CAREER: DNA as a Nutrient-A Role for Competence Gene Homologs in Long-Term Survival

细菌自然史的大多数模型包括“盛宴和饥荒”的循环，其中生物体经历营养丰富以及营养胁迫。然而，对于大多数微生物来说，营养物质的可用性通常是有限的。为了了解细菌在实验室条件下的生存机制，更好地反映自然环境，我们研究了营养限制的固定相的E。大肠杆菌生活周期。我们已经确定了E.大肠杆菌在稳定期的长期培养中存活。这些基因的活性使细菌能够利用细胞外DNA作为碳和能量的唯一来源。这些基因是已知参与水平基因转移的其他生物体中基因的同源物，使细胞能够进行自然转化。因此，它们被称为“com”基因。然而，与天然具有遗传转化能力的细菌如流感嗜血杆菌或枯草芽孢杆菌不同，E.已知大肠杆菌不是天然可转化的。这些基因在大肠杆菌中的鉴定。大肠杆菌的研究表明，有机体摄取DNA不一定是为了用作遗传信息，也可以用作碳源和能源。本项目的重点是了解E.以DNA为营养源，研究了玉米基因在DNA催化中的作用，阐明了玉米基因的表达和调控模式。该项目还包括引入一门新课程，“细菌生存，适应进化的机制”，其重点是探索各种微生物在不同环境中生存的机制，使它们能够适应环境变化。

Most models of the natural history of bacteria include cycles of "feast and famine," where the organism experiences nutrient abundance as well as nutrient stress. However, for most microorganisms, nutrient availability is usually restricted. To understand mechanisms of bacterial survival under laboratory conditions that better reflect the natural environment, we study the nutrient-limited stationary phase of the E. coli life cycle. We have identified a gene family essential for E. coli to survive long-term incubation during stationary phase. The activities of these genes enable the bacteria to use extracellular DNA as the sole source of carbon and energy. These genes are homologs of genes in other organisms known to be involved in horizontal gene transfer, making the cells competent for natural transformation. Therefore, they are known as "com" genes. However, unlike bacteria such as Haemophilus influenzae or Bacillus subtilis that are naturally competent for genetic transformation, E. coli is not known to be naturally transformable. The identification of these genes in E. coli suggests that the organism takes up DNA not necessarily to be used as genetic information, but also to be used as a carbon and energy source. The focus of this project is to understand the ability of E. coli to use DNA as a nutrient, determine the roles of these com genes in DNA catabolism, and elucidate the patterns of com gene expression and regulation. This project also includes the introduction of a new course, "Mechanisms of Bacterial Survival, Adaptation & Evolution", whose focus is to explore the mechanisms used by a variety of microorganisms to survive in disparate environments, allowing them to adapt to environmental change.