Extracellular Cellulolytic Enzymes Research Articles

Intracellular Nitric Oxide and cAMP Are Involved in Cellulolytic Enzyme Production in Neurospora crassa.

Although molecular regulation of cellulolytic enzyme production in filamentous fungi has been actively explored, the underlying signaling processes in fungal cells are still not clearly understood. In this study, the molecular signaling mechanism regulating cellulase production in Neurospora crassa was investigated. We found that the transcription and extracellular cellulolytic activity of four cellulolytic enzymes (cbh1, gh6-2, gh5-1, and gh3-4) increased in Avicel (microcrystalline cellulose) medium. Intracellular nitric oxide (NO) and reactive oxygen species (ROS) detected by fluorescent dyes were observed in larger areas of fungal hyphae grown in Avicel medium compared to those grown in glucose medium. The transcription of the four cellulolytic enzyme genes in fungal hyphae grown in Avicel medium was significantly decreased and increased after NO was intracellularly removed and extracellularly added, respectively. Furthermore, we found that the cyclic AMP (cAMP) level in fungal cells was significantly decreased after intracellular NO removal, and the addition of cAMP could enhance cellulolytic enzyme activity. Taken together, our data suggest that the increase in intracellular NO in response to cellulose in media may have promoted the transcription of cellulolytic enzymes and participated in the elevation of intracellular cAMP, eventually leading to improved extracellular cellulolytic enzyme activity.

Development of a powerful synthetic hybrid promoter to improve the cellulase system of Trichoderma reesei for efficient saccharification of corncob residues

BackgroundThe filamentous fungus Trichoderma reesei is a widely used workhorse for cellulase production in industry due to its prominent secretion capacity of extracellular cellulolytic enzymes. However, some key components are not always sufficient in this cellulase cocktail, making the conversion of cellulose-based biomass costly on the industrial scale. Development of strong and efficient promoters would enable cellulase cocktail to be optimized for bioconversion of biomass.ResultsIn this study, a synthetic hybrid promoter was constructed and applied to optimize the cellulolytic system of T. reesei for efficient saccharification towards corncob residues. Firstly, a series of 5’ truncated promoters in different lengths were established based on the strong constitutive promoter Pcdna1. The strongest promoter amongst them was Pcdna1-3 (− 640 to − 1 bp upstream of the translation initiation codon ATG), exhibiting a 1.4-fold higher activity than that of the native cdna1 promoter. Meanwhile, the activation region (− 821 to − 622 bp upstream of the translation initiation codon ATG and devoid of the Cre1-binding sites) of the strong inducible promoter Pcbh1 was cloned and identified to be an amplifier in initiating gene expression. Finally, this activation region was fused to the strongest promoter Pcdna1-3, generating the novel synthetic hybrid promoter Pcc. This engineered promoter Pcc drove strong gene expression by displaying 1.6- and 1.8-fold stronger fluorescence intensity than Pcbh1 and Pcdna1 under the inducible condition using egfp as the reporter gene, respectively. Furthermore, Pcc was applied to overexpress the Aspergillus niger β-glucosidase BGLA coding gene bglA and the native endoglucanase EG2 coding gene eg2, achieving 43.5-fold BGL activity and 1.2-fold EG activity increase, respectively. Ultimately, to overcome the defects of the native cellulase system in T. reesei, the bglA and eg2 were co-overexpressed under the control of Pcc promoter. The bglA-eg2 double expression strain QPEB70 exhibited a 178% increase in total cellulase activity, whose cellulase system displayed 2.3- and 2.4-fold higher saccharification efficiency towards acid-pretreated and delignified corncob residues than the parental strain, respectively.ConclusionsThe synthetic hybrid promoter Pcc was generated and employed to improve the cellulase system of T. reesei by expressing specific components. Therefore, construction of synthetic hybrid promoters would allow particular cellulase genes to be expressed at desired levels, which is a viable strategy to optimize the cellulolytic enzyme system for efficient biomass bioconversion.

A novel amylolytic/xylanolytic/cellulolytic multienzyme complex from Clostridium manihotivorum that hydrolyzes polysaccharides in cassava pulp.

Some anaerobic bacteria, particularly Clostridium species, produce extracellular cellulolytic and xylanolytic enzymes as multienzyme complexes (MECs). However, an amylolytic/xylanolytic/cellulolytic multienzyme complex (AXC-MEC) from anaerobic bacteria is rarely found. In this work, the glycoprotein AXC-MEC, composed of subunits of amylolytic, xylanolytic, and cellulolytic enzymes, was isolated from crude extracellular enzyme of the mesophilic anaerobic bacteriumClostridium manihotivorumCT4, grown on cassava pulp, using a milled cassava pulp column and Sephacryl S-500 gel filtration chromatography. The isolated AXC-MEC showed a single band upon native-polyacrylamide gel electrophoresis (native-PAGE). Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed at least eight protein bands of the multienzyme complex which predominantly exhibited amylolytic enzyme activity, followed by xylanolytic and cellulolytic enzyme activities. The AXC-MEC is highly capable of degrading starch and non-starch polysaccharides present in cassava pulp into glucose and oligosaccharides, without conventional pretreatment. Base on the genomic analysis of C. manihotivorum CT4, we found no evidence of the known structural components of the well-known multienzyme complexes from Clostridium species, cellulosomes such as scaffoldin, cohesin, and dockerin, indicating that AXC-MEC from strain CT4 exhibit a different manner of assembly from the cellulosomes. These results suggest that AXC-MEC from C. manihotivorumCT4 is a new MEC capable of hydrolyzing cassava pulp into value-added products, which will benefit the starch industry. KEY POINTS: • Glycoprotein AXC-MEC was first reported in Clostridium manihotivorum. • Unlike cellulosomes, AXC-MEC consists of amylase, xylanase, and cellulase. • Glucose and oligosaccharides were hydrolysis products from cassava pulp by AXC-MEC.

Penicillium oxalicum S-adenosylmethionine synthetase is essential for the viability of fungal cells and the expression of genes encoding cellulolytic enzymes

As the universal methyl donor for methylation reactions, S-adenosylmethionine (AdoMet) plays an indispensable role in most cellular metabolic processes. AdoMet is synthesized by AdoMet synthetase. We identified the only one AdoMet synthetase (PoSasA) in filamentous fungus Penicillium oxalicum. PoSasA was widely distributed in mycelium at different growth stages. The absence of PoSasA was lethal for P. oxalicum. The misregulation of the PoSasA encoding gene affected the synthesis of extracellular cellulolytic enzymes. The expression levels of cellobiohydrolase encoding gene cbh1/cel7A, β-1-4 endoglucanase eg1/cel7B, and xylanase encoding gene xyn10A were remarkably downregulated as a result of decreased PosasA gene expression. The production of extracellular cellulases and hemicellulases was also reduced. By contrast, the overexpression of PosasA improved the production of extracellular cellulases and hemicellulases. A total of 133 putative interacting proteins with PoSasA were identified using tandem affinity purification and mass spectrometry. The results of functional enrichment on these proteins showed that they were mainly related to ATP binding, magnesium ion binding, and ATP synthetase activity. Several methyltransferases were also observed among these proteins. These results were consistent with the intrinsic feature of AdoMet synthetase. This work reveals the indispensable role of PoSasA in various biological processes.

Enhancement of Versatile Extracellular Cellulolytic and Hemicellulolytic Enzyme Productions by Lactobacillus plantarum RI 11 Isolated from Malaysian Food Using Renewable Natural Polymers.

Lactobacillus plantarum RI 11 was reported recently to be a potential lignocellulosic biomass degrader since it has the capability of producing versatile extracellular cellulolytic and hemicellulolytic enzymes. Thus, this study was conducted to evaluate further the effects of various renewable natural polymers on the growth and production of extracellular cellulolytic and hemicellulolytic enzymes by this novel isolate. Basal medium supplemented with molasses and yeast extract produced the highest cell biomass (log 10.51 CFU/mL) and extracellular endoglucanase (11.70 µg/min/mg), exoglucanase (9.99 µg/min/mg), β-glucosidase (10.43 nmol/min/mg), and mannanase (8.03 µg/min/mg), respectively. Subsequently, a statistical optimization approach was employed for the enhancement of cell biomass, and cellulolytic and hemicellulolytic enzyme productions. Basal medium that supplemented with glucose, molasses and soybean pulp (F5 medium) or with rice straw, yeast extract and soybean pulp (F6 medium) produced the highest cell population of log 11.76 CFU/mL, respectively. However, formulated F12 medium supplemented with glucose, molasses and palm kernel cake enhanced extracellular endoglucanase (4 folds), exoglucanase (2.6 folds) and mannanase (2.6 folds) specific activities significantly, indicating that the F12 medium could induce the highest production of extracellular cellulolytic and hemicellulolytic enzymes concomitantly. In conclusion, L. plantarum RI 11 is a promising and versatile bio-transformation agent for lignocellulolytic biomass.

Glycoside hydrolases from a thermophilic microbial consortium and their implication in the saccharification of agroresidues

Abstract This study investigates the potential of a thermophilic lignocellulolytic microbial consortium to act as a repository of different Glycoside hydrolases (GHs) for saccharification of agroresidues. An active thermophilic lignocellulolytic microbial consortium (TWC) was bred at 60 °C from forest soil using destarched wheat bran as the sole carbon source. TWC was screened for production of extracellular GHs at various pH and temperatures for four days. The consortium produced several extracellular GHs, such as endoglucanase, exoglucanase, β-glucosidase, endoxylanase and β-xylosidase with enhanced activity at 60 °C (as compared with 37 °C) and pH 5 − 6 at 48 h of incubation. Zymogram analysis also indicated the presence of multiple xylanase and β-glucosidase activities at 48 h of incubation. The extracellular cellulolytic enzyme cocktail (CEC) obtained from TWC was implicated in the saccharification of heat treated agro-residues. Among seven agroresidues tested, wheat bran and sugarcane bagasse were efficiently saccharified by the CEC with continued release of reducing sugars till 72 h of incubation at 60 °C. Release of reducing sugars from destarched wheat bran pretreated with moist heat was 359 mg g−1 of non-starch polysaccharides, which was about two fold greater in comparison to that released from untreated wheat bran (181 mg g−1). The production of thermophilic GHs by the microbial consortium seems promising and thus establishes their potential for application in industrial saccharification where thermotolerant enzymes are required.

WOOD-DESTROYING PROPERTIES OF FOMITOPSIS PINICOLA (SW.) P. KARST. FROM MIDDLE SIBERIA

Presents the results of a research of wood-destroying properties of the basidiomycete Fomitopsis pinicola (Sw.) P. Karst. The strains were isolated in pure culture from fruiting bodies that grew on the Abies sibirica Ledeb, Pinus sylvestris Ledeb, Pinus sibirica Du Tour and Larix sibirica Ledeb in the forests of the Krasnoyarsk Territory (56°09'–56°22' N; 92°10'–92°58' E). The cultures screened for growth parameters and the dynamics of enzymatic activity during cultivation on cellulose-containing media. The radial growth rate of Siberian strains on the agar medium and plant substrates is 1,1–3,3 mm / day; the growth coefficient is 10–42. All studied cultures synthesize extracellular cellulolytic enzymes that hydrolyze the sodium salt of carboxymethylcellulose. The enzymatic activity is in the range 0,05–0,39 U / ml with a maximum of 7–9 days. The most active strain of Fp5-15 F. pinicola used for bioconversion of coniferous plant substrates under solid-phase culture conditions. The maximum wood-destroying activity observed on pine and larch wood – the mass loss of substrates was 16 and 20%, respectively. On Pinus sylvestris sawdust, the total content of polysaccharides decreased by 1,2 times due to the fermentolysis of the hardly hydrolyzable fraction (a decrease of 1,4 times); the content of lignin substances did not change significantly. On the sawdust of Larix sibirica, the amount of polysaccharides decreased by 1,3 times in comparison with the initial substrate; lignin – in 1,2 times.

Complete genome sequence of Bacillus sp. 275, producing extracellular cellulolytic, xylanolytic and ligninolytic enzymes

Technologies for degradation of three major components of lignocellulose (e.g. cellulose, hemicellulose and lignin) are needed to efficiently utilize lignocellulose. Here, we report Bacillus sp. 275 isolated from a mudflat exhibiting various lignocellulolytic activities including cellulase, xylanase, laccase and peroxidase in the cell culture supernatant. The complete genome of Bacillus sp. 275 strain contains 3832 protein cording sequences and an average G+C content of 46.32% on one chromosome (4045,581bp) and one plasmid (6389bp). The genes encoding enzymes related to the degradation of cellulose, xylan and lignin were detected in the Bacillus sp. 275 genome. In addition, the genes encoding glucosidases that hydrolyze starch, mannan, galactoside and arabinan were also found in the genome, implying that Bacillus sp. 275 has potentially a wide range of uses in the degradation of polysaccharide in lignocellulosic biomasses.

Expression and chromatin structures of cellulolytic enzyme gene regulated by heterochromatin protein 1.

BackgroundHeterochromatin protein 1 (HP1, homologue HepA in Penicillium oxalicum) binding is associated with a highly compact chromatin state accompanied by gene silencing or repression. HP1 loss leads to the derepression of gene expression. We investigated HepA roles in regulating cellulolytic enzyme gene expression, as an increasingly number of studies have suggested that cellulolytic enzyme gene expression is not only regulated by transcription factors, but is also affected by the chromatin status.ResultsAmong the genes that exhibited significant differences between the hepA deletion strain (ΔhepA) and the wild type (WT), most (95.0 %) were upregulated in ΔhepA compared with WT. The expression of the key transcription factor for cellulolytic enzyme gene (e.g., repressor CreA and activator ClrB) increased significantly. However, the deletion of hepA led to downregulation of prominent extracellular cellulolytic enzyme genes. Among the top 10 extracellular glycoside hydrolases (Amy15A, Amy13A, Cel7A/CBHI, Cel61A, Chi18A, Cel3A/BGLI, Xyn10A, Cel7B/EGI, Cel5B/EGII, and Cel6A/CBHII), in which secretion amount is from the highest to the tenth in P. oxalicum secretome, eight genes, including two amylase genes (amy15A and amy13A), all five cellulase genes (cel7A/cbh1, cel6A/cbh2, cel7B/eg1, cel5B/eg2, and cel3A/bgl1), and the cellulose-active LPMO gene (cel61A) expression were downregulated. Results of chromatin accessibility real-time PCR (CHART-PCR) showed that the chromatin of all three tested upstream regions opened specifically because of the deletion of hepA in the case of two prominent cellulase genes cel7A/cbh1 and cel7B/eg1. However, the open chromatin status did not occur along with the activation of cellulolytic enzyme gene expression. The overexpression of hepA upregulated the cellulolytic enzyme gene expression without chromatin modification. The overexpression of hepA remarkably activated the cellulolytic enzyme synthesis, not only in WT (~150 % filter paper activity (FPA) increase), but also in the industry strain RE-10 (~20–30 % FPA increase).ConclusionsHepA is required for chromatin condensation of prominent cellulase genes. However, the opening of chromatin mediated by the deletion of hepA was not positively correlated with cellulolytic enzyme gene activation. HepA is actually a positive regulator for cellulolytic enzyme gene expression and could be a promising target for genetic modification to improve cellulolytic enzyme synthesis.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-016-0624-9) contains supplementary material, which is available to authorized users.

Extracellular proteins of Trametes hirsuta st. 072 induced by copper ions and a lignocellulose substrate.

BackgroundFungi are organisms with the highest natural capacity to degrade lignocellulose substrates, which is enabled by complex systems of extracellular enzymes, whose expression and secretion depend on the characteristics of substrates and the environment.ResultsThis study reports a secretome analysis for white-rot basidiomycete Trametes hirsuta cultivated on a synthetic media and a lignocellulose substrate. We demonstrate that T. hirsuta st. 072 produces multiple extracellular ligninolytic, cellulolytic, hemicellulolytic, peroxide generating, and proteolytic enzymes, as well as cerato-platanins. In contrast to other white rot species described earlier, which mostly secreted glucanases and mannosidases in response to the presence of the lignocellulose substrate, T. hirsuta expressed a spectrum of extracellular cellulolytic enzymes containing predominantly cellobiases and xylanases. As proteomic analysis could not detect lignin peroxidase (LiP) among the secreted lignin degrading enzymes, we attributed the observed extracellular LiP - like activity to the expressed versatile peroxidase (VP). An accessory enzyme, glyoxal oxidase, was found among the proteins secreted in the media during submerged cultivation of T. hirsuta both in the presence and in the absence of copper. However, aryl-alcohol oxidase (AAO) was not identified, despite the presence of AAO enzymatic activity secreted by the fungus.The spectra of the expressed enzymes dramatically changed depending on the growth conditions. Transfer from submerged cultivation to surface cultivation with the lignocellulose substrate switched off expression of exo-β-1,3-glucanase and α-amylase and turned on secretion of endo-β-1,3-glucanase and a range of glycosidases. In addition, an aspartic peptidase started being expressed instead of family S53 protease. For the first time, we report production of cerato-platanin proteins by Trametes species. The secretion of cerato-platanins was observed only in response to contact with lignocellulose, thus indicating a specific role of these proteins in degradation of the lignocellulose substrates.ConclusionsOur results suggest a sequential mechanism of natural substrate degradation by T. hirsuta, in which the fungus produces different sets of enzymes to digest all main components of the substrate during cultivation.Electronic supplementary materialThe online version of this article (doi:10.1186/s12866-016-0729-0) contains supplementary material, which is available to authorized users.

The impact of different physicochemical parameters of fermentation on extracellular cellulolytic enzyme production by Trichoderma harzianum

The impact of different physicochemical parameters of fermentation on extracellular cellulolytic enzyme production by Trichoderma harzianum

Pilot-scale production and optimizing of cellulolytic <i>Penicillium oxalicum</i> for controlling of mango malformation

Penicillium oxalicum Curie et Thom isolated from blossom of mango (var. Saddekia) was evaluated against mango malformation incited by Fu- sarium subglutinis. Both in vitro and in vivo conditions. The mechanism of this isolate for controlling Fusarium was the reduction of growth development. The Penicillium oxalicum isolate produced extracellular cellulolytic enzymes (exo-glucanase or cellobiohydrolases and endo-glucanase, that possibly related to the biocontrol process. Optimize and fermentation conditions (growth period, carbon and nitrogen sources) for spores and cellulolytic enzymes production were determined. Liquid formulation containing (6 × 106) with sodium alginate (0.5%) and Tween 80 (0.01%) was used. For field evaluation, susceptible cultivars as Ewais, Saddika, Alphonso, Taimour and Zebda were selected. Liquid bioformulations were sprayed twice and 30 days intervals. The spray was initiated from pre-flowering stage. Bioformulation was found to be significant in reducing the malformation incidence. Results cleared that spraying of liquid bioformulations, substantially improved the fruit numbers and yield for the five mango cultivars and suggested to be most promotive for fairly quality in tested cultivars.

Biohydrogen production from pure and natural lignocellulosic feedstock with chemical pretreatment and bacterial hydrolysis

Pretreatment and saccharification of lignocellulosic materials is the key technology affecting the efficiency of cellulosic biohydrogen production. In this work, two pure cellulosic materials (i.e., carboxymethyl-cellulose (CMC) and xylan) were directly hydrolyzed (without pretreatment) by a cellulolytic isolate Cellulomonas uda E3-01 able to release extracellular cellulolytic enzymes. Natural cellulosic feedstock (i.e., sugarcane bagasse) was chemically pretreated prior to the bacterial hydrolysis.A temperature-shift strategy (35 °C for cellulolytic enzymes production and 45 °C for hydrolysis reaction) was used to increase the production of reducing sugars during the bacterial hydrolysis. The hydrolysates of CMC, xylan, and bagasse were efficiently converted to H 2 via dark fermentation with Clostridium butyricum CGS5. The maximum hydrogen yield was 8.80 mmol H 2/g reducing sugar (i.e., 1.58 mol H 2/mol hexose) for CMC, 6.03 mmol H 2/g reducing sugar (i.e., 0.91 mol H 2/mol pentose) for xylan, and 6.01 mmol H 2/g reducing sugar for bagasse.

Characterization of cellulolytic enzymes and bioH 2 production from anaerobic thermophilic Clostridium sp. TCW1

A thermophilic anaerobic bacterium Clostridium sp. TCW1 was isolated from dairy cow dung and was used to produce hydrogen from cellulosic feedstock. Extracellular cellulolytic enzymes produced from TCW1 strain were identified as endoglucanases (45, 53 and 70 kDa), exoglucanase (70 kDa), xylanases (53 and 60 kDa), and β-glucosidase (45 kDa). The endoglucanase and xylanase were more abundant. The optimal conditions for H 2 production and enzyme production of the TCW1 strain were the same (60 °C, initial pH 7, agitation rate of 200 rpm). Ten cellulosic feedstock, including pure or natural cellulosic materials, were used as feedstock for hydrogen production by Clostridium strain TCW1 under optimal culture conditions. Using filter paper at 5.0 g/L resulted in the most effective hydrogen production performance, achieving a H 2 production rate and yield of 57.7 ml/h/L and 2.03 mol H 2/mol hexose, respectively. Production of cellulolytic enzyme activities was positively correlated with the efficiency of dark-H 2 fermentation.

The Distribution of Extracellular Cellulase Activity in Marine Eukaryotes, Thraustochytrids

Cellulolytic ability was evaluated in 19 strains of thraustochytrids, representing nine genera, using carboxymethylcellulose (CMC) as a substrate. Extracellular cellulolytic enzyme activity was determined in the culture supernatants during cell growth. CMC hydrolysis was observed in 14 out of the 19 strains examined. These belonged to the genera Aplanochytrium, Botryochytrium, Oblongichytrium, Parietichytrium, Schizochytrium, Sicyoidochytrium, Thraustochytrium and Ulkenia. On the other hand, cellulolytic enzyme activity was not detected in any strains belonging to the genus Aurantiochytrium.

Optimization, Purification, and Characterization of Extracellular Mesophilic Alkaline Cellulase from Sponge-Associated Marinobacter sp. MSI032

Marinobacter sp. (MSI032) isolated from the marine sponge Dendrilla nigra was optimized for the production of extracellular cellulolytic enzyme (CMCase) by submerged fermentation. Initial experiments showed that the culture medium containing 1% maltose as carbon source and 1% peptone and casein as nitrogen source supported maximal enzyme production at 27 degrees C and at a pH of 9.0. Further optimization carried out showed the maximal enzyme production was supported by the presence of 2% NaCl and 10 mM Zn(2+) ions in the production media. The production of enzyme cellulase occurred at 48 h of incubation which proved the importance of this strain for cellulase production in large scale. Further, the enzyme was purified to 12.5-fold with a 37% yield and a specific activity of 2,548.75 U/mg. The purified enzyme displayed maximum activity at mesophilic temperature (27-35 degrees C) and at a broad pH range with optimal activity at pH 9.0. The purified enzyme was stable even at a higher alkaline pH of 12.0 which is greater than the pH stability that has not been reported in any of the cellulolytic isolates studied so far. Thus, from the present study, it is crucial that, instead of exploring the thermophilic resource that is limited in natural environments, the mesophilic bacteria that occurs commonly in nature can be added up to the database of cellulolytic bacteria. Thus, it is possible that a wide diversity of mesophilic bacteria associated with marine sponges opens up a new doorstep for the degradation of cellulosic waste material for the production of liquid fuels. This is the first report elucidating the prospects of sponge-associated marine bacterium for the production of extracellular alkaline cellulase.

Fungal bioconversion of lignocellulosic residues; opportunities & perspectives.

The development of alternative energy technology is critically important because of the rising prices of crude oil, security issues regarding the oil supply, and environmental issues such as global warming and air pollution. Bioconversion of biomass has significant advantages over other alternative energy strategies because biomass is the most abundant and also the most renewable biomaterial on our planet. Bioconversion of lignocellulosic residues is initiated primarily by microorganisms such as fungi and bacteria which are capable of degrading lignocellulolytic materials. Fungi such as Trichoderma reesei and Aspergillus niger produce large amounts of extracellular cellulolytic enzymes, whereas bacterial and a few anaerobic fungal strains mostly produce cellulolytic enzymes in a complex called cellulosome, which is associated with the cell wall. In filamentous fungi, cellulolytic enzymes including endoglucanases, cellobiohydrolases (exoglucanases) and beta-glucosidases work efficiently on cellulolytic residues in a synergistic manner. In addition to cellulolytic/hemicellulolytic activities, higher fungi such as basidiomycetes (e.g. Phanerochaete chrysosporium) have unique oxidative systems which together with ligninolytic enzymes are responsible for lignocellulose degradation. This review gives an overview of different fungal lignocellulolytic enzymatic systems including extracellular and cellulosome-associated in aerobic and anaerobic fungi, respectively. In addition, oxidative lignocellulose-degradation mechanisms of higher fungi are discussed. Moreover, this paper reviews the current status of the technology for bioconversion of biomass by fungi, with focus on mutagenesis, co-culturing and heterologous gene expression attempts to improve fungal lignocellulolytic activities to create robust fungal strains.

Biosynthesis of cellulolytic enzymes by Tricothecium roseum with citric acid mediated induction

Tricothecium roseum, an unexplored fungus for the production of cellulolytic enzymes, was used in this study for carboxymethylcellulase (CMcase) and b-glucosidase production. The culture filtrate of this organism exhibited highest total cellulolytic activity and extracellular protein content on 9th day during the course of its growth on potato dextrose yeast extract (PDYE) broth medium supplemented with 1.0% (w/v) carboxymethylcellulose. Among various soluble carbon and complex nitrogen sources tested in this study, carboxymethylcellulose and peptone supported maximum production of both cellulolytic enzymes. Under all suitable growth conditions, the enzyme biosynthesis was remarkably increased when the inducer citric acid was added to the PDYE media containing carboxymethylcellulose. Maximum CMcase production (1.59 U/ml) and b-glucosidase production (1.82 U/ml) were achieved in citric acid amended PDYE media at 37°C. Both the cellulolytic enzyme production was highest at initial pH 6.5 and after 7 days incubation. The study clearly demonstrated that citric acid is a good inducer for extracellular cellulolytic enzyme production by the fungus.

Effect of Minerals and Moisture Level on the Solid Cultures of A. niger and T. viride for Extracellular Cellulolytic and Xylanolytic Enzymes Production

Effect of Minerals and Moisture Level on the Solid Cultures of A. niger and T. viride for Extracellular Cellulolytic and Xylanolytic Enzymes Production

Production of xylanase and CMCase on solid state fermentation in different residues by Thermoascus aurantiacus miehe

The use of waste as raw material is important for government economy and natural balance. The purpose of this work was to study the production of CMCase and xylanase by a Brazilian strain of Thermoascus aurantiacus in solid state fermentation (SSF) using different agricultural residues (wheat bran, sugarcane bagasse, orange bagasse, corncob, green grass, dried grass, sawdust and corn straw) as substrates without enrichment of the medium and characterize the crude enzymes.The study of the extracellular cellulolytic and hemicellulolytic enzymes showed that T. arantiacus is more xylanolytic than cellulolytic. The highest levels of enzymes were produced in corncob, grasses and corn straw. All the enzymes were stable at room temperature by 24 h over a broad pH range (3.0-9.0) and also were stable at 60oC for 1 h. The optimum pH and temperature for xylanase and CMCase were 5.0-5.5 and 5.0 and 75oC, respectively. The microorganism grew quickly in stationary, simple and low cost medium. The secreted extracellular enzymes presented properties that match with those frequently required in industrial environment.