期刊
BIOTECHNOLOGY FOR BIOFUELS
卷 10, 期 -, 页码 -出版社
BMC
DOI: 10.1186/s13068-017-0763-7
关键词
Saccharomyces; Biodiversity; Ammonia fiber expansion (AFEX); AFEX-pretreated corn stover hydrolysate (ACSH); Hybridization; Bioethanol; Xylose; Hydrolysate toxins
资金
- DOE Great Lakes Bioenergy Research Center (DOE Office of Science BER) [DE-FC02-07ER64494]
- National Science Foundation [DEB-1253634]
- USDA National Institute of Food and Agriculture Hatch Project [1003258]
- ANPCyT [PICT 2542]
- CONICET [PIP 0392]
- UNComahue Grant [B171]
- National Natural Science Foundation of China [31470150]
- NSERC Discovery Grant
- National Institutes of Health [GM080669, 5 T32 GM007133-40]
- National Science Foundation Graduate Research Fellowship [DGE-1256259]
- Predoctoral Training Program in Genetics
- NIH Genome Analysis Training Grant
- Pew Charitable Trusts
- Direct For Biological Sciences
- Division Of Environmental Biology [1253634] Funding Source: National Science Foundation
Background: Lignocellulosic biomass is a common resource across the globe, and its fermentation offers a promising option for generating renewable liquid transportation fuels. The deconstruction of lignocellulosic biomass releases sugars that can be fermented by microbes, but these processes also produce fermentation inhibitors, such as aromatic acids and aldehydes. Several research projects have investigated lignocellulosic biomass fermentation by the baker's yeast Saccharomyces cerevisiae. Most projects have taken synthetic biological approaches or have explored naturally occurring diversity in S. cerevisiae to enhance stress tolerance, xylose consumption, or ethanol production. Despite these efforts, improved strains with new properties are needed. In other industrial processes, such as wine and beer fermentation, interspecies hybrids have combined important traits from multiple species, suggesting that interspecies hybridization may also offer potential for biofuel research. Results: To investigate the efficacy of this approach for traits relevant to lignocellulosic biofuel production, we generated synthetic hybrids by crossing engineered xylose-fermenting strains of S. cerevisiae with wild strains from various Saccharomyces species. These interspecies hybrids retained important parental traits, such as xylose consumption and stress tolerance, while displaying intermediate kinetic parameters and, in some cases, heterosis (hybrid vigor). Next, we exposed them to adaptive evolution in ammonia fiber expansion-pretreated corn stover hydrolysate and recovered strains with improved fermentative traits. Genome sequencing showed that the genomes of these evolved synthetic hybrids underwent rearrangements, duplications, and deletions. To determine whether the genus Saccharomyces contains additional untapped potential, we screened a genetically diverse collection of more than 500 wild, non-engineered Saccharomyces isolates and uncovered a wide range of capabilities for traits relevant to cellulosic biofuel production. Notably, Saccharomyces mikatae strains have high innate tolerance to hydrolysate toxins, while some Saccharomyces species have a robust native capacity to consume xylose. Conclusions: This research demonstrates that hybridization is a viable method to combine industrially relevant traits from diverse yeast species and that members of the genus Saccharomyces beyond S. cerevisiae may offer advantageous genes and traits of interest to the lignocellulosic biofuel industry.
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