ARS | Publication request: Culture nutrition key to inhibitor-tolerant yeast performance

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: May 5, 2011
Publication Date: N/A

Technical Abstract: Inhibitory compounds generated during acid hydrolysis pretreatment of lignocellulosic biomass interfere with subsequent fermentation to ethanol. A tolerant yeast strain Saccharomyces cerevisiae Y-50049 has recently been developed by targeted evolution in the presence of 5-hydroxymethylfurfural and furfural inhibitors. In order to optimize its performance, comparative data were collected on both the tolerant strain Y-50049 and its parent in experiments testing the impact of nitrogen sources, vitamins, and minerals on ethanol production potential. With respect to optimal ethanol production, a striking difference in the nutritional requirements of the two strains was observed in both synthetic media and dilute acid hydrolyzates of switchgrass that were supplemented with a variety of commercially available nitrogen sources. Pending nutrient availability, ethanol yields ranged from 0.04 g/g to 0.35 g/g glucose for Y-50049 growing on switchgrass hydrolyzate and from 0.025 to 0.42 g/g glucose on synthetic medium. While the parent strain yield range was similar to that of Y-50049 on synthetic medium, it was significantly less volatile to nitrogen source changes, especially in switchgrass hydrolyzate. Since nutrient availability significantly impacted both ethanol yield and production kinetics, and was strain-dependent, these results suggest the importance of including a nutrient supplementation analysis in the optimization and design of hydrolyzate fermentation processes.