Wood-degrading fungi use a sequence of oxidative and hydrolytic mechanisms to loosen lignocellulose and then release and metabolize embedded sugars. These temporal sequences have recently been mapped at high resolution using directional growth on wood wafers, revealing previously obscured dynamics as fungi progressively colonize wood. Here, we applied secretomics in the same wafer design to track temporal trends on aspen decayed by fungi with distinct nutritional modes: two brown rot (BR) fungi (Postia placenta and Gloeophyllum trabeum) and two white rot (WR) fungi (Stereum hirsutum and Trametes versicolor). We matched secretomic data from three zones of decay (early, middle, and late) with enzyme activities in these zones, and we included measures of total protein and ergosterol as measures of fungal biomass. In line with previous transcriptomics data, the fungi tested showed an initial investment in pectinases and a delayed investment in glycoside hydrolases (GHs). Brown rot fungi also staggered the abundance of some oxidoreductases ahead of GHs to produce a familiar two-step mechanism. White rot fungi, however, showed late-stage investment in pectinases as well, unlike brown rot fungi. Ligninolytic enzyme activities and abundances were also different between the two white rot fungi. Specifically, S. hirsutum ligninolytic activity was delayed, which was explained almost entirely by the activity and abundance of five atypical manganese peroxidases, unlike more varied peroxidases and laccases in T. versicolor. These secretomic analyses support brown rot patterns generated via transcriptomics, they reveal distinct patterns among and within rot types, and they link spectral counts with activities to help functionalize these multistrain secretomic data.
Bibliographical noteFunding Information:
This work was funded in part by the U.S. Department of Energy (DOE) Office of Science (Early Career grant DE-SC0004012 to J.S.S. from the Office of Biological and Ecological Research [BER] and BER grant DE-SC0012742 to J.S.S. and E.P.). This work was also funded by the National Science Foundation Graduate Research Fellowship Programs under grant 00039202 to G.N.P. Any opinions, findings, and conclusions or recommendations expressed in this material are those of the authors and do not necessarily reflect the views of the DOE or NSF
© 2018 American Society for Microbiology.
- Manganese peroxidase