Identification and manipulation of genes involved in sensitivity to furfural.

BACKGROUND

Biofuels derived from lignocellulosic biomass are a viable alternative to fossil fuels required for transportation. Following plant biomass pretreatment, the furan derivative furfural is present at concentrations which are inhibitory to yeasts. Detoxification of furfural is thus important for efficient fermentation. Here, we searched for new genetic attributes in the fungus that may be linked to furfural tolerance. The fact that furfural is involved in the natural process of sexual spore germination of and that this fungus is highly amenable to genetic manipulations makes it a rational candidate for this study.

RESULTS

Both hypothesis-based and unbiased (random promotor mutagenesis) approaches were performed to identify genes associated with the response to furfural. Changes in the transcriptional profile following exposure to furfural revealed that the affected processes were, overall, similar to those observed in . was more tolerant (by ~ 30%) to furfural when carboxymethyl cellulose was the main carbon source as opposed to sucrose, indicative of a link between carbohydrate metabolism and furfural tolerance. We also observed increased tolerance in a Δ- mutant (CRE-1 is a key transcription factor that regulates the ability of fungi to utilize non-preferred carbon sources). In addition, analysis of aldehyde dehydrogenase mutants showed that - (NCU00378) was involved in tolerance to furfural as well as the predicted membrane transporter NCU05580 (-), a homolog of in . Further to the rational screening, an unbiased approach revealed additional genes whose inactivation conferred increased tolerance to furfural: (i) NCU02488, which affected the abundance of the non-anchored cell wall protein NCW-1 (NCU05137), and (ii) the zinc finger protein NCU01407.

CONCLUSIONS

We identified attributes in associated with tolerance or degradation of furfural, using complementary research approaches. The manipulation of the genes involved in furan sensitivity can provide a means for improving the production of biofuel producing strains. Similar research approaches can be utilized in and other filamentous fungi to identify additional attributes relevant to other furans or toxic chemicals.