Casas Veronica, Magbanua Joseph, Sobrepeña Gerico, Kelley Scott T, Maloy Stanley R
Department of Biology, Center for Microbial Sciences, San Diego State University, 5500 Campanile Drive, San Diego, CA 92182-1010, USA.
Int J Microbiol. 2010;2010:754368. doi: 10.1155/2010/754368. Epub 2011 Jan 9.
Many bacteria produce secreted virulence factors called exotoxins. Exotoxins are often encoded by mobile genetic elements, including bacteriophage (phage). Phage can transfer genetic information to the bacteria they infect. When a phage transfers virulence genes to an avirulent bacterium, the bacterium can acquire the ability to cause disease. It is important to understand the role played by the phage that carry these genes in the evolution of pathogens. This is the first report of an environmental reservoir of a bacterial exotoxin gene in an atypical host. Screening bacterial isolates from the environment via PCR identified an isolate with a DNA sequence >95% identical to the Staphylococcus aureus enterotoxin A gene (sea). 16S DNA sequence comparisons and growth studies identified the environmental isolate as a psychrophilic Pseudomonas spp. The results indicate that the sea gene is present in an alternative bacterial host, providing the first evidence for an environmental pool of exotoxin genes in bacteria.
许多细菌会产生被称为外毒素的分泌型毒力因子。外毒素通常由包括噬菌体在内的可移动遗传元件编码。噬菌体能够将遗传信息传递给它们所感染的细菌。当噬菌体将毒力基因转移到无毒细菌时，该细菌就可能获得致病能力。了解携带这些基因的噬菌体在病原体进化过程中所起的作用很重要。这是关于非典型宿主中细菌外毒素基因环境储存库的首次报告。通过聚合酶链反应（PCR）从环境中筛选细菌分离株，鉴定出一株DNA序列与金黄色葡萄球菌肠毒素A基因（sea）相似度超过95%的分离株。16S DNA序列比较和生长研究确定该环境分离株为嗜冷假单胞菌属。结果表明sea基因存在于另一种细菌宿主中，为细菌中外毒素基因的环境库提供了首个证据。
