The Effect Of Simulated Microgravity On Biological Characteristics Of Klebsiella Pneumoniae

Objective: A large number of domestic and foreign researches have proved that microgravity environment can cause some changes on biological properties of microorganism, including the growth, reproduction and metabolism of bacteria. In this study, growth and Proliferation, antibiotics sensitivity, surface morphology and ultrastructure, protein expression and virulence genes of Klebsiella pneumoniae were different in simulated microgravity environment.Methods: The simulated microgravity model is Klebsiella pneumoniae ATCC13883 culturing in RCCS, which includes earth gravity group(control group by rotating the bottle in the axis vertical to the ground) and simulated microgravity group(experiment group by rotating the bottle in the axis parallel to the ground). The strain,s growth and propagation are detected by spectrophotometric, the antibiotics sensitivity is measured in the way of broth microdilution method and K-B disk diffusion method in different periods(1d、3d、5d、7d、14d). After 14 days culturing in microgravity, the surface morphology is observed by scanning electron microscopy(SEM), the ultrastructure is observed by transmission electron microscopy(TEM), the protein expression is detected by SELDI-TOF-MS, and the expressions of virulence genes(wab G、ure A、fim H、uge) are detected by real-time fluorescence quantitative PCR.Results: Under simulated microgravity environment, the growth and reproduction of Klebsiella pneumoniae are accelerated when compared with the control group; Thediameter of inhibition zone of different antibiotics(contain piperacillin、ciprofloxacin、amikacin) were reduced. The results show that the morphological of K.pneumoniae slender thalli increased by scanning electron microscopy, transmission electron microscopy results showed that ultrastructural changes, and granular material in cell cytoplasm increased compared with the control group; Compared with the control group, the 18 proteins expression changes(P<0.05) after analysis of protein mass spectrometry detection results, in which nine proteins up-regulated, nine proteins down-regulated. As demonstrated by Real-time PCR results, virulence genes(wab G、ure A、fim H、uge) relative expression levels were decreased significantly.Conclusion: K.pneumoniae accearate growth and reproduction abililty, continous training to 14 days to piperacillin, ciprofloxacin, amikacin drug sensitivity change in Simulated microgravity. The K.pneumoniae ultrastructure, protein expression, and virulence genes expression are different to the control group.