Bioconversion of Glucose-Rich Lignocellulosic Wood Hydrolysates to 3-Hydroxypropionic Acid and Succinic Acid using Engineered Saccharomyces cerevisiae

Background3-hydroxypropionic acid (3-HP) and succinic acid (SA) were announced as two of the top twelve value-added platform chemicals from biomass out of a group of over 300 potential compounds that could be made from biomass in a government report in 2004 (Werpy and Petersen, 2004) and in an updated report in 2010 (Bozell and Petersen, 2010). The screening criteria used in the report classified 3-HP and SA as direct petroleum replacement building block chemicals. 3-HP is a precursor to several high-value compounds, such as acrylic acid, 1,3-propanediol, acrylamide, and methyl acrylates, that ultimately end up in products such as fibers, contact lenses, diapers, fabric coatings, and other super absorbent polymers (SAPs). SA is a high-value platform chemical used in polyester production and a precursor for nylon and other bioplastics. Additionally, these reports identified pathways to building block compounds from sugars. Yeast fermentations were identified in these reports as a preferred potential pathway to 3-HP and SA production from sugars because of yeasts natural low pH tolerance. ResultsThe laboratory strain Saccharomyces cerevisiae BY4741 was engineered to produce either 3-HP or SA. These yeasts can convert fermentable sugars from glucose-rich lignocellulosic hardwood feedstocks into organic acid products such as 3-HP and SA under low pH conditions using exponential fed-batch cultivation strategies. Glucose-rich wood sugars provided a better growth environment for the engineered yeast strains, increasing production titers by 6.1 and 6.5 times for SA and 3-HP, respectively. ConclusionsThis study shows the potential of locally produced glucose-rich wood sugars to increase the production of platform chemicals necessary in the production of biobased polymers by engineered yeast cell factories.