Sexual Recombination and the Development of Complex Phenotypes
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Adaptive laboratory evolution facilitates the development and study of complex phenotypes. In an evolving population, individuals with mutations conveying a fitness benefit are selected for, and become enriched, in the environment. However, the rate of adaptation can be limited by the frequency of beneficial mutations; and competition amongst co-occurring beneficial mutations can lead to a loss of information. In this work, we describe the use of horizontal gene transfer (HGT) in conjunction with modulating mutation rate to more rapidly develop complex phenotypes in E. coli. We first characterize a previously developed “genderless” strain of E. coli proficient in continuous HGT during liquid culture. We next examine a few steps that can be taken to broaden and enhance the characteristics of this strain. We then introduced an inducible mutator system to the genderless strain in order allow modulation of mutation rate to enhance the supply of mutations during ALE. The strain was evolved in several well-characterized experimental environments to determine the influences of HGT and mutation rate on the rate of adaptation. The results indicate HGT and increasing mutation rate can act together to speed adaptive laboratory evolution, in many adaptive landscapes (environment). We then leveraged the HGT to more rapidly combine different complex phenotypes, to help expedite strain development of more industrially focused phenotypes. Finally, less developed works, which focus on applying different aspects of ALE toward strain development, are briefly discussed.
Peabody V, George Lee (2017). Sexual Recombination and the Development of Complex Phenotypes. Doctoral dissertation, Texas A & M University. Available electronically from