迟缓爱德华氏菌
色氨酸酶
群集运动
生物
微生物学
羧苄青霉素
毒力
突变体
吲哚试验
大肠杆菌
基因
遗传学
生物化学
抗生素
群体感应
氨苄西林
作者
Heng Yin,Chunli Yang,Qian Yang,Zhigang Qi,Wenzheng Liu,Zhihong Xu,Weiming Zhu,Peter Bossier,Xiaohua Zhang
标识
DOI:10.1111/j.1758-2229.2011.00269.x
摘要
Summary A fish pathogen Edwardsiella tarda LTB‐4 produced various indole alkaloids, including indole, 2‐(1 H ‐indol‐3‐yl)ethanol, 4‐di(1 H ‐indol‐3‐yl)methylphenol, tri(1 H ‐indol‐3‐yl)methane and 2‐[2,2‐bis(1 H ‐indol‐3‐yl)]ethylphenylamine. Indole was the most abundant among these indole alkaloids. E. tarda LTB‐4 produced indoles during its whole growth phase and maintained a high level (around 35.5 µM) during the stationary phase. The relevant tryptophanase (TnaA) gene tnaA was cloned from LTB‐4 and conditionally expressed in Escherichia coli ; the recombinant TnaA catalysed L‐tryptophan to indole. A tnaA in‐frame deletion mutant Δ tnaA was constructed through double cross‐over allelic exchange by means of the suicide vector pRE118; deletion of tnaA caused some phenotypic changes including decreased swarming and twitching motility, lipopolysaccharide production and multiple antibiotic resistances. Also, subtherapeutic doses of chloromycetin, carbenicillin and tetracyline could cause the decrease of bacterial growth, but greatly induce the production of indole by E. tarda . Most importantly, attenuated virulence of the Δ tnaA mutant to zebra fish by increasing the LD 50 for about 55‐fold indicated that TnaA involved in the virulence of E. tarda .
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