Submitted to: American Society for Microbiology Annual Meeting
Publication Type: Abstract Only
Publication Acceptance Date: May 25, 2006
Publication Date: May 25, 2006
Citation: Nichols, N.N., Mertens, J.A., Dien, B.S. 2006. Identification and transcriptional profiling of furoic acid metabolism genes in Pseudomonas putida [abstract]. American Society for Microbiology. Paper No. Q-449. Technical Abstract: Furfural (2-furaldehyde) is a furan compound formed by dehydration of pentose sugars. In sugar mixtures obtained from agricultural biomass, furfural and other inhibitory compounds may be formed during acid hydrolysis of lignocellulose polymers, resulting in suboptimal or failed fermentations. Despite its inhibitory effects, some microorganisms such as Pseudomonas putida can metabolize furfural through conversion to 2-oxoglutarate, via 2-furoic acid and CoA intermediates. To identify genes responsible for furfural degradation in P. putida, we constructed transposon mutants. Two mutants were identified that had impaired growth on furoic acid. The mutant strains grew at wild-type rates on succinate and 4-hydroxybenzoate, indicating the mutations are specific to the furfural degradation pathway. Genes flanking the transposon insertion site were cloned from both mutant strains. In mutant PSF2, the transposon was located in a LysR-family regulatory gene, upstream of open reading frames similar to genes encoding aldehyde dehydrogenases, dehydrogenase accessory proteins, aromatic decarboxylases, and hydrolases. The PSF9 mutant had the transposon in an AraC-family regulatory gene, adjacent to a putative permease gene. Several of the cloned genes are induced specifically for degradation of furfural and furoic acid. Real-time RT-PCR with RNA from the wild type and mutant strains grown in the presence or absence of furoic acid demonstrated a 10-fold to greater than 1000-fold increase in transcription in response to furoic acid. The LysR-family regulatory gene appears to act positively, and the AraC-family gene negatively, in regulating gene expression. Individual gene deletions are being constructed to elucidate their function in metabolism of furfural and furoic acid.