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Lignin peroxidase (LiP), which has been studied extensively in white-rot basidiomycetes and their potential to degrade dyes from textile wastewater, plays a role in the biodegradation of lignin from pulp and paper industry wastewater, as well as agricultural waste. Lignin peroxidase (LsLiP) was successfully purified from the newly isolated Lentinus squarrosulus MPN12 with a 47.1-fold purification and a 15.7% yield. After 48 h-incubation, LsLiP was able to decolorize all tested dyes up to 92% for Acid Blue 62 (NY3), followed by Porocion Brilliant blue HGR (PB, 73.5%), Acid Blue 281 (NY5, 70.5%), Acid Blue 113 (IN13, 61%), Acid red 266 (NY7, 56%), and 34.5% for Acid red 299 (NY1), compared to the negative control with the heat-denatured enzyme. The biodegradation potential of LsLiP was further suggested by the change of lignin structure based on Fourier transform infrared (FTIR) analyses. Lignin structure was noticeably changed before and after LsLiP treatment, especially in the fingerprint regions (1600 to 1000 cm-1) and 2930 cm-1 corresponding to the stretching vibrations of various groups in lignin. Thus, LsLiP has potential application in both enzyme-based decolorization of synthetic dyes and lignin biodegradation.

Fungi are known to be capable of biosynthesizing various enzymes such as extracellular hydrolytic enzymes and oxydizing to effectively attack lignocellulose structures in the plant cell wall. Lignin peroxidase (LiP) is an extracellular enzyme biosynthesized in a variety of fungi and first isolated in 1987 from P. chrysosporium. The LiP enzyme is capable of oxydizing compounds with high redox potential (aromatic ring polymers) in the presence of H2O2 resulting in electron oxydation of various compounds including phenols, aromatic amines. Therefore, LiP is an important component of the extracellular enzyme system for lignocellulose degradation. Through polymerization, phenolic compounds reduced reactivity and solubility to be precipitated, thereby reducing toxycity. Therefore, LiP is applied in wastewater cleaning in wastwater containing high phenol content and halogenated phenol toxyns, that are the hydroxyl phenolic compounds. In this study, 39 fungal strains isolated from two ecological regions (Cuc Phuong National Park in Ninh Binh and Muong Phang inDien Bien provinces) were screened for LiP enzyme production. In which, 14 strains grew on a straw substrate medium exhibiting LiP activity with the level ranging from 13.8 to 108.8 U/mL. The LiP of Lentinus squarrosulus MPN 12 identified by molecular analysis exhibited the highest activity as 108 U/mL on basic culture medium and 896 U/mL in optimal culture medium, that was basic medium supplemented with an inducer veratryl alcohol (0.3 g/L), sucrose (10 g/L), urea (5 g/L) for 9 days fermentation at 28 °C, pH 5.0 and 200 rpm. This strain has a high potential for the production of LiP enzyme to convert lignocellulose material.

Feruloyl esterase catalyze the hydrolysis of a wide variety of glycosidic linkages between two or more carbohydrates or between a carbohydrate and a non-carbohydrate moiety. Thereby, they play a role in the initial degradation of lignocelluloses, which may be advantageous for the efficient degradation of the plant cell-wall complex that contains both diverse sugar residues and esterified structures. The contribution of the enzyme AltFAE was purified from Alternaria tenuissima to the conversion of lignocellulosic materials without any chemical pretreatment to release the carbohydrates, was studied. It was determined the activity of feruloyl esterase (AltFAE) production by A. tenuissima in liquid cultures with potential inducing agents sawdust, rice straw, tomato, potato, soybean, and corn starch. At the applied concentrations of soybean (2%), the highest levels ~ 689 U L-1 of enzyme activities were obtained. The disintegrating effect of enzymatic lignocellulose treatment can be significantly improved by using different kinds of hydrolytic and oxidizing enzymes. Synergistic conversion of cane bagasse also resulted in a release of 18.4 mg g-1 total carbohydrates (galactose, glucose, mannose, and xylose) per gram substrate using an “enzyme cocktail” [Cell/Xyl 50 U gds-1, AltFAE 10 U gds-1, and Lac 15 U gds-1] after incubating for 48 hrs at 45oC. The information presented in this paper is helpful to better understand the bioconversion of lignocellulosic materials with the contribution of a feruloyl esterase hydrolase from A. tenuissima to release carbohydrates.

Fungal enzymes are well-known as effective in hydrolyze lignocellulose-rich materials. This decomposition process requires many enzymes to participate in a coordinated factor to hydrolyze the polymer structure. Among them, there are some of popular oxidized enzymes such as lignin peroxidase, mangan peroxidase and laccase. Cellobiose dehydrogenase (CDH) is an extracellular enzyme found in various fungi, it was first discovered in 1974 by Westermark in white rot fungus Trametes verscolor and Phanerochaete chrysosporium. The biological role of CDH has been proven to participate in the decomposition of natural polymers such as cellulose, hemicellulose and lignin by generating hydroxyl radical through Fenton reaction. CDH has unique biochemical and catalytic properties that have been used in biosensors to detect cellodextrin, maltose, lactose and diphenol compounds or in biomedical applications such as lactobionic acid production. Therefore, CDH is an important component of the extracellular enzyme system for lignocellulose decomposition. In this study, 47 fungal strains isolated from rainforests of Cuc Phuong and Muong Phang National Parks and screened for CDH activity. Of which, 33 active fungi exhibited CDH activity from 8.89 to 74.4 U/L during growth on solid medium with rice straw as raw substrate. The highest enzyme production was identified for Coprinellus aureogranulatus (MPG14) reach 77.4 U/L on basic medium and its CDH activity of up to 237.4 U/L under optimal condition: supplemented with carbon source of α- cellulose (20 g/L), nitrogen source (5 g/L peptone) incubated for 12 days at 30℃, pH 5.5 and 200 rpm after inoculation. Thus, the fungus has the potential to exploit the CDH enzyme applied in the pretreatment of lignocellulose-rich materials.

From the biotechnological viewpoint, the enzymatic disintegration of plant lignocellulosic biomass is a promising goal since it would deliver fermentable sugars for the chemical sector. Cellobiose dehydrogenase (CDH) is a vital component of the extracellular lignocellulose-degrading enzyme system of fungi and has a great potential to improve catalyst efficiency for biomass processing. In the present study, a CDH from a newly isolated strain of the agaricomycete Coprinellus aureogranulatus (CauCDH) was successfully purified with a specific activity of 28.9 U mg−1. This pure enzyme (MW = 109 kDa, pI = 5.4) displayed the high oxidative activity towards β-1–4-linked oligosaccharides. Not least, CauCDH was used for the enzymatic degradation of rice straw without chemical pretreatment. As main metabolites, glucose (up to 165.18 ± 3.19 mg g−1), xylose (64.21 ± 1.22 mg g−1), and gluconic acid (5.17 ± 0.13 mg g−1) could be identified during the synergistic conversion of this raw material with the fungal hydrolases (e.g., esterase, cellulase, and xylanase) and further optimization by using an RSM statistical approach.

Three ascomycetous soft-rot fungi belonging to the family Xylariaceae were found to produce high levels of a p-nitrophenyl acetate-hydrolyzing activity during growth on lignocellulosic materials, i.e., wheat straw and beech wood chips. Accordingly, Kretzschmaria deusta, Morchella elata, Xylaria polymorpha were seemingly most noteworthy acetyl esterase producers and, of which, X. polymorpha (strain A35) was chosen for further studies. Induction study indicated that raw carbohydrate sources, such as beech wood, rape straw, birch wood, and wheat straw, were extremely important for acetyl esterase production. Acetyl esterase of X. polymorpha was produced in solid-state culture on wheat straw and purified by different steps of anion-exchange and size-exclusion chromatography. This purified enzyme (M W = 44 kDa and pI values of 3.5–3.6) exhibited the capability to solubilise in vitro beech wood to release water-soluble lignin fragments with molecular masses of 1–3 kDa as analyzed by high performance size exclusion chromatography.

In this study, the unpretreated sugar cane bagasse was milled to a particle size of 0.5 – 1 mm and be used as material for bioconversion into fermentable sugars by using an enzyme cocktail acted synergistically. Experimental planning was used to optimize the enzyme conversion through assessment and analysis of individual parameter. As the result, the optimal condition for enzymatic conversion of sugar cane bagasse into reducing sugar product are at pH = 5, 400C, and 48 h incubation in rate of enzyme (Cell/Xyl, AltFAE, XpoAE) and substrate (bagasse meal) is 3.1. From the above application, the mathematical model is found to describe equation of the bioconversion of bagasse into reducing sugars: = 206.946 + 29.954x1 + 5.501x2 + 7.323x3 + 2.288x2x3 – 7.011; and using flexible algorithm of nonlinear planning to identify optimal conditions of enzyme mixture of conversion into reducing sugars that the reaction reached max = 251.86 mg per gram bagasse with x1 = 1.215, x2 = 1.215, x3 = 1.215 or Cell/Xyl = 1 ml (100U), AltFAE = 0.5 ml (7.56U), XpoAE = 0.4 ml (10.8U) on the test range. Experimental verification has the same result in constant conditons and reached total reducing sugars of 260.2 mg per gram substrate.