Production and characterization of cellulolytic enzymes from the thermoacidophilic fungal Aspergillus terreus M11 under solid-state cultivation of corn stover

Simple one-step treatment for saccharification of mango peels using an optimized enzyme cocktail of Aspergillus niger ATCC 9642

Developing efficient microbiological methods to convert polysaccharide-rich materials into fermentable sugars, particularly monosaccharides, is vital for advancing the bioeconomy and producing renewable chemicals and energy sources. This study focused on optimizing the production conditions of an enzyme cocktail from Aspergillus niger ATCC 9642 using solid-state fermentation (SSF) and assessing its effectiveness in saccharifying mango peels through a simple, rapid, and efficient one-step process. A rotatable central composite design was employed to determine optimal conditions of moisture, time, and pH for enzyme production in SSF medium. The optimized enzyme cocktail exhibited cellulase activity (CMCase) at 6.28 U/g, filter paper activity (FPase) at 3.29 U/g, and pectinase activity at 117.02 U/g. These optimal activities were achieved with an SSF duration of 81 h, pH of 4.66, and a moisture content of 59%. The optimized enzyme cocktail effectively saccharified the mango peels without the need for chemical agents. The maximum saccharification yield reached approximately 81%, indicating efficient conversion of mango peels into sugars. The enzyme cocktail displayed consistent thermal stability within the tested temperature range of 30-60°C. Notably, the highest sugar release occurred within 36 h, with glucose, arabinose, galactose, and xylose being the primary monosaccharides released during saccharification. This study highlights the potential application of Aspergillus niger ATCC 9642 and SSF for enzymatic production, offering a simple and high-performance process for monosaccharide production. The optimized enzyme cocktail obtained through solid-state fermentation demonstrated efficient saccharification of mango peels, suggesting its suitability for industrial-scale applications.

Thermotolerance Mechanism of Fungal GH6 Cellobiohydrolase. Part II. Structural Analysis of Thermotolerant Mutant from the Basidiomycete Phanerochaete chrysosporium

Glycoside hydrolase family 6 cellobiohydrolase (GH6 CBH) is a group of cellulases capable of hydrolyzing crystalline cellulose. However, the synergistic reaction of GH6 CBH with other cellulases is hindered by its relatively low thermotolerance. We previously obtained a thermotolerant double mutant, C240S/C393S, of GH6 CBH from the basidiomycete Phanerochaete chrysosporium (PcCel6A) by replacing the two free cysteine (Cys) residues, C240 and C393, with serine (Yamaguchi et al., J Appl Glycosci. 2020; 67;79-86). In the accompanying paper (Part I; Yamaguchi et al., J Appl Glycosci. 2024; 71: 55-62), we measured the temperature dependence of the activity and folding of C240S/C393S and its single mutants, C240S and C393S, and found that replacement of C393 was the major contributor to the increased thermotolerance of C240S/C393S. Here, in order to investigate the mechanism involved, we crystallized the wild-type and the mutant enzymes and compared their X-ray crystal structures. The overall structures of the wild-type and the three mutant enzymes were similar. However, C240S/C393S had the lowest relative B-factor at both the N-terminal loop (residues 172-177) and the C-terminal loop (residues 390-425). This result suggests that reduced structural fluctuation of the substrate-enclosing loops, possibly due to stronger hydrogen bonding involving C393, could account for the increased thermotolerance of C240S/C393S.

Heterologous expression and characterization of mutant cellulase from indigenous strain of Aspergillus niger

The purpose of current research work was to investigate the effect of mutagenesis on endoglucanase B activity of indigenous strain of Aspergillus niger and its heterologous expression studies in the pET28a+ vector. The physical and chemical mutagens were employed to incorporate mutations in A. niger. For determination of mutations, mRNA was isolated followed by cDNA synthesis and cellulase gene was amplified, purified and sequenced both from native and mutant A. niger. On comparison of gene sequences, it was observed that 5 nucleotide base pairs have been replaced in the mutant cellulase. The mutant recombinant enzyme showed 4.5 times higher activity (428.5 µmol/mL/min) as compared to activity of native enzyme (94 µmol/mL/min). The mutant gene was further investigated using Phyre2 and I-Tesser tools which exhibited 71% structural homology with Endoglucanase B of Thermoascus aurantiacus. The root mean square deviation (RMSD), root mean square fluctuation (RMSF), solvent accessible surface area (SASA), radius of gyration (Rg) and hydrogen bonds analysis were carried at 35°C and 50°C to explore the integrity of structure of recombinant mutant endoglucanase B which corresponded to its optimal temperature. Hydrogen bonds analysis showed more stability of recombinant mutant endoglucanase B as compared to native enzyme. Both native and mutant endoglucanase B genes were expressed in pET 28a+ and purified with nickel affinity chromatography. Theoretical masses determined through ExPaSy Protparam were found 38.7 and 38.5 kDa for native and mutant enzymes, respectively. The optimal pH and temperature values for the mutant were 5.0 and 50°C while for native these were found 4.0 and 35°C, respectively. On reacting with carboxy methyl cellulose (CMC) as substrate, the mutant enzyme exhibited less Km (0.452 mg/mL) and more Vmax (50.25 µmol/ml/min) as compared to native having 0.534 mg/mL as Km and 38.76 µmol/ml/min as Vmax. Among metal ions, Mg2+ showed maximum inducing effect (200%) on cellulase activity at 50 mM concentration followed by Ca2+ (140%) at 100 mM concentration. Hence, expression of a recombinant mutant cellulase from A. niger significantly enhanced its cellulytic potential which could be employed for further industrial applications at pilot scale.

Green ecofriendly enhancement of cellulase productivity using agricultural wastes by Aspergillus terreus MN901491: statistical designs and detergent ability on cotton fabrics

BACKGROUND

Cellulase is considered a group member of the hydrolytic enzymes, responsible for catalyzing the hydrolysis of cellulose and has various industrial applications. Agricultural wastes are used as an inexpensive source for several utilizable products throughout the world. So, searching for cellulase enzymes from fungal strains capable of utilizing agricultural wastes to increase productivity, reduce costs and overcome waste accumulation in the environment is very important to evaluate its potency as a bio-additive to detergent agents.

RESULTS

In the current study, the previously identified fungal strain Aspergillus terreus MN901491 was screened and selected for cellulase production. Medium parameters were optimized using one-factor-at-a-time (OFAT) and multi-factorial (Plackett-Burman and Box-Behnken) design methods. OFAT showed the ability of the fungal strain to utilize agricultural wastes (corn cob and rice straw) as a substrate. Also, yeast extract was the best nitrogen source for enhancing cellulase productivity. The most significant variables were determined by Plackett-Burman Design (PBD) and their concentrations were optimized by Response Surface Methodology (RSM) using Box-Behnken Design (BBD). Among eleven independent variables screened by PBD, malt extract, (NH4)2SO4, and KCl were the most significant ones followed by rice straw which affected cellulase production positively. The ANOVA results particularly the R2-value of PBD (0.9879) and BBD (0.9883) confirmed the model efficiency and provided a good interpretation of the experiments. PBD and BBD improved cellulase productivity by 6.1-fold greater than that obtained from OFAT. Medium optimization using OFAT and statistical models increased cellulase production from A. terreus MN901491 by 9.3-fold compared to the non-optimized medium. Moreover, the efficiency of cellulase activity on cotton fabrics as a bio-additive detergent was evaluated and estimated using whiteness and scanning electron microscope (SEM) that affirmed its potential effect and remarkable detergent ability to improve whiteness by 200% in comparison with non-washed fabric and by 190% in comparison with fabric washed by water.

CONCLUSION

The presented work was stabilized as a multi-efficiency in which wastes were used to produce cellulase enzyme from the fungal strain, Aspergillus terreus MN901491 as a bio-additive to detergent applications that involved ecofriendly and green processes.

Isolation and characterization of cellulase producing bacteria from forest, cow dung, Dashen brewery and agro-industrial waste

The continuous accumulation of waste, particularly from industries, often ends up in landfills. However, this waste can be transformed into a valuable resource through innovative methods. This process not only reduces environmental pollution but also generates additional useful products. This study aims to screen novel high-efficiency cellulose-degrading bacteria from cow dung, forest soil, brewery waste, and agro-industrial waste in the Debre Berhan area for the treatment of cellulose-rich agricultural waste. The serial dilution and pour plate method was used to screen for cellulolytic bacteria and further characterized using morphological and biochemical methods. From eleven isolates cow dung 1 (CD1), cow dung 6 (CD6) and cow dung (CD3) which produced the largest cellulolytic index (3.1, 2.9 and 2.87) were selected. Samples from forest soil, and spent grain didn't form a zone of clearance, and effluent treatment and industrial waste (IW9) shows the smallest cellulolytic index. Three potential isolates were then tested for cellulolytic activity, with cow dung 1 (CD1) displaying promising cellulase activity. These bacterial isolates were then identified as Bacillus species, which were isolated from cow dung 1 (CD1) with maximum cellulase production. Cow dung waste is a rich source of cellulase-producing bacteria, which can be valuable and innovative enzymes for converting lignocellulosic waste.

Bioprocessing of Epothilone B from Aspergillus fumigatus under solid state fermentation: Antiproliferative activity, tubulin polymerization and cell cycle analysis

Epothilone derivatives have been recognized as one of the most powerful anticancer drugs towards solid tumors, for their unique affinity to bind with β-tubulin microtubule arrays, stabilizing their disassembly, causing cell death. Sornagium cellulosum is the main source for Epothilone, however, the fermentation bioprocessing of this myxobacteria is the main challenge for commercial production of Epothilone. The metabolic biosynthetic potency of epothilone by Aspergillus fumigatus, an endophyte of Catharanthus roseus, raises the hope for commercial epothilone production, for their fast growth rate and feasibility of manipulating their secondary metabolites. Thus, nutritional optimization of A. fumigatus for maximizing their epothilone productivity under solid state fermentation process is the objective. The highest yield of epothilone was obtained by growing A. fumigatus on orange peels under solid state fermentation (2.2 μg/g), bioprocessed by the Plackett-Burman design. The chemical structure of the extracted epothilone was resolved from the HPLC and LC-MS/MS analysis, with molecular mass 507.2 m/z and identical molecular fragmentation pattern of epothilone B of S. cellulosum. The purified A. fumigatus epothilone had a significant activity towards HepG2 (IC50 0.98 μg/ml), Pancl (IC50 1.5 μg/ml), MCF7 (IC50 3.7 μg/ml) and WI38 (IC50 4.6 μg/ml), as well as a strong anti-tubulin polymerization activity (IC50 0.52 μg/ml) compared to Paclitaxel (2.0 μg/ml). The effect of A. fumigatus epothilone on the immigration ability of HepG2 cells was assessed, as revealed from the wound closure of the monolayer cells that was estimated by ~ 63.7 and 72.5%, in response to the sample and doxorubicin, respectively, compared to negative control. From the Annexin V-PI flow cytometry results, a significant shift of the normal cells to the apoptosis was observed in response to A. fumigatus epothilone by ~ 20 folds compared to control cells, with the highest growth arrest of the HepG2 cells at the G0-G1 stage.

Microbial production and applications of β-glucosidase-A review

β-Glucosidase exists in all areas of living organisms, and microbial β-glucosidase has become the main source of its production because of its unique physicochemical properties and the advantages of high-yield production by fermentation. With the rise of the green circular economy, the production of enzymes through the fermentation of waste as the substrate has become a popular trend. Lignocellulosic biomass is an easily accessible and sustainable feedstock that exists in nature, and the production of biofuels from lignocellulosic biomass requires the involvement of β-glucosidase. This review proposes ways to improve β-glucosidase yield and catalytic efficiency. Optimization of growth conditions and purification strategies of enzymes can increase enzyme yield, and enzyme immobilization, genetic engineering, protein engineering, and whole-cell catalysis provide solutions to enhance the catalytic efficiency and activity of β-glucosidase. Besides, the diversified industrial applications, challenges and prospects of β-glucosidase are also described.

Quantification of Xylanolytic and Cellulolytic Activities of Fungal Strains Isolated from Palmaria palmata to Enhance R-Phycoerythrin Extraction of Palmaria palmata: From Seaweed to Seaweed

R-phycoerythrin (R-PE) can be enzymatically extracted from red seaweeds such as Palmaria palmata. This pigment has numerous applications and is notably known as an antioxidant, antitumoral or anti-inflammatory agent. Enzymes secreted by P. palmata associated fungal strains were assumed to be efficient and adapted for R-PE extraction from this macroalga. The aim of the present study was to quantify both xylanolytic and cellulolytic activities of enzymatic extracts obtained from six Palmaria palmata derived fungal strains. Degradation of P. palmata biomass by fungal enzymatic extracts was also investigated, focused on soluble protein and R-PE extraction. Enzymatic extracts were obtained by solid state fermentation. Macroalgal degradation abilities were evaluated by measuring reducing sugar release using DNS assays. Soluble proteins and R-PE recovery yields were evaluated through bicinchoninic acid and spectrophotometric assays, respectively. Various enzymatic activities were obtained according to fungal isolates up to 978 U/mL for xylanase and 50 U/mL for cellulase. Enzymatic extract allowed high degrading abilities, with four of the six fungal strains assessed exhibiting at least equal results as the commercial enzymes for the reducing sugar release. Similarly, all six strains allowed the same soluble protein extraction yield and four of them led to an improvement of R-PE extraction. R-PE extraction from P. palamata using marine fungal enzymes appeared particularly promising. To the best of our knowledge, this study is the first on the use of enzymes of P. palmata associated fungi in the degradation of its own biomass for biomolecules recovery.

Bioprocess development for extraction and purification of cellulases from Aspergillus niger 3ASZ using statistical experimental design techniques

The amount of cellulosic materials is large and may lead to environmental pollution, so they can be converted into useful materials for use in food or energy. Statistical design (Plackett-Burman and Box-Behnken) was the main topic of this study and was used to optimize the effect of environmental factors on cellulase production by Aspergillus niger. Cellulase production using Plackett-Burman was 6.86-fold higher than the production of cellulase using the basal medium. B0X-Benken showed an increase in the cellulase production equal to 18 times compared to the basal medium, where the cellulase produced had an activity equal to 79.4 U/mL/min. Ammonium sulfate precipitation was applied to the crude enzyme, followed by sequential fractionation with an Amicon system. The Amicon was used to demonstrate the final volume, total enzyme activity, specific activity, purification fold, and yield of cellulase (partially purified enzyme). Numerous cellulolytic enzymes are abundant in Aspergillus species. All of the data showed that Aspergillus sp. might be a reliable source of industrially and economically useful cellulases. By statistically calculating the relevance of a large number of elements in one experiment using a multifactorial statistical design, time may be saved while still maintaining the validity of each component.

Integration of agricultural residues as biomass source to saccharification bioprocess and for the production of cellulases from filamentous fungi

The production of second-generation bioethanol has several challenges, among them finding cheap and efficient enzymes for a sustainable process. In this work, we analyzed two native fungi, Cladosporium cladosporioides and Penicillium funiculosum, as a source of cellulolytic enzyme production, and corn stover, wheat bran, chickpeas, and bean straw as a carbon source in two fermentation systems: submerged and solid fermentation. Corn stover was selected for cellulase production in both fermentation systems, because we found the highest enzymatic activities when carboxymethyl cellulase activity (CMCase) was assessed using CMC as substrate. C. cladosporioides showed the highest CMCase activity (1.6 U/mL), while P. funiculosum had the highest filter paper activity (Fpase) (0.39 U/mL). The ß-glucosidase activities produced by both fungi were similar in submerged fermentation using corn stover as substrate. Through in-gel zymography, three polypeptides with cellulolytic activities were identified in each fungus: with molecular weights of ~ 38, 45 and 70 kDa in C. cladosporioides and ~ 21, 63 and 100 kDa in P. funiculosum. The best results for saccharification (10.11 g/L of reducing sugars) of diluted acid pretreated corn stover were obtained after 36 h of the hydrolytic process at pH 5 and 50 °C using the enzyme extract of P. funiculosum. This is the first report of cellulase identification in C. cladosporioides and the saccharification of corn stover using enzymes of this fungus. Enzymatic extracts of C. cladosporioides and P. funiculosum obtained from low-cost lignocellulosic biomass have great potential for use in the production of second-generation bioethanol.

A Combined Study on Optimization, In Silico Modeling, and Genetic Modification of Large Scale Microbial Cellulase Production

Cellulase is a biocatalyst that hydrolyzes cellulosic biomass and is considered a major group of industrial enzymes for its applications. Extensive work has been done on microbial cellulase but fungi are considered a novel strain for their maximum cellulase production. Production cost and novel microbial strains are major challenges for its improvement where cheap agro wastes can be essential sources of cellulose as substrates. The researcher searches for more cellulolytic microbes from natural sources but the production level of isolated strains is comparatively low. So genetic modification or mutation can be employed for large-scale cellulase production before optimization. After genetic modification than in silico molecular modeling can be evaluated for substrate molecule's binding affinity. In this review, we focus not only on the conventional methods of cellulase production but also on modern biotechnological approaches applied to cellulase production by a sequential study on common cellulase-producing microbes, modified microbes, culture media, carbon sources, substrate pretreatment process, and the importance of optimum pH and temperature on fermentation. In this review, we also compare different cellulase activity determination methods. As a result, this review provides insights into the interrelationship between the characteristics of optimizing different culture conditions, genetic modification, and in silico enzyme modeling for the production of cellulase enzymes, which may aid in the advancement of large-scale integrated enzyme manufacturing of substrate-specific enzymes.

Optimization and production of holocellulosic enzyme cocktail from fungi Aspergillus nidulans under solid-state fermentation for the production of poly(3-hydroxybutyrate)

The production of petroleum-based plastics increased dramatically following industrialization. Because of multifaceted properties such as durability, thermostability, water resistance, and many others, these plastics have become an indispensable part of daily life. However, while improving people's quality of life, indiscriminate use of plastics has caused pollution and raised environmental concerns. To address this situation and reduce environmental risks, microbially produced biopolymers such as poly-3-hydroxyalkanoates can be used to make bioplastics that are completely biodegradable under normal environmental conditions. At the moment, the cost of bioplastic production is high when compared to petroleum-based plastics, so alternate strategies for making the bioplastic process economical are urgently needed. Agricultural waste is abundant around the world and can be efficiently used as a low-cost renewable feedstock after pretreatment and enzymatic hydrolysis. Fungi are well known as primary degraders of lignocellulosic waste, and this property was used in the current study to enzymatically hydrolyze the pretreated paddy straw for the production of reducing sugars, which were then used in the microbial fermentation for the production of PHB. In this study, Aspergillus nidulans was used to advance a low-cost and efficient enzyme hydrolysis system for the generation of reducing sugars from lignocellulosic biomass. For the production of the holocellulosic enzyme complex, the fungus was grown on wheat straw with Reese mineral medium as a wetting agent. After 216 h of solid-state fermentation at 30 °C, pH 6.0, the enzyme extract from A. nidulans demonstrated the highest activity, CMCase 68.58 (± 0.55), FPase 12.0 (± 0.06), Xylanase 27.17 (± 0.83), and β-glucosidase 1.89 (± 0.037). The initial pH, incubation temperature, and time all had a significant impact on final enzyme activity. Enzymatic hydrolysis of pretreated paddy straw produced reducing sugars (8.484 to 30.91 gL^-1) that were then used to produce poly(3-hydroxybutyrate) using halophilic bacterial isolates. Burkholderia gladioli 2S4R1 and Bacillus cereus LB7 accumulated 26.80% and 20.47% PHB of the cell dry weight, respectively. This suggests that the holocellulosic enzyme cocktail could play a role in the enzymatic hydrolysis of lignocellulosic materials and the production of PHA from less expensive feedstocks such as agricultural waste.

Effect of Different Inducer Sources on Cellulase Enzyme Production by White-Rot Basidiomycetes Pleurotus ostreatus and Phanerochaete chrysosporium under Submerged Fermentation

Cellulase enzymes attract a lot of research due to their industrial application. Diverse cellulase-producing organisms and substances that induce cellulase are highly sought after. This study aimed to evaluate the effect of different inducer sources on cellulase production by white rot fungi P. ostreatus CGMCC 3.7292 and P. chrysosporium CGMCC 3.7212 under submerged fermentation employing a completely randomized experimental design. The different inducer sources tested were nitrogen (yeast, potassium nitrate, sodium nitrate, ammonium sulphate, aqueous ammonia and urea), carbon (malt extract, glucose, fructose, carboxymethylcellulose, starch and xylose) and agro-biomass (stevia straw, wheat straw, oat straw, alfalfa straw, corn cobs and corn stover). These inducer sources strongly impacted enzyme activities by P. ostreatus CGMCC 3.7292 and P. chrysosporium CGMCC 3.7212. The suitable nitrogen and carbon inducer sources for cellulase activity by P. ostreatus and P. chrysosporium were yeast (1.354 U/mL and 1.154 U/mL) and carboxymethylcellulose (0.976 U/mL and 0.776 U/mL) while the suitable agro-biomass were wheat straw (6.880 U/mL) and corn stover (6.525 U/mL), respectively. The least inducer sources in terms of nitrogen, carbon and agro-biomass for cellulase activity by P. ostreatus and P. chrysosporium were urea (0.213 U/mL and 0.081 U/mL), glucose (0.042 U/mL and 0.035), xylose (0.042 U/mL and 0.035 U/mL) and stevia straw (1.555 U/mL and 0.960 U/mL). In submerged fermentation, the cellulase enzyme activity of P. ostreatus in response to various inducer sources was relatively higher than P. chrysosporium.

Bioconversion of Some Agro-Residues into Organic Acids by Cellulolytic Rock-Phosphate-Solubilizing Aspergillus japonicus

Biological-based conversion of agricultural residues into bioactive compounds may be considered to be the basis for various vital industries. However, finding a suitable microorganism is a challenge in the bioconversion process. Therefore, this study was conducted to find local fungal isolates able to convert a combination of plant biomass residues into organic acids (OAs). Based on their cellulase and phytase activities and rock phosphate (RP) solubilization potential, an efficient 15 fungal isolates (named F1 to F15) were selected and identified by both morphological and molecular methods using the 18S rRNA sequencing technique. The best fungal isolate (F15) was identified as Aspergillus japonicus. After 4 weeks of incubation below solid-state fermentation (SSF) with a mix of sugarcane bagasse and faba bean straw (3:7), with 7.5% (v/w) fungal inoculum to the growth medium, the biodegradation process by the fungus reached its peak, i.e., maximum cellulolytic activity and RP solubilization ability. Under such fermentation conditions, seven organic acids were detected using HPLC, in the following order: ascorbic acid > oxalic acid > formic acid > malic acid > succinic acid > lactic acid > citric acid. Based on the results, Aspergillus japonicus (F15) could produce OAs and cellulose enzymes, and could be considered a new single-step bio-converter of sugarcane bagasse and faba bean straw residues into OAs. Furthermore, this fungus could be a new source of fungal cellulose, and could present a practical approach to reducing environmental contamination. Additional work is encouraged for more optimization of fermentation conditions.

Degradation of pretreated agroforestry residues by selected micromycetes

Nowadays, there are huge amounts of lignocellulosic materials left in agroforestry practice, which can be transformed into useful products. Biomass exploitation could be aiming not only at replacing conventional energy sources but also at preserving biodiversity and natural ecosystems. Five micromycetes were studied with goal to determine their potential to produce active cellulases as well as the ability to decompose pretreated wheat straw and oak sawdust after seven days of solid-state fermentation. Wheat straw was better lignocellulosic substrate than oak sawdust for the production of cellulases in all five micromycetes. Thus, Penicillium solitum BEOFB 1190m has shown to be the best producer of highly active forms of xylanases (7532.36 ? 89.37 U/L). The most active endo- and exocellulases (2299.70 ? 72.17 U/L and 195.66 ? 4.64 U/L, respectively) were produced by Trichoderma harzianum BEOFB 1230m, while the maximal value of ?-glucosidase activity (215.69 ? 3.13 U/L) was detected after Fusarium graminearum BEOFB 820m cultivation. T. harzianum also showed high efficiency in wheat straw cellulose and hemicellulose depolymerization (23.90% and 33.00%, respectively), which resulted in the highest dry matter loss (36.25%). The results of the study showed great potential of tested micromycetes to synthesize cellulolytic enzymes and consequently transform abundant, low-cost plant residues such as wheat straw into useful products including biofuel.

Fomitopsis meliae CFA 2, a novel brown rot for endoglucanase: emphasis towards enhanced endoglucanase production by statistical approach

Brown rot basidiomycetes are a principal group of wood-decaying fungi which degrade wood cellulose and hemicellulose by the combination of carbohydrate active enzymes and non-enzymatic oxidation reactions. Very scant information is available on carbohydrate active enzymes of brown rot fungi. In this context, present study focused on the production of cellulolytic–hemicellulolytic enzymes from newly isolated brown rot Fomitopsis meliae CFA 2. Under solid-state fermentation using wheat bran as the substrate Fomitopsis meliae CFA 2 was able to produce a maximum of 1391.12 ± 21.13 U/g of endoglucanase along with other cellulolytic and hemicellulolytic enzymes. Various fermentation parameters were optimised for enhanced production of endoglucanase by employing Plackett-Burman design followed by Box-Behnken design. A well-fitted regression equation with R² value of 98.91% was attained for endoglucanase. The yield of endoglucanase was enhanced by 1.83-fold after executing statistical optimisation of various fermentative parameters. The newly isolated Fomitopsis meliae CFA 2 was found to be a potential producer of endoglucanase. Enzymatic saccharification of alkali-treated wheat straw and rice straw resulted in release of 190.8 and 318.8 mg/g of reducing sugars, respectively.

Use of Industrial Wastes as Sustainable Nutrient Sources for Bacterial Cellulose (BC) Production: Mechanism, Advances, and Future Perspectives

A novel nanomaterial, bacterial cellulose (BC), has become noteworthy recently due to its better physicochemical properties and biodegradability, which are desirable for various applications. Since cost is a significant limitation in the production of cellulose, current efforts are focused on the use of industrial waste as a cost-effective substrate for the synthesis of BC or microbial cellulose. The utilization of industrial wastes and byproduct streams as fermentation media could improve the cost-competitiveness of BC production. This paper examines the feasibility of using typical wastes generated by industry sectors as sources of nutrients (carbon and nitrogen) for the commercial-scale production of BC. Numerous preliminary findings in the literature data have revealed the potential to yield a high concentration of BC from various industrial wastes. These findings indicated the need to optimize culture conditions, aiming for improved large-scale production of BC from waste streams.

Lignocellulosic Waste Degradation Potential of Some Cellulolytic Fungal Strains Isolated from Putrid Fruits

Fungi are plentiful in nature and they are found growing on wastes of wood materials. These wastes are equally found in our environment with no usefulness. The aim of this study was to exploit the probability of the isolated fungi from fruits to produce cellulase from wastes of lignocellulosic materials. Cellulase- producing fungi were isolated from fruits (tomato, banana, plantain). The organisms were screened for cellulase production. Culture conditions were optimized with pH, temperature and carbon. Cellulase was produced using lignocellulosic wastes; sawdust, corn cob, sugarcane bagasse. Six cellulase producers were isolated, four of which were selected for synthesis and quantification of the cellulase. The fungi were identified as Saccharomyces cerevisiae4, Trichoderma species1 and Scopulariopsis brevicaulis1. Of all the tested substrates used in this study, pretreated sugarcane bagasse at 3% w/v concentration with Scopulariopsis brevicaulis gave highest cellulase production 18.18 U/mL at 40°C, 5day incubation time and pH 5, followed by Trichoderma with 12.39 U/mL. These fungi are good potentials cellulase producers that can be considered at industrial level.

The functioning of a novel protein, Swollenin, in promoting the lignocellulose degradation capacity of Trichoderma guizhouense NJAU4742 from a proteomic perspective

The functioning of a novel auxiliary enzyme, TgSWO from Trichoderma guizhouense NJAU4742, was investigated based on the proteomic analysis of wild-type (WT), knockout (KO) and overexpression (OE) treatments. The results showed that the cellulase and hemicellulase activities of OE and WT were significantly higher than those of KO. Simultaneously, tandem mass tag (TMT) analysis results indicated that cellulases and hemicellulases were significantly upregulated in OE, especially hydrophobin (HFB, A1A105805.1) and endo-β-1,4-glucanases (A1A101831.1), with ratios of 43.73 and 9.88, respectively, compared with WT. The synergistic effect of TgSWO on cellulases increased the reducing sugar content by 1.45 times in KO + TgSWO (1.8 mg) compared with KO, and there was no significant difference between KO + TgSWO (1.2 mg) and WT. This study elucidated the function of TgSWO in promoting the lignocellulose degradation capacity of NAJU4742, which provides new insights into the efficient conversion of lignocellulose.

Assessment and evaluation of cellulase production using ragi (Eleusine coracana) husk as a substrate from thermo-acidophilic Aspergillus fumigatus JCM 10253

The cellulase production by filamentous fungi Aspergillus fumigatus JCM 10253 was carried out using agro-industrial waste ragi husk as a substrate in the microbial fermentation. The effect of the process parameters such as temperature, substrate concentration, pH, and incubation process time and their interdependence was studied using response surface methodology. The optimum cellulase activities were obtained at 50 °C under the conditions with 1-2% of substrate concentration at pH 2-4 for the incubation period of 7-8 days. The maximum carboxymethyl cellulase (CMCase) and β-glucosidase activities with optimized process variables were 95.2 IU/mL and 0.174 IU/mL, respectively. The morphological characterization of fungus by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR) revealed the presence of secondary protein structures. Furthermore, this study demonstrated that the application of ragi husk could be a promising feedstock for value-added industrial products. The thermo-acidophilic nature of isolated strain Aspergillus fumigatus JCM 10253 possessed a significant potential for higher titer of cellulase production that could be further employed for lignocellulosic bioethanol production.

Black liquor: A potential moistening agent for production of cost-effective hydrolytic enzymes by a newly isolated cellulo-xylano fungal strain Aspergillus tubingensis and its role in higher saccharification efficiency

In the present study, black liquor generated during mild alkali pre-treatment was evaluated as a moistening agent to produce cost effective hydrolytic enzymes using novel cellulo-xylano fungal strain Aspergillus tubingensis M7. The fungus competently produced 21.90 and 22.46 filter paper, 1004 and 1369 endoglucanase, 117 and 142 β-glucosidase and 8188 and 7981 U/g xylanase activity by using modified Mandel & weber's and black liquor medium, respectively. The crude hydrolytic enzymes from black liquor were evaluated for saccharification of pre-treated biomass. Reducing sugar yields (mg/g substrate) and the corresponding saccharification efficiency (%) from rice straw, corncob, sugarcane bagasse and banana stem were 745.50 (86.02; 18 h); 596 (74.50; 24 h); 358.15 (42.98; 24 h) and 245.70 (33.00; 24 h), respectively. Residual biomass compositional analysis revealed that reduced onset temperature, increased activation energy and pre-exponential factor in saccharified biomass as compared to pre-treated and untreated biomass, suggesting their utilization for pyrolysis to obtain value added products.

Aspergillus terreus obtained from mangrove exhibits antagonistic activities against Pythium aphanidermatum-induced damping-off of cucumber

A study was conducted to investigate the potential of Aspergillus terreus obtained from Avicennia marina mangrove roots in inhibiting Pythium aphanidermatum and damping-off disease of cucumber. Aspergillus terreus exhibited in vitro inhibition of Pythium aphanidermatum growth. Electron microscope examination revealed that the antagonistic fungal isolate resulted in shrinking and groves in Pythium hypha. When Aspergillus terreus culture filtrate was added to Pythium aphanidermatum, it resulted in a significant increase (by 73%) in electrolyte leakage from Pythium hypha compared to the control, as well as significant reduction (by 71%) in oospore production. The Aspergillus terreus culture was also found to produce a cellulase enzyme, which is suggested to be involved in the antagonism against Pythium aphanidermatum. Adding Aspergillus terreus to soil infested with Pythium aphanidermatum significantly reduced percent mortality in cucumber seedlings by 70%. Aspergillus terreus, when applied alone on cucumber seedlings, did not show any suppressive effects on cucumber growth (length and fresh and dry weight). This appears to be the first report of isolation from mangrove of Aspergillus terreus with antagonistic activity against Pythium aphanidermatum-induced damping-off of cucumber. The study indicates that fungal isolates obtained from marine environments may serve as potential biocontrol agents against some plant pathogens.

Comparative Study of Extracellular Proteolytic, Cellulolytic, and Hemicellulolytic Enzyme Activities and Biotransformation of Palm Kernel Cake Biomass by Lactic Acid Bacteria Isolated from Malaysian Foods

Biotransformation via solid state fermentation (SSF) mediated by microorganisms is a promising approach to produce useful products from agricultural biomass. Lactic acid bacteria (LAB) that are commonly found in fermented foods have been shown to exhibit extracellular proteolytic, β-glucosidase, β-mannosidase, and β-mannanase activities. Therefore, extracellular proteolytic, cellulolytic, and hemicellulolytic enzyme activities of seven Lactobacillus plantarum strains (a prominent species of LAB) isolated from Malaysian foods were compared in this study. The biotransformation of palm kernel cake (PKC) biomass mediated by selected L. plantarum strains was subsequently conducted. The results obtained in this study exhibited the studied L. plantarum strains produced versatile multi extracellular hydrolytic enzyme activities that were active from acidic to alkaline pH conditions. The highest total score of extracellular hydrolytic enzyme activities were recorded by L. plantarum RI11, L. plantarum RG11, and L. plantarum RG14. Therefore, they were selected for the subsequent biotransformation of PKC biomass via SSF. The hydrolytic enzyme activities of treated PKC extract were compared for each sampling interval. The scanning electron microscopy analyses revealed the formation of extracellular matrices around L. plantarum strains attached to the surface of PKC biomass during SSF, inferring that the investigated L. plantarum strains have the capability to grow on PKC biomass and perform synergistic secretions of various extracellular proteolytic, cellulolytic, and hemicellulolytic enzymes that were essential for the effective biodegradation of PKC. The substantial growth of selected L. plamtraum strains on PKC during SSF revealed the promising application of selected L. plantarum strains as a biotransformation agent for cellulosic biomass.

Production and characterization of β-glucosidase from Aspergillus niger fermentation: Application for organic fraction of municipal solid waste hydrolysis and methane enhancement

The anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) is currently an attractive treatment process with energy production in the form of biogas. Hydrolysis is the rate-limiting step for the anaerobic digestion of solid wastes. Thus, in the present study fungal enzymatic pretreatment of OFMSW was applied to enhance biogas production. Two enzyme cocktails rich on β-glucosidase were produced from submerged fermentation of Aspergillus niger on basal medium using OFMSW as carbon source and urea (Urea cocktail) and Ulva rigida as nitrogen source (Ulva cocktail). Ulva cocktail displayed an important effect on OFMSW solubilization. Therefore, an increase of reducing sugar concentration about 60% was obtained which was in correlation with chemical oxygen demand (COD) increase. The performance of enzymatic pretreatment on anaerobic digestion of OFMSW was studied by conducting biochemical methane potential tests. Results showed that the enzymatic pretreatment improved methane yield of OFMSW even at high solid concentration. High methane yield about 500 ml/g total volatile solid was obtained, which corresponds up to 68% enhancement over the control.

Raw oil palm frond leaves as cost-effective substrate for cellulase and xylanase productions by Trichoderma asperellum UC1 under solid-state fermentation

Production of cellulases and xylanase by a novel Trichoderma asperellum UC1 (GenBank accession no. MF774876) under solid state fermentation (SSF) of raw oil palm frond leaves (OPFL) was optimized. Under optimum fermentation parameters (30 °C, 60-80% moisture content, 2.5 × 10⁶ spores/g inoculum size) maximum CMCase, FPase, β-glucosidase and xylanase activity were recorded at 136.16 IU/g, 26.03 U/g, 130.09 IU/g and 255.01 U/g, respectively. Cellulases and xylanase were produced between a broad pH range of pH 6.0-12.0. The enzyme complex that comprised of four endo-β-1,4-xylanases and endoglucanases, alongside exoglucanase and β-glucosidase showed thermophilic and acidophilic characteristics at 50-60 °C and pH 3.0-4.0, respectively. Glucose (16.87 mg/g) and fructose (18.09 mg/g) were among the dominant sugar products from the in situ hydrolysis of OPFL, aside from cellobiose (105.92 mg/g) and xylose (1.08 mg/g). Thermal and pH stability tests revealed that enzymes CMCase, FPase, β-glucosidase and xylanase retained 50% residual activities for up to 15.18, 4.06, 17.47 and 15.16 h of incubation at 60 °C, as well as 64.59, 25.14, 68.59 and 19.20 h at pH 4.0, respectively. Based on the findings, it appeared that the unique polymeric structure of raw OPFL favored cellulases and xylanase productions.

Moringa straw as cellulase production inducer and cellulolytic fungi source

Currently, the valorization of agroindustrial waste is of great interest. Moringa oleifera is a multipurpose tree whose softwood residues could be used as raw material for low-cost cellulase production. The aim of this study was to isolate, identify, and characterize microorganisms with cellulolytic activity in different carbon sources. We isolated and purified 42 microorganisms from M. oleifera biomass. Fungi presenting the largest hydrolytic halos in carboxymethylcellulose as a substrate were molecularly identified as Penicillium funiculosum (FG1), Fusarium verticillioides (FG3) and Cladosporium cladosporioides (FC2). The ability of these fungal strains to break down cellulose was assessed in a submerged fermentation using either amorphous CMC or crystalline form (Avicel). P. funiculosum and C. cladosporioides displayed similar endoglucanase (606U/l) and exoglucanase (205U/l) activities in the Avicel-containing medium, whereas F. verticillioides showed the highest level of β-glucosidase activity (664U/l) in the carboxymethylcellulose medium. In addition, the effect of three culture media (A, B, and C) on cellulase production was evaluated in P. funiculosum using moringa straw as a carbon source. The results showed a volumetric productivity improvement of cellulases that was 2.77-, 8.26-, and 2.30-fold higher for endoglucanase, exoglucanase and β-glucosidase, respectively when medium C containing moringa straw was used as a carbon source. The enzymatic extracts produced by these fungi have biotechnological potential especially for second-generation bioethanol production (2G) from moringa straw. This is the first report on the use of M. oleifera biomass to induce the production of various cellulases in P. funiculosum.

Saccharification of macroalgal polysaccharides through prioritized cellulase producing bacteria

Marine macroalgal cell wall is predominantly comprised of cellulose (polysaccharide) with the complex chain of glycosidic linkages. Bioethanol production from macroalgae entails breaking this complex chain into simple glucose molecule, which has been the major challenge faced by the industries. Cellulases have been preferred for hydrolysis of cellulose due to the absence of inhibitors affecting the subsequent fermentation process. Cellulose degrading bacteria were isolated from wide-ranging sources from marine habitats to herbivore residues and gastrointestinal region. The investigation reveals that Vibrio parahaemolyticus bacteria has higher hydrolytic capacity with salt tolerance up to 14% and 3.5% salinity is optimum for growth. Higher hydrolytic activity of 2.45 was recorded on carboxymethyl cellulose medium at 48 h and hydrolytic activity of 2.46 on Ulva intestinalis hydrolysate, 3.06 on Ulva lactuca hydrolysate at 72 h of incubation. Total activity of enzyme of 2.11 U/ml and specific activity of 6.05 U/mg were recorded at 24 h. Enzyme hydrolysis of macroalgal biomass; U. intestinalis and U. lactuca produced 135.9 mg/g and 107.6 mg/g of reducing sugar respectively. The study reveals that the enzyme extracted from salt tolerant Vibrio parahaemolyticus bacteria is suitable for optimal saccharification of seaweed polysaccharides towards biofuel production.

Solid state fermentation of de-oiled rice bran: Effect on in vitro protein digestibility, fatty acid profile and anti-nutritional factors

An experiment was conducted to study the effect of solid state fermentation of de-oiled rice bran (DORB) with Rhizopus oryzae on in vitro protein digestibility, anti-nutritional factors and fatty acid profile. The fermentation of DORB with Rhizopus oryzae significantly reduced the in vitro protein digestibility of DORB (p < .05). The fermentation of DORB with Rhizopus oryzae increased the saturated fatty acid (SFA) content by 46.83%, while decreased the MUFA and PUFA contents by 14.01 and 8.76%, respectively. The n-6 fatty acid content of FDORB increased by 6.19%, while n-3 fatty acid content decreased by 53.92%. The fermentation of DORB resulted in significant reduction in phytate and trypsin inhibitor activity (p < .05). Based on the present result it is concluded that the fermentation of DORB with Rhizopus oryzae improves the n-6 fatty acid profile and brings significant reduction in the phyate and trypsin inhibitor content but fails to improve the in vitro protein digestibility and hence cannot be recommended as a suitable microbe for DORB fermentation.

Production, purification, characterization and application of a new halotolerant and thermostable endoglucanase of Botrytis ricini URM 5627

A halotolerant endoglucanase with a molecular mass of 39 kDa was obtained from the solid fermentation of sugarcane bagasse by the fungus Botrytis ricini URM 5627 and isolated using only two purification processes: fractionation with ammonium sulphate and size-exclusion chromatography resulting in an activity of 1289.83 U/mL. After the isolation, biochemical characterizations were performed, giving a temperature of 50 °C and optimum pH of 5. The enzyme was stable at 39-60 °C for 60 min and at a pH of 4-6. The enzymatic activity increased in the presence of Na⁺, Mn²⁺, Mg²⁺ and Zn²⁺ and decreased in the presence of Ca²⁺, Cu²⁺, and Fe²⁺. The endoglucanase revealed a halotolerant profile since its activity increased proportionally to an increase in NaCl concentration. The maximum activity was reached at 2 M NaCl with a 75% increase in activity. The enzyme had a K_m of 0.1299 ± 0.0096 mg/mL and a V_max of 0.097 ± 0.00121 mol/min/mL. During application in saccharification tests, the enzyme was able to hydrolyse sugarcane bagasse, rice husk, and wheat bran, with the highest production of reducers/fermentable sugars within 24 h of saccharification for wheat bran (137.21 mg/g). Therefore, these properties combined make this isolated enzyme a potential candidate for biotechnological and industrial applications.

Rice straw fermentation by Schizophyllum commune ARC-11 to produce high level of xylanase for its application in pre-bleaching

Rice straw is valuable resource that has been used as substrate for cost effective production of xylanase under solid-state fermentation by a newly isolated white rot fungi, S. commune ARC-11. Out of eleven carbon sources tested, rice straw was found most effective for the induction of xylanase that produced 4288.3 IU/gds of xylanase by S. commune ARC-11. Maximum xylanase production (6721.9 IU/gds) was observed on 8th day of incubation at temperature (30 °C), initial pH (7.0) and initial moisture content (70.0%). The supplementation of ammonium sulphate (0.08% N, as available nitrogen) enhanced the xylanase production up to 8591.4 IU/gds. The xylanase production by S. commune ARC-11 was further improved by the addition of 0.10%, (w/v) of Tween-20 as surfactant. The maximum xylanase activities were found at pH 5.0 and temperature 55 °C with a longer stability (180 min) at temperature 45, 50 and 55 °C. This xylanase preparation was also evaluated for the pre-bleaching of ethanol-soda pulp from Eulaliopsis binata. An enzyme dosage of 10 IU/g of xylanase resulted maximum decrease in kappa number (14.51%) with a maximum improvement 2.9% in ISO brightness compared to control.

Illumina-MiSeq analysis of fungi in acid lime roots reveals dominance of Fusarium and variation in fungal taxa

A study was conducted to analyze fungal diversity in the roots of acid lime (Citrus aurantifolia) collected from Oman, a semi-arid country located in the South Eastern part of the Arabian Peninsula. MiSeq analysis showed the Ascomycota and Sordariomycetes were the most abundant phylum and class in acid lime roots, respectively. Glomeromycota, Basidiomycota and Microsporidia were the other fungal phyla, while Glomeromycetes and some other classes belonging to Ascomycota and Basidiomycota were detected at lower frequencies. The genus Fusarium was the most abundant in all samples, making up 46 to 95% of the total reads. Some fungal genera of Arbuscular mycorrhizae and nematophagous fungi were detected in some of the acid lime roots. Analysis of the level of fungal diversity showed that no significant differences exist among groups of root samples (from different locations) in their Chao richness and Shannon diversity levels (P < 0.05). Principle component analysis of fungal communities significantly separated samples according to their locations. This is the first study to evaluate fungal diversity in acid lime roots using high throughput sequencing analysis. The study reveals the presence of various fungal taxa in the roots, dominated by Fusarium species and including some mycorrhizae and nematophagous fungi.

Obtaining filamentous fungi and lipases from sewage treatment plant residue for fat degradation in anaerobic reactors

A residue from the primary treatment of a Wastewater Treatment Plant (WWTP) was used to isolate filamentous fungi with lipase production potential. Two of the 27 isolated fungi presented high hydrolysis index and were selected for lipase production by solid-state fermentation (SSF). The fermentations were conducted at 30 °C for 48 h, with moist air circulation, using 20% (w/w) of the residue mixture with a basal medium (agroindustrial residue-babassu cake), obtaining a solid enzymatic preparation (SEP) with lipase activity of 19 U/g with the fungus identified as Aspergillus terreus. Scum, collected in an anaerobic reactor operating in a WWTP, was hydrolyzed with SEP and subjected to anaerobic biodegradability tests at 30 °C. Different dilutions of crude (Control) or hydrolyzed scum in raw sewage were evaluated. The dilution of 5% (v/v) of hydrolyzed scum in raw sewage proved the most adequate, as it resulted in higher methane yield compared to the raw sewage (196 and 133 mL CH4/g CODadded, respectively), without increasing the chemical oxygen demand (COD) of the treated sewage (138 and 134 mg/L). The enzymatic hydrolysis of the scum, followed by dilution in the influent sewage, is technically feasible and increases methane production in anaerobic reactors.

Microbial Strategies for Cellulase and Xylanase Production through Solid-State Fermentation of Digestate from Biowaste

Solid-state fermentation (SSF) is a promising technology for producing bioproducts from organic wastes. The objective of this study is to assess the feasibility of using digestate as substrate to produce hydrolytic enzymes, mainly cellulase and xylanase, by exploring three different inoculation strategies: (i) SSF with autochthonous microbiota; (ii) non-sterile SSF inoculated with Trichoderma reesei and (iii) sequential batch operation to select a specialized inoculum, testing two different residence times. Native microbial population did not show a significant cellulase production, suggesting the need for a specialized inoculum. The inoculation of Trichoderma reesei did not improve the enzymatic activity. On the other hand, inconsistent operation was achieved during sequential batch reactor in terms of specific oxygen uptake rate, temperature and enzymatic activity profile. Low cellulase and xylanase activities were attained and the main hypotheses are non-appropriate biomass selection and some degree of hydrolysis by non-targeted proteases produced during fermentation.