The impact of stress-response related transcription factors on lignocellulosic hydrolysate inhibitor tolerance of Saccharomyces strains

Authors: Mertens, Jeffrey; Hector, Ronald - Ron; Skory, Christopher - Chris

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/1/2017
Publication Date: 7/30/2017
Citation: Mertens, J.A., Hector, R.E., Skory, C.D. 2017. The impact of stress-response related transcription factors on lignocellulosic hydrolysate inhibitor tolerance of Saccharomyces strains [abstract]. Meeting Abstract for Society for Industrial Microbiology, Denver, Colorado, 07/30-08/3/2017. poster #11.

Interpretive Summary:

Technical Abstract: Plant biomass is a desirable feedstock for the production of renewable fuels and chemicals. Unfortunately, pretreatment processes to release sugars locked in plant biomass, or lignocellulosic feedstocks, lead to the production of fermentation inhibitors, such as furfural and hydroxymethyl furfural, resulting in the inefficient fermentation of the lignocellulosic derived sugars by Saccharomyces cerevisiae. Numerous transcription factor genes associated with stress response are upregulated in Saccharomyces cultures grown in the presence of these inhibitors and overexpression of these transcription factors offers a potential route to improved inhibitor tolerance. Overexpression of one of these transcription factors, YAP1, in Saccharomyces strains has led to mixed results with respect to improved lag times in growth and growth rate. In this work, we initially tested overexpression of YAP1 and MSN4, in a Saccharomyces lab strain and three environmental strains previously shown to have good tolerance to a number of lignocellulosic inhibitors. While YAP1 and MSN4 overexpression is beneficial to growth of the lab strain at lower inhibitor concentrations, at higher concentrations it was less effective. In contrast, overexpression of YAP1 at different expression levels in the environmental isolates did not improve growth characteristics. Additional stress related transcription factors were also overexpressed in the environmental isolates and failed to improve inhibitor tolerance. It appears overexpression of transcription factors, while potentially leading to improved tolerance of lab strains with inherently weak inhibitor tolerance, is unlikely to be a viable route to increase inhibitor tolerance of environmental strains.