| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術暨檢驗學系 === 102 === According to the genome sequence of Stenotrophomonas maltophilia K279a, eight putative RND-type efflux systems, SmeABC, SmeDEF, SmeGH, SmeIJK, SmeMN, SmeOP, SmeVWX, and SmeYZ, are annotated. Of the eight RND-type efflux systems, SmeABC, SmeDEF and SmeVWX have their own cognate outer membrane proteins (OMPs). In addition, like the TolC of Escherichia coli, a possible promiscuous OMP TolCsm has been characterized in S. maltophilia. There are four axes in this research. (1) To assess the impact of the overexpression of SmeF, SmeX, and TolCsm on the antibiotics susceptibility. The results demonstrated that overexpression of SmeF and SmeX decreased the resistance of strain KJ to aminoglycosides and macrolides. However, TolCsm overexpression made little influence on antibiotic susceptibility. (2) To characterize the physiology functions of TolCsm in S. maltophilia. The results indicated that deletion of TolCsm impaired the cell growth and biofilm formation, but made little effect on colony morphology. (3) To elucidate the stimuli which can further induce the expression of tolCsm. The results demonstrated that the expression of tolCsm was response to the challenge of oxidative stress. (4) To evaluate whether (i) knockout the intrinsically expressed tolCsm or (ii) overexpression of smeF triggers the σE-mediated envelope stress response. The result demonstrated that knockout tolCsm activated the σE system, but overexpression of smeF did not.
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