atmosphere for 24 h to determine whether endospores of B. subtilis on the contaminated rover wheel could be transferred to the surface of the analog soil and survive martian conditions. The experiment simulated conditions in which a rover wheel might come into contact with martian regolith immediately after landing, such as is designed for the upcoming Mars Science Laboratory (MSL) rover. The contaminated rover wheel transferred viable endospores of B. subtilis to the Mars analog soil, as demonstrated by 31.7% of samples showing positive growth. However, when contaminated soil samples were exposed to full martian conditions for 24 h, only 16.7% of samples exhibited positive growth-a 50% reduction in the number of soil samples positive for the transferred viable endospores.     

Influence of Space-Flight Factors on the Properties of Microorganisms, Producers of Biologically Active Substances

The following substances were isolated under the influence of space-flight factors in cosmic experiments aboard the Mirorbital station: an MIB-90 monoisolant, which is distinguished by its morphological and biochemical properties and enhanced productivity, was isolated from the Bacillus thuringiensis ssp. Kurstaki var. Z-52culture, which is a producer of the plant protection agent Lepidocide; and MIA-74 and MIP-89 monoisolants, which are highly active toward heavy petroleum fractions (C₂₃–C₃₃), were isolated from the Arthrobacter OC-1culture, which is a producer of biodegradants for petroleum.     

Ariane 5 flight environments

This paper presents a status of the ARIANE 5 launch vehicle dynamic environments after the 5 first flights. It concerns mainly the low frequency vibrations, the acoustic and the shocks that the payloads experience and the related external excitations. The flight measurement plan is described. The results show that the frequencies are well characterized and the levels are low pointing out margins with regard to the specifications Furthermore, one describe the efficiency of attenuation solutions implemented to reduce the payload environments.     

UV photochemistry of DNA in vitro and in Bacillus subtilis spores at earth-ambient and low atmospheric pressure: implications for spore survival on other planets or moons in the solar system

Two major parameters influencing the survival of Bacillus subtilis spores in space and on bodies within the Solar System are UV radiation and vacuum, both of which induce inactivating damage to DNA. To date, however, spore survival and DNA photochemistry have been explored only at the extremes of Earth-normal atmospheric pressure (101.3 kPa) and at simulated space vacuum (10(-3)-10(-6) Pa). In this study, wild-type spores, mutant spores lacking alpha/beta-type small, acid-soluble spore proteins (SASP), naked DNA, and complexes between SASP SspC and DNA were exposed simultaneously to UV (254 nm) at intermediate pressure (1-2 Pa), and the UV photoproducts cis,syn-thymine-thymine cyclobutane dimer (c,sTT), trans,syn-thymine-thymine cyclobutane dimer (t,sTT), and "spore photoproduct" (SP) were quantified. At 101.3 kPa, UV-treated wild-type spores accumulated only SP, but spores treated with UV radiation at 1-2 Pa exhibited a spectrum of DNA damage similar to that of spores treated at 10(-6) Pa, with accumulation of SP, c,sTT, and t,sTT. The presence or absence of alpha/beta-type SASP in spores was partly responsible for the shift observed between levels of SP and c,sTT, but not t,sTT. The changes observed in spore DNA photochemistry at 1-2 Pa in vivo were not reproduced by irradiation of naked DNA or SspC:DNA complexes in vitro, suggesting that factors other than SASP are involved in spore DNA photochemistry at low pressure.     

Determination of the inertia tensor of the <Emphasis Type="Italic">International Space Station</Emphasis> on the basis of telemetry data

We describe the method and results of determination of the inertia tensor of the International Space Station using telemetry data related to its attitude motion and the total angular momentum of gyrodines. A linear system of differential equations describing the variation of the total angular momentum of gyrodines on some time interval is derived on the basis of the data related to the station orientation in the same time interval. This linear system represents the theorem related to the variation of the total angular momentum of the station and gyrodines and takes into account the action of gravitational and aerodynamic moments upon the station. The solution to the system depends linearly on the components of the inertia tensor of the station and on the parameters specifying the aerodynamic moment. The estimates of these quantities are carried out by the least squares method on the condition of the best approximation by the solutions to the considered linear system of the telemetry values of the total angular momentum of the gyrodines.__________Translated from Kosmicheskie Issledovaniya, Vol. 43, No. 2, 2005, pp. 135–146.Original Russian Text Copyright © 2005 by Banit, Belyaev, Dobrinskaya, Efimov, Sazonov, Stazhkov.     

基于直方图修改的卫星遥感图像无损隐藏传输

针对星上低速率数据的传输问题,提出了一种基于直方图修改技术的卫星遥感图像无损隐藏传输方法。该方法通过对星上高速率遥感图像相邻像素差的直方图进行修改,将低速率数据嵌入到原始高速率遥感载体图像中,并利用卫星高速数传系统进行下传。地面接收端可以从载体图像中正确提取低速率数据,并无损恢复原始高速率遥感图像数据。该方法在不增加卫星数传系统复杂度和信息传输速率的前提下,提高了卫星数传系统的利用率,增强了数据传输的隐蔽性。实验结果表明,本文算法在保证良好的不可见性的情况下,获得了较高的纯载荷嵌入容量。与其它无损嵌入方法相比,在峰值信噪比和纯载荷嵌入容量方面都有很大的优势。     

FY-2C星用户利用站分系统

介绍了风云二号(FY-2)气象卫星地面应用系统中用户利用站(USS)的构成和特点.给出了其中规模用户利用站(MDUS)、低速率用户利用站(LRUS)和数据收集平台(DCP)的配置、特点、主要功能及部分硬件的技术指标.     

Bacterial community in ancient Siberian permafrost as characterized by culture and culture-independent methods

The microbial composition of ancient permafrost sediments from the Kolyma lowland of Northeast Eurasia was examined through culture and culture-independent approaches. These sediments have been continuously frozen for 5,000 to 2-3 million years. A total of 265 Bacteria 16S rRNA gene sequences were amplified from the permafrost total-community genomic DNA and screened by amplified ribosomal 16S rRNA restriction analysis. Members of three major lineages were found: gamma-Proteobacteria (mostly Xanthomonadaceae), Actinobacteria, and Firmicutes. We also determined partial 16S rRNA gene sequences of 49 isolates from a collection of 462 aerobes isolated from these sediments. The bacteria included Actinomycetales (Arthrobacter and Microbacteriaceae); followed by the Firmicutes (Exiguobacterium and Planomicrobium); the Bacteroidetes (Flavobacterium); the gamma-Proteobacteria (Psychrobacter); and the alpha-Proteobacteria (Sphingomonas). Both culture and culture-independent approaches showed the presence of high and low G+C Gram-positive bacteria and gamma-Proteobacteria. Some of the 16S rRNA gene sequences of environmental clones matched those of Arthrobacter isolates. Two-thirds of the isolates grew at -2.5 degrees C, indicating that they are psychroactive, and all are closely related to phylogenetic groups with strains from other cold environments, mostly commonly from Antarctica. The culturable and non-culturable microorganisms found in the terrestrial permafrost provide a prototype for possible life on the cryogenic planets of the Solar System.     

In situ microbial detection in Mojave Desert soil using native fluorescence

We report on the use of a portable instrument for microbial detection in the Mojave Desert soil and the potential for its use on Mars. The instrument is based on native fluorescence and employs four excitation wavelengths combined with four emission wavelengths. A soil dilution series in which known numbers of Bacillus subtilis spores were added to soil was used to determine the sensitivity of the instrument. We found that the fluorescence of the biological and organic components of the desert soil samples studied can be as strong as the fluorescence of the mineral component of these soils. Using the calibration derived from B. subtilis spores, we estimated that microbial content at our primary sampling site was 10(7) bacteria per gram of soil, a level confirmed by phospholipid fatty acid analysis. At a nearby site, but in a slightly different geological setting, we tested the instrument's ability to map out microbial concentrations in situ. Over a ～50 m diameter circle, soil microbial concentrations determined with the B. subtilis calibration indicate that the concentrations of microorganisms detected varies from 10(4) to 10(7) cells per gram of soil. We conclude that fluorescence is a promising method for detecting soil microbes in noncontact applications in extreme environments on Earth and may have applications on future missions to Mars.