Multi-resistant biofilm-forming pathogens on the International Space Station

The International Space Station (ISS) is a confined and closed habitat with unique conditions such as cosmic radiation, andmicrogravity. These conditions have a strong effect on the human and spacecraft microflora. They can affect the immuneresponse of the crew-members, thus posing a threat to their health. Microbial diversity and abundance of microorganismsfrom surfaces, air filters and air samples on the ISS have been studied. Enterobacteriaceae, Bacillus spp., Propionibacterium spp., Corynebacterium spp., and Staphylococcus spp. were among the most frequently isolated bacteria. Microbialgrowth, biofilm formation, stress response, and pathogenicity are affected by microgravity. Increased resistance toantibiotics in bacteria isolated from the ISS has often been reported. Enterococcus faecalis and Staphylococcus spp. isolatesfrom the ISS have been shown to harbor plasmid-encoded transfer genes. These genes facilitate the dissemination ofantibiotic resistances. These features of ISS-pathogens call for novel approaches including highly effective antimicrobialswhich can be easily used on the ISS. A promising material is the antimicrobial surface coating AGXX, a self-recyclingmaterial consisting of two noble metals. It drastically reduced microbial growth of multi-resistant human pathogens, such asstaphylococci and enterococci. Further novel approaches include the application of cold atmospheric plasma for thesterilization of spacecrafts.

A Fosmid Cloning Strategy for Detecting the Widest Possible Spectrum of Microbes from the International Space Station Drinking Water System

In this study, fosmid cloning strategies were used to assess the microbial populations in water from the International Space Station (ISS) drinking water system (henceforth referred to as Prebiocide and Tank A water samples). The goals of this study were: to compare the sensitivity of the fosmid cloning strategy with that of traditional culture-based and 16S rRNA-based approaches and to detect the widest possible spectrum of microbial populations during the water purification process. Initially, microbes could not be cultivated, and conventional PCR failed to amplify 16S rDNA fragments from these low biomass samples. Therefore, randomly primed rolling-circle amplification was used to amplify any DNA that might be present in the samples, followed by size selection by using pulsed-field gel electrophoresis. The amplified high-molecular-weight DNA from both samples was cloned into fosmid vectors. Several hundred clones were randomly selected for sequencing, followed by Blastn/Blastx searches. Sequences encoding specific genes from Burkholderia, a species abundant in the soil and groundwater, were found in both samples. Bradyrhizobium and Mesorhizobium, which belong to rhizobia, a large community of nitrogen fixers often found in association with plant roots, were present in the Prebiocide samples. Ralstonia, which is prevalent in soils with a high heavy metal content, was detected in the Tank A samples. The detection of many unidentified sequences suggests the presence of potentially novel microbial fingerprints. The bacterial diversity detected in this pilot study using a fosmid vector approach was higher than that detected by conventional 16S rRNA gene sequencing.

Space Life Science Researches Aboard International Space Station / 航天医学与医学工程

The launch of Expedition 1 to the International Space Station (ISS) opened a new era in the history of human space flight, so far fourteen Expeditions had been achieved. But the astronauts were exposed to abnormal environment such as microgravity, radiation, isolation, confinement, and misalignment of circadian rhythm during space flight. In order to reduce health risks incurred by living in space, the 59 projects have been or will be studied aboard ISS. Those researches has elucidated the rate of subregional bone loss and its recovery, characteristics of atrophy and reduced contraction function in antigravity skeletal muscle, decrease in spinal cord excitability, and relationship between reduced immune function and reactivation of some viruses. The psychological and behavior changes in a prolonged isolation and confinement condition, as well as the fast circadian rhythm inducing sleep disruption has been observed. It has been found exposure to radiation not only causing cataracts and cancers, but also damaging the reproductive organs and nervous system, and inducing genetic damage. The efficacy of countermeasures of medicine, nutrition and vibration have been validated aboard the ISS. The effective countermeasures on different systems were checked further. All of those studies and observations have made a solid foundation for developing novel countermeasures which will be more effective.