## 3 Results and Discussion
### Solid-State Production of A. olivimuriae Extracellular Glycosyl Hydrolases and Lyaases
The former catalyzes the xylobiose hydrolysis and the detachment of xylooligosaccharides from the xylan's non-reducing end. The latter brings about the detachment of mannosyl residues from the mannans' non-reducing end. Among the non-amended cultures, those on barley straw attained the endo-\(\beta\)-1,4-xylanase activity (7.56 \(\pm\) 0.79 IU g\({}^{-1}\) substrate), but RTB cultures also led to significant activity levels (5.52 \(\pm\) 1.17 IU g\({}^{-1}\) substrate) (Figure 2A). Although the presence of WB increased the activity levels of this enzyme in cultures on barley straw and RTB (8.95 and 6.65 IU g\({}^{-1}\) substrate, respectively), the only statistically significant increase occurred on SCG (3.23 \(\pm\) 0.76 vs. 1.04 \(\pm\) 0.18 IU g\({}^{-1}\) substrate). It is likely that WB stimulated this enzyme's production, since this amendment brings xylose-based polymers to the growth substrate, whereas the hemicellulose fraction in SCG is devoid of these components [36,39]. On the same growth substrate, the presence of WB also led to a 4.5-fold increase in \(\beta\)-xylosidase activity (Figure 2B). As evidence of the previous considerations  
Figure 1: Specific activities, referred to unit mass of initial substrate, of endo-\(\beta\)-1,4-glucanase (**A**), cellobiohydrolase (**B**), \(\beta\)-glucosidase (**C**), and FP-ase (**D**) in 14-day-old solid-state cultures conducted on residual thistle biomass (RTB), spent coffee grounds (SCG), barley straw (BS) and digestate solid fraction (DSF) in the presence and in the absence of wheat bran (WB) as the amendment. Data are the mean \(\pm\) standard deviation of four replicates. about the hemicellulose composition in SCG, the highest \(\beta\)-mannanase activity was found precisely on this matrix (3.72 \(\pm\) 0.2 IU g\({}^{-1}\) substrate) (Figure 2C), thus confirming the adequacy of coffee wastes to support the production of this enzyme by _Aspergillus_ species [63]. The \(\beta\)-mannosidase activity was also the highest in cultures carried out on non-amended SCG (0.90 \(\pm\) 0.04 IU g\({}^{-1}\) substrate) compared to other cultures (Figure 2D). Regardless of the growth substrate, the amendment's presence did not significantly affect the production of both \(\beta\)-mannanase and \(\beta\)-mannosidase (Figure 2C,D). As was already observed for cellulolytic enzymes, _A. olivumariae_ production levels of hemicellulases on the tested residues were significantly lower than those achieved by solid-state cultures of other _Aspergillus_ species on different residues. For instance, [PERSON] et al. [64] found that _A. niger_ SCBM1 and _A. fumigatus_ SCBM6, grown individually on a mixture of spent bagasse and WB, produced very high activity levels for both endo-\(\beta\)-1,4-xylanase (2271.7 and 1164.8 IU g\({}^{-1}\) substrate, respectively) and \(\beta\)-xylosidase (145 and 2.5 IU g\({}^{-1}\) substrate, respectively). Although none of the used solid substrates is a pectin-rich material, the investigation was also extended to the determination of polymethylgalacturonase (E.C. 3.2.1.15), polygalacturonase (E.C. 3.2.1.67) and pectinesterase (E.C. 3.1.11) activities. Polymethylgalacturonase, ambiguously called pectinase, catalyzes the random hydrolysis of \(\alpha\) (1 \(\rightarrow\) 4) bonds between adjacent residues in spectate and other galacturonans and, depending on the microbial source, has different tolerances to the methyl esterification of galacturonic residues. On the contrary, polygalacturonase is specific to D-homogalacturonan oligomers and cannot degrade unsaturated or methyl esterified substrates. The role of pectinesterase is to facilitate the action of depolymerizing enzymes by hydrolyzing the carboxylic esters present in the D-galacturonic residues of the pectin, producing pectates and methanol.