The transfer of DNA between bacteria in the environment has important consequences. When DNA is passed from one organism to another in a fashion that does not involve a parent providing genetic material to its offspring, the process is called horizontal gene transfer (HGT). This type of inheritance contributes significantly to human health, biotechnology, and fundamental mechanisms of evolution. For example, HGT underlies the serious problem of bacterial resistance to antibiotics. Beneficial aspects of HGT include the ability of bacteria to detoxify pollutants. HGT also holds exciting promise for applications that enable bacteria to produce useful compounds, including fuels. This project focuses on the fate of foreign DNA after it has been transferred to a new bacterial host. A novel experimental system will facilitate investigations of HGT to improve understanding of how genetic material functions and adapts in diverse contexts. These studies will be used to develop and improve techniques that accelerate the success of biotechnology applications. The researchers have a successful history of training students at all levels and in enhancing diversity and inclusiveness in the scientific community, including training of students with disabilities. This project will be used to augment such activities. Furthermore, this project involves collaborations with researchers at the National Renewable Energy Lab to develop applications in bioenergy production. Training opportunities will enable students to visit and conduct research at this national laboratory.
An accelerated approach to experimental evolution will be used to follow the fate of foreign genes after their insertion into the chromosome of a soil bacterium, Acinetobacter baylyi. These genes will be amplified in a tandem array to enable copy number of the repeated segment (amplicon) to increase or decrease spontaneously. This process of expansion and contraction allows evolution of rudimentary control of the expression of newly acquired genes. This experimental system mimics the natural interplay between HGT and gene amplification. Gene dosage can increase a weak but beneficial function provided by foreign DNA. As mutations accrue within the amplicons, gene copies that are less fit will be lost and alleles that are more fit may increase via selection. This project exploits gene amplification to accelerate the evolutionary process so that gene divergence can be the focus of experimental study. Additional studies will alter the genetic content of the foreign DNA, changing synonymous codon usage, G+C content and chromosomal location. It will then be possible to test how these alterations affect the amelioration and retention of the genes. Strains will be grown under continuous culture in controlled environments. Copy number, mRNA, protein and DNA sequence changes will be analyzed.
