| Summary: | 碩士 === 元智大學 === 生物科技與工程研究所 === 106 === Bacillus subtilis biofilm formation mechanism has been extensively studied, but the detailed mechanism is not yet clear. We found that the ResDE two-molecule system has a direct or indirect effect on the formation of Bacillus subtilis biofilm. E. resDE genes broadly existed among many Gram-positive bacteria and most researches on resD genes are related to redox respiration mechanisms but on biofilms are less. Therefore, we intend to understand the role of resD gene in the regulation of biofilm. First, we compared the wild type, resD mutant, its complemented strains, and other related strains on the biofilm formation grown in an Msgg medium, and the Δ resD mutant fail to form biofilm. In the β-galactosidase assay, it shows that the activity of Peps-lacZ was about 50 MU in the wild-type strain but only about 12 MU in the △resD mutant strain. The activity of wild type and △resD mutant in PtasA-lacZ ranged from 65 to 70 but wild type and △resD strains in PyuaB-lacZ are all around 15 MU. resDsinR mutant revealed the eps promoter restored and was above one fold increasing compared to its wild type. There is no effect on the activation of tasA-lacZ and yuaB-lacZ when compared to resD and their wild type strains. In addition, the non-phosphorylated resD D57A mutant was not able to form biofilm. Fially, we found that the randomly transposon TnYLB-1 insertion nine genes to restore the formation of biofilms in resD mutant. It was found that the nadR and ndh genes are related to NADH dehydrogenase. We suggests that the regulatory oxidation mechanisms may affect biofilm formation.
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