New isolate of Trichoderma viride strain for enhanced cellulolytic enzyme complex production

Cellulase production under solid-state fermentation by Aspergillus sp. IN5: Parameter optimization and application

Microbial cellulases are highly versatile catalysts with significant potential in various industries, including pulp and paper, textile manufacturing, laundry, biofuel production, food and animal feed, brewing, and agriculture. Cellulases have attracted considerable attention from the scientific community owing to their broad industrial applications and the complex nature of enzymatic systems. In the present study, a novel fungal isolate of Aspergillus sp. IN5 was used to produce cellulases. We optimized each parameter, including carbon source, incubation temperature, pH, and incubation time, for maximum cellulase production using isolate IN5 under solid-state fermentation conditions. The optimized parameters for cellulase production by isolate IN5 under solid-state fermentation were as follows: substrate, soybean residue; incubation temperature, 35 °C; pH, 7.0; and incubation duration, 5 days. These conditions resulted in the highest total cellulase activity (0.26 U/g substrate), and carboxymethyl cellulase and β-glucosidase activities of 3.32 and 196.09 U/g substrate, respectively. The obtained fungal cellulase was used for the enzymatic hydrolysis of acid- or alkali-pretreated rice straw, which served as a model substrate. Notably, compared with acid pretreatment, the pretreatment of rice straw with diluted alkali led to higher yields of reducing sugars. Maximum reducing sugar yield (286.06 ± 2.77 mg/g substrate) was obtained after 24-h incubation of diluted alkali-pretreated rice straw mixed with an enzyme loading of 15 U/g substrate. The findings of this study provide an alternative strategy for utilizing agricultural waste and an approach to efficiently produce cellulase for the degradation of lignocellulosic materials, with promising benefits for sustainable waste management.

Enzymatic hydrolysis of lignocellulosic biomass using native cellulase produced by Aspergillus niger ITV02 under liquid state fermentation

The objective of this work was to evaluate the biochemical characteristics of an enzymatic extract obtained from autochthonous fungus Aspergillus niger ITV02 and its application in the enzymatic hydrolysis of wheat straw and corn stubble pretreated by steam explosion. The enzymatic extract was obtained by submerged fermentation using delignified sweet sorghum bagasse as a carbon source. The results obtained showed that the enzymatic extract had β-glucosidase and endoglucanase activities. The effects of pH and temperature on cellulase activity were evaluated and its thermostability was determined. The optimal parameters of the β-glucosidase and endoglucanase activities obtained were pH 5 and 70 °C. The enzymatic extract of A. niger ITV02 was used to hydrolyze wheat straw and corn stubble, and the hydrolysis yields were compared with those obtained by a commercial cellulase (Celluclast 1.5L NS 50013) and CellicCTec3. The results showed that with the use the mixture of Celluclast 1.5L-A. niger ITV02 and CellicCTec3-A. niger ITV02 in the hydrolysis, conversions of 86.36% and 67.8% were obtained, respectively. Glucose production for the mixture extract increased 2.15 times more than when the enzyme was used independently alone. The present work shows that A. niger ITV02 has a potential as an enzyme producer for lignocellulosic hydrolysis.

A novel Trichoderma reesei mutant RP698 with enhanced cellulase production

A new strain of Trichoderma reesei (teleomorph Hypocrea jecorina) with high cellulase production was obtained by exposing the spores from T. reesei QM9414 to an ultraviolet light followed by selecting fast-growing colonies on plates containing CMC (1% w/v) as the carbon source. The mutant T. reesei RP698 reduced cultivation period to 5 days and increased tolerance to the end-products of enzymatic cellulose digestion. Under submerged fermentation conditions, FPase, CMCase, and Avicelase production increased up to 2-fold as compared to the original QM9414 strain. The highest levels of cellulase activity were obtained at 27 °C after 72 h with Avicel®, cellobiose, and sugarcane bagasse as carbon sources. The temperature and pH activity optima of the FPase, CMCase, and Avicelase were approximately 60 °C and 5.0, respectively. The cellulase activity was unaffected by the addition of 140 mM glucose in the enzyme assay. When T. reesei RP698 crude extract was supplemented by the addition of β-glucosidase from Scytalidium thermophilum, a 2.3-fold increase in glucose release was observed, confirming the low inhibition by the end-product of cellulose hydrolysis. These features indicate the utility of this mutant strain in the production of enzymatic cocktails for biomass degradation.

Enhanced cellulase and reducing sugar production by a new mutant strain Trichoderma harzianum EUA20

Trichoderma harzianum EU2-77 was a mutant strain of the wild-type strain T. harzianum NP13a isolated in Singapore. A multi-mutagenesis one-screening (MMOS) method was developed to further improve strain EU2-77 and a new mutant EUA20 was obtained. It exhibited filter paper cellulase (FPase) activity up to 14.79 IU/mL within 6 days shake flask cultivation. Activities of FPase, endoglucanase, β-glucosidase, and xylanase, and protein content by EUA20 were respectively increased to 5.73, 4.35, 7.34, 1.80 and 2.70 folds. Using pretreated oil palm empty fruit bunch (OPEFB) and corncob powder as the substrates, strain EUA20 presented approximate 6.52 and 8.80 IU/ml FPase activity. Reducing sugar yield of 615.8 and 636.8 mg/g biomass were respectively obtained for OPEFB and corncob powder using cellulolytic enzymes of strain EUA20. Our results demonstrated that mutant strain EUA20 had great potential in on-site cellulase production for effective biomass bioconversion.

An alternative to mineral phosphorus fertilizers: The combined effects of Trichoderma harzianum and compost on Zea mays, as revealed by 1H NMR and GC-MS metabolomics

The ability of Trichoderma harzianum (strain OMG-08) as plant growth promoting fungus (PGPF), was tested on Zea mays plants grown in soil pots added with different inorganic (triple superphosphate and rock phosphate) and organic (cow and horse manure composts) P fertilizers. The effect of treatments was evaluated by following the variations of plants dry biomass and nutrient content, as well as the metabolic changes in plant leaves by both GC-MS and NMR spectroscopy. A synergic effect was observed in treatments with both composts and fungus inoculation, in which not only plant growth and P uptake were enhanced, but also the expression of different metabolites related to an improved photosynthetic activity. Conversely, the combination of Trichoderma with inorganic fertilizers was less effective and even showed a reduction of plants shoot biomass and N content. The corresponding plant metabolome revealed metabolic compounds typical of biotic or abiotic stresses, which may be attributed to a reduced capacity of inorganic fertilizers to provide a sufficient P availability during plant growth. Our findings also indicate that the molecular composition of compost differentiated the Trichoderma activity in sustaining plant growth. The positive effects of the combined Trichoderma and compost treatment suggest that it may become an alternative to the phosphorus mineral fertilization.

Identificación y evaluación de actividad celulolítica en aislamientos nativos de Trichoderma spp obtenidos de biomasa de palma de aceite

Se aislaron previamente ocho cepas nativas de racimos de palma de aceite en descomposición de Trichoderma sp. provenientes de la región de Cumaral, Meta, Colombia. Se utilizó la región de los ITS1-ITS4 para la identificación molecular y se determinó la actividad celulolítica (actividad sobre papel filtro) del complejo producido por las cepas utilizando residuos de palma como sustrato. Siete aislamientos nativos presentarón 100% de similaridad con hongos del género Trichoderma. Se observó para siete cepas, la presencia de las cinco anclas que identifican hongos del género Trichoderma, identificándose cuatro de los hongos nativos como Trichoderma koningiopsis (HR-04-89; HR-11-89; HR-19-89; y HR-06-89) y cuatro como Trichoderma asperellum (HR-01-89; HR-03-89; HR-16-89; HR-18-89). El bioensayo mostró que las cepas evaluadas de Trichoderma son estadísticamente significativas sobre la actividad enzimática de celulasas sobre papel filtro (p<0.05). Además, las cepas HR-01-89, HR-03-89, HR-11-89, HR-04-89 y HR-18-89 no presentaron diferencias en la actividad enzimática. La cepa Trichoderma reesei utilizada como referencia, presentó un comportamiento superior y diferente comparado con las cepas nativas. La cepa nativa HR-18-89 (Trichoderma asperellum) presentó mayores niveles de actividad enzimática, 78% del valor de la cepa referencia. Es importante identificar y evaluar cepas nativas de Trichoderma sp. con novedosas actividades biológicas que permitan degradar la celulosa recalcitrante de los racimos de palma africana.

Correlation of structure, function and protein dynamics in GH7 cellobiohydrolases from Trichoderma atroviride, T. reesei and T. harzianum

BACKGROUND

The ascomycete fungus Trichoderma reesei is the predominant source of enzymes for industrial conversion of lignocellulose. Its glycoside hydrolase family 7 cellobiohydrolase (GH7 CBH) TreCel7A constitutes nearly half of the enzyme cocktail by weight and is the major workhorse in the cellulose hydrolysis process. The orthologs from Trichoderma atroviride (TatCel7A) and Trichoderma harzianum (ThaCel7A) show high sequence identity with TreCel7A, ~ 80%, and represent naturally evolved combinations of cellulose-binding tunnel-enclosing loop motifs, which have been suggested to influence intrinsic cellobiohydrolase properties, such as endo-initiation, processivity, and off-rate.

RESULTS

The TatCel7A, ThaCel7A, and TreCel7A enzymes were characterized for comparison of function. The catalytic domain of TatCel7A was crystallized, and two structures were determined: without ligand and with thio-cellotriose in the active site. Initial hydrolysis of bacterial cellulose was faster with TatCel7A than either ThaCel7A or TreCel7A. In synergistic saccharification of pretreated corn stover, both TatCel7A and ThaCel7A were more efficient than TreCel7A, although TatCel7A was more sensitive to thermal inactivation. Structural analyses and molecular dynamics (MD) simulations were performed to elucidate important structure/function correlations. Moreover, reverse conservation analysis (RCA) of sequence diversity revealed divergent regions of interest located outside the cellulose-binding tunnel of Trichoderma spp. GH7 CBHs.

CONCLUSIONS

We hypothesize that the combination of loop motifs is the main determinant for the observed differences in Cel7A activity on cellulosic substrates. Fine-tuning of the loop flexibility appears to be an important evolutionary target in Trichoderma spp., a conclusion supported by the RCA data. Our results indicate that, for industrial use, it would be beneficial to combine loop motifs from TatCel7A with the thermostability features of TreCel7A. Furthermore, one region implicated in thermal unfolding is suggested as a primary target for protein engineering.

Retraction: Characterization of cellulolytic activities of newly isolated Thelephora sowerbyi from North-Western Himalayas on different lignocellulosic substrates

Characterization of cellulolytic activities of newly isolated Thelephora sowerbyi from North-Western Himalayas on different lignocellulosic substrate J. Basic Microbiol. 2015, 55, 1-11 - DOI: 10.1002/jobm.201500107 The above article from the Journal of Basic Microbiology, published online on 08 June 2015 in Wiley Online Library as Early View (http://onlinelibrary.wiley.com/doi/10.1002/jobm.201500107/pdf), has been retracted by agreement between the authors, the Editor-in-Chief and Wiley-VCH GmbH & Co. KGaA. The retraction has been agreed because the microorganism studied in the described experiments has been identified as the fungus Cotylidia pannosa (Gene Accession No. KT008117) instead of Thelephora sowerbyi. The culture has been identified on the basis of the sequence of the amplified ITS region of the microorganism which was submitted by the authors to the NCBI database.

Biocontrol Activities of Gamma Induced Mutants of Trichoderma harzianum against some Soilborne Fungal Pathogens and their DNA Fingerprinting

BACKGROUND

Random induced mutation by gamma radiation is one of the genetic manipulation strategies to improve the antagonistic ability of biocontrol agents.

OBJECTIVES

This study aimed to induce mutants with more sporulation, colonization rate leading to enhanced antagonistic ability (in vitro assay) comparing to wild type (WT) and the assessment of genetic differences (in situ evaluation) using molecular markers. The superior mutants could be appropriate biocontrol agents against soil borne fungal diseases.

MATERIALS AND METHODS

In this research sampling and isolation of Trichoderma isolates were performed from soils with low incidence of soil borne disease. T. harzianum 65 was selected and irradiation was conducted with gammacell at optimal dose 250 Gray/s. Mutants (115) were obtained from the WT. The antagonistic abilities of twenty-four mutants were evaluated using dual culture and culture filtrate tests.

RESULTS

The results of in vitro assays revealed that Th15, Th11 and Th1 mutants exhibited stronger growth inhibition (GI) and colonization rate on Macrophomina phaseolina and Rhizoctonia solani AG4 compared to the wild type. Th15 and Th11 mutants exhibited stronger GI and colonization rate on Sclerotinia sclerotiorum in dual culture and culture filtrate tests and Th1 and Th11 mutants exhibited stronger GI on Fusarium grminearum in culture filtrate test. The DNA fingerprinting was carried out using RAPD and rep-PCR markers. Two (Th9 and Th17) out of the 24 mutants categorized distantly from the rest based on different polymorphism obtained by molecular markers. However, Th9 was different in GI% from Th17. RAPD analysis separated WT from mutants, Th9 from Th17 and also phenotypically superior mutants from other mutants. Meanwhile, rep-PCR analysis categorized WT isolate and mutants according to their antagonistic properties.

CONCLUSIONS

The latter marker (rep-PCR) appeared to be reproducible and simple to distinguish mutants from a single isolate of T. harzianum. Mutants (3 isolates) were phenotypically and genotypically distinct from WT. These mutants demonstrated a pronounced biocontrol activities against soilborne fungal phytopathogens.

The influence of pretreatment methods on saccharification of sugarcane bagasse by an enzyme extract from Chrysoporthe cubensis and commercial cocktails: A comparative study

Biomass enzymatic hydrolysis depends on the pretreatment methods employed, the composition of initial feedstock and the enzyme cocktail used to release sugars for subsequent fermentation into ethanol. In this study, sugarcane bagasse was pretreated with 1% H2SO4 and 1% NaOH and the biomass saccharification was performed with 8% solids loading using 10 FPase units/g of bagasse of the enzymatic extract from Chrysoporthe cubensis and three commercial cocktails for a comparative study. Overall, the best glucose and xylose release was obtained from alkaline pretreated sugarcane bagasse. The C. cubensis extract promoted higher release of glucose (5.32 g/L) and xylose (9.00 g/L) than the commercial mixtures. Moreover, the C. cubensis extract presented high specific enzyme activities when compared to commercial cocktails mainly concerning to endoglucanase (331.84 U/mg of protein), β-glucosidase (29.48 U/mg of protein), β-xylosidase (2.95 U/mg of protein), pectinase (127.46 U/mg of protein) and laccase (2.49 U/mg of protein).

Production of cellulolytic enzymes and application of crude enzymatic extract for saccharification of lignocellulosic biomass

In this study, the optimal conditions for production of cellulolytic enzymes by Trichoderma reesei NRRL-6156 using the solid-state fermentation were assessed in conical flasks and validated in a packed-bed bioreactor. Afterwards, the crude enzymatic extract obtained in the optimized condition was used for hydrolysis of sugarcane bagasse in water and ultrasound baths. The enzyme activities determined in this work were filter paper, exocellulase, endocellulase, and xylanase. The optimized condition for production was moisture content 68.6 wt% and soybean bran concentration 0.9 wt%. The crude enzymatic extract was applied for hydrolysis of sugarcane bagasse, being obtained 224.0 and 229 g kg(-1) at temperature of 43.4 °C and concentration of enzymatic extract of 18.6 % in water and ultrasound baths, respectively. The yields obtained are comparable to commercial enzymes.

Bioethanol production from wheat straw via enzymatic route employing Penicillium janthinellum cellulases

This study concerns in-house development of cellulases from a mutant Penicillium janthinellum EMS-UV-8 and its application in separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes for bioethanol production from pre-treated wheat straw. In a 5L fermentor, the above strain could produce cellulases having activity of 3.1 FPU/mL and a specific activity of 0.83 FPU/mg of protein. In-house developed cellulase worked more efficiently in case of SSF as ethanol concentration of 21.6g/L and yield of 54.4% were obtained which were higher in comparison to SHF (ethanol concentration 12 g/L and 30.2% yield). This enzyme preparation when compared with commercial cellulase for hydrolysis of pre-treated wheat straw was found competitive. This study demonstrates that P. janthinellum EMS-UV-8 is a potential fungus for future large-scale production of cellulases.

Genome shuffling of Aspergillus glaucus HGZ-2 for enhanced cellulase production

The production of cellulase from Aspergillus glaucus HGZ-2 was improved by using genome shuffling. The starting populations, obtained by UV irradiation, were subjected to recursive protoplast fusion. The optimal conditions for protoplast formation and regeneration were 7 mg/ml snailase and 5 mg/ml cellulase at 34 °C for 3.0 h using 0.7 M NaCl as an osmotic stabilizer. The protoplasts were inactivated under UV for 30 min or heated at 50 °C for 50 min, and a fusant probability of about 100 % was observed. The positive colonies were created by fusing the inactivated protoplasts. The optimal conditions for protoplast fusion were PEG6000 concentration of 35 %, CaCl2 concentration of 0.02 M, and incubation time of 12 min. After two rounds of genome shuffling, one strain (Y) was obtained. Its filter paper cellulase (FPase) and carboxymethyl cellulase (CMCase) activity reached 71 and 70 U/ml, respectively, which were increased by 1.95-fold and 1.72-fold in comparison with that of its ancestor strain. The results indicated that genome shuffling was an efficient means for the improved production of cellulases by A. glaucus HGZ-2.

Physiological and growth response of rice plants (Oryza sativa L.) to Trichoderma spp. inoculants

Trichoderma spp., a known beneficial fungus is reported to have several mechanisms to enhance plant growth. In this study, the effectiveness of seven isolates of Trichoderma spp. to promote growth and increase physiological performance in rice was evaluated experimentally using completely randomized design under greenhouse condition. This study indicated that all the Trichoderma spp. isolates tested were able to increase several rice physiological processes which include net photosynthetic rate, stomatal conductance, transpiration, internal CO₂ concentration and water use efficiency. These Trichoderma spp. isolates were also able to enhance rice growth components including plant height, leaf number, tiller number, root length and root fresh weight. Among the Trichoderma spp. isolates, Trichoderma sp. SL2 inoculated rice plants exhibited greater net photosynthetic rate (8.66 μmolCO₂ m⁻² s⁻¹), internal CO₂ concentration (336.97 ppm), water use efficiency (1.15 μmoCO₂/mmoH₂O), plant height (70.47 cm), tiller number (12), root length (22.5 cm) and root fresh weight (15.21 g) compared to the plants treated with other Trichoderma isolates tested. We conclude that beneficial fungi can be used as a potential growth promoting agent in rice cultivation.

Crude cellulase from oil palm empty fruit bunch by Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2 for fermentable sugars production

Cellulase is an enzyme that converts the polymer structure of polysaccharides into fermentable sugars. The high market demand for this enzyme together with the variety of applications in the industry has brought the research on cellulase into focus. In this study, crude cellulase was produced from oil palm empty fruit bunch (OPEFB) pretreated with 2% NaOH with autoclave, which was composed of 59.7% cellulose, 21.6% hemicellulose, and 12.3% lignin using Trichoderma asperellum UPM1 and Aspergillus fumigatus UPM2. Approximately 0.8 U/ml of FPase, 24.7 U/ml of CMCase and 5.0 U/ml of β-glucosidase were produced by T. asperellum UPM1 at a temperature of 35 °C and at an initial pH of 7.0. A 1.7 U/ml of FPase, 24.2 U/ml of CMCase, and 1.1 U/ml of β-glucosidase were produced by A. fumigatus UPM2 at a temperature of 45 °C and at initial pH of 6.0. The crude cellulase was best produced at 1% of substrate concentration for both T. asperellum UPM1 and A. fumigatus UPM2. The hydrolysis percentage of pretreated OPEFB using 5% of crude cellulase concentration from T. asperellum UPM1 and A. fumigatus UPM2 were 3.33% and 19.11%, with the reducing sugars concentration of 1.47 and 8.63 g/l, respectively.

Chrysoporthe cubensis: a new source of cellulases and hemicellulases to application in biomass saccharification processes

The plant pathogenic fungus Chrysoporthe cubensis was cultivated under solid state employing different substrates and the highest endoglucanase (33.84Ug(-1)), FPase (2.52Ug(-1)), β-glucosidase (21.55Ug(-1)) and xylanase (362.38Ug(-1)) activities were obtained using wheat bran as carbon source. Cellulases and xylanase produced by C. cubensis showed maximal hydrolysis rate at pH 4.0 and in a temperature range of 50-60°C. All enzymatic activities were highly stable at 40 and 50°C through 48h of pre-incubation. Saccharification of alkaline pretreated sugarcane bagasse by crude enzyme extract from C. cubensis resulted in release of 320.8mg/g and 288.7mg/g of glucose and xylose, respectively. On another hand, a similar assay employing commercial cellulase preparation resulted in release of 250.6mg/g and 62.1mg/g of glucose and xylose, respectively. Cellulolytic extract from C. cubensis showed a great potential to be used in biomass saccharification processes.

Production and Partial Characterization of Cellulases from Trichoderma sp. IS-05 Isolated from Sandy Coastal Plains of Northeast Brazil

This study evaluated the production of cellulolytic enzymes by Trichoderma sp. IS-05 strain, isolated from sand dunes, according to its ability to grow on cellulose as carbon source. Wheat bran was tested as the carbon source and peptone tested as the nitrogen source. Different concentrations of carbon and nitrogen were tested using a factorial design to identify optimal cellulase activity production. The results showed that media containing wheat bran 4.0% (w/v) and peptone 0.25% (w/v) lead to the highest production, 564.0 U L⁻¹ of cellulase, obtained after 2 days of fermentation. The pH and temperature profile showed optimal activity at pH 3.0 and 60°C. As for thermostability, the cellulase was most tolerant at 60°C, retaining more than 59.6% of maximal activity even after 4 hours of incubation. The combination of acid pH, high temperature tolerance, and production of cellulase from agro-industrial residues by Trichoderma sp. IS-05 offers possibilities condition for the biomass hydrolysis process to produce bioethanol.