Effect of simulated microgravity on biological characteristics of Klebsiella pneumoniae / 军事医学

ABSTRACT

Objective To investigate the effect of simulated microgravity on growth , morphology, protein expression and virulence gene expression of Klebsiella pneumoniae (KPN).Methods KPN was divided into simulated microgravity group and control group in the experiment .The former group was in the ambient of simulated microgravity in a clinostat .The bacterial growth curves , morphologyical changes in electron microscopy , and protein expression were detected by SELDI-TOF-MS, and the expression of 4 virulence genes(ureA,wabG,uge and fimH) by real-time fluorescence quantitative PCR (RT-PCR) in both groups.Results Compared with the control group , the growth of KPN under simulated microgravity was accelerated , and the total bacterial count increased in microgravity group .The bacterial morphology in microgravity group was changed under scanning electron microscopy (SEM), and thinner and longer bacteria were increased .The transmission electron microscopy ( TEM) analysis revealed increase in cytoplasmic granular substance in microgravity group .Proteome analysis showed that the expression of 18 proteins was changed , half of which up-regulated and the rest were down-regula-ted.Those 18 proteins were searched in the protein library .And 21 proteins of a similar molecular mass were retrieved ,13 of which,proteins with known functions ,were closely related to bacterial life activities .RT-PCR results showed that four virulence genes of KPN were down-regulated.Conclusion Upon exposure to simulated microgravity , the growth and repro-duction of KPN are accelerated and enhanced .The bacterial morphology is changed .The strain′s protein expression and four virulence genes expressionare also changed .Therefore,microgravity can change the characteristics of KPN .