https://www.scielo.br/pdf/bjm/v47n1/1517-8382-bjm-47-01-0110.pdf

Enzymatic saccharification and fermentation of cellulosic date palm wastes to glucose and lactic acid

Various economic and environmental sustainability concerns as well as consumer preference for bio-based products from natural sources have paved the way for the development and expansion of biorefining technologies. These involve the conversion of renewable biomass feedstock to fuels and chemicals using biological systems as alternatives to petroleum-based products. Filamentous fungi possess an expansive portfolio of products including the multifunctional organic acids itaconic, fumaric, and malic acids that have wide-ranging current applications and potentially addressable markets as platform chemicals. However, current bioprocessing technologies for the production of these compounds are mostly based on submerged fermentation, which necessitates physicochemical pretreatment and hydrolysis of lignocellulose biomass to soluble fermentable sugars in liquid media. This review will focus on current research work on fungal production of itaconic, fumaric, and malic acids and perspectives on the potential application of solid-state fungal cultivation techniques for the consolidated hydrolysis and organic acid fermentation of lignocellulosic biomass.

Direct fungal fermentation of lignocellulosic biomass into itaconic, fumaric, and malic acids: current and future prospects

Consolidated BioProcessing (CBP) can provide an important contribution to reducing ethanol production costs and moving from cellulosic feedstock to fuel ethanol tanks. Several efforts have so far been focused mainly on CBP category II engineering an ethanologen yeast or bacterium to be cellulolytic, but the limited ability of the category II CBP system for producing enzymes for lignocellulose degradation remains a challenge. As an alternative, category I CBP, aimed at engineering a cellulase producer to be ethanologenic, could be pursued, but it is still in its infancy. Some cellulolytic thermophilic bacteria have been described as potential candidates for category I CBP. However, only fungi naturally produce the needed titers of cellulases required for the complete saccharification of pretreated lignocellulose. In this review, potential of cellulolytic fungi as candidates for category I CBP is discussed.

Potential of fungi as category I Consolidated BioProcessing organisms for cellulosic ethanol production

Efficient, low-cost enzymatic hydrolysis of lignocellulosic residues is essential for cost-effective production of bioethanol. The production of β-glucosidase, β-xylosidase and xylanase by Colletotrichum graminicola was optimized using Response Surface Methodology (RSM). Maximal production occurred in wheat bran. Sugarcane trash, peanut hulls and corncob enhanced β-glucosidase, β-xylosidase and xylanase production, respectively. Maximal levels after optimization reached 159.3 ± 12.7 U g−1, 128.1 ± 6.4 U g−1 and 378.1 ± 23.3 U g−1, respectively, but the enzymes were produced simultaneously at good levels under culture conditions optimized for each one of them. Optima of pH and temperature were 5.0 and 65 °C for the three enzymes, which maintained full activity for 72 h at 50 °C and for 120 min at 60 °C (β-glucosidase) or 65 °C (β-xylosidase and xylanase). Mixed with Trichoderma reesei cellulases, C. graminicola crude extract hydrolyzed raw sugarcane trash with glucose yield of 33.1% after 48 h, demonstrating good potential to compose efficient cocktails for lignocellulosic materials hydrolysis.

https://www.mdpi.com/1422-0067/14/2/2875/pdf

Optimization of β-glucosidase, β-xylosidase and xylanase production by Colletotrichum graminicola under solid-state fermentation and application in raw sugarcane trash saccharification.

Lignocellulolytic enzymes constitute a large group of mainly extracellular proteins including ligninolytic enzymes (peroxidases and oxidases) and hydrolytic enzymes (cellulases, hemicellulases, pectinases, chitinases, amylases, proteases, esterases, and mannases). These enzymes have attracted a wide range of industrial and environmental applications including pulping, de-inking, decolourization and detoxification of textile wastes, wastewater treatment and bioremediation of polluted soils. This work gives an updated review and summarizes the main fungal strains, substrates, lignocellulosic enzymes and their applications with an emphasis on tropical fungi. The main groups of lignocellulolytic enzymes and their applications are summarized in a manner that provides a useful reference for both enzyme scientists and technologists. Moreover, current debates and significant gaps in the lignocellulolytic fungal enzymes’ research have been highlighted. Future prospects in lignocellulolytic enzymes research are directed towards bioprospecting of robust novel fungal enzymes to overcome the challenge of recalcitrant substrates, physiological regulations of enzymes, use of novel inducers to enhance production, use of multiple fungal strains or mixture of enzymes, gene cloning to screen for new generation of enzymes and nanobiotechnologal applications in enzymology. This review revealed that for the past seven years, lignocellulolytic enzymes research and development have been steadily advancing from cellular to molecular; and from micro- to nano- levels, and more efforts should be directed to new research frontiers including molecular cloning, sequencing and functional genomics.

	 

	Key words: Biodegradation, lignocellulolytic enzymes activities, liquid culture, nanobiotechnology, solid state fermentation.

/pdf/lignocellulolytic-enzymes-from-tropical-fungi-types-rz9cisuq53.pdf

Lignocellulolytic enzymes from tropical fungi: Types, substrates and applications

The ability of Aspergillus terreus for the production of cellulolytic enzymes and reduction of lignocellulose contents of rice straw in solid state fermentation was investigated in this study. Results suggested that, 8 days fermentation was appropriate, with enzymes activities as follows: FPase = 410.76 U/gDM, CMCase = 351.96U/gDM, -glucosidase = 16.37 U/gDM, xylanase = 6166.01 U/gDM and amyloglucosidase = 425.04 U/gDM (with maximum 993.71 U/gDM on day 6). In addition, the solid state fermentation significantly (P < 0.01) reduced the concentrations of NDF, ADF, cellulose and hemicellulose in the rice straw by 19.96, 13.8, 16.32 and 32.87%, respectively. The high degradation of the hemicellulose was reflected by the high activity of xylanase enzyme, which hydrolyses xylan in hemicellulose to xylose. Higher reducing sugar and microbial cell mass productions were also obtained after 8 days fermentation. Present data showed that, A. terreus is capable of producing high quantity of cellulolytic enzymes for the reduction of lignocellulose contents of biomass in a shorter incubation time when compared with the previously reported for biological treatment of agricultural by-products using white rot fungi. Key words : Aspergillus terreus, biomass, biological treatment, enzyme activity, solid state fermentation.

/pdf/efficiency-of-rice-straw-lignocelluloses-degradability-by-2p9gmefjqm.pdf

Efficiency of rice straw lignocelluloses degradability by Aspergillus terreus ATCC 74135 in solid state fermentation

The objective of this study was to evaluate the use of solid state fermentation for the improvement of the quality of rice straw as animal feed. Rice straw was fermented using Aspergillus niger (K8) with and without additional nitrogen source (urea). Cellulose, hemicelluloses, organic matter (OM), dry matter (DM), acid detergent fibre (ADF), neutral detergent fibre (NDF) and acid detergent lignin (ADL) contents of rice straw were determined before and after 10 days of fermentation. Fermentation has significant (P 0.05), but crude protein (CP) increased significantly (P < 0.01) after fermentation. In vitro gas production technique was used to evaluate the effect of the biological treatment on activity of rumen microorganisms. Fermentation of rice straw using A. niger significantly reduced total gas production (P < 0.01), DM disappearance (P < 0.01) and acetate, propionate and  total volatile fatty acids (VFA) production (P < 0.05). Results of the present study showed that solid state fermentation of rice straw using A. niger reduced lignocellulose content, but has negative effect on microbial activity in the rumen ecosystem, presumably due to antagonistic activity of A. niger , or other intermediate products from the fermentation, on the rumen microorganisms. Key words: Aspergillus niger , biomass, solid state fermentation, biological treatment, in vitro gas production.

/pdf/effects-of-aspergillus-niger-k8-on-nutritive-value-of-rice-4kqgamo4sg.pdf

M. Rosfarizan

Papers

Efficiency of rice straw lignocelluloses degradability by Aspergillus terreus ATCC 74135 in solid state fermentation

Effects of Aspergillus niger (K8) on nutritive value of rice straw