Differential Carbon Catabolite Repression and Hemicellulolytic Ability among Pathotypes of Colletotrichum lindemuthianum against Natural Plant Substrates.

Colletotrichum lindemuthianum is a phytopathogenic fungus that causes anthracnose in common beans (Phaseolus vulgaris) and presents a great diversity of pathotypes with different levels of virulence against bean varieties worldwide. The purpose of this study was to establish whether pathotypic diversity is associated with differences in the mycelial growth and secretion of plant-cell-wall-degrading enzymes (PCWDEs). We evaluated growth, hemicellulase and cellulase activity, and PCWDE secretion in four pathotypes of C. lindemuthianum in cultures with glucose, bean hypocotyls and green beans of P. vulgaris, and water hyacinth (Eichhornia crassipes). The results showed differences in the mycelial growth, hemicellulolytic activity, and PCWDE secretion among the pathotypes. Glucose was not the preferred carbon source for the best mycelial growth in all pathotypes, each of which showed a unique PCWDE secretion profile, indicating different levels of carbon catabolite regulation (CCR). The pathotypes showed a high differential hemicellulolytic capacity to degrade host and water hyacinth tissues, suggesting CCR by pentoses and that there are differences in the absorption and metabolism of different monosaccharides and/or disaccharides. We propose that different levels of CCR could optimize growth in different host tissues and could allow for consortium behavior in interactions with bean crops.

Fusarium graminearum as a producer of xylanases with low cellulases when grown on wheat bran.

The xylanolytic potential of endophytic fungi isolated from leaves of Theobroma cacao was explored for the first time. Four fungal strains showed significant amounts of xylanase activity and low cellulase levels when grown on wheat bran as the sole carbon source. Strain Ec220 of Fusarium graminearum had the highest xylanase production (1.79 U/ml), whereas its cellulase activity was minimal (0.24 U/ml). Optimal conditions for xylanase production were: 154 h of incubation time, pH 5.79 and 29.8 °C. Furthermore, two protein spots detected by two-dimensional gel electrophoresis showed molecular weights (26.05 and 27.70 kDa) and isoelectric points (6.18 and 9.20) corresponding to previously reported F. graminearum xylanases, Xyl A and Xyl B, respectively. Therefore, endophytic fungi of T. cacao can be an important source of xylanolytic activities when cultured on wheat bran, and xylanases with low cellulases found in strain Ec220 require further characterization as they show promise for possible industrial applications.

Hemicellulolytic bacteria in the anterior intestine of the earthworm Eisenia fetida (Sav.).

Tropical agriculture produces large amounts of lignocellulosic residues that can potentially be used as a natural source of value-added products. The complexity of lignocellulose makes industrial-scale processing difficult. New processing techniques must be developed to improve the yield and avoid this valuable resource going to waste. Hemicelluloses comprise a variety of polysaccharides with different backbone compositions and decorations (such as methylations and acetylations), and form part of an intricate framework that confers structural stability to the plant cell wall. Organisms that are able to degrade these biopolymers include earthworms (Eisenia fetida), which can rapidly decompose a wide variety of lignocellulosic substrates. This ability probably derives from enzymes and symbiotic microorganisms in the earthworm gut. In this work, two substrates with similar C/N ratios but different hemicellulose content were selected. Palm fibre and coffee husk have relatively high (28%) and low (5%) hemicellulose contents, respectively. A vermicomposting mixture was prepared for the earthworms to feed on by mixing a hemicellulose substrate with organic market waste. Xylanase activity was determined in earthworm gut and used as a selection criterion for the isolation of hemicellulose-degrading bacteria. Xylanase activity was similar for both substrates, even though their physicochemical properties principally pH and electrical conductivity, as shown by the MANOVA analysis) were different for the total duration of the experiment (120 days). Xylanolytic strains isolated from earthworm gut were identified by sequence analysis of the 16S rRNA gene. Our results indicate that the four Actinobacteria, two Proteobacteria, and one Firmicutes isolated are active participants of the xylanolytic degradation by microbiota in the intestine of E. fetida. Most bacteria were more active at pH 7 and 28 °C, and those with higher activities are reported as being facultatively anaerobic, coinciding with the microenvironment reported for the earthworm gut. Each strain had a different degradative capacity.

The boosting effect of recombinant hemicellulases on the enzymatic hydrolysis of steam-treated sugarcane bagasse.

To increase the efficiency of enzyme cocktails in deconstructing cellulose and hemicelluloses present in the plant cell wall, a combination of enzymes with complementary activities is required. Xylan is the main hemicellulose component of energy crops and for its complete hydrolysis a system consisting of several enzymes acting cooperatively, including endoxylanases (XYN), ß-xylosidases (XYL) and α-l-arabinofuranosidases (ABF) is necessary. The current work aimed at evaluating the effect of recombinant hemicellulolytic enzymes on the enzymatic hydrolysis of steam-exploded sugarcane bagasse (SEB). One recombinant endoxylanase (HXYN2) and one recombinant ß-xylosidase (HXYLA) from Humicola grisea var thermoidea, together with an α-l-arabinofuranosidase (AFB3) from Penicillium pupurogenum, all produced in Pichia pastoris, were used to formulate an efficient enzyme mixture for SEB hydrolysis using a 23 Central Composite Rotatable Design (CCRD). The most potent enzyme for SEB hydrolysis was ABF3. Subsequently, the optimal enzyme mixture was used in combination with commercial cellulases (Accellerase 1500), either simultaneously or in sequential experiments. The supplementation of Accellerase 1500 with hemicellulases enhanced the glucose yield from SEB hydrolysis by 14.6%, but this effect could be raised to 50% when hemicellulases were added prior to hydrolysis with commercial cellulases. These results were supported by scanning electron microscopy, which revealed the effect of enzymatic hydrolysis on SEB fibers. Our results show the potential of complementary enzyme activities to improve enzymatic hydrolysis of SEB, thus improving the efficiency of the hydrolytic process.

Integrative Proteomic Analysis of Digestive Tract Glycosidases from the Invasive Golden Apple Snail, Pomacea canaliculata.

The freshwater snail Pomacea canaliculata, an invasive species of global significance, possesses a well-developed digestive system and diverse feeding mechanisms enabling the intake of a wide variety of food. The identification of glycosidases in adult snails would increase the understanding of their digestive physiology and potentially generate new opportunities to eradicate and/or control this invasive species. In this study, liquid chromatography coupled to tandem mass spectrometry was applied to define the occurrence, diversity, and origin of glycoside hydrolases along the digestive tract of P. canaliculata. A range of cellulases, hemicellulases, amylases, maltases, fucosidases, and galactosidases were identified across the digestive tract. The digestive gland and the contents of the crop and style sac yield a higher diversity of glycosidase-derived peptides. Subsequently, peptides derived from 81 glycosidases (46 proteins from the public database and 35 uniquely from the transcriptome database) that were distributed among 13 glycoside hydrolase families were selected and quantified using multiple reaction monitoring mass spectrometry. This study showed a high glycosidase abundance and diversity in the gut contents of P. canaliculata which participate in extracellular digestion of complex dietary carbohydrates. Salivary and digestive glands were the main tissues involved in their synthesis and secretion.

Use of an (Hemi) Cellulolytic Enzymatic Extract Produced by Aspergilli Species Consortium in the Saccharification of Biomass Sorghum.

This study evaluated the production of lignocellulose-degrading enzymes by solid-state fermentation (SSF) using a microbial consortium of Aspergillus fumigatus SCBM6 and A. niger SCBM1 (AFN extract). The fungal strains were cultivated in sugarcane bagasse (SCB) and wheat bran (WB) as lignocellulosic substrates for 7 days at 30 °C. After SSF, the highest peaks of enzyme production were 150 and 80 U g-1 for ß-xylosidase and ß-glucosidase at 48 h, 375 U g-1 for xylanase at 96 h, and 80 U g-1 for endoglucanase and 4 U g-1 for cellulase activity on filter paper (FPase) at 144 h. The efficiency of the produced AFN extract was investigated in the enzymatic hydrolysis of crude biomass sorghum (BS) and after the removal of extractives (ES). After saccharification, the glucose and xylose concentrations were 10× superior in ES than in BS hydrolysate (2.5 g L-1 after 12 h). The presence of inhibitors of alcoholic fermentation, such as formic acid, was also reduced in ES hydrolysates, indicating that the removal of extractives positively contributed to the effectiveness of enzymatic hydrolysis of biomass sorghum using AFN extract.

Endophytic Actinomycetes as Potential Producers of Hemicellulases and Related Enzymes for Plant Biomass Degradation

Abstract Tailor made enzymatic preparation must be design to hydrolyze efficiently plant biomass, once that each plant biomass possesses a distinct cell wall composition. Most of actinomycetes used for plant cell wall degradation are focused on the cellulases and xylanases production. However, a wide range of enzymes must be produced for an efficient degradation of lignocellulose materials. During the last decade several unusual environments were studied to obtain strains that produce glycohydrolases with innovator characteristics. In this context, the present work concerned the selection of endophytic actinomycetes as producers of hemicellulases and related enzymes with different enzymatic profiles, for use in the deconstruction of lignocellulosic biomass. A total of 45 Brazilian actinomycetes previously isolated from plants (endophytics) and soil were prospected for hemicellulases and β-glucosidase production. Four strains highlighted for hemicellulase production (DR61, DR63, DR69 and DR66) and were selected for cultivation under other inductors substrates (xylan and pectin). All strains belong to Streptomyces genera and have their extracts tested for degradation of several hemicellulolytic substrates. The strains presented different glicohydrolyse enzymes profiles mainly for xylans and glucans that can be used for specific formulations of enzymes applied on the biomass deconstruction, principally on sugar cane bagasse.

Biomass sorghum as a novel substrate in solid-state fermentation for the production of hemicellulases and cellulases by Aspergillus niger and A. fumigatus.

AIMS: We investigated the role of carbon and nitrogen sources in the production of cellulase and hemicellulase by Aspergillus strains. METHODS AND RESULTS: The strains Aspergillus niger SCBM1 and Aspergillus fumigatus SCBM6 were cultivated under solid-state fermentation (SSF), with biomass sorghum (BS) and wheat bran (WB) as lignocellulosic substrates, in different proportions, along with variable nitrogen sources. The best SSF condition for the induction of such enzymes was observed employing A. niger SCBM1 in BS supplemented with peptone; maximum production levels were achieved as follows: 72 h of fermentation for xylanase and exoglucanase (300·07 and 30·64 U g-1 respectively), 120 h for ß-glucosidase and endoglucanase (54·90 and 41·47 U g-1 respectively) and 144 h for ß-xylosidase (64·88 U g-1 ). CONCLUSIONS: This work demonstrated the viability of the use of BS for the production of hemi- and cellulolytic enzymes; the high concentration of celluloses in BS could be associated with the significant production of cellulases, mainly exoglucanase. SIGNIFICANCE AND IMPACT OF THE STUDY: This is the first study which presents the promising use of biomass sorghum (genetically modified sorghum to increase its biomass content) as an alternative carbon source for the production of enzymes by SSF.

In vitro degradability of coffee husks treated with doses of fibrolytic enzymes for use in ruminant nutrition / Avaliação da degradabilidade in vitro da casca de café tratada com doses de enzimas fibrolíticas para aproveitamento na alimentação de ruminantes

The agricultural activity has generated a progressive amount of waste, which needs a proper treatment to avoid negative environmental impacts. At the same time, values can be added to such waste, as its use in animal feed. This research was conducted at the laboratory of Animal Nutrition, State University of Southwestern Bahia, campuses of Vitória da Conquista and Itapetinga. The objective of this study was to evaluate the effect of coffee husks on ruminant feeds by increasing doses of fibrolytic enzymes, evaluating their effects on in vitro ruminal degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (FDA) of the coffee husk (CH). The experiment was a completely randomized design in a 2x4 factorial scheme. It compounded the following treatments: Coffee husk (CH1): 1.5% enzymes (E) and 24 h enzymatic action (EA); CH2: 3.0% (E) and 24h (EA); CH3: 4.5% (E) and 24 h (EA); CH4: 6% (E) and 24 h (EA); CH5: 1.5% (E) 48 h (EA); CH6: 3% (E) and 48h (EA); CH7: 4.5% (E) and 48h (EA); and CH8: 6% (E) and 48 h (EA), all based on dry matter. An improvement in the degradability of the nutritional parameters MS, NDF, and FDA occurred with the addition of enzymes, with 3% enzyme addition being the best level, and 24 hours, as the best action time. In addition to that, as the EA on coffee husk increased, the degradation rate decreased. Therefore, the use of enzymes can improve the digestibility of the fibrous fraction, enabling the use of the coffee husk andpossibly other agroindustrial residues, thus minimizing their adverse effects on nature.(AU)

A atividade agrícola tem gerado uma quantidade progressiva de resíduos, os quais necessitam serem tratados de forma adequada para que não promovam impactos ambientais negativos e que, ao mesmo tempo, sejam agregados valores a estes para que possam ser utilizados na alimentação animal. A pesquisa foi conduzida no laboratório de Nutrição Animal da Universidade Estadual do Sudoeste da Bahia, campus de Vitória da Conquista e Itapetinga. Objetivou-se o aproveitamento da casca de café na alimentação de ruminantes através do tratamento com doses crescentes de enzimas fibrolíticas avaliando seus efeitos sobre a degradabilidade ruminal in vitro da matéria seca (MS), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) da casca de café (CC). O delineamento experimental utilizado foi inteiramente casualisado, com esquema fatorial 2x4, constituindo os seguintes tratamentos Casca de café (CC1): 1,5% de Enzimas (E) e 24h de Ação Enzimática (AE); CC2: 3% (E) e 24h (AE); CC3: 4,5%(E) e 24 h(AE); CC4:6 % (E) e 24 h(AE); CC5: 1,5% (E) 48 h(AE); CC6: 3% (E) e 48h(AE); CC7:4,5% (E) e 48h(AE); CC8: 6% (E) e 48 h(AE), com base na matéria seca. Constatou-se que com adição de enzimas, ocorreu uma melhora na degradabilidade dos parâmetros nutricionais MS, FDN e FDA, sendo 3% de enzimas o melhor nível e 24 horas o melhor tempo de ação. Além disso, à medida que a ação enzimática na casca de café aumentou, a taxa de degradação diminuiu. Portanto, o uso de enzimaspode melhorar a digestibilidade da fração fibrosa, possibilitando o uso da casca de café e possivelmenteoutros resíduos agroindustriais, minimizando assim seus efeitos adversos sobre a natureza.(AU)

In vitro degradability of coffee husks treated with doses of fibrolytic enzymes for use in ruminant nutrition / Avaliação da degradabilidade in vitro da casca de café tratada com doses de enzimas fibrolíticas para aproveitamento na alimentação de ruminantes

The agricultural activity has generated a progressive amount of waste, which needs a proper treatment to avoid negative environmental impacts. At the same time, values can be added to such waste, as its use in animal feed. This research was conducted at the laboratory of Animal Nutrition, State University of Southwestern Bahia, campuses of Vitória da Conquista and Itapetinga. The objective of this study was to evaluate the effect of coffee husks on ruminant feeds by increasing doses of fibrolytic enzymes, evaluating their effects on in vitro ruminal degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (FDA) of the coffee husk (CH). The experiment was a completely randomized design in a 2x4 factorial scheme. It compounded the following treatments: Coffee husk (CH1): 1.5% enzymes (E) and 24 h enzymatic action (EA); CH2: 3.0% (E) and 24h (EA); CH3: 4.5% (E) and 24 h (EA); CH4: 6% (E) and 24 h (EA); CH5: 1.5% (E) 48 h (EA); CH6: 3% (E) and 48h (EA); CH7: 4.5% (E) and 48h (EA); and CH8: 6% (E) and 48 h (EA), all based on dry matter. An improvement in the degradability of the nutritional parameters MS, NDF, and FDA occurred with the addition of enzymes, with 3% enzyme addition being the best level, and 24 hours, as the best action time. In addition to that, as the EA on coffee husk increased, the degradation rate decreased. Therefore, the use of enzymes can improve the digestibility of the fibrous fraction, enabling the use of the coffee husk andpossibly other agroindustrial residues, thus minimizing their adverse effects on nature.

A atividade agrícola tem gerado uma quantidade progressiva de resíduos, os quais necessitam serem tratados de forma adequada para que não promovam impactos ambientais negativos e que, ao mesmo tempo, sejam agregados valores a estes para que possam ser utilizados na alimentação animal. A pesquisa foi conduzida no laboratório de Nutrição Animal da Universidade Estadual do Sudoeste da Bahia, campus de Vitória da Conquista e Itapetinga. Objetivou-se o aproveitamento da casca de café na alimentação de ruminantes através do tratamento com doses crescentes de enzimas fibrolíticas avaliando seus efeitos sobre a degradabilidade ruminal in vitro da matéria seca (MS), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) da casca de café (CC). O delineamento experimental utilizado foi inteiramente casualisado, com esquema fatorial 2x4, constituindo os seguintes tratamentos Casca de café (CC1): 1,5% de Enzimas (E) e 24h de Ação Enzimática (AE); CC2: 3% (E) e 24h (AE); CC3: 4,5%(E) e 24 h(AE); CC4:6 % (E) e 24 h(AE); CC5: 1,5% (E) 48 h(AE); CC6: 3% (E) e 48h(AE); CC7:4,5% (E) e 48h(AE); CC8: 6% (E) e 48 h(AE), com base na matéria seca. Constatou-se que com adição de enzimas, ocorreu uma melhora na degradabilidade dos parâmetros nutricionais MS, FDN e FDA, sendo 3% de enzimas o melhor nível e 24 horas o melhor tempo de ação. Além disso, à medida que a ação enzimática na casca de café aumentou, a taxa de degradação diminuiu. Portanto, o uso de enzimaspode melhorar a digestibilidade da fração fibrosa, possibilitando o uso da casca de café e possivelmenteoutros resíduos agroindustriais, minimizando assim seus efeitos adversos sobre a natureza.

In vitro degradability of coffee husks treated with doses of fibrolytic enzymes for use in ruminant nutrition / Avaliação da degradabilidade in vitro da casca de café tratada com doses de enzimas fibrolíticas para aproveitamento na alimentação de ruminantes

The agricultural activity has generated a progressive amount of waste, which needs a proper treatment to avoid negative environmental impacts. At the same time, values can be added to such waste, as its use in animal feed. This research was conducted at the laboratory of Animal Nutrition, State University of Southwestern Bahia, campuses of Vitória da Conquista and Itapetinga. The objective of this study was to evaluate the effect of coffee husks on ruminant feeds by increasing doses of fibrolytic enzymes, evaluating their effects on in vitro ruminal degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (FDA) of the coffee husk (CH). The experiment was a completely randomized design in a 2x4 factorial scheme. It compounded the following treatments: Coffee husk (CH1): 1.5% enzymes (E) and 24 h enzymatic action (EA); CH2: 3.0% (E) and 24h (EA); CH3: 4.5% (E) and 24 h (EA); CH4: 6% (E) and 24 h (EA); CH5: 1.5% (E) 48 h (EA); CH6: 3% (E) and 48h (EA); CH7: 4.5% (E) and 48h (EA); and CH8: 6% (E) and 48 h (EA), all based on dry matter. An improvement in the degradability of the nutritional parameters MS, NDF, and FDA occurred with the addition of enzymes, with 3% enzyme addition being the best level, and 24 hours, as the best action time. In addition to that, as the EA on coffee husk increased, the degradation rate decreased. Therefore, the use of e

A atividade agrícola tem gerado uma quantidade progressiva de resíduos, os quais necessitam serem tratados de forma adequada para que não promovam impactos ambientais negativos e que, ao mesmo tempo, sejam agregados valores a estes para que possam ser utilizados na alimentação animal. A pesquisa foi conduzida no laboratório de Nutrição Animal da Universidade Estadual do Sudoeste da Bahia, campus de Vitória da Conquista e Itapetinga. Objetivou-se o aproveitamento da casca de café na alimentação de ruminantes através do tratamento com doses crescentes de enzimas fibrolíticas avaliando seus efeitos sobre a degradabilidade ruminal in vitro da matéria seca (MS), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) da casca de café (CC). O delineamento experimental utilizado foi inteiramente casualisado, com esquema fatorial 2x4, constituindo os seguintes tratamentos Casca de café (CC1): 1,5% de Enzimas (E) e 24h de Ação Enzimática (AE); CC2: 3% (E) e 24h (AE); CC3: 4,5%(E) e 24 h(AE); CC4:6 % (E) e 24 h(AE); CC5: 1,5% (E) 48 h(AE); CC6: 3% (E) e 48h(AE); CC7:4,5% (E) e 48h(AE); CC8: 6% (E) e 48 h(AE), com base na matéria seca. Constatou-se que com adição de enzimas, ocorreu uma melhora na degradabilidade dos parâmetros nutricionais MS, FDN e FDA, sendo 3% de enzimas o melhor nível e 24 horas o melhor tempo de ação. Além disso, à medida que a ação enzimática na casca de

In vitro degradability of coffee husks treated with doses of fibrolytic enzymes for use in ruminant nutrition / Avaliação da degradabilidade in vitro da casca de café tratada com doses de enzimas fibrolíticas para aproveitamento na alimentação de ruminantes

The agricultural activity has generated a progressive amount of waste, which needs a proper treatment to avoid negative environmental impacts. At the same time, values can be added to such waste, as its use in animal feed. This research was conducted at the laboratory of Animal Nutrition, State University of Southwestern Bahia, campuses of Vitória da Conquista and Itapetinga. The objective of this study was to evaluate the effect of coffee husks on ruminant feeds by increasing doses of fibrolytic enzymes, evaluating their effects on in vitro ruminal degradability of dry matter (DM), neutral detergent fiber (NDF), and acid detergent fiber (FDA) of the coffee husk (CH). The experiment was a completely randomized design in a 2x4 factorial scheme. It compounded the following treatments: Coffee husk (CH1): 1.5% enzymes (E) and 24 h enzymatic action (EA); CH2: 3.0% (E) and 24h (EA); CH3: 4.5% (E) and 24 h (EA); CH4: 6% (E) and 24 h (EA); CH5: 1.5% (E) 48 h (EA); CH6: 3% (E) and 48h (EA); CH7: 4.5% (E) and 48h (EA); and CH8: 6% (E) and 48 h (EA), all based on dry matter. An improvement in the degradability of the nutritional parameters MS, NDF, and FDA occurred with the addition of enzymes, with 3% enzyme addition being the best level, and 24 hours, as the best action time. In addition to that, as the EA on coffee husk increased, the degradation rate decreased. Therefore, the use of e

A atividade agrícola tem gerado uma quantidade progressiva de resíduos, os quais necessitam serem tratados de forma adequada para que não promovam impactos ambientais negativos e que, ao mesmo tempo, sejam agregados valores a estes para que possam ser utilizados na alimentação animal. A pesquisa foi conduzida no laboratório de Nutrição Animal da Universidade Estadual do Sudoeste da Bahia, campus de Vitória da Conquista e Itapetinga. Objetivou-se o aproveitamento da casca de café na alimentação de ruminantes através do tratamento com doses crescentes de enzimas fibrolíticas avaliando seus efeitos sobre a degradabilidade ruminal in vitro da matéria seca (MS), fibra em detergente neutro (FDN) e fibra em detergente ácido (FDA) da casca de café (CC). O delineamento experimental utilizado foi inteiramente casualisado, com esquema fatorial 2x4, constituindo os seguintes tratamentos Casca de café (CC1): 1,5% de Enzimas (E) e 24h de Ação Enzimática (AE); CC2: 3% (E) e 24h (AE); CC3: 4,5%(E) e 24 h(AE); CC4:6 % (E) e 24 h(AE); CC5: 1,5% (E) 48 h(AE); CC6: 3% (E) e 48h(AE); CC7:4,5% (E) e 48h(AE); CC8: 6% (E) e 48 h(AE), com base na matéria seca. Constatou-se que com adição de enzimas, ocorreu uma melhora na degradabilidade dos parâmetros nutricionais MS, FDN e FDA, sendo 3% de enzimas o melhor nível e 24 horas o melhor tempo de ação. Além disso, à medida que a ação enzimática na casca de

Insights into the mechanism of enzymatic hydrolysis of xylan.

Hemicelluloses are a vast group of complex, non-cellulosic heteropolysaccharides that are classified according to the principal monosaccharides present in its structure. Xylan is the most abundant hemicellulose found in lignocellulosic biomass. In the current trend of a more effective utilization of lignocellulosic biomass and developments of environmentally friendly industrial processes, increasing research activities have been directed to a practical application of the xylan component of plants and plant residues as biopolymer resources. A variety of enzymes, including main- and side-chain acting enzymes, are responsible for xylan breakdown. Xylanase is a main-chain enzyme that randomly cleaves the ß-1,4 linkages between the xylopyranosyl residues in xylan backbone. This enzyme presents varying folds, mechanisms of action, substrate specificities, hydrolytic activities, and physicochemical characteristics. This review pays particular attention to different aspects of the mechanisms of action of xylan-degrading enzymes and their contribution to improve the production of bioproducts from plant biomass. Furthermore, the influence of phenolic compounds on xylanase activity is also discussed.

Production of beta-glucosidase on solid-state fermentation by Lichtheimia ramosa in agroindustrial residues: characterization and catalytic properties of the enzymatic extract

Background β-Glucosidases catalyze the hydrolysis of cellobiose and cellodextrins, releasing glucose as the main product. This enzyme is used in the food, pharmaceutical, and biofuel industries. The aim of this work is to improve the β-glucosidase production by the fungus Lichtheimia ramosa by solid-state fermentation (SSF) using various agroindustrial residues and to evaluate the catalytic properties of this enzyme. Results A high production of β-glucosidase, about 274 U/g of dry substrate (or 27.4 U/mL), was obtained by cultivating the fungus on wheat bran with 65% of initial substrate moisture, at 96 h of incubation at 35°C. The enzymatic extract also exhibited carboxymethylcellulase (CMCase), xylanase, and β-xylosidase activities. The optimal activity of β-glucosidase was observed at pH 5.5 and 65°C and was stable over a pH range of 3.5-10.5. The enzyme maintained its activity (about 98% residual activity) after 1 h at 55°C. The enzyme was subject to reversible competitive inhibition with glucose and showed high catalytic activity in solutions containing up to 10% of ethanol. Conclusions β-Glucosidase characteristics associated with its ability to hydrolyze cellobiose, underscore the utility of this enzyme in diverse industrial processes.

Efficient production of lignocellulolytic enzymes xylanase, ß-xylosidase, ferulic acid esterase and ß-glucosidase by the mutant strain Aspergillus awamori 2B.361 U2/1.

The production of xylanase, ß-xylosidase, ferulic acid esterase and ß-glucosidase by Aspergillus awamori 2B.361 U2/1, a hyper producer of glucoamylase and pectinase, was evaluated using selected conditions regarding nitrogen nutrition. Submerged cultivations were carried out at 30 °C and 200 rpm in growth media containing 30 g wheat bran/L as main carbon source and either yeast extract, ammonium sulfate, sodium nitrate or urea, as nitrogen sources; in all cases it was used a fixed molar carbon to molar nitrogen concentration of 10.3. The use of poor nitrogen sources favored the accumulation of xylanase, ß-xylosidase and ferulic acid esterase to a peak concentrations of 44,880; 640 and 118 U/L, respectively, for sodium nitrate and of 34,580, 685 and 170 U/L, respectively, for urea. However, the highest ß-glucosidase accumulation of 10,470 U/L was observed when the rich organic nitrogen source yeast extract was used. The maxima accumulation of filter paper activity, xylanase, ß-xylosidase, ferulic acid esterase and ß-glucosidase by A. awamori 2B.361 U2/1 was compared to that produced by Trichoderma reesei Rut-C30. The level of ß-glucosidase was over 17-fold higher for the Aspergillus strain, whereas the levels of xylanase and ß-xylosidase were over 2-fold higher. This strain also produced ferulic acid esterase (170 U/L), which was not detected in the T. reesei culture.

Efficient production of lignocellulolytic enzymes xylanase, -xylosidase, ferulic acid esterase and -glucosidase by the mutant strain Aspergillus awamori 2B.361 U2/1

The production of xylanase, -xylosidase, ferulic acid esterase and -glucosidase by Aspergillus awamori 2B.361 U2/1, a hyper producer of glucoamylase and pectinase, was evaluated using selected conditions regarding nitrogen nutrition. Submerged cultivations were carried out at 30 ºC and 200 rpm in growth media containing 30 g wheat bran/L as main carbon source and either yeast extract, ammonium sulfate, sodium nitrate or urea, as nitrogen sources, in all cases it was used a fixed molar carbon to molar nitrogen concentration of 10.3. The use of poor nitrogen sources favored the accumulation of xylanase, -xylosidase and ferulic acid esterase to a peak concentrations of 44,880, 640 and 118 U/L, respectively, for sodium nitrate and of 34,580, 685 and 170 U/L, respectively, for urea. However, the highest -glucosidase accumulation of 10,470 U/L was observed when the rich organic nitrogen source yeast extract was used. The maxima accumulation of filter paper activity, xylanase, -xylosidase, ferulic acid esterase and -glucosidase by A. awamori 2B.361 U2/1 was compared to that produced by Trichoderma reesei Rut-C30. The level of -glucosidase was over 17-fold higher for the Aspergillus strain, whereas the levels of xylanase and -xylosidase were over 2-fold higher. This strain also produced ferulic acid esterase (170 U/L), which was not detected in the T. reesei culture.(AU)

Efficient production of lignocellulolytic enzymes xylanase, β-xylosidase, ferulic acid esterase and β-glucosidase by the mutant strain Aspergillus awamori 2B.361 U2/1

The production of xylanase, β-xylosidase, ferulic acid esterase and β-glucosidase by Aspergillus awamori 2B.361 U2/1, a hyper producer of glucoamylase and pectinase, was evaluated using selected conditions regarding nitrogen nutrition. Submerged cultivations were carried out at 30 ºC and 200 rpm in growth media containing 30 g wheat bran/L as main carbon source and either yeast extract, ammonium sulfate, sodium nitrate or urea, as nitrogen sources; in all cases it was used a fixed molar carbon to molar nitrogen concentration of 10.3. The use of poor nitrogen sources favored the accumulation of xylanase, β-xylosidase and ferulic acid esterase to a peak concentrations of 44,880; 640 and 118 U/L, respectively, for sodium nitrate and of 34,580, 685 and 170 U/L, respectively, for urea. However, the highest β-glucosidase accumulation of 10,470 U/L was observed when the rich organic nitrogen source yeast extract was used. The maxima accumulation of filter paper activity, xylanase, β-xylosidase, ferulic acid esterase and β-glucosidase by A. awamori 2B.361 U2/1 was compared to that produced by Trichoderma reesei Rut-C30. The level of β-glucosidase was over 17-fold higher for the Aspergillus strain, whereas the levels of xylanase and β-xylosidase were over 2-fold higher. This strain also produced ferulic acid esterase (170 U/L), which was not detected in the T. reesei culture.

Extracellular enzymes of Fusarium graminearum isolates

Fusarium graminearum isolates from three different agroecological regions in Argentina were examined according to the production of different extracellular enzyme activities of potential biotechnological interest: pectinases (PGase: polygalacturonase and PMGase: polymethylgalacturonase), cellulase (CMCase: carboxymethylcellulase) and hemicellulase (xylanase). The isolates were grown in minimum salt medium supplemented with 0.25 percent glucose, 0.125 percent citric pectin and 0.125 percent oat bran as carbon sources and/or enzyme inducers. PGase activity was detected early (after two days of incubation) in all the cultures; it was found to be the highest for all the isolates. PMGase was high only for those isolates of the II region. CMCase and endoxylanase activities were particularly found at late stages (after four and seven days of incubation, respectively) and the maximum values were lower than pectinase activities.