The cellulolytic system of Trichoderma reesei relies on β-glucosidases (BGLs) as central enzyme completing biomass hydrolysis and triggering cellulase induction through disaccharides such as sophorose. Three BGLs from Aspergillus clavatus (AC), Penicillium oxalicum (PO) and Talaromyces stipitatus (TS) were expressed in Komagataella phaffii and characterized for parameters relevant to biomass hydrolysis and inducer generation. PO and TS enzymes showed higher thermostability (60 to 70 °C) than AC, which was inactivated above 50 °C. All were glucose-inhibited, with AC least affected (Ki 8.4 mM), followed by PO (6 mM) and TS (2.3 mM). Supplementation of Celluclast® with TS-BGL enhanced glucose release from cellulose and wheat straw, reaching levels comparable to Cellic®CTec2 on the latter. All enzymes catalyzed condensation reactions, generating up to 50 g/L disaccharides, with TS yielding highest sophorose titers in high glucose solutions (700 g/L). The impact of disaccharide composition on induction was assessed in T. reesei RUT-C30 cultivated using glucose (GLU), a TS-derived disaccharide solution (DS) or steam-pretreated wheat straw hydrolysate (PWS). DS elicited the strongest cellulolytic response, with BGL, CBH and EG activities (100 %). Using GLU as an inducer, BGL and CBH1 reached only 26 % and 20 %, while PWS hydrolysates induced intermediate levels of 65 % and 24 %. Hemicellulolytic activities peaked under PWS (xylanase, β-xylosidase set to 100 %), with DS and GLU showing substantially lower values. Proteomics confirmed that DS upregulated core cellulases (EGL1 +2.80, CBH1 +1.66, EGL5 +3.16), while PWS enriched CBH2 (-2.02), GH11 xylanases (-3.27) and GH3 β-xylosidases (-6.45, -2.49).