Vibrio cholerae colonization of the fly rectum and activation of natural competen

描述(申请人提供)：霍乱弧菌是一种环境革兰氏阴性细菌，是一种流行和大流行的人类腹泻病原体。霍乱弧菌基因组在环境中的快速进化导致了免疫决定因素的交换和抗生素耐药性特征的获得。这些变化周期性地扩大了易感人群或复杂的疾病治疗。自然能力是细菌吸收环境DNA的能力，通过这个过程获得新基因的过程被称为水平基因转移。最近，研究人员发现，霍乱弧菌在激活群体感应和存在甲壳素的条件下培养时，会变得自然具有能力，并能够将新的DNA整合到其基因组中。由于河口霍乱弧菌的丰度有时与浮游动物的存在有关，而这些生物是甲壳素的丰富来源，因此它们的外骨骼被假设为环境表面，在那里自然能力被激活，霍乱弧菌基因组进化。然而，甲壳素是地球上发现的最丰富的聚合物之一，是包括藻类、真菌和昆虫在内的许多生物的表面成分。我们认为，如果宿主的微生物区系将特别有利的遗传元素转移到定植的病原体，即使是一个不太丰富或不经常遇到的环境宿主也可能对病原体的成功产生很大影响。多篇文章报道了从家蝇中分离出霍乱弧菌、其他肠道病原体和人类共生菌。在医院和农场附近，从苍蝇身上找到的细菌往往对多种抗生素具有抗药性。因此，我们 假设苍蝇可能为获得编码毒力特征和抗生素耐药性的基因提供了一个丰富的环境。以果蝇黑腹果蝇为模型， 我们最近发现霍乱弧菌在直肠的几丁质衬里上形成了一层致密的生物膜。初步结果表明，群体和甲壳素感应在这个隔间起作用，导致自然能力所需基因的激活。在这里，我们建议研究霍乱弧菌在家蝇直肠中定植的结构、信号和调控系统，研究苍蝇直肠中自然能力基因的调控，然后评估苍蝇中的水平基因转移。这些研究可能与数百个霍乱弧菌在LB肉汤中形成生物膜的研究有关，可能揭示霍乱弧菌自然能力被激活的环境生态位，并可能建议控制苍蝇作为一种简单的方法来限制新的毒力和抗生素耐药性特征向致病霍乱弧菌的转移。

DESCRIPTION (provided by applicant): Vibrio cholerae is an environmental Gram-negative bacterium and an epidemic and pandemic human diarrheal pathogen. Rapid evolution of the V. cholerae genome in the environment has resulted in exchange of immunity determinants and acquisition of antibiotic resistance traits. These changes have periodically expanded the pool of susceptible individuals or complicated treatment of disease. Natural competence is the ability of bacteria to take up environmental DNA, and the acquisition of new genes through this process is known as horizontal gene transfer. Recently, investigators have found that V. cholerae becomes naturally competent and is able to incorporate new DNA into its genome when cultured under conditions in which quorum sensing is activated and chitin is present. Because V. cholerae abundance in estuaries sometimes correlates with the presence of zooplankton, and these organisms are a rich source of chitin, their exoskeletons are hypothesized to be the environmental surface on which natural competence is activated and the V. cholerae genome evolves. However, chitin, one of the most abundant polymers found on earth, is a surface component of many organisms including algae, fungi, and insects. We propose that, if a host's microbiota transfers particularly advantageous genetic elements to a colonizing pathogen, even a less abundant or less frequently encountered environmental host may have a great impact on a pathogen's success. Multiple publications have reported isolation of V. cholerae, other enteric pathogens, and human commensal bacteria from house flies. In the vicinity of hospitals and farms, the bacteria recovered from flies are often resistant to multiple antibiotics. Therefore, we hypothesized that the fly might provide a rich environment for acquisition of genes encoding virulence traits and antibiotic resistance. Using the fruit fly Drosophila melanogaster as a model, we recently discovered that V. cholerae forms a dense biofilm on the chitinous lining of an intestinal compartment known as the rectum. Preliminary results suggest that quorum and chitin sensing are operative in this compartment, leading to activation of the genes required for natural competence. Here we propose to examine the structures, signals, and regulatory systems that contribute to V. cholerae colonization of the house fly rectum, to study regulation of natural competence genes in the fly rectum, and then to assess horizontal gene transfer in the fly. These studies may impart relevance to the hundreds of studies of V. cholerae biofilm formation in LB broth, may reveal an environmental niche in which V. cholerae natural competence is activated, and may suggest fly control as a simple method to limit the transfer of new virulence and antibiotic resistance traits to pathogenic V. cholerae.