Fusarium oxysporum cultured with complex nitrogen sources can degrade agricultural residues: Evidence from analysis of secreted enzymes and intracellular proteome

Bioethanol production by using agricultural residues is an ecofriendly and renewable approach for energy production. Fusarium oxysporum URM 7401 produces an enzymatic arsenal that can be useful for biomass degradation and the cellulose saccharification. Thus, we aimed to identify in F. oxysporum URM 7401, cultured with 1% casein or feather meal in a submerged bioprocess, the intracellular protein profile in 2D gels, as well as evaluate the secreted enzymes in crude extracts and their capacity to degrade agricultural residues. Peptidase and xylanase production was higher with the use of feather meal than casein, whereas lipase production was increased upon culture with casein. Pectinase, β-glucosidase, filter paper-digesting activity, amylase and invertase was similar in both cultures. Intracellular analysis identified proteins involved in carbohydrate and protein metabolisms, energy generation and, notably, transaldolase a key enzyme for enhancing bioethanol production. The extract from the casein culture released reducing sugars from agricultural residues 2-fold more efficiently than did the extract from the feather-meal culture. Conversely, highest proteolytic activity in the feather-meal crude extract can account for the impaired sugar release measured. Our results emphasize the potential of using F. oxysporum URM 7401 for consolidated bioprocesses, due to the modulation of the cell metabolic machinery.