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Enzymes derived from microbial sources have gained increasing popularity in industrial applications over the past decades. Despite the high production cost, alkaline proteases have wide applications in industries such as tanneries, food production, and detergents. In recent years, there has been a shift towards utilizing natural carbon sources for cultivating microorganisms and extracting proteases in order to reduce production costs. This study aimed to investigate the biochemical and kinetic properties of protease enzymes obtained from Aspergillus niger cultivated in a paper waste medium and compare with the enzyme produced in a basal medium. Glucose is a more favorable carbon source compared to cellulose, so paper waste was pretreated with cellulose-degrading bacteria to convert cellulose into smaller carbohydrates. After the growth of A. niger in basal and combinational media, the enzymatic properties were compared between the extracted enzymes by using casein as substrate. The results demonstrated that A. niger could produce protease enzymes in the paper waste medium similar to the basal medium with more than 5-fold cost saving. The specific activity of the enzymes isolated from the basal and paper waste media was calculated to be 184.95 ± 10.56 U ml -1 and 169.88 ± 11.05 U ml -1 , respectively. Carbon sources did not affect the optimum pH and temperature of the protease enzyme, which were found to be 8 and 37 °C, respectively. This study provides valuable insights into the production of alkaline protease from A. niger using a combinational medium (paper waste pretreated by cellulose-degrading bacteria), offering a cost-effective approach for industrial applications., (Copyright © 2023 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.)

In the present study Aspergillus niger and Aspergillus flavus isolated from paper mill effluent showed tolerance and accumulation of toxic metals Ni, Zn, Cd, Pb, Cr and Cu from synthetic medium and paper mill effluent. Physico-chemical and heavy metals characterization of industrially treated paper mill effluent showed insignificant reduction in BOD, hardness, TDS and heavy metals as compared to permissible limits of BIS and WHO. A. niger and A. flavus were treated with synthetic medium containing 100-1000 mg l(-1) of six heavy metals. A. niger was able to tolerate and grow in 1000 mg l(-1) Pb, 500 mg l(-1) Cu, 250 mg l(-1) Zn and 100 mg l(-1) Cr, Ni respectively. No growth of A. niger was observed in 100 mg l-(-1) of Cd. A. flavus was capable to tolerate and grow in 1000 mg l(-1) Pb, Zn and Ni, 100mg l(-1) Cu. A. flavus growth was completely inhibited in 100 mg l(-1) of Cd and Cr. The Cd, Zn, Cu and Pb reduction were found significant (p < 0.05) in the paper effluent inoculated with A. niger and A. flavus biomass compared to industrial treated effluent. A. niger and A. flavus accumulated maximum of Pb (75.82%) followed by Zn (49.40%) > Cu (45.34%) > Ni (25.20%), while only 41% Cr was accumulated by A. nigerfrom 100 mg l(-1) of Cr solution.

Gluconic acid production was investigated using an enzymatic hydrolysate of waste office automation paper in a culture of Aspergillus niger. In repeated batch cultures using flasks, saccharified solution medium (SM) did not show any inhibitory effects on gluconic acid production compared to glucose medium (GM). The average gluconic acid yields were 92% (SM) and 80% (GM). In repeated batch cultures using SM in a turbine blade reactor (TBR), the gluconic acid yields were 60% (SM) and 67% (GM) with 80-100 g/l of gluconic acid. When pure oxygen was supplied the production rate increased to four times higher than when supplying air. Remarkable differences in the morphology of A. niger and dry cell weight between SM and GM were observed. The difference in morphology may have caused a reduction of oxygen transfer, resulting in a decrease in gluconic acid production rate in SM.

Melanins play a fundamental role in the biology and ecology of several fungal species. Unfortunately, this group of amorphous macromolecules also severely (and most times irreversibly) stains cultural heritage objects. Despite efforts made throughout the years, knowledge of the chemical composition and structure of melanins is still insufficient, which hampers the task of safely cleaning these colourants from cultural heritage materials in a targeted way without causing further deterioration. This work aimed therefore to contribute towards enlightening the characteristics of fungal melanins from three fungi that are common paper colonizers: Aspergillus niger, Chaetomium globosum and Cladosporium cladosporioides. The extracted melanins were characterized by FTIR, Raman, UV-vis, Solid-State NMR and MALDI-TOF MS spectroscopies and the effect of inhibitors of DHN-melanin and DOPA-melanin pathways on colony pigmentation and growth was evaluated. Although all the extracted colourants show a predominantly aromatic structure with carbonyl and phenolic groups, some differences between the melanins can be highlighted. Melanins obtained from Ch. globosum and Cl. cladosporioides exhibited similar structures and composition and both presented DHN-melanin characteristics, while A. niger’s melanins revealed a more complex and ordered structure, with a higher prevalence of highly conjugated carbonyls than the others, besides the additional presence of a yellow/green component. These conclusions cannot be overlooked while selecting targeted cleaning methodologies for melanin stains on cultural heritage materials.

Although the moderate load (COD of 5000-10,000 mg/L) and biodegradability of the APMP pulping effluent should allow biological treatment, toxic compounds in the effluent can interfere with this type of treatment. Studies were conducted to determine if treatment of the effluent with Aspergillus niger S13 was feasible. Under the optimized conditions (3% inoculum, pH 6, shaking at 160 rpm, 60-72 h, and 30°C), this fungus was able to remove about 97% of the methyl tertiary butyl ether (MTBE) extractives, and 60%, 77% and 43% of the chemical oxygen demand, turbidity and color even without a pre-flocculation step. These results are of practical interest in China because the APMP process has become popular, and efficient and cost-effective effluent treatment technologies are in high demand., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

A novel two-stage biological/flocculation process was developed for treating the pulping effluent from the alkaline peroxide mechanical pulping (APMP) process. In the first biological stage, the aerobic fermentation by using Aspergillus niger can decrease the chemical oxygen demand (COD) by about 60% while producing about 7 g/l of solid biomass. In the second stage (post-coagulation/flocculation), the residual COD, turbidity and color, can be further decreased by using alum and polyacrylamide (PAM). The overall removal efficiencies of COD, color and turbidity from the APMP pulping effluent by the above two-stage biological-coagulation/flocculation process were 93%, 92% and 99%, respectively, under the conditions studied., (Copyright © 2011 Elsevier Ltd. All rights reserved.)

Alkaline peroxide mechanical pulping (APMP) of wheat straw with enzyme treatment was studied. Instead of direct enzyme pretreatment on wheat straw, an alternative treatment method was used, in which coarse pulps from refiner defibrated wheat straw rather than wheat straw were pretreated with a crude enzyme containing mainly xylanase, then impregnated with alkaline H2O2 solution and further refined. The optimum conditions of enzyme treatment were xylanase dosage of 10-15 IU/g of oven-dried wheat straw, 90 min, 50-60 degrees C, pulp consistency of 5-10%, and initial pH of 5.0, and those for chemical impregnation were 6% NaOH, 70-80 degrees C, 60-90 min, and 4 to 5% H2O2. Enzyme treatment improved pulpability of wheat straw by the APMP process, and final pulp quality such as brightness, breaking length, and burst index of pulp. Pulp from the APMP process with enzyme treatment could be bleached to a brightness of 70.5% ISO by two-stage H2O2 bleaching sequence with only 4% H2O2, and breaking length of the bleach pulp reached 4470 m

This study aims to investigate, analyze and conserve the general arrangement plan of the Egyptian royal yacht “Safra El-Bahr” from the National Archives of Egypt’s tracing paper collection. The yacht was specifically designed for Abbas II, the khedive of Egypt in 1894 A.D. The following analytical techniques were used for this study: pH value measurement, fungal testing, XRD, ATR-FTIR and SEM-EDX. Results revealed that the pH value of the plan paper is 6.5. Fungal testing proved the presence of Aspergillus Niger and Penicillium sp. The crystallinity index of cellulose in the historical paper increased compared to modern tracing paper indicating the occurrence of deterioration. The ATR-FTIR spectrum of the studied tracing paper revealed the presence of gelatin as a sizing material. The SEM investigation showed the effect of the natural ageing and surrounding environmental conditions on the surface morphology of the fibers. The EDX analysis revealed the use of kaolinite Al2Si2O3(OH)4, Cl, NaOH and CaCo3 in paper manufacture. Copper carbonate (CuCO3) was used for the blue color. Conservation treatments conducted on the object included cleaning, removal of pressure sensitive tape, removal of adhesive residues, tear mending and lining. These processes revealed the aesthetic value of the general arrangement plan - screw yacht “SAFA-EL-BAHRE. [ABSTRACT FROM AUTHOR]

Despite substantial literature on the dyeing of textiles, there is a lack of research about colouring Japanese mending papers (tissue papers) used for paper conservation purposes. This study investigates the fungal bioreceptivity of Japanese tissue papers after they have been treated with various dyes and pigments. A variety of toning materials including plant dyes, watercolours, acrylic paints, inks, pastels, gouaches, and colour pencils are commonly used by conservators for paper toning purposes. In this study, two Japanese tissue papers (Yukyu-shiandSekishu Mare) were treated with selected plant dyes, watercolours, and acrylic paints and then inoculated with fungal species. Quantitative real-time polymerase chain reaction (qPCR) was used to quantify the DNA fromAspergillus nigerandPenicillium rubrumas a proxy for fungal species abundance before and after inoculation and artificial moist heat ageing. qPCR primers which were universal for fungi amplified DNA from papers inoculated withA. nigerandP. rubrumand these species were found to grow less on treatedSekishu MareandYukyu-shipapers compared with untreated papers.Sekishu Marepapers treated with artists' acrylic paints were found to be more resistant to fungal growth than similarly treatedYukyu-shipapers. This study suggests that for the best long-term preservation outcomes for paper materials in archives, libraries, galleries, and museums, acrylic paints generally perform better in conservation terms than most plant dyes and watercolours, although most colourants displayed some bioinhibition. [ABSTRACT FROM PUBLISHER]

A well-known industrial fungus for enzyme production, Aspergillus niger, was selected to produce the feruloyl esterase FAEA by homologous overexpression for pulp bleaching application. The gpd gene promoter was used to drive FAEA expression. Changing the nature and concentration of the carbon source nature (maltose to glucose; from 2.5 to 60 g l(-1)), improved FAEA activity 24.5-fold and a yield of 1 g l(-1) of the corresponding protein in the culture medium was achieved. The secreted FAEA was purified 3.5-fold to homogeneity in a two-step purification procedure with a recovery of 69%. The overproduced protein was characterised and presented properties in good agreement with those of native FAEA. The recombinant FAEA was tested for wheat straw pulp bleaching, with or without a laccase mediator system and xylanase. Best results were obtained using a bi-sequential process with a sequence including xylanase, FAEA and laccase, and yielded very efficient delignification--close to 75%--and a kappa number of 3.9. This is the first report on the potential application of recombinant FAEA in the pulp and paper sector.

The main purpose of this study is maximizing the utilization of paper waste material and decrease its harmful effect. Eleven fungal isolates were selected and tested to assess their cellulolytic potential. The isolates13A which were isolated from immature compost showed the highest Cellulolytic Index values 0.47 mm. According to the morphological characteristics and the 18S rRNA gene sequence, the isolate13A was identified as Aspergillus niger strain13A. The effect of pH and temperature on growth of Aspergillus niger strain13A and its production of cellulase were investigated, the optimal culture conditions was recorded at pH 6.0 after 6 days of incubation at 35 °C. Under optimal conditions various paper waste materials were used for enzyme production under submerged and solid-state fermentation. Maximum production of cellulase by Aspergillus niger strain13A was shown using kraft brown bags and cardboard under solid state fermentation. Aspergillus niger strain13A exhibited also good degradability for a mixture of kraft, cardboard, foolscap and printout paper, under solid state fermentation resulting in the production of bioorganic material. Results of this study showed that treatment of soil with bioorganic materials demnstrarting high effectiveness in controlling Fusarium wilt of cucumber (Cucumis sativus L.) could be considered as promising alternative to chemical fungicides. [ABSTRACT FROM AUTHOR]

In paper conservation ethanol is used as an antifungal agent. However, information on the antifungal efficacy of this alcohol is scarce and often inconsistent. In this study, we clarify if ethanol is effective and safe to use in paper conservation in the short as well as in the long term. None of the tested ethanol concentrations (5–100%) promoted conidia germination, but rather delayed or entirely inhibited it, depending on alcohol concentration and contact time. In a simulation of an interventive treatment of samples colonized by fungi, all the tested ethanolic solutions (30, 70, and 100%) revealed antifungal activity. The best results were obtained with 70% ethanol, showing fungicidal properties on four of the five-tested fungal species (Aspergillus niger,Cladosporium cladosporioides,Penicillium chrysogenum, andPenicillium corylophilum). No deleterious effects of 70% ethanol on the tested paper were observed either in the short or in the long term. [ABSTRACT FROM PUBLISHER]

In this study, extractives from Pinus rigida heartwood (PRW), Eucalyptus camaldulensis var. obtusa aerial parts (ECL), and Eucalyptus flower buds (ECF) were used as additives in paper sheets produced from the pulp of linen fibers, and their effects on the mechanical and antifungal properties of the paper sheets were studied. The highest tensile and tear indices were 31.5 Nm/g, and 17.3 mNm2/g as pulp treated with PRW (4%), and ECL (1%), respectively. All the pulp additives yielded lower burst index values compared to the control (2.24 KPa.m2/g); the nearest value was 2.23 KPa.m2/g (ECL 4% pulp additive). The brightness percentages (ISO%) ranged from 65.7% to 70.2%, which were lower than the control treatment (70.3%). The paper sheets produced from pulp treated with 2% or 4% PRW, and with 4% ECL suppressed Aspergillus niger growth on the paper disc; pulp treated with 2% or 4% PRW, 4% ECL, and with 2% or 4% ECF completely suppressed A. terreus growth. However, all pulp extract additives did not inhibit the growth of Fusarium culmorum. [ABSTRACT FROM AUTHOR]

The object of this project was to determine spread of fungal contamination of Iraqi paper currency in summer and winter. 60paper currency obtained from different occupational groups in Kirkuk, Iraq . The results showed that all collected samples were contaminated with one or more fungal species representing 100% contamination and none from the new (control) notes. The currency was processed for fungal isolation using the direct and streaking technique on Potato Dextrose Agar (PDA) and Sabouraud Dextrose Agar. Isolated fungi in summer with its percentagewere Rhizopus stolonifer 33.6%, Aspergillus niger 26%, A. flavus 8.8%, Sacchromyces spp. 8.8%, Penicillium spp. 7.1%, Trichophyton spp. 4.2%, A. terrus 2.1%, Rhodotorula spp. 2.9%, Alternaria spp. 2.5%, Trichoderma spp. 2.1%, Stemphylium spp. 1.2%, Candida spp. 0.4%. While the Isolated fungi in winter with its percentage were Rhodotorula spp. 39.2%, Penicillium spp. 28.1%, Sacchromyces spp. 8.8%, Aspergillus niger 5.1%, Trichophyton spp. 3.7%, A. clavatus 2.9%, Stemphylium spp. 2.9%, Cladosporium sphaerosperum 4.4%, A.tamarii 2.2%, Alternaria spp. 1.4%, Drechslera spp. 0.7%. The higher denomination (5000, 10000 and 25000) IQD had the lower fungal contamination as compare with lower one (250, 500 and 1000) IQD while the paper currency of 1000 IQD were more contaminated from 250 and 500 IQD. The results showed that three fungal isolates achieve a high growth on CMC Czapek’s agar medium. A fourteen A. flavus strains cultures were isolated from Iraqi paper currency as toxigenic or atoxigenic using coconut agar medium (CAM), it was strains confirmed that there were 4 only toxigenic and 10 atoxigenic. The toxigenic isolates were identified at molecular detection by using PCR technique, DNA of 4 strains have been extracted, and the target region ITS1 5.8S ITS2 has been amplified by using the common primers ITS1–ITS4, the PCR products were in size 595 bpthe results compatible with microscopic and morphologicalidentification. [ABSTRACT FROM AUTHOR]

Melanins play a fundamental role in the biology and ecology of several fungal species. Unfortunately, this group of amorphous macromolecules also severely (and most times irreversibly) stains cultural heritage objects. Despite efforts made throughout the years, knowledge of the chemical composition and structure of melanins is still insufficient, which hampers the task of safely cleaning these colourants from cultural heritage materials in a targeted way without causing further deterioration. This work aimed therefore to contribute towards enlightening the characteristics of fungal melanins from three fungi that are common paper colonizers: Aspergillus niger, Chaetomium globosum and Cladosporium cladosporioides. The extracted melanins were characterized by FTIR, Raman, UV-vis, Solid-State NMR and MALDI-TOF MS spectroscopies and the effect of inhibitors of DHN-melanin and DOPA-melanin pathways on colony pigmentation and growth was evaluated. Although all the extracted colourants show a predominantly aromatic structure with carbonyl and phenolic groups, some differences between the melanins can be highlighted. Melanins obtained from Ch. globosum and Cl. cladosporioides exhibited similar structures and composition and both presented DHN-melanin characteristics, while A. niger's melanins revealed a more complex and ordered structure, with a higher prevalence of highly conjugated carbonyls than the others, besides the additional presence of a yellow/green component. These conclusions cannot be overlooked while selecting targeted cleaning methodologies for melanin stains on cultural heritage materials. [ABSTRACT FROM AUTHOR]

The purpose of this study was to develop a biotechnological process to produce citric acid using paper residues from Urban Solid Waste (USW), like raw material. The selected microorganism to transform degraded cellulose from paper to produce citric acid was Aspergillus niger. The aerobic bioreaction was carried out in a heterogeneous bioreactor. The efficiency of the biotransformation in this study was measured under different operating conditions: 2 and 3 pH levels, 30 and 40 °C temperatures, and high and low concentrations of trace elements: Copper (Cu), Manganese (Mn) and Zinc (Zn). In optimized operation conditions from 20 g of waste paper the maximum citric acid amount obtained was 5.73 g l−1. [ABSTRACT FROM AUTHOR]

Cellulase has by vast applications in the biofuel, pulp and paper, detergent and textile industries. The three components of the enzyme complex (endoglucanase, exoglucanase and β-glucosidase) can effectively depolymerize the cellulose chains in lignocellulosic substrate. Solid-state fermentation (SSF) by fungi is a preferable production route for cellulase because of its low cost, among other advantages. This work describes the cellulase production by Aspergillus niger NRRL3 grown on SSF. SSF was carried out on soybean hulls and waste paper as supports. The effect of the support on cellulase production was assessed under a completely randomized factorial design. The support-time interaction was significant for all the variables studied. Both materials were characterized in terms of water absorption index and critical humidity point. Samples of culture were analyzed with scanning electron microscopy (SEM) to study spores and fungal growth. Maximum endoglucanase activity was found at 96 h using soybean hulls as support (5914.29 U L −1 ), being four times higher than that obtained using waste paper at the same fermentation time. The exoglucanase activity in soybean hulls was maximal at 96 h (4551.19 U L −1 ), being 9.6 times higher than that obtained in waste paper at the same time. The maximum β-glucosidase activity in soybean hulls (984.01 U L −1 ) was reached at 96 h, being 1.7 times greater than that obtained in waste paper. Besides, the use of soybean hulls provided high volumetric productivities at shorter times, which may decrease production costs considering a scaled process. [ABSTRACT FROM AUTHOR]

Bioethanol and enzymes were produced from fiber sludges through sequential microbial cultivations. After a first simultaneous saccharification and fermentation (SSF) with yeast, the bioethanol concentrations of sulfate and sulfite fiber sludges were 45.6 and 64.7 g/L, respectively. The second SSF, which included fresh fiber sludges and recycled yeast and enzymes from the first SSF, resulted in ethanol concentrations of 38.3 g/L for sulfate fiber sludge and 24.4 g/L for sulfite fiber sludge. Aspergillus niger carrying the endoglucanase-encoding Cel7B gene of Trichoderma reesei was grown in the spent fiber sludge hydrolysates. The cellulase activities obtained with spent hydrolysates of sulfate and sulfite fiber sludges were 2,700 and 2,900 nkat/mL, respectively. The high cellulase activities produced by using stillage and the significant ethanol concentrations produced in the second SSF suggest that onsite enzyme production and recycling of enzyme are realistic concepts that warrant further attention.

The deinking in the paper industry is in great demand, and microbial enzymes are key players. In the present study, the endoglucanase production from newly isolated fungi Aspergillus niger MPS25 is reported. The optimization of endoglucanase production was carried out using one factor at a time approach resulting in endoglucanase activity (2.37 IU/ml) at 45 °C and pH 8 in submerged fermentation (SmF), which shows optimum enzyme activity at 60 °C. Interestingly, the metal ions viz. Co2+ stimulated the endoglucanase activity, whereas Mn2+ reduced the enzyme activity, which shows that this enzyme can be used for effluent treatment released through deinking. The enzymatic hydrolysis of wheat straw produced 26.96 ± 0.108 mg/g of reducing sugars, indicating its potential in saccharification and the biofuel industry. Furthermore, the validation of the deinking efficiency of this enzyme resulted in improved deinking of mixed office waste and old newspapers by 31.5% and 20.4%, respectively. The strength properties, viz. burst factor and tear index, breaking length, and tensile index of the handmade paper sheets, were also improved which were analyzed by the scanning electron micrographs. The FTIR and XRD analysis of pulp provided insights into the changes in functional groups and cellulose crystallinity, respectively. These results indicate that multi-efficient endoglucanase from Aspergillus niger MPS25 is suitable for enzyme-based eco-friendly deinking for waste paper recycling and lignocellulosic biomass saccharification. [Display omitted] • The endoglucanase from newly isolated fungi Aspergillus niger MPS25 is reported. • The endoglucanase showed stability at 60 °C with wide pH range. • The endoglucanase significantly improved the deinking efficiency for mixed office waste (31.5%) and old newspapers (20.4%). • The SEM, FTIR and XRD analysis provided technological insights for process scale up. • This multi-efficient endoglucanase proved to be suitable enzyme in eco-friendly recycling of MOW and ONP. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to identify the most common fungal species that grow on paper manuscripts and cause bio-deterioration. It also detects the impact of additive materials on fungal degrading and builds a wide database. Thus, it helps conservators understand this phenomenon. Design/methodology/approach: In total, 15 samples were collected from different paper manuscripts suffering from fungi. The achievement of the study objectives depends on using a variety of analyzes, such as a microbiological study, which indicated that three main fungi grew on the paper samples. Then, a digital microscope and an environmental scanning electron microscope were used to detect the effect of fungi on paper fibers. Fourier transform infrared microscopy was used to identify the binding medium and the X-ray diffraction method was used to measure the crystallinity index of cellulose of the paper samples. Findings: Arabic gum was used as a binder medium with the samples. Aspergillus Niger, Aspergillus Fumigatus and Aspergillus Clavatus were the most common fungal species that grew on the Qur'an papers under investigation. They also caused much common damage to the paper samples. The results of the analyzes also showed that the highest crystallinity index of cellulose was in the samples that contained the lowest rate of fungal growth. Originality/value: This paper highlights the relationship between fungal degradation and the multi-component nature of paper manuscripts. It builds a wide database that correlates the composition and the degradation of the Qur'an papers. [ABSTRACT FROM AUTHOR]

This study reports on the concentrations of airborne fungi in a waste paper and cardboard recycling factory (WPCRF) in Tehran, Iran. Sampling occurred every six days during winter at nine locations. The following order was observed in all processing units: Penicillium sp. (92 ± 6 CFU m−3) > Cladosporium sp. (74 ± 7 CFU m−3) > Aspergillus niger (19 ± 9 CFU m−3). In the processing units, the lifetime average daily dose ranged from 1.49 × 10−3 to 7.8 CFU (kg.d)−1 for the inhalation route and from 2.74 × 10−6 to 6.29 × 10−6 CFU (kg.d)−1 for the dermal route. [ABSTRACT FROM AUTHOR]

Pycnoporus cinnabarinus laccase was fused to the C-terminal linker and carbohydrate binding module (CBM) of Aspergillus niger cellobiohydrolase B (CBHB). The chimeric enzyme of molecular mass 100 kDa was successfully produced in A. niger. Laccase-CBM was further purified to determine its main biochemical properties. The Michaelis-Menten constant and pH activity profile were not modified, but the chimeric enzyme was less thermostable than either the P. cinnabarinus laccase or the recombinant laccase produced in the same strain. Laccase-CBM was able to bind to a cellulosic substrate and, to a greater extent, to softwood kraft pulp. Binding to the pulp was shown to be mainly time and temperature-dependent. Laccase-CBM was further investigated for its softwood kraft pulp biobleaching potential and compared with the P. cinnabarinus laccase. Addition of a CBM was shown to greatly improve the delignification capabilities of the laccase in the presence of 1-hydroxybenzotriazole (HBT). In addition, ClO(2) reduction using 5 U of chimeric enzyme per gram of pulp was almost double than that observed using 20 U of P. cinnabarinus laccase per gram of pulp. We demonstrated that conferring a carbohydrate binding capability to the laccase could significantly enhance its biobleaching properties.

Xylanase is a hemicellulase enzyme that catalyses the hydrolysis of xylan to xylose which is widely used in processing of feed, pulp and paper. It is produced by many microorganisms especially filamentous fungi like Trichoderma and Aspergillus. A potential xylanolytic fungal isolate Aspergillus niger was isolated from forest soils of Tirumala, AP, India, and its crude enzyme was checked for its potential in paper bleaching. Under submerged fermentation, production of xylanase, cellulase, biomass, total protein and sugar released were analysed after 7 days of incubation at room temperature. Maximum enzyme activity was recorded on the fifth day of incubation, biomass after the seventh day, total protein and sugar released on the sixth day of incubation. Enzyme pretreatment of paper reduced 3.5 points in kappa number, 3.1 points increase in brightness and removal of chromophores and hydrophobic compounds. The FTIR and SEM analysis of enzyme-treated sample had shown modification in surface morphology and functional groups. These results clearly demonstrated that the xylanase produced by A. niger was effective as a pulp biobleaching agent which can be used on an industrial scale. [ABSTRACT FROM AUTHOR]

In the context of e-waste recycling by fungal bioleaching, nickel and cobalt precipitate as toxic metals by oxalic acid, whereas organic acids, such as citric, act as a high-performance chelating agent in dissolving these metals. Oxalic acid elimination requires an excess and uneconomical carbon source concentration in culture media. To resolve this issue, a novel and straightforward systems metabolic engineering method was devised to switch metabolic flux from oxalic acid to citric acid. In this technique, the genome-scale metabolic model of Aspergillus niger was applied to predicting flux variability and key reactions through the calculation of multiple optimal solutions for cellular regulation. Accordingly, BRENDA regulators and a novel molecular docking-oriented approach were defined a regulatory medium for this end. Then, ligands were evaluated in fungal culture to assess their impact on organic acid production for bioleaching of copper and nickel from waste telecommunication printed circuit boards. The protein structure of oxaloacetate hydrolase was modeled based on homology modeling for molecular docking. Metformin, glutathione, and sodium fluoride were found to be effective as inhibitors of oxalic acid production, enabling the production of 8100 ppm citric acid by controlling cellular metabolism. Indirect bioleaching demonstrated that nickel did not precipitate, and the bioleaching efficiency of copper and nickel increased from 40% and 24% to 61% and 100%, respectively. Bioleaching efficiency was evaluated qualitatively by FE-SEM, EDX, mapping, and XRD analysis. KEY POINTS: • A regulatory-systemic procedure for controlling cellular metabolism was introduced • Metformin inhibited oxalic acid, leading to 8100 ppm citric acid production • Bioleaching of copper and nickel in TPCBs improved by 21% and 76., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

The filamentous fungus Aspergillus niger is well known for its high protein secretion capacity and a preferred host for homologous and heterologous protein production. To improve the protein production capacity of A. niger even further, a set of dedicated protein production strains was made containing up to 10 glucoamylase landing sites (GLSs) at predetermined sites in the genome. These GLSs replace genes encoding enzymes abundantly present or encoding unwanted functions. Each GLS contains the promotor and terminator region of the glucoamylase gene (glaA), one of the highest expressed genes in A. niger. Integrating multiple gene copies, often realized by random integration, is known to boost protein production yields. In our approach the GLSs allow for rapid targeted gene replacement using CRISPR/Cas9-mediated genome editing. By introducing the same or different unique DNA sequences (dubbed KORE sequences) in each GLS and designing Cas9-compatible single guide RNAs, one is able to select at which GLS integration of a target gene occurs. In this way a set of identical strains with different copy numbers of the gene of interest can be easily and rapidly made to compare protein production levels. As an illustration of its potential, we successfully used the expression platform to generate multicopy A. niger strains producing the Penicillium expansum PatE::6xHis protein catalysing the final step in patulin biosynthesis. The A. niger strain expressing 10 copies of the patE::6xHis expression cassette produced about 70 μg·mL -1 PatE protein in the culture medium with a purity just under 90%., (© 2023 The Authors. The FEBS Journal published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies.)

A variety of liquid energy exists in papermaking engineering and has not yet been developed and utilized. In addition, for the papermaking industry, the presence of slime can seriously affect the quality of the finished paper and can lead to paper breaking. The current slime control strategies cannot completely solve the problem and also have some low toxicity. In this study, a method of self-powered sterilization of cellulose fibers by using triboelectric pulsed direct current is reported. A liquid–solid triboelectric nanogenerator (L–S TENG) was used to convert the liquid energy of nanocellulose suspension into electrical energy and convert this electrical energy into pulsed direct current for self-powered sterilization of cellulose fiber. A hydrophobic coating material is used as solid triboelectric material and electrode for sterilization. Driven by L–S TENG, the electrodes exhibited an excellent sterilization rate against four microorganisms including Escherichia coli, Aspergillus niger, Candida albicans, and Klebsiella pneumoniae, which from slime in the papermaking industry. This study could provide a basic research theory for liquid energy harvesting in the papermaking industry, and also provide a new strategy for pulp sterilization. [ABSTRACT FROM AUTHOR]

The synthesis of xylosyloligosaccharides from beta-(1----4)-xylobiose in the presence of D-mannose by transxylosylation with beta-xylosidase from Aspergillus niger IFO 6662 was studied. At first, the transxylosylation products were separated by charcoal column chromatography in 5% ethanol elution into three peaks, P-1, P-2, and P-3. They were further separated on thin layer chromatography, and their three products, saccharides O-4, O-5, and O-N were purified by preparative paper chromatography. Saccharides O-4 and O-5 were identified as O-beta-D-xylopyranosyl-(1----4)-D- mannopyranose and O-beta-D-xylopyranosyl-(1----6)-D-mannopyranose, respectively, by measurement of the degree of polymerization, specific rotation, acid hydrolysis, and methylation analysis. By 1H-NMR spectroscopy in addition to these analyses, saccharide O-N was identified as O-beta-D-xylopyranosyl-(1----1')-beta-D-xylopyranose, a new nonreducing xylobiose.

Historic cultural heritage and archival manuscripts have a significant importance worldwide and efforts should be considered to preserve such property for as long as possible. The current study aimed to establish a non-toxic, and eco-friendly conservation strategy for retarding paper biodeterioration. To this end, fungal isolates associated with the biodeteriorated paper manuscripts of the historical book "DESCRIPTION DE L´EGYPTE" dating back to 1823 A.D were isolated. These isolates were identified as Asperigllus niger, Aspergillus flavus, Penicillium chrysogenum and Alternaria alternata and then evaluated for cellulolytic activities. Amongst them, Aspergillus niger A2 exhibited the highest cellulase activity. In in vitro study using filter papers as model, the suppressive effect of biosynthesized silver and zinc oxide nanoparticles (NPs) on A. niger A2 bioderteriorant activity was evaluated. Biosynthesized Ag-NPs and ZnO-NPs were characterized by UV-Vis spectroscopy, X-ray diffraction patterns (XRD), Transmission Electron Microscopy (TEM) and Fourier Transform Infrared Spectroscopy (FT-IR). Color changes, tensile strength, FT-IR-spectroscopy, and scanning electron microscopy of NPs-treated papers were examined. Treatments with 2 mM Ag-NPs and 2 mM ZnO-NPs exhibited the best conservation effect on treated papers and alleviated cellulose degradation. Furthermore, this treatments enhanced tensile strength and preserved the original morphology of paper fibers. These results introduced a potential approach for historical documents conservation against fungal biodeterioration through NPs sprays. It can be also used for preparing anti-biodeterioration paper for expected manuscripts uses. [ABSTRACT FROM AUTHOR]

Objective: To develop an endo-β-1,4-xylanase with high specificity for production of prebiotic xylooligosaccharides that optimally works at moderate temperature desirable to reduce the energy cost in the production process., Results: The xylB gene, encoding for a glycosyl hydrolase family 11 xylanase from a thermoresistant fungus, Aspergillus niger BCC14405 was expressed in a methylotrophic yeast P. pastoris KM71 in a secreted form. The recombinant XylB showed a high specific activity of 3852 and 169 U mg -1 protein on beechwood xylan and arabinoxylan, respectively with no detectable side activities against different forms of cellulose (Avicel Ò PH101 microcrystalline cellulose, phosphoric acid swollen cellulose and carboxymethylcellulose). The enzyme worked optimally at 45 °C, pH 6.0. It showed a specific cleavage pattern by releasing xylobiose (X2) as the major product from xylooligosaccharides (X3 to X6) substrates. The highest XOS yield of 708 mg g -1 substrate comprising X2, X3 and X6 was obtained from beechwood xylan hydrolysis., Conclusion: The enzyme is potent for XOS production and for saccharification of lignocellulosic biomass., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)