Abstract Detail

Lignocellulose Deconstruction by Fungi

Cullen, Daniel [1].

Mechanisms of lignocellulose degradation inferred from recent genome investigations of wood decay fungi.

The white-rot basidiomycetes efficiently mineralize all wood cell wall polymers. As exemplified by Phanerochaete chrysosporium, these fungi typically degrade cellulose and lignin simultaneously. However, decay pattern vary among species and certain isolates of Ceriporiopsis subvermispora selectively remove lignin in advance of cellulose degradation. To examine the mechanism(s) of selective ligninolysis, C. subvermispora was grown in liquid medium containing ball-milled aspen as the sole carbon source. A combination of expression microarrays and nano-liquid chromatography-tandem mass spectrometry was used to define the transcriptome and secretome, respectively. Manganese peroxidases and an aryl alcohol oxidase, extracellular enzymes implicated in lignin degradation, were highly expressed within 72 hours of inoculation. In contrast, glycoside hydrolases and lytic polysaccharide monooxygeneases involved in cellulose degradation were more abundant after 5-7 days growth. This pattern of gene expression is consistent with selective ligninolysis by C. subvermispora.
   A different decay pattern is exhibited by Phlebiopsis gigantea. This unusual white rot fungus is capable of colonizing freshly exposed conifer sapwood despite the high content of resin acids, triglycerides and long chain fatty acids. To ascertain the mechanism(s) by which P. gigantea tolerates and metabolizes resinous compounds, its transcriptome and secretome were examined following growth on fresh-cut versus solvent-extracted loblolly pine. The expression of genes typically ascribed to cellulose and lignin degradation was largely unaffected by extraction. However, genes likely involved in the transformation and detoxification of pitch were highly induced in its presence. Their products included an ABC transporter, lipases, cytochrome P450s, glutathione S-transferase and aldehyde dehydrogenase. Other regulated genes of unknown function and several constitutively expressed genes are also likely involved in P. gigantea’s pitch metabolism. These results contribute to our fundamental understanding of conifer colonization and provide a framework for future functional analysis.

1 - Forest Products Laboratory, One Gifford Pinchot Dr, Madison, WI, 53726, USA

Keywords:
lignin
Ceriporiopsis
Phlebiopsis
Phanerochaete.

Presentation Type: Symposium or Colloquium Presentation
Session: SY9
Location: Room 104 AB/Kellogg Hotel and Conference Center
Date: Wednesday, June 11th, 2014
Time: 1:30 PM
Number: SY9002
Abstract ID:84
Candidate for Awards:None