| Summary: | 碩士 === 慈濟大學 === 微免暨分子醫學研究所 === 94 === Thermus thermophilus HB8 is a Gram-negative rod-form bacterium with biofilm-forming ability. There were small (S) and L (large) variants, two major variants with different colony sizes isolated from T. thermophilus HB8 growing on agar plate. Meanwhile, no phenotypical conversion between S and L variants was observed under different physiological condisions. No matter variants were subcultured repeatedly, incubated with rich mediums, or starved, variation or reversion was still not found. The S variant formed smaller and smoother colonies than did the L variant. Formation of small colonies may be due to a stronger ability of cell-to-cell aggregation. Our results indicated this may indeed the case since the S variant tended to aggregate more than the L variant
and forms cell clusters rapidly in biofilm. Additionally, biofilm structures of the L variant were flat and more stable than that of S variants after biofilm maturation. Proteomic analysis showed 6 proteins differentially expressed under biofilm formation, and also showed 15 proteins differentially
expressed between S and L variants. According to these results, it was interesting to focus on the membrane lipoprotein which was expressed in S variants only. It may be a surface structure related protein which affects the interaction between bacteria. Mutants of membrane lipoprotein were generated by the double cross over. In the future, mutants will be analyzed to understand the role of membrane lipoprotein in colony variation of T. thermophilus HB8.
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