Production of Xylanase and Cellulase by Two Isolated Aspergillus Strains Through Solid-State Fermentation of Lignocellulosic Residues

Efficient high-temperature simultaneous saccharification and fermentation of lignocellulosic substrates enabled by engineering thermotolerance in an enzyme-secreting industrial Saccharomyces cerevisiae strain.

The high cost of commercial enzyme cocktails remains a major barrier for lignocellulosic (second-generation) bioethanol production. Simultaneous saccharification and fermentation (SSF) at elevated temperatures using enzyme-secreting yeast can reduce enzyme demand, but is constrained by the limited thermotolerance of industrial strains. In this study, thermotolerant isolates of an inhibitor-tolerant, xylose-utilizing, enzyme-secreting industrial Saccharomyces cerevisiae strain were generated using whole-genome transformation (WGT). Screening in mixed-sugar fermentations at 41 °C identified several improved isolates, of which one isolate, designated Cellusec®4.0, achieved an ethanol titer of 5.45%(v/v), representing an 86% increase compared to the parental strain. This was driven by near-complete utilization of glucose, xylose, and cellobiose. In SSF at 40 °C with sorghum pulp, Cellusec®4.0 reached 5.83%(v/v) ethanol, 24% higher than the parental strain. Fed-batch SSF of pretreated softwood demonstrated the benefit of elevated temperature, with Cellusec®4.0 achieving 4.36%(v/v) ethanol at 40 °C, 29% higher than at 35 °C. In addition, fed-batch SSF of alkali-pretreated sugarcane bagasse at 39 °C using an in-house produced enzyme cocktail resulted in ethanol titers of up to 8.0% (v/v) within 48 h, corresponding to an 83% yield. These results demonstrate that WGT is an effective strategy to introduce thermotolerance into industrial yeast while maintaining key traits. The improved thermotolerance of Cellusec® 4.0 enabled high-temperature SSF, thereby increasing ethanol titers. Combined with retained inhibitor tolerance, enzyme secretion, and mixed-sugar utilization, this supported efficient ethanol production across multiple lignocellulosic substrates under industrially relevant conditions.

Production of Cellulases by Trichoderma, Aspergillus, and Penicillium: Optimization Strategies, Biomass Valorization, and Industrial Perspectives

Fungal cellulases are key biocatalysts for lignocellulosic biomass valorization and the development of sustainable biorefineries and the complementary characteristics of these fungi genera support their application in integrated biomass conversion and future lignocellulosic biorefineries.

Production of Bioethanol from Maize Cob (Zea mays) Using Different Pretreatment Strategies and Fermentation Methods with Saccharomyces cerevisiae and Zymomonas mobilis

Maize cob is an abundant lignocellulosic agricultural residue with potential as a non-edible feedstock for bioethanol production, although its recalcitrant structure limits enzymatic conversion. This study evaluated different chemical and physicochemical pretreatments, enzymatic hydrolysis and fermentation strategies for bioethanol production from maize cob. Pretreated biomass was hydrolysed using commercial cellulase and fermented through Separate Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF) using Saccharomyces cerevisiae and Zymomonas mobilis under controlled conditions. Pretreatment significantly influenced cellulose, hemicellulose, lignin, ash content, solid loss, sugar release and ethanol production. The combination of 4% NaOH and 5% H₂O₂ (N2P1) produced the highest cellulose content (61.84%) and reduced the lignin content to 7.68%. This treatment also achieved the highest ethanol yield of 12.70% under SSF using S. cerevisiae. The highest SSF ethanol yield obtained using Z. mobilis was 12.15% with 4% NaOH and 1% H₂SO₄ (N2H1). SSF generally produced more ethanol than SHF, while combined alkali-based pretreatments performed better than the control and individual treatments. Correlation analysis showed positive associations between cellulose, sugar fractions and ethanol yields, whereas lignin and ash were negatively associated with conversion performance. Overall, combined pretreatment followed by SSF, particularly N2P1 with S. cerevisiae, was the most effective tested approach for bioethanol production from maize cob.

Integrated bioprocess optimization of cellulase and xylanase production by Penicillium argillaceum using lignocellulosic agro-industrial residues

High-cell-density fermentation of Komagataella phaffii enables the overproduction of a novel, broad-substrate endoglucanase, WcEG394 from Fuling (Wolfiporia cocos), for lignocellulose biorefining.

Recombinant WcEG394 efficiently hydrolyzed carboxymethyl cellulose, microcrystalline cellulose, and filter paper, and demonstrated broad substrate specificity toward xylans, pectin, chitin, agarose and agricultural residues such as corn cob and sugarcane bagasse.

A Thermostable Multifunctional GH5 Endoglucanase From Bacillus sp. for Lignocellulosic Biomass Saccharification

BSEG2 is highly thermostable, tolerant of high salt and ionic liquids, and notably resistant to cellobiose inhibition up to 200 mM, suggesting potential to reduce freshwater demand in biomass processing and a strong candidate for simplified, cost-effective enzyme formulations for glucose production from lignocellulosic feedstocks.