Decreased metabolism and increased tolerability to extreme environment in Staphylococcus warneri with long-term space flight

Abstract

BackgroundMany studies have shown that space environment can affect bacteria to cause a range of mutations. However, so far, there are less studies on the effects of long-term space flight (>1 month) on bacteria. In this study, a Staphylococcus warneri strain, which was isolated from the Shenzhou-10 spacecraft that had experienced a space flight (15-day), was carried into space again. After 64-day flight, the combined phenotypic, genomic, transcriptomic and proteomic analyses were performed to compare the influence of the two space flights on this bacteria.\n\nResultsCompared with short-term space flight, long-term space flight increased the biofilm formation ability of S. warneri and the cell wall resistance to external environment stress, but reduced the sensitivity to chemical stimulation. Further analysis showed that these changes might be related to the significantly up-regulated gene expression of phosphotransferase system, which regulated glucose metabolism pathway, including glucose, mannose, fructose and cellobiose. The mutation of S. warneri caused by 15-day space flight was limited at phenotype and gene level after ground culture.\n\nConclusionAfter a 79-day space flight, the changes of S. warneri are meaningful. Phosphotransferase system of S. warneri was up-regulated by long-term space stimulation, which resulted in a series of changes in cell wall, biofilm and chemical sensitivity, thus enhancing the resistance and adaptability of bacteria to the external environment.\n\nImportanceTaking S. warneri as an example, we found that the mutation of bacteria in long-term space flight mainly focused on the adaptation and tolerance like environmental adaptation, physical resistance and cell repair to various pressures and these changes should be more obvious or even become stable mutations. But the clinical changes, for example drug resistance and virulence should not be significant because there is no threat of antibiotics.