Comparative secretome of white-rot fungi reveals co-regulated carbohydrate-active enzymes associated with selective ligninolysis of ramie stalks

In the present research,Phanerochaete chrysosporiumandIrpex Lacteussimultaneously degraded lignin and cellulose in ramie stalks, whereasPleurotus ostreatusandPleurotus eryngiicould depolymerize lignin but little cellulose. Comparative proteomic analysis of these four white-rot fungi was used to investigate the molecular mechanism of this selective ligninolysis. 292 proteins, including CAZymes, sugar transporters, cytochrome P450, proteases, phosphatases and proteins with other function, were successfully identified. A total of 58 CAZyme proteins were differentially expressed, and at the same time, oxidoreductases participated in lignin degradation were expressed at higher levels inP. eryngiiandP. ostreatus. Enzyme activity results indicated that cellulase activities were higher inP. chrysosporiumandI. lacteus, while the activities of lignin-degrading enzymes were higher inP. eryngiiandP. ostreatus. In addition to the lignocellulosic degrading enzymes, several proteins including sugar transporters, cytochrome P450 monooxygenases, peptidases, proteinases, phosphatases and kinases were also found to be differentially expressed among these four species of white-rot fungi. In summary, the protein expression patterns ofP. eryngiiandP. ostreatusexhibit co-upregulated oxidoreductase potential and co-downregulated cellulolytic capability relative to those ofP. chrysosporiumandI. lacteus, providing a mechanism consistent with selective ligninolysis byP. eryngiiandP. ostreatus.

Automated summary

The research compared the proteomic analysis of four white-rot fungi and found that Pleurotus eryngii and Pleurotus ostreatus exhibited higher potential for lignin degradation and lower cellulolytic capability, presenting a mechanism consistent with selective ligninolysis.