Proteomics of space Enterococcus faecium mutant strain LCT-EF18

Objective To identify the proteins and analyze their differential expressions in space Enterococcus faecium (E.faecium)mutant loaded in Shenzhou 8 spacecraft. Methods E.faecium mutant loaded in Shenzhou 8 spacecraft was isolated with Biolog biochemical reaction plate. Total protein was extracted from E.faecium mutant and quantified by SDS-PAGE. After the total protein was measured by BCA, the differential expressions of proteins in space E.faecium mutant and ground control strain were analyzed by isobaric tags for relative and absolute quantitation (iTRAQ). Results The space mutant stain LCT-EF20 was obtained by screening its phenotype, which can use inosine and L-malic acid but cannot utilize p-hydroxy phenylacetic acid. Differential proteomic analysis showed that the expression was up-regulated in 50 and down-regulated in 74 out of the 124 proteins with their expression changed. Conclusion Space environment can affect the biological features of E. faecium mutants and the expression of proteins. The differentially expressed proteins are mainly involved in the bacterial metabolic process.