Engineering yeast genomes and populations

The field of synthetic biology seeks to use design principles of life to create new genes, organisms and populations to both better understand biology as well as generate species with useful properties. Budding yeast has been a workhorse for synthetic biology, as well as an important model organism in the broader fields of molecular biology and genetics. This thesis aimed to create genome engineering tools for the manipulation of genomes, with direct applications in yeast. I focused developing high-throughput and highly efficient methods for making genomic modifications in yeast to allow for the generation of large libraries of precisely modified yeast genomes.;By manipulation of endogenous DNA recombinases and mismatch repair enzymes in yeast, we were able to develop an oligonucleotide only method for genome engineering to generate libraries as large as 10.;5 individuals with a frequencyof modification as high as 1%. Additionally, we validated the use of RNA-guided CRISPR/Cas9 endonucleases to make changes in yeast genomes, resulting in frequencies of genome modification >90% in transformed populations. We further optimized this method to generate larger libraries as high as 10.;5 individuals and exploreda proof of concept epistasis experiment involving thermotolerance. Lastly, the propagation of changes to successive generations is useful when engineering organisms on the population level. To this end we explored the use of RNA-guided gene drives to bias inheritance in S. cerevisiae. We show that inheritance of these selfish elements can be biased to over 99% and is reversible.