| Summary: | 碩士 === 臺中健康暨管理學院 === 生物科技學系碩士班 === 93 === Abstract
Xanthomonas campestris pv. campestris (Xcc) is the causative agent of black rot disease in cruciferous plants. This bacterium synthesizes great amounts of xanthan gum rendering the colonies mucoid. Xanthan gum has many industrial applications, such as oil drilling, food, agriculture and industry. Production of xanthan gum is also refuired for the virulence of this bacterium.
To adapt to the diverse environmental changes, bacteria develop various responsive mechanisms. Bacteria are able to activate or switch off specific sets of genes as they face changing environmental conditions. This can be achieved through the activities of RNA polymerases containing alternate sigma factors and their cognate regulatory proteins. Biogenesis of flagellum is very complicate and is delicately regulated by several sigma factors and transcription regulators.
Xcc fleN mutants were constructed by insertional mutagenesis. Mutation in fleN does not interfere with the pathogenicity and exocellular enzymes production and growth of the cell. Transcriptional fusion assay indicated that fleN Electron microscopy photography revealed that fleN mutants are hyper-flagellated but immotile, fleN regulates expression of six flagellar genes, including fliE, fliL, fliQ, flgB, flgG and flhF, in a negative manner. However, fleN is not necessery for the expression of the major flagellin gene fliC, nor for the type IV pilin gene pilA1.
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