Cellulase and xylanase have been widely studied for bioconversion processes and applied in various industries. The high cost of these enzymes remains to be the major bottleneck for large-scale commercial application of lignocellulosic biorefinery. The use of agroindustrial residues and weeds as fermentation substrates is an important strategy to increase cellulolytic enzymes production and reduce costs. Penicillium crustosum was newly isolated and selected to study its enzyme production during solid-state fermentation (SSF). Natural and pretreated water hyacinth (WH) biomass was used as support, substrate and inducer of cellulases and xylanases. Thermochemical pretreatments of WH biomass at 121 °C and sulfuric acid at three concentrations (0.2, 0.6 and 1 M) were assayed. The pretreatments of WH biomass released mono- and oligo-saccharides that favored fungal growth and enzymes production on SSF. WH is a cost-effective substrate-support and inducer, which to be used as a solid medium, was impregnated with a saline solution, containing only (NH₄)₂SO₄, KH₂PO₄ y MgCl₂. Maximum cellulases (carboxymethylcellulase (CMCase)) and xylanases productions of P. crustosum cultured on SSF were reached using the WH pretreated biomass with H₂SO₄ 0.6 M and 121 °C. The simultaneous CMCase and xylanases production reached (647.51 and 4257.35 U/g dry WH, respectively) are among the highest values ever reported.

This study aimed to isolate and identify fungi capable of producing xylanases and cellulases. Thirty-eight fungal strains were isolated from decaying water hyacinth (WH), and two were selected based on their superior enzyme production under solid-state fermentation (SSF). The strains were identified through morphological, cultural, and molecular analyses as Aspergillus austwickii B6 and Trichoderma harzianum M7. Their ribosomal ITS sequences were deposited in GenBank under accession numbers PQ142799.1 for A. austwickii B6 and PQ007458.1 for T. harzianum M7. Enzyme production was evaluated under SSF using eight culture medium variants prepared with natural or pretreated biomasses of WH and sugarcane bagasse (SCB), combined with either NaNO₃ or (NH₄)₂SO₄ as nitrogen sources. The maximum xylanase and cellulase activities were 752 and 65 U/g dry matter (DM), respectively, for A. austwickii B6, and 1724 and 152 U/g DM for T. harzianum M7, when cultivated on a low-cost medium composed of pretreated WH, (NH₄)₂SO₄, and a simple mineral salt solution. These findings highlight the potential of locally isolated fungal strains and lignocellulosic residues as cost-effective substrates and inducers of xylanase and cellulase production under SSF and underscore the importance of WH pretreatment to enhance substrate availability and maximize enzyme yields.

Seventy-five thermophilic fungi capable of growing at 45 °C were isolated from sugarcane bagasse samples and cultivated under solid-state fermentation (SSF). Two isolates showing the highest xylanase and cellulase production were selected and identified as Aspergillus fumigatus 5S2 and Aspergillus sp. 1.6C. Water hyacinth (WH) and sugarcane bagasse (SCB) were evaluated as lignocellulosic supports and carbon sources for enzyme production under SSF. Eight culture conditions were evaluated to identify the most suitable condition for enzyme production. Results revealed that substrate recalcitrance was a major limiting factor for enzyme production and that thermochemical pretreatment significantly improved substrate utilization. The highest enzyme activities were achieved on pretreated WH (PWH) supplemented with NaNO₃ and mineral salts. A. fumigatus 5S2 reached 810 U/g dry matter (DM) for xylanase and 95 U/g DM for cellulase, whereas Aspergillus sp. 1.6C reached 649 U/g DM of xylanase and 33 U/g DM of cellulase under the corresponding optimal culture conditions. PWH was mixed with SCB to improve the physical properties of the SSF support, including aeration, porosity, and water retention. The highest enzyme production levels were obtained using 1:1 and 1:0.5 (w/w) mixtures of PWH and SCB for A. fumigatus 5S2 and Aspergillus sp. 1.6C, respectively. SSF column bioreactors packed with these mixtures produced similar enzyme titers at 30 °C and 40 °C, confirming the thermotolerant nature of both strains.

The valorization of lignocellulosic residues through xylooligosaccharides (XOS) production offers a promising route for obtaining value-added compounds from underutilized biomass. In this study, five biocatalysts were produced by solid-state fermentation using water hyacinth (WH) as the substrate and solid support for five fungal strains. Xylanases were extracted from each fermented solid, exhibiting maximum activity between 45–55 °C and pH 5–7. Additionally, the recovery of hemicellulosic fractions from WH and sugarcane bagasse (SCB) reached 14.3 ± 0.91% and 18.4 ± 0.22% of initial dry biomass, respectively. Commercial xylan and hemicellulosic fractions from WH (WHh) and SCB (SCBh), at an initial concentration of 25 g/L, were partially hydrolyzed, releasing 12–18, 9–12 and 2–4 g/L of reducing sugars, respectively, after 6 h of reaction, depending on the enzyme extract used. Xylobiose was detected in all hydrolysates, with the Trichoderma harzianum extract yielding the highest concentrations: 8.3, 4.4, and 2.4 g/L from xylan, WHh, and SCBh, respectively. Hydrolysates supplemented into MRS medium enhanced the growth of Bifidobacterium lactis and Lactococcus lactis compared to the control medium. These findings demonstrate the feasibility of using waste-derived biocatalysts and WH and SCB as inexpensive and abundant sources of hemicellulose to produce XOS-containing hydrolysates with potential prebiotic applications.