Secretome of the Coprophilous Fungus Doratomyces stemonitis C8, Isolated from Koala Feces∇†
Robyn Peterson,* Jasmine Grinyer, and Helena Nevalainen
Department of Chemistry and Biomolecular Sciences, Macquarie University, Sydney, New South Wales, Australia
ABSTRACT
Coprophilous fungi inhabit herbivore feces, secreting enzymes to degrade the most recalcitrant parts of plant
biomass that have resisted the digestive process. Consequently, the secretomes of coprophilous fungi have high
potential to contain novel and efficient plant cell wall degrading enzymes of biotechnological interest. We have
used one-dimensional and two-dimensional gel electrophoresis, matrix-assisted laser desorption ionization–
time-of-flight tandem mass spectrometry (MALDI-TOF/TOF MS/MS), and quadrupole time-of-flight liquid
chromatography–tandem mass spectrometry (Q-TOF LC-MS/MS) to identify proteins from the secretome of
the coprophilous fungusDoratomyces stemonitis C8 (EU551185) isolated from koala feces. As the genome of D.
stemonitishas not been sequenced, cross-species identification, de novo sequencing, and zymography formed an
integral part of the analysis. A broad range of enzymes involved in the degradation of cellulose, hemicellulose,
pectin, lignin, and protein were revealed, dominated by cellobiohydrolase of the glycosyl hydrolase family 7 and
endo-1,4-ß-xylanase of the glycosyl hydrolase family 10. A high degree of specialization for pectin degradation
in theD. stemonitis C8 secretome distinguishes it from the secretomes of some other saprophytic fungi, such
as the industrially exploited T. reesei. In the first proteomic analysis of the secretome of a coprophilous fungus
reported to date, the identified enzymes provide valuable insight into how coprophilous fungi subsist on
herbivore feces, and these findings hold potential for increasing the efficiency of plant biomass degradation in
industrial processes such as biofuel production in the future.