Comparative Secretomics Analysis Of Penicillium Oxalicum 16 And Trichoderma Reesei RUT‐C30 In Solid State Fermentation

Straw is a renewable biomass resource,and using biotechnology to convert straw cell wall polysaccharides into biochemical products or biofuels is an effective means to increase the added value of straw in China.Filamentous fungi is the main producer of lignocellulose in industry at present,and can secrete a great deal of cellulases hemicellulases,and auxiliary degrading enzymes,which ultimately converts straw into monosaccharide.Although some studies have analyzed the secretomics of filamentous fungi such as Penicillium oxalicum and Trichoderma reesei,their main components have not been systematically and completely summarized.Exploring the holoenzyme expression patterns of P.oxalicum and T.reesei RUT-C30 during biomass degradation has theoretical significance and application value.In addition,P.oxalicum 16 screened by ourselves had a weaker cellulase production ability than T.reesei RUT-C30.Therefore,it is necessary to conduct quantitative analysis of its secretome information before strain modification.In this study,wheat bran(WB)and rice straw(RS)were used as carbon source for solid state co-fermentation with T.reesei RUT-C30 and P.oxalicum 16,respectively.The activities of induced β-1,4-endoglucanase(EG),β-1,4-glucosidase(BGL),xylanase and amylase were determined by DNS method,and the enzyme activity of cellobiohydrolase(CBH)was measured by p NPC method.Quantitative protein was assayed by Bradford.Total sugar content was determined at 600 nm by anthrone colorimetric method.LC-MS/MS was used to identify and quantify enzyme,and revealed the function and action type.The main findings are as follows:(1)Compared with T.reesei RUT-C30,P.oxalicum 16 secreted more glycoside hydrolases.Compared with RS,the main up-regulated proteins induced by WB were amylase,pectinase,and protease,and the main down-regulated proteins were cellulase,hemicellulase,swollenin and lytic polysaccharide monooxygenase(LPMOs).Specifically,WB induced more BGL(S8B0F3,A0A024RWA5),but RS induced more CBH(A0A024RXP8,A024SH76,S7B6D6)and EG(S7ZP52,A024SH20,A024S2H5,S8BGM3,S7ZX22,S8AIJ2).(2)The P.oxalicum 16 xylanases S8AH74 and S7ZA57 were the main components for degradation of soluble xylan.S8BDN2 could degrade solid hemicellulose,but had little effect on soluble xylan.In RS,the main component of hemicellulase from T.reesei RUT-C30 was xylanase A0A024S9Z6,with an abundance of 16%.It didn’t contain mannanase,but contained a small amount of xylanase.P.oxalicum 16 produced more amylase than T.reesei RUT-C30,and the results showed that the amylase S7Z6T2 could degrade soluble starch.The percentage of the glucoamylase S8B6D7 did not change significantly,and the average abundance was 5.5%.(3)The main auxiliary degrading enzymes of P.oxalicum 16 were LPMOs(S7Z716 and S7ZPW1),and the main auxiliary degrading enzymes of T.reesei RUTC30 were expansin,and LPMOs(A0A024S-M10,A0A024SFJ2,A0A024RZP7).Compared with RS,WB produced more abundant and balanced glycoside hydrolase,but RS induced more cellulase and hemicellulase.In addition,P.oxalicum 16 had more glycoside hydrolase than T.reesei RUT-C30,and was more likely to become a major producer of lignocellulase degradation.