Fast Forward' Genetics for Renewable Fuels
Genetic studies traditionally proceed in a stepwise fashion with each mutant or transformant gene being characterized as it is developed. Improved strains are obtained and used often without knowledge of the changes involved. While useful commercially, it is difficult to recreate these improvements in other strains or to understand their basis. In recent years, however, high-throughput genetic sequencing has enabled the exact nucleotide characterization of entire genomes.
Researchers at the Forest Products Laboratory used mutagenesis, strain selection and genetic manipulation over a period of seven years to develop improved strains of yeasts that will produce renewable fuel (ethanol) from wood residues. In a collaboration between the FPL and the Department of Energy Joint Genome Institute, the genome of the parental yeast, P. stipitis CBS 6054, was sequenced in 2006. Four sequentially derived mutants of the parent were then re-sequenced and characterized. Surprisingly, only 14 separate nucleotide changes were found despite several rounds of mutagenesis and selection. This work was the first of its kind: the use of direct sequencing to characterize improved mutant strains from a eukaryotic organism. These findings will enable more rapid development of yeasts for the bioconversion of wood residues into fuels and chemicals.
Forest Service Partners