ARS | Publication request: Use of a microbe to mitigate inhibitors in biomass fermentations

Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: October 1, 2010
Publication Date: October 1, 2010
Citation: Nichols, N.N., Dien, B.S., Saha, B.C., Cotta, M.A. 2010. Use of a microbe to mitigate inhibitors in biomass fermentations [abstract}. In: Proceedings of the 2010 AIChE Midwest Regional Conference, September 30-October 1, 2010, Chicago, Illinois. p. 34.

Technical Abstract: The presence of inhibitory compounds in biomass sugars is a significant hurdle to conversion of biomass to fuels and chemicals. The fibrous nature of lignocellulosic biomass necessitates physical-chemical pretreatment to deconstruct plant cell walls and render cellulose accessible to enzymatic digestion. Pretreatment in turn generates inhibitory compounds that affect microbial cell membranes, macromolecular synthesis, and glycolytic and fermentative enzymes. Inhibitors, comprising furan aldehydes, organic acids, and aromatic aldehydes and phenolics, result in failed or extensively prolonged fermentations as microorganisms attempt to adjust their metabolism to cope with the inhibitors. The microbial inhibitors present in biomass hydrolysates must therefore be mitigated to enable efficient fermentations. The inhibitory compounds, however, can also serve as a source of carbon and energy for some microbes. To this end, a soil microbe was isolated by selective screening that is uniquely suited for mitigating fermentation inhibitors, by metabolizing inhibitory compounds present in biomass dilute acid hydrolysates. Biological abatement using the fungal isolate, Coniochaeta ligniaria, results in improved fermentability of pretreated sugar streams, compared to unconditioned hydrolysates. Bioabatement has been evaluated in fermentations of crop residues and potential energy crops, and is advantageous to other methods of inhibitor mitigation.