| Summary: | 碩士 === 慈濟大學 === 微生物及免疫學碩士班 === 105 === Acinetobacter baumannii bacteria are ubiquitous in environment. They can survive on desiccated medical appliances surface for several days and are an impotent pathogen in nosocomial infection, especially in ICU. Biofilm formation is considered to enhance Acinetobacter baumannii against harsh condiion such as dry and detergents. To investigate genes involved in biofilm formation, mutagenersis using mini-Tn10 to construct mutant library of Acinetobacter baumannii ATCC17978(wild type), and test biofilm formation ability, one strain named C6 with a biofilm formation capacity increase 3.45 fold than ATCC17978 was selected, C6 can not form pellicle on the liquid-gas surface. No difference in the growth rate between the C6 mutant and the wild type. The C6 mutant secreted more extracellular substances than wild type and formed network-like structure as observed in SEM and TEM. Than, after invers PCR and sequencing, transposon on C6 genomic DNA was insert in A1S_3476 gene, between 178 and 179 bp, this locus was annotated as secretory lipase. In this study, lipase activity of C6 and wild type were measured; In extracellular, C6 higher than wild type, but in intercellular was inverse. Finally in this study, virulence was measured on Zebrafish and silkworm, and under the same dose of 1 X 106 CFU, C6 for zebrafish mortality compared with wild type decreased 17.5%. The A1S_3476 gene of Acinetobacter baumannii on plasmid, when this gene was inserted by transposon mini-Tn10, the biofilm formation capability will increased, and extracellular substance increased and decreased the ability of the bacteria to move on the semi-solid surface. The A1S_3476 gene will effect Acinetoacter baumannii biofilm formation capilaty and pathogenesis.
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