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Sufficient evidence indicates that orbiting space stations contain diverse microbial populations, which may threaten astronaut health and equipment reliability. Understanding the composition of microbial communities in space stations will facilitate further development of targeted biological safety prevention and maintenance practices. Therefore, this study systematically investigated the microbial community of China's Space Station (CSS). Air and surface samples from 46 sites on the CSS and Assembly Integration and Test (AIT) center were collected, from which 40 bacteria strains were isolated and identified. Most isolates were cold- and desiccation-resistant and adapted to oligotrophic conditions. Bacillus was the dominant bacterial genus detected by both cultivation-based and Illumina MiSeq amplicon sequencing methods. Microbial contamination on the CSS was correlated with encapsulation staff activities. Analysis by spread plate and qPCR revealed that the CSS surface contained 2.24 × 103–5.47 × 103 CFU/100 cm2 culturable bacteria and 9.32 × 105–5.64 × 106 16S rRNA gene copies/100cm2; BacLight™ analysis revealed that the viable/total bacterial cell ratio was 1.98–13.28%. This is the first study to provide important systematic insights into the microbiome of the CSS during assembly that describes the pre-launch microbial diversity of the space station. Our findings revealed the following. (1) Bacillus strains and staff activities should be considered major concerns for future biological safety. (2) Autotrophic and multi-resistant microbial communities were widespread in the AIT environment. Although harsh cleaning methods reduced the number of microorganisms, stress-resistant strains were not completely removed. (3) Sampling, storage and analytical methods for the space station were thoroughly optimized, and are expected to be applicable to low-biomass environments in general. Microbiology-related future works will follow up to comprehensively understand the changing characteristics of microbial communities in CSS. [ABSTRACT FROM AUTHOR]

Abstract: Genetic diversity and structure within and between 17 populations of invasive Conyza sumatrensis (Asteraceae) around the world’s biggest hydroelectric dam (Three Gorges Dam (TGD) on the Yangtze River in China) and nearby localities were surveyed using inter-simple sequence repeat (ISSR) markers to determine the spread pattern of this invader in TGD and nearby regions. A total of 434 individuals were analysed, for which 15 ISSR primers amplified 81 bands, with 54 (66.7%) being polymorphic. The percentage of polymorphic loci within a population ranged from 31% to 58%, Nei’s gene diversity was 0.385 ± 0.056, and mean Shannon’s Index was 0.5815 ± 0.0833, indicating a high genetic variation in this self-fertile plant. Mass seed production and multiple introductions associated with dam construction and local development were thought to be responsible for the high level of genetic variation. Analysis of Molecular Variance revealed 36.5% of genetic variation residing within populations, 35.0% among populations within regions, and 28.5% among the three regions: TGD, upper reaches of TGD, and lower reaches of TGD. Most populations were genetically related to their nearest neighbors, while gene flow (mainly via seed movement) across TGD existed. Long-distance dispersal of seeds and pollen such as by water current, wind and human transportation could explain the low level of geographic structure of genetic variation. The highest genetic variation was found in a population in TGD, and most populations from TGD showed closer genetic relationship to the lower reaches population, which indicated that C. sumatrensis at TGD has likely experienced multiple introductions mainly from lower reaches, which is near the area of primary introduction (southern China) of C. sumatrensis. [ABSTRACT FROM AUTHOR]