|Slininger, Patricia - Pat|
Submitted to: Biotechnology for Biofuels
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/17/2009
Publication Date: 1/15/2010
Citation: Allen, S.A., Clark, W., Mccaffery, J.M., Cai, Z., Lanctot, A., Slininger, P.J., Liu, Z., Gorsich, S.W. 2010. Furfural Induces Reactive Oxygen Species Accumulation and Cellular Damage in Saccharomyces cerevisiae. Biotechnology for Biofuels. 3(2):1-10. Interpretive Summary: We have demonstrated that furfural induces the internal accumulation of compounds called reactive oxygen species (ROS). As a result, furfural causes damage via ROS to internal cell structures (such as vacuole membranes, actin, and chromatin) rather than the external cell wall. Biofuels offer a viable alternative to petroleum-based fuel. One challenge is the development of a robust fermentative microorganism that can tolerate the inhibitors present during lignocellulosic fermentation. These inhibitors include the furan aldehyde, furfural, which is released as a byproduct of weak acid pretreatment of lignocellulose. To survive in the presence of furfural, yeasts need to not only detoxify furfural, but also to protect themselves and repair any damage it causes. In this research, we investigated how furfural is involved in cellular damage. By understanding the cellular effects of furfural, we will be able to identify how to engineer robust yeast strains better able to survive stresses associated with lignocellulosic fermentation.
Technical Abstract: Background: Biofuels offer a viable alternative to petroleum-based fuel. However, current methods are not sufficient and technology to use lignocellulosic biomass as a fermentation substrate faces several challenges. One challenge is the need of a robust fermentative microorganism that can tolerate the inhibitors present during lignocellulosic fermentation. These inhibitors include the furan aldehyde, furfural, which is released as a byproduct of xylose during weak acid pretreatment of lignocellulose. To survive in the presence of furfural yeast need to not only reduce furfural to the less toxic furfuryl alcohol, but also protect themselves and repair any damage caused by furfural. Since furfural tolerance in yeast requires a functional pentose phosphate pathway (PPP), and the PPP is associated with reactive oxygen species (ROS) tolerance, we investigated whether or not furfural induces ROS and ROS related cellular damage. Results: We have demonstrated that furfural induces the accumulation of ROS. In addition, furfural was shown to cause cellular damage that is consistent with ROS accumulation in cells. This includes damage to mitochondria and vacuole membranes, the actin cytoskeleton, and nuclear chromatin, but not damage to the external structure of the cell. At non-lethal concentrations of furfural (25 mM), the damage is less severe compared to lethal concentrations (50 mM). The less severe damage may be a factor in the cells ability to survive after the furfural has been detoxified. Conclusion: These data suggest that during the furfural-induced lag time, yeast not only detoxify furfural into furfuryl alcohol, but also protect themselves from the cellular effects of furfural and repair any damage caused by furfural. Understanding the cellular effects of furfural will aid in engineering robust yeast strains capable of surviving the stresses associated with lignocellulosic fermentation.