Effects of short-term space conditions on cellulose degradation ability and biodiversity of microorganisms

Exposure to radiation and due to the microgravity in outer space, alterations of the gene expression of microorganisms have been reported, making them more virulent and enhancing their degradation capabilities. In the present study, cellulose-degrading microbes were isolated from China’s space station assembly clean room (CSSAC). They then were sent for a short space flight of 16 h by Long March 7 carrier rocket (space sample). At the same time, the microflora was tested on the ground as a control experiment (earth sample). Interestingly, the quantities of β-endoglucanase and total extracellular proteins were found significantly increased in the space sample, which resulted in increased cellulose degradation ability and changes in the structure of microbial flora. After identification, the culturable cellulose-degrading bacteria in the space sample is Bacillus sp. Y (M234399). Two different Fusarium strains were isolated from both samples and Trichoderma sp. S3 was isolated only from the space sample. Clone library results revealed that Escherichia, Shigella, and Salmonella were found in both samples and Shigella sp. B17 was found only in the space sample. Fusarium was also found in both samples, but they do not belong to the same species. Mutation studies revealed no changes in the endoglucanase gene. Still, enhanced growth of the strains from space samples was observed in Scanning Electron Microscopy (SEM) results along with upregulation of cellulase gene. This study confirmed the presence of cellulolytic microbes and increased celluolytic activity after short space flight, so, in the future, more care should be given while designing spacesuits and astronauts' belongings.