利用跳躍子突變探討Shewanella sp. TeC 抗重金屬鎘與類金屬碲之特性

Screening and characterization of cadmium sensitive and reduced tellurite-reduction mutants of Shewanella sp. TeC by transposon mutagenesis

蔣明蕙(Ming-Hui Chiang)

指導教授 ： 簡志青

元智大學/工程學院/生物科技與工程研究所/碩士(2009年)

摘要

本研究探討具有重金屬鎘與類金屬碲抗性之微生物Shewanella
sp. TeC 及用Tn5 轉位子插入基因之突變株Shewanella sp. A8 與
Shewanella sp. B21。本論文證實Shewanella sp. TeC 可在高濃度(3,000 μM)亞碲酸鹽環境中生長，並且具有還原亞碲酸鹽為元素態碲之能力；而Shewanella sp. A8 經由生長曲線測定、亞碲酸鹽還原量測定及含亞碲酸鹽培養盤等實驗顯示，被Tn5 轉位子插入之基因與還原亞碲酸鹽為元素態碲相關。Shewanella sp. B21 則是推測與亞碲酸鹽抗性相關之基因被破壞。利用分生實驗技術解序被Tn5 轉位子插入Shewanella sp. A8 之基因，經由定序及blastx 比對，得到與Pseudomonas fluorescens Pf0-1 之hflC 基因轉譯的HlfC 蛋白質有80%之同源性，同時於hflC 基因上游序列比對出與Pseudomonas entomophila L48 之hflK 基因轉譯的HlfK 蛋白質有80%之同源性；而被Tn5 轉位子插入Shewanella sp. B21 之基因轉譯後之序列則是比對到與Azotobacter vinelandii DJ 之metallopeptidase 蛋白質有46%之同源性。過去文獻顯示hflK 及hflC 基因具有相關性，未來將進一步探討此二基因在Shewanella sp. TeC 中，對還原能力所扮演的角色及釐清metallopeptidase 蛋白質與金屬抗性兩者之間的關聯。

關鍵字

重金屬抗性 ； 亞碲酸鹽 ； 鎘離子 ； Shewanella

並列摘要

Shewanella sp. TeC was isolated from soil contaminated with heavy metal and was able to tolerate high concentration of tellurite (up to 3,000μM) and cadmium. Black precipitates (presumably due to the production of tellurium from tellurite reduction) occurred in the growth
media of strain TeC. A cadmium sensitive strain B21 and a reduced tellurite-reduction strain A8 were obtained after screening mutants of Shewanella sp. TeC generated by transposon (Tn5) mutagenesis. Gene disrupted by Tn5 in strain A8 was identified as a homologue of hflC of
Pseudomonas fluorescens Pf0-1. In strain B21, a gene encode
homologue of metallopeptidase of Azotobacter vinelandii DJ was disrupted by Tn5. The possible roles of hflC homologue in tellurite reduction and metallopeptidase in heavy metals/metalloids resistance in Shewanella sp. TeC remain to be studied.

並列關鍵字

heavy metal resistance ； tellurite ； cadmium ； Shewanella

參考文獻

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