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Oat (Avena sativa) processing generates a large amount of by-products, especially oat bran. These by-products are excellent sources of bioactive compounds such as polyphenols and essential fatty acids. Therefore, enhancing the extraction of these bioactive substances and incorporating them into the human diet is critical. This study investigates the effect of acid pretreatment on the solid-state fermentation of oat bran with Aspergillus niger, with an emphasis on the bioaccessibility of phenolic acids and lipid profile. The results showed a considerable increase in reducing sugars following acid pretreatment. On the sixth day, there was a notable increase in the total phenolic content, reaching 58.114 ± 0.09 mg GAE/g DW, and the vanillic acid level significantly rose to 77.419 ± 0.27 μg/g DW. The lipid profile study revealed changes ranging from 4.66 % in the control to 7.33 % on the sixth day of SSF. Aside from biochemical alterations, antioxidant activity measurement using the DPPH technique demonstrated the maximum scavenging activity on day 4 (83.33 %). This study highlights acid pretreatment's role in enhancing bioactive compound accessibility in solid-state fermentation and its importance for functional food development., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)

An adhesive solid-state fermentation (adSSF) mode was developed to produce Aspergillus niger conidia, which used a stainless-steel Dixon ring as the support and water-retaining adhesive to load nutritional media on its surface. To obtain high conidia yields, the components of the water-retaining adhesive were screened, optimized by single-factor optimization and response surface methodology, and the optimal dosages of the main components were: wheat bran powder 0.023 g·cm -3 bed , cassava starch 0.0022 g·cm -3 bed , and xanthan gum 0.0083 g·cm -3 bed . The experimentally tested conidia yield was 4.2-fold that without water-retaining adhesive but was 3.7% lower than the maximum yield predicted by the model. The observed double-side growth of A. niger on the Dixon ring supports improved space utilization of the fermentation bed, and the void fraction can increase with the shrinkage of the gel layer. In 1.6 L tray reactors with three-point online temperature monitoring, the inner-bed temperature of adSSF was at most 4 °C lower than the adsorbed carrier solid-state fermentation (ACSSF) mode, and the conidia yield was 1.68 × 10 8 conidia .cm -3 bed , 61.5% higher than that of the ACSSF bed at the same time, but when the fermentation time was extended to 168 h, the conidia yield of the adSSF bed and ACSSF bed were close to each other. The results revealed that the high voidage of the adSSF bed was the main reason for low bed temperature, which can benefit the inner-bed natural convection and water evaporation., (© 2024. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Biosurfactants are a diverse group of compounds derived from microorganisms, possessing various structures and applications. The current study was seeking to isolate and identify a new biosurfactant-producing fungus from soil contaminated with petrochemical waste. The bioprocess conditions were optimized to maximize biosurfactant production for Aspergillus carneus OQ152507 using a glucose peptone culture medium with a pH of 7.0 and a temperature of 35 °C. The carbon source was glucose (3%), and ammonium sulfate (0.25%) was utilized as the nitrogen source. For Aspergillus niger OQ195934, the optimized conditions involved a starch nitrate culture medium with a pH of 7.0 and a temperature of 30 °C. The carbon source used was sucrose (3.5%), and ammonium sulfate (0.25%) served as the nitrogen source. The phenol-H 2 SO 4 and phosphate tests showed that the biosurfactants that were extracted did contain glycolipid and/or phospholipid molecules. They showed considerable antimicrobial activity against certain microbes. The obtained biosurfactants increased the solubility of tested polyaromatic hydrocarbons, including fluoranthene, pyrene, anthracene, and fluorine, and successfully removed the lubricating oil from contaminated soil and aqueous media surface tension reduction. Based on the obtained results, A. carneus and A. niger biosurfactants could be potential candidates for environmental oil remediation processes., (© 2024. The Author(s).)

Itaconic acid is an industrially crucial organic acid due to its broad range of applications. The main hurdle in itaconic acid production is the high cost of the substrate, i.e ., pure glucose, required for the fermentation process. Pakistan annually produces about 1.7 to 1.8 million metric tonnes of mango fruit. Keeping this in view, the potential of a sugar-rich fruit by-product, i.e ., mango peels, was analyzed to be used as a substrate for the biosynthesis of itaconic acid using Aspergillus niger by submerged fermentation. Different physicochemical parameters (incubation period, temperature, agitation rate, inoculum size, and pH) were optimized using the central composite design (CCD) design of response surface methodology (RSM). The maximum production of itaconic acid, i.e ., 4.6 g/L, was analyzed using 10% mango peels w/v (water hydrolysate), 3 mL inoculum volume after 5 days of fermentation period at pH 3, and a temperature of 32 °C when the media was kept at a 200-rpm agitation speed. The itaconic acid extraction from mango peels was done using the solvent extraction method using n-butanol. The identification and quantification of itaconic acid produced in the study were done using the Fourier Transform Infrared Spectroscopy (FTIR) spectrum and the High-Performance Liquid Chromatography (HPLC) method. According to HPLC analysis, 98.74% purity of itaconic acid was obtained in the research. Hence, it is concluded from the results that sugar-rich mango peels can act as a promising substrate for the biosynthesis of itaconic acid. Further conditions can be optimized at the bioreactor level to meet industrial requirements., Competing Interests: The authors declare that they have no competing interests., (© 2024 Saeed et al.)

D-Xylitol is a naturally occurring sugar alcohol present in diverse plants that is used as an alternative sweetener based on a sweetness similar to sucrose and several health benefits compared to conventional sugar. However, current industrial methods for D-xylitol production are based on chemical hydrogenation of D-xylose, which is energy-intensive and environmentally harmful. However, efficient conversion of L-arabinose as an additional highly abundant pentose in lignocellulosic materials holds great potential to broaden the range of applicable feedstocks. Both pentoses D-xylose and L-arabinose are converted to D-xylitol as a common metabolic intermediate in the native fungal pentose catabolism.To engineer a strain capable of accumulating D-xylitol from arabinan-rich agricultural residues, pentose catabolism was stopped in the ascomycete filamentous fungus Aspergillus niger at the stage of D-xylitol by knocking out three genes encoding enzymes involved in D-xylitol degradation (ΔxdhA, ΔsdhA, ΔxkiA). Additionally, to facilitate its secretion into the medium, an aquaglyceroporin from Saccharomyces cerevisiae was tested. In S. cerevisiae, Fps1 is known to passively transport glycerol and is regulated to convey osmotic stress tolerance but also exhibits the ability to transport other polyols such as D-xylitol. Thus, a constitutively open version of this transporter was introduced into A. niger, controlled by multiple promoters with varying expression strengths. The strain expressing the transporter under control of the PtvdA promoter in the background of the pentose catabolism-deficient triple knock-out yielded the most favorable outcome, producing up to 45% D-xylitol from L-arabinose in culture supernatants, while displaying minimal side effects during osmotic stress. Due to its additional ability to extract D-xylose and L-arabinose from lignocellulosic material via the production of highly active pectinases and hemicellulases, A. niger emerges as an ideal candidate cell factory for D-xylitol production from lignocellulosic biomasses rich in both pentoses.In summary, we are showing for the first time an efficient biosynthesis of D-xylitol from L-arabinose utilizing a filamentous ascomycete fungus. This broadens the potential resources to include also arabinan-rich agricultural waste streams like sugar beet pulp and could thus help to make alternative sweetener production more environmentally friendly and cost-effective., (© 2024. The Author(s).)

Drug biotransformation studies emerges as an alternative to pharmacological investigations of metabolites, development of new drug candidates with reduced investment and most efficient production. The present study aims to evaluate the capacity of biotransformation of rifampicin by the filamentous fungus Aspergillus niger ATCC 9029. After incubation for 312 h, the drug was metabolized to two molecules: an isomer (m/z 455) and the rifampicin quinone (m/z 821). The monitoring of metabolite formation was performed by high-performance liquid chromatography, followed by their identification through ultra-high-performance liquid chromatography coupled to tandem mass spectrometer. In vitro antimicrobial activity of the proposed metabolites was evaluated against Staphylococus aureus microorganism, resulting in the loss of inhibitory activity when compared with the standards, with minimum inhibitory concentration of 7.5 μg/ml. The significant biotransformation power of the ATCC 9029 strain of A. niger was confirmed in this study, making this strain a candidate for pilot studies in fermentation tanks for the enzymatic metabolization of the antimicrobial rifampicin. The unprecedented result allows us to conclude that the prospect of new biotransforming strains in species of anemophilic fungi is a promising choice., (© 2024 John Wiley & Sons Ltd.)

To promote the sustainability of hydrothermal liquefaction (HTL) for biofuel production, fungal fermentation was investigated to treat HTL aqueous phase (HTLAP) from corn stover. The most promising fungus, Aspergillus niger demonstrated superior tolerance to HTLAP and capability to produce oxalic acid as a value-added product. The fungal-bacterial co-culture of A. niger and Rhodococcus jostii was beneficial at low COD (chemical oxygen demand) loading of 3800 mg/L in HTLAP, achieving 69% COD removal while producing 0.5 g/L oxalic acid and 11% lipid content in microbial biomass. However, higher COD loading of 4500, 6040, and 7800 mg/L significantly inhibited R. jostii, but promoted A. niger growth with increased oxalic acid production while COD removal remained similar (58-65%). Additionally, most total organic carbon (TOC) in HTLAP was transformed into oxalic acid, representing 46-56% of the consumed TOC. These findings highlighted the potential of fungi for bio-upcycling of HTLAP into value-added products., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

The present study deals with the production of cellulase-free endoxylanase by Aspergillus niger ISL-9 using wheat bran as a solid substrate. Endoxylanase was produced under a solid-state fermentation. Various growth parameters were optimized for the improved production of the enzyme. The Substrate level of 15 g was optimized as it provided the fungus with balanced aeration and nutrition. Among the six moisture contents investigated, Moisture Content 5 (MC5) was optimized (g/l: malt extract, 10; (NH 4 ) 2 HPO 4 , 2.5; urea, 1.0) and 10 mL of MC5 was found to give the highest production of endoxylanase. The pH and time of incubation were optimized to 6.2 and 48 h respectively. The Inoculum size of 2 mL (1.4 × 10 6 spores/mL) gave the maximum enzyme production. After optimization of these growth parameters, a significantly high endoxylanase activity of 21.87 U/g was achieved. Very negligible Carboxymethylcellulase (CMCase) activity was observed indicating the production of cellulase-free endoxylanase. The notable finding is that the endoxylanase activity was increased by 1.4-fold under optimized conditions (p ≤ 0.05). The overall comparison of kinetic parameters for enhanced production of endoxylanase by A. niger ISL-9 under Solid State Fermentation (SSF) was also studied. Different kinetic variables which included specific growth rate, product yield coefficients, volumetric rates and specific rates were observed at 48, 72 and 96 h incubation time and were compared for MC1 and MC5. Among the kinetic parameters, the most significant result was obtained with volumetric rate constant for product formation (Q p ) that was found to be optimum (1.89 U/h) at 72 h incubation period and a high value of Q p i.e.1.68 U/h was also observed at 48 h incubation period. Thus, the study demonstrates a cost-effective and environmentally sustainable process for xylanase production and exhibits scope towards successful industrial applications., (© 2024. The Author(s).)

Filamentous fungi with their diverse inventory of carbohydrate-active enzymes promise a holistic usage of lignocellulosic residues. A major challenge for application is the inherent repression of enzyme production by carbon catabolite repression (CCR). In the presence of preferred carbon sources, the transcription factor CreA/CRE-1 binds to specific but conserved motifs in promoters of genes involved in sugar metabolism, but the status of CCR is notoriously difficult to quantify. To allow for a real-time evaluation of CreA/CRE-1-mediated CCR at the transcriptional level, we developed a luciferase-based construct, representing a dynamic, highly responsive reporter system that is inhibited by monosaccharides in a quantitative fashion. Using this tool, CreA/CRE-1-dependent CCR triggered by several monosaccharides could be measured in Neurospora crassa, Aspergillus niger and Aspergillus nidulans over the course of hours, demonstrating distinct and dynamic regulatory processes. Furthermore, we used the reporter to visualize the direct impacts of multiple CreA truncations on CCR induction. Our reporter thus offers a widely applicable quantitative approach to evaluate CreA/CRE-1-mediated CCR across diverse fungal species and will help to elucidate the multifaceted effects of CCR on fungal physiology for both basic research and industrial strain engineering endeavours., (© 2024 The Author(s). Microbial Biotechnology published by John Wiley & Sons Ltd.)

This study explores the enhancement of phosphate rock (PR) solubilization through solid-state fermentation (SSF) by optimizing oxalic acid production using Aspergillus niger. Key process parameters, including the use of agro-industrial by-products (sugarcane bagasse (SCB), wheat bran (WB), soybean bran (SB)), pH levels, sucrose supplementation, and methanol addition, were systematically evaluated through sequential experimental designs. The results identified SCB and SB in a 1:1 ratio as the most effective substrate. Remarkably, the inclusion of methanol (7 %) and sucrose (0.5 %) resulted in a 3-fold increase in oxalic acid production. Under these optimized conditions, significant phosphorus solubilization of Bayóvar, Itafós, and Registro PRs was achieved, with Bayóvar rock releasing up to 12.1 g/kgds of soluble P (63.8 % efficiency). Additionally, the SSF process effectively released organic phosphorus from the agro-industrial substrates. These findings hold promise for advancing the bio-based economy and developing future industrial biofertilizers., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Ginsenoside F2 is a protopanaxadiol saponin compound with various biological activities, including antioxidant, anti-inflammatory, and anticancer properties. Ginsenoside F2 can be found in ginseng, but in low quantities. Therefore, ginsenoside F2 production predominantly relies on the biotransformation of various ginsenosides, such as ginsenosides Rb1 and Rd. In this study, we reported the production of ginsenoside F2 by gypenoside biotransformation with Aspergillus niger JGL8, isolated from Gynostemma pentaphyllum . Ginsenoside F2 could be produced by two different biotransformation pathways, namely Gyp-V-Rd-F2 and Gyp-XVII-F2. The product exhibited antioxidant activity against free radicals (DPPH) with IC 50 value of 29.54 µg/mL. Optimal biotransformation conditions were a pH of 5.0, temperature of 40 °C, and 2 mg/mL of substrate. Enzyme kinetic parameters revealed that the hydrolysis rate of Gyp-V, Rd, and Gyp-XVII was 0.625, 0.588, and 0.417 mM/h, respectively. In conclusion, we demonstrated that gypenoside is a substitutable substrate for ginsenoside F2 biotransformation.

Epothilones are one of the common prescribed anticancer drugs for solid tumors, for their exceptional binding affinity with β-tubulin microtubule, stabilizing their disassembly, causing an ultimate arrest to the cellular growth. Epothilones were initially isolated from Sornagium cellulosum, however, their extremely slow growth rate and low yield of epothilone is the challenge. So, screening for a novel fungal endophyte dwelling medicinal plants, with higher epothilone productivity and feasibility of growth manipulation was the objective. Aspergillus niger EFBL-SR OR342867, an endophyte of Latania loddegesii, has been recognized as the heady epothilone producer (140.2 μg/L). The chemical structural identity of the TLC-purified putative sample of A. niger was resolved from the HPLC, FTIR and LC-ESI-MS/MS analyses, with an identical molecular structure of the authentic epothilone B. The purified A. niger epothilone B showed a resilient activity against MCF-7 (0.022 μM), HepG-2 (0.037 μM), and HCT-116 (0.12 μM), with selectivity indices 21.8, 12.9 and 4, respectively. The purified epothilone B exhibited a potential anti-wound healing activity to HepG-2 and MCF-7 cells by ~ 54.07 and 60.0%, respectively, after 24 h, compared to the untreated cells. The purified epothilone has a significant antiproliferative effect by arresting the cellular growth of MCF-7 at G2/M phase by ~ 2.1 folds, inducing the total apoptosis by ~ 12.2 folds, normalized to the control cells. The epothilone B productivity by A. niger was optimized by the response surface methodology, with ~ 1.4 fold increments (266.9 μg/L), over the control. The epothilone productivity by A. niger was reduced by ~ 2.4 folds by 6 months storage as a slope culture at 4 °C, however, the epothilone productivity was slightly restored with ethylacetate extracts of L. loddegesii, confirming the plant-derived chemical signals that partially triggers the biosynthetic genes of A. niger epothilones. So, this is the first report emphasizing the metabolic potency of A. niger, an endophyte of L. loddegesii, to produce epothilone B, that could be a new platform for industrial production of this drug., (© 2024. The Author(s).)

Probiotic fermentation studies are vital in many areas, particularly when it comes to feeding applications. This work examines probiotic fermentation in oil tea crops. The assessment of tea saponin-degrading bacteria and optimization of fermentation conditions using fermented oil tea cake under natural conditions, screening out six strains with strong ability to degrade tea saponin; selection of the best tea saponin degradation strain L.2 and recognition of its morphological features and ITS sequence to obtain L.2 strain is Aspergillus Niger. Oil tea is rich in tea saponin. Aspergillus Niger degraded tea saponins in oil teacakes at a rate of 93.96 % under the ideal conditions of 31.3 oC, 103.5 h, and 4.57 mL of initial acid addition. This has been accomplished via solid-state fermentation of L.2 using single factor studies and surface response optimization experiments. Moreover, Aspergillus Niger degraded tea saponins in oil tea cakes at a rate of 93.96% at the ideal circumstances of 31.3 C, 103.5 h, and 4.57 mL of initial acid addition., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Inc. All rights reserved.)

Aromatic compounds serve as the primary source of floral and fruity aromas in sauce-flavor (Maotai flavor) baijiu, constituting the skeleton components of its flavor profile. Nevertheless, the formation mechanism of these compounds and key aroma-producing enzymes in sauce-flavor Daqu (fermentation agent, SFD) remain elusive. Here, we combined metagenomics, metaproteomics, metabolomics, and key enzyme activity to verify the biosynthesis pathway of aromatic compounds and to identify key enzymes, genes, and characteristic microorganisms in SFD. The results showed that the later period of fermentation was critical for the generation of aromatic compounds in SFD. In-situ verification was conducted on the potential key enzymes and profiles in various metabolites, providing comprehensive evidence for the main synthetic pathways of aromatic compounds in SFD. Notably, our results showed that primary amine oxidase (PrAO) and aldehyde dehydrogenase (ALDH) emerged as two key enzymes promoting aromatic compound synthesis. Additionally, two potential key functional genes regulating aromatics generation were identified during SFD fermentation through correlation analysis between proteins and relevant metabolites, coupled with in vitro amplification test. Furthermore, original functional strains (Aspergillus flavus-C10 and Aspergillus niger-IN2) exhibiting high PrAO and ALDH production were successfully isolated from SFD, thus validating the results of metagenomics and metaproteomics analyses. This study comprehensively elucidates the pathway of aromatic compound formation in SFD at the genetic, proteomic, enzymatic, and metabolomic levels, providing new ideas for the investigation of key flavor substances in baijiu. Additionally, these findings offer valuable insights into the regulatory mechanisms of aromatic compounds generation., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Background: The booming palm oil industry is in line with the growing population worldwide and surge in demand. This leads to a massive generation of palm oil mill effluent (POME). POME is composed of sterilizer condensate (SC), separator sludge (SS), and hydro-cyclone wastewater (HCW). Comparatively, SS exhibits the highest organic content, resulting in various environmental impacts. However, past studies mainly focused on treating the final effluent. Therefore, this pioneering research investigated the optimization of pollutant removal in SS via different aspects of bioremediation, including experimental conditions, treatment efficiencies, mechanisms, and degradation pathways., Methods: A two-level factorial design was employed to optimize the removal of chemical oxygen demand (COD) and turbidity using Aspergillus niger . Bioremediation of SS was performed through submerged fermentation (SmF) under several independent variables, including temperature (20-40 °C), agitation speed (100-200 RPM), fermentation duration (72-240 h), and initial sample concentration (20-100%). The characteristics of the treated SS were then compared to that of raw sludge., Results: Optimal COD and turbidity removal were achieved at 37 °C 100 RPM, 156 h, and 100% sludge. The analysis of variance (ANOVA) revealed a significant effect of selective individual and interacting variables ( p  < 0.05). The highest COD and turbidity removal were 97.43% and 95.11%, respectively, with less than 5% error from the predicted values. Remarkably, the selected optimized conditions also reduced other polluting attributes, namely, biological oxygen demand (BOD), oil and grease (OG), color, and carbon content. In short, this study demonstrated the effectiveness of A. niger in treating SS through the application of a two-level factorial design., Competing Interests: The authors declare there are no competing interests., (©2024 Thegarathah et al.)

Phosphogypsum (PG) is the produced solid waste during phosphorus (P) extraction from phosphate rocks. PG is featured by its abundant PO 4 3- and SO 4 2- . This study investigated the utilization of PG as a material for lead (Pb) remediation, with the assistance of functional fungus. Aspergillus niger (A. niger) is a typical phosphate-solubilizing fungi (PSF), which has high ability to secret organic acids. Oxalic acid is its major secreted organic acid, which is often applied to enhance the P release from phosphate minerals. In this study, synthetic oxalic acid increased the immobilization rate of Pb 2+ up to >99 % with the addition of PG. Then, it was observed that biogenic oxalic acid from A. niger can achieve comparable remediation effects. This was due to that PG could provide sufficient P for fungal growth, which allowed sustainable remediation. Subsequently, oxalic acid secreted by A. niger significantly increased the release of active P from PG, and then induced the formation of PPb minerals. In addition, other metabolites of A. niger (such as tyrosine-like substance) can also be complexed with Pb 2+ . Simultaneously, A. niger did not induce evidently elevation water-soluble fluorine (F) as PG contained abundant Ca 2+ . Moreover, this study elucidated that oversupply of PG promoted the formation of anglesite (K sp  = 1.6 × 10 -8 , relatively unstable), whereas the formation of lead oxalate (K sp  = 4.8 × 10 -10 , relatively stable) was reduced. This study hence shed a bright light on the sustainable utilization of PG for fungus-assisted remediation of heavy metals., Competing Interests: Declaration of competing interest The authors have no conflict of interest., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Among the several threats to humanity by anthropogenic activities, contamination of the environment by heavy metals is of great concern. Upon entry into the food chain, these metals cause serious hazards to plants and other organisms including humans. Use of microbes for bioremediation of the soil and stress mitigation in plants are among the preferred strategies to provide an efficient, cost-effective, eco-friendly solution of the problem. The current investigation is an attempt in this direction where fungal strain PH1 was isolated from the rhizosphere of Parthenium hysterophorus which was identified as Aspergillus niger by sequence homology of the ITS 1 and ITS 4 regions of the rRNA. The strain was tested for its effect on growth and biochemical parameters as reflection of its potential to mitigate Pb stress in Zea mays exposed to 100, 200 and 500 µg of Pb/g of soil. In the initial screening, it was revealed that the strain has the ability to tolerate lead stress, solubilize insoluble phosphate and produce plant growth promoting hormones (IAA and SA) and other metabolites like phenolics, flavonoids, sugar, protein and lipids. Under 500 µg of Pb/g of soil, Z. mays exhibited significant growth retardation with a reduction of 31% in root length, 30.5% in shoot length, 57.5% in fresh weight and 45.2% in dry weight as compared to control plants. Inoculation of A. niger to Pb treated plants not only restored root and shoot length, rather promoted it to a level significantly higher than the control plants. Association of the strain modulated the physio-hormonal attributes of maize plants that resulted in their better growth which indicated a state of low stress. Additionally, the strain boosted the antioxidant defence system of the maize there by causing a significant reduction in the ascorbic acid peroxidase (1.5%), catalase (19%) and 1,1-diphenyl-2 picrylhydrazyl (DPPH) radical scavenging activity (33.3%), indicating a lower stress condition as compared to their non-inoculated stressed plants. Based on current evidence, this strain can potentially be used as a biofertilizer for Pb-contaminated sites where it will improve overall plant health with the hope of achieving better biological and agricultural yields., (© 2024. The Author(s).)

In recent years, with the booming of the edible mushroom industry, chitin production has become increasingly dependent on fungi and other non-traditional sources. Fungal chitin has advantages including superior performance, simpler separation processes, abundant raw materials, and the absence of shellfish allergens. As a kind of edible mushroom, flammulina velutipes (F. velutipes) also has the advantages of wide source and large annual yield. This provided the possibility for the extraction of chitin. Here, a procedure to extract chitin from F. velutipes waste be presented. This method comprises low-concentration acid pretreatment coupled with consolidated bioprocessing with Aspergillus niger. Characterization by SEM, FTIR, XRD, NMR, and TGA confirmed that the extracted chitin was β-chitin. To achieve optimal fermentation of F. velutipes waste (80 g/L), ammonium sulfate and glucose were selected as nitrogen and carbon sources (5 g/L), with a fermentation time of 5 days. The extracted chitin could be further deacetylated and purified to obtain high-purity chitosan (99.2 % ± 1.07 %). This chitosan exhibited a wide degree of deacetylation (50.0 % ± 1.33 % - 92.1 % ± 0.97 %) and a molecular weight distribution of 92-192 kDa. Notably, the yield of chitosan extracted in this study was increased by 56.3 % ± 0.47 % compared to the traditional chemical extraction method., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier B.V. All rights reserved.)

Galactitol, a rare sugar alcohol, has promising potential in the food industry and pharmaceutical field. The available industrial production methods rely on harsh hydrogenation processes, which incur high costs and environmental concerns. It is urgent to develop environmentally friendly and efficient biosynthesis technologies. In this study, a xylose reductase named AnXR derived from Aspergillus niger CBS 513.88 was identified and characterized for the enzymatic properties. AnXR exhibited the highest activity at 25 ℃ and pH 8.0, and it belonged to the NADPH-dependent aldose reductase family. To engineer a strain for galactitol production, we deleted the galactokinase (GAL1) gene in Saccharomyes cerevisiae by using the recombinant gene technology, which significantly reduced the metabolic utilization of D-galactose by host cells. Subsequently, we introduced the gene encoding AnXR into this modified strain, creating an engineered strain capable of catalyzing the conversion of D-galactose into galactitol. Furthermore, we optimized the whole-cell catalysis conditions for the engineered strain, which achieved a maximum galactitol yield of 12.10 g/L. Finally, we tested the reduction ability of the strain for other monosaccharides and discovered that it could produce functional sugar alcohols such as xylitol and arabinitol. The engineered strain demonstrates efficient biotransformation capabilities for galactitol and other functional sugar alcohols, representing a significant advancement in environmentally sustainable production practices.

Eucommiae Cortex (EC) is frequently used alone or in combination with other active ingredients to treat a range of illnesses. An efficient technical instrument for changing cheap or plentiful organic chemicals into rare or costly counterparts is biotransformation. It combines EC with biotransformation techniques with the aim of producing some novel active ingredients, using different strains of bacteria that were introduced to biotransform EC in an aseptic environment. The high-quality strains were screened for identification after the fermentation broth was found using HPLC, and the primary unidentified chemicals were separated and purified in order to be structurally identified. Strain 1 was identified as Aspergillus niger and strain 2 as Actinomucor elegans ; the main transformation product A was identified as pinoresinol (Pin) and B as dehydrodiconiferyl alcohol (DA). The biotransformation of EC utilizing Aspergillus niger and Actinomucor elegans is reported for the first time in this study's conclusion, resulting in the production of Pin and DA.

Disposal and recycling of heavy metal-enriched biomass is the key to measure the success of phytoremediation. This study employed innovative approach to use Aspergillus niger (A. niger) for the treatment of Cd-contaminated Helianthus annuus L. (sunflower) stalk after phytoremediation. Single-factor results showed that the removal of Cd at an initial pH of 3 was superior to sucrose and inoculation amount. 67.67% of Cd was removed by A. niger leaching system after 11 days based on response surface methodology optimum conditions (sucrose: 76.266 g L -1 ; inoculation amount: 10%; initial pH: 3), while the concentrations of nitrogen, phosphorus and potassium (N, P and K) of sunflower stalk were unaffected. While physicochemical pretreatment effectively enhanced the bioleaching efficiency, it also resulted in significant loss of P and K elements, thereby reducing the value of biomass for recycling and utilization. Therefore, the direct A. niger leaching method without pretreatment is more advantageous for the safe treatment and recycling of Cd-contaminated sunflower stalks., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Inactivation of flbA in Aspergillus niger results in thinner cell walls, increased cell lysis, abolished sporulation, and an increased secretome complexity. A total of 36 transcription factor (TF) genes are differentially expressed in ΔflbA. Here, seven of these genes (abaA, aslA, aslB, azf1, htfA, nosA, and srbA) were inactivated. Inactivation of each of these genes affected sporulation and, with the exception of abaA, cell wall integrity and protein secretion. The impact on secretion was strongest in the case of ΔaslA and ΔaslB that showed increased pepsin, cellulase, and amylase activity. Biomass was reduced of agar cultures of ΔabaA, ΔaslA, ΔnosA, and ΔsrbA, while biomass was higher in liquid shaken cultures of ΔaslA and ΔaslB. The ΔaslA and ΔhtfA strains showed increased resistance to H 2 O 2 , while ΔaslB was more sensitive to this reactive oxygen species. Together, inactivation of the seven TF genes impacted biomass formation, sporulation, protein secretion, and stress resistance, and thereby these genes explain at least part of the pleiotropic phenotype of ΔflbA of A. niger., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Author(s). Published by Elsevier Inc. All rights reserved.)

Fermentation of pulses as a clean processing technique has been reported to have a favorable impact on the functional and nutritional quality of the starting materials. Compared to commonly fermented pulses such as peas and chickpeas, limited information is available on the effect of fermentation on lentils, especially when using a high protein isolate (>80% protein) as compared to seeds or flours. Therefore, in the present work, lentil protein isolate was used as a feedstock for submerged fermentation with Aspergillus niger, Aspergillus oryzae, or Lactobacillus plantarum. After 48 h, the samples showed increased protein content with enhanced solubility and oil-holding capacity. Controlled fermentation, as opposed to spontaneous fermentation, maintained the high foaming capacity; however, all fermented samples had lower foam and emulsion stabilizing properties and reduced water-holding capacity compared to the control. The fermented proteins were also less digestible, possibly due to an increase in phenolics and saponins. New volatile compounds were identified in fermented samples that show promise for improved sensory attributes. Significant differences were observed in specific quality attributes depending on the microbial strain used. Further research is required to better understand the fermentative metabolism of microbial communities when provided high-protein lentil ingredients as growth substrates. PRACTICAL APPLICATION: Fermented lentil protein isolate has promising flavor profiles that may improve its sensory properties for food application., (© 2024 Institute of Food Technologists.)

In this article, the degradability by Aspergillus niger and Aspergillus clavatus of three bio-based polyurethane (PU) foams is compared to previous degradability studies involving a Pseudomonas sp. bacterium and similar initial materials (Spontón et al. in Int. Biodet. Biodeg. 85:85-94, 2013, https://doi.org/10.1016/j.ibiod.2013.05.019 ). First, three new polyester-polyurethane foams were prepared from mixtures of castor oil (CO), maleated castor oil (MACO), toluene diisocyanate (TDI), and water. Then, their degradation tests were carried out in an aqueous medium, and employing the two mentioned fungi, after their isolation from the environment. From the degradation tests, the following was observed: (a) the insoluble (and slightly collapsed) foams exhibited free hydroxyl, carboxyl, and amine moieties; and (b) the water soluble (and low molar mass) compounds contained amines, carboxylic acids, and glycerol. The most degraded foam contained the highest amount of MACO, and therefore the highest concentration of hydrolytic bonds. A basic biodegradation mechanism was proposed that involves hydrolysis and oxidation reactions., (© 2023. The Author(s), under exclusive licence to Springer Nature B.V.)

In the development of fungal based materials for applications in construction through to biomedical materials and fashion, understanding how to regulate and direct growth is key for gaining control over the form of material generated. Here, we show how simple 'chemical food' cues can be used to manipulate the growth of fungal networks by taking Aspergillus niger as an exemplar species. Chemotrophic responses towards a range of nitrogen and carbon containing biomolecules including amino acids, sugars and sugar alcohols were quantified in terms of chemotrophic index (CI) under a range of basal media compositions (low and high concentrations of N and C sources). Growth of filamentous networks was followed using fluorescence microscopy at single time points and during growth by an AI analytical approach to explore chemo sensing behaviour of the fungus when exposed to pairs (C-C, C-N, N-N) of biomolecules simultaneously. Data suggests that the directive growth of A. niger can be controlled towards simple biomolecules with CI values giving a good approximation for expected growth under a range of growth conditions. This is a first step towards identifying conditions for researcher-led directed growth of hyphae to make mycelial mats with tuneable morphological, physicochemical, and mechanical characteristics., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The emergence of drug resistance, caused due the presence of pharmaceutical contaminant in the environment, highlights the critical need for pharmaceutical drugs management. Pharmaceutical drugs are sourced in wastewater as pharmaceutical industrial effluents, antibiotic misuse, and inappropriate disposal of expired pharmaceuticals, eventually ending up in sewage deposition. In this work, we aimed to degrade paracetamol (APAP) through the mycoremediation approach in laboratory scale. The isolated paracetamol degradation fungal strain, identified as Aspergillus niger KCAC efficiently degraded the drug into non-toxic metabolites. The results demonstrated that 99.6% degradation rate was achieved by Aspergillus niger KCAC. Unique, low-cost, eco-friendly bioformulation of the fungal isolate was prepared during the study using used vegetable cooking oil as substrate. The bioformulation showed extended shelf-life and can be used in future for large-scale application. Thus, this detailed investigation on paracetamol biodegradation may be useful in developing a wastewater treatment system effective against paracetamol-contaminated wastewater., (© 2023. The Author(s), under exclusive licence to Springer Nature Switzerland AG.)

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., (© 2024. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

In this investigation, we explore the harnessing of bamboo shoot residues (BSR) as a viable source for ruminant feed through fungal treatment, with the overarching objective of elevating feed quality and optimizing bamboo shoot utilization. The white-rot fungi (Wr.fungi), Aspergillus niger (A.niger), and its co-cultures (A.niger&Wr.fungi) were employed to ferment BSR. And the impact of different fermentation methods and culture time on the chemical composition (Crude protein Ash, neutral detergent fibre and acid detergent fibers), enzyme activity (Cellulase, Laccase, Filter paperase and Lignin peroxidase activities), and rumen digestibility in vitro were assessed. The findings reveal a nota ble 30.39% increase in crude protein in fermented BSR, accompanied by respective decreases of 13.02% and 17.31% in acid detergent fiber and neutral detergent fibre content. Enzyme activities experienced augmentation post-fermentation with A.niger&Wr.fungi. Specifically, the peak Cellulase, Laccase, and Lignin peroxidase activities for BSR with Wr.fungi treatment reached 748.4 U/g, 156.92 U/g, and 291.61 U/g, respectively, on the sixth day of fermentation. Concurrently, NH3-N concentration exhibited an upward trend with prolonged fermentation time. Total volatile fatty acids registered a decline, and the Acetate/Propionate ratio reached its nadir after 6 days of fermentation under the A.niger&Wr.fungi treatment. These outcomes furnish a theoretical foundation for the development of ruminant feeds treated via fungal co-culture., Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright: © 2024 Huo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)

Bacterial-fungal interactions influence microbial community performance of most ecosystems and elicit specific microbial behaviours, including stimulating specialised metabolite production. Here, we use a co-culture experimental evolution approach to investigate bacterial adaptation to the presence of a fungus, using a simple model of bacterial-fungal interactions encompassing the bacterium Bacillus subtilis and the fungus Aspergillus niger. We find in one evolving population that B. subtilis was selected for enhanced production of the lipopeptide surfactin and accelerated surface spreading ability, leading to inhibition of fungal expansion and acidification of the environment. These phenotypes were explained by specific mutations in the DegS-DegU two-component system. In the presence of surfactin, fungal hyphae exhibited bulging cells with delocalised secretory vesicles possibly provoking an RlmA-dependent cell wall stress. Thus, our results indicate that the presence of the fungus selects for increased surfactin production, which inhibits fungal growth and facilitates the competitive success of the bacterium., (© 2024. The Author(s).)

The Martian surface and shallow subsurface lacks stable liquid water, yet hygroscopic salts in the regolith may enable the transient formation of liquid brines. This study investigated the combined impact of water scarcity, UV exposure, and regolith depth on microbial survival under Mars-like environmental conditions. Both vegetative cells of Debaryomyces hansenii and Planococcus halocryophilus, alongside with spores of Aspergillus niger, were exposed to an experimental chamber simulating Martian environmental conditions (constant temperatures of about - 11 °C, low pressure of approximately 6 mbar, a CO 2 atmosphere, and 2 h of daily UV irradiation). We evaluated colony-forming units (CFU) and water content at three different regolith depths before and after exposure periods of 3 and 7 days, respectively. Each organism was tested under three conditions: one without the addition of salts to the regolith, one containing sodium chlorate, and one with sodium perchlorate. Our results reveal that the residual water content after the exposure experiments increased with regolith depth, along with the organism survival rates in chlorate-containing and salt-free samples. The survival rates of the three organisms in perchlorate-containing regolith were consistently lower for all organisms and depths compared to chlorate, with the most significant difference being observed at a depth of 10-12 cm, which corresponds to the depth with the highest residual water content. The postulated reason for this is an increase in the salt concentration at this depth due to the freezing of water, showing that for these organisms, perchlorate brines are more toxic than chlorate brines under the experimental conditions. This underscores the significance of chlorate salts when considering the habitability of Martian environments., (© 2024. The Author(s).)

Fungal biomineralization plays an important role in the biogeochemical cycling of metals in the environment and has been extensively explored for bioremediation and element biorecovery. However, the cellular and metabolic responses of fungi in the presence of toxic metals during biomineralization and their impact on organic matter transformations are unclear. This is an important question because co-contamination by toxic metals and organic pollutants is a common phenomenon in the natural environment. In this research, the biomineralization process and oxidative stress response of the geoactive soil fungus Aspergillus niger were investigated in the presence of toxic metals (Co, Cu, Mn, and Fe) and the azo dye orange II (AO II). We have found that the co-existence of toxic metals and AO II not only enhanced the fungal biomineralization of toxic metals but also accelerated the removal of AO II. We hypothesize that the fungus and in situ mycogenic biominerals (toxic metal oxalates) constituted a quasi-bioreactor, where the biominerals removed organic pollutants by catalyzing reactive oxygen species (ROS) generation resulting from oxidative stress. We have therefore demonstrated that a fungal/biomineral system can successfully achieve the goal of toxic metal immobilization and organic pollutant decomposition. Such findings inform the potential development of fungal-biomineral hybrid systems for mixed pollutant bioremediation as well as provide further understanding of fungal organic-inorganic pollutant transformations in the environment and their importance in biogeochemical cycles., Competing Interests: Declaration of interests The authors declare no competing interests., (Copyright © 2024 Elsevier Inc. All rights reserved.)

Microbial production of L-malic acid from renewable carbon sources has attracted extensive attention. The reduced cofactor NADPH plays a key role in biotransformation because it participates in both biosynthetic reactions and cellular stress responses. In this study, NADPH or its precursors nicotinamide and nicotinic acid were added to the fermentation medium of Aspergillus niger RG0095, which significantly increased the yield of malic acid by 11%. To further improve the titer and productivity of L-malic acid, we increased the cytoplasmic NADPH levels of A. niger by upregulating the NAD kinases Utr1p and Yef1p. Biochemical analyses demonstrated that overexpression of Utr1p and Yef1p reduced oxidative stress, while also providing more NADPH to catalyze the conversion of glucose into malic acid. Notably, the strain overexpressing Utr1p reached a malate titer of 110.72 ± 1.91 g L -1 after 108 h, corresponding to a productivity of 1.03 ± 0.02 g L -1  h -1 . Thus, the titer and productivity of malate were increased by 24.5% and 44.7%, respectively. The strategies developed in this study may also be useful for the metabolic engineering of fungi to produce other industrially relevant bulk chemicals., (© 2024 Wiley‐VCH GmbH.)

Biotransformation is acknowledged as one of the green chemistry methods to synthesis various analogues for further valorization of natural product compounds chemistry and bioactivities. It has huge advantage over chemical synthesis due to its cost-efficiency and higher selectivity. In this work, a xanthorrhizol derivatives, namely (7  R ,10 S )-10,11-dihydro-10,11-dihydroxyxanthorrhizol was produced in 60% yield from the biotransformation process utilizing A. niger . The structure of the compound was established by extensive spectroscopic methods and comparison with literature data. This biotransformation successfully afforded enantioselective dihydroxylation reaction via green chemistry route. This is the first report on both biotransformation of xanthorrhizol and utilization of A. niger as its biocatalyst.

The demand for environment-friendly cleanup techniques has arisen due to an increase in environmental pollutants. Fungi is the most prevalent and effective class of heavy metal-resistant microorganisms with the ability to leach metals. The objective of the present study was to isolate the fungi from the agricultural soil of Kashmir valley, investigate their multi-metal tolerance to heavy metals and evaluate the metal uptake capacities of the resistant fungi. The fungi were isolated and identified on the basis of morphological and molecular approach (ITS1 and ITS4). The tolerance limits of the isolated fungal strains to various doses of lead (Pb), cadmium (Cd), zinc (Zn), chromium (Cr), copper (Cu), nickel (Ni), and cobalt (Co) was evaluated. Five fungal strains, Aspergillus niger, Fusarium oxysporum, Fusarium verticillioides, Aspergillus fischeri, Epicoccum mackenziei were isolated from the soil samples. To the best of our knowledge, this is the first report on the study of metal resistance of Aspergillus fischeri and Epicoccum mackenziei. Among the identified fungal species, Aspergillus niger and Fusarium oxysporum were found to be most tolerant with a minimum inhibitory concentration (MIC) of 600 ppm against Cu and Cr respectively. Results indicated removal of considerable amount of heavy metals by some of the fungi. The highest metal uptake of 8.31 mg/g was found in Fusarium verticillioides for Zn. Surprisingly, these fungal strains demonstrated resistance to metal concentrations above the levels that are universally acceptable for polluted soils, and hence prove to be appealing contenders for use as bioremediation agents for cleaning up heavy metal-polluted environments., (© 2024. The Author(s), under exclusive licence to Springer Nature B.V.)

Alternative splicing (AS) greatly expands the protein diversity in eukaryotes. Although AS variants have been frequently reported existing in filamentous fungi, it remains unclear whether lignocellulose-degrading enzyme genes in industrially important fungi undergo AS events. In this work, AS events of lignocellulose-degrading enzymes genes in Aspergillus niger under two carbon sources (glucose and wheat straw) were investigated by RNA-Seq. The results showed that a total of 23 out of the 56 lignocellulose-degrading enzyme genes had AS events and intron retention was the main type of these AS events. The AS variant enzymes from the annotated endo-β-1,4-xylanase F1 gene (xynF1) and the endo-β-1,4-glucanase D gene (eglD), noted as XYNF1-AS and EGLD-AS, were characterized compared to their normal splicing products XYNF1 and EGLD, respectively. The AS variant XYNF1-AS displayed xylanase activity whereas XYNF1 did not. As for EGLD-AS and EGLD, neither of them showed annotated endo-β-1,4-glucanase activity. Instead, both showed lytic polysaccharide monooxygenase (LPMO) activity with some differences in catalytic properties. Our work demonstrated that the AS variants in A. niger were good sources for discovering novel lignocellulose-degrading enzymes. KEY POINTS: • AS events were identified in the lignocellulose-degrading enzyme genes of A. niger. • New β-1,4-xylanase and LPMO derived from AS events were characterized., (© 2024. The Author(s).)

Currently, the L-malic acid titer achieved through Aspergillus niger fermentation reaches 201 g/L, meeting industrial demands satisfactorily. However, the co-presence of structurally similar fumaric acid and succinic acid in fermentation products suggests a theoretical potential for further improvement in L-malic acid production. In the tricarboxylic acid cycle, fumarate reductase mediates the conversion of succinic acid to fumaric acid. Subsequently, fumarase catalyzes the conversion of fumaric acid to L-malic acid. Notably, both enzymatic reactions are reversible. Our investigation revealed that A. niger contains only one mitochondria-located fumarase FumA. Employing CRISPR-Cas9 technology, we performed a replacement of the fumA promoter with a doxycycline-induced promoter Tet. Under non-inducing condition, the conditional strain exhibited increased levels of fumaric acid and succinic acid. It strongly suggests that FumA mainly promotes the flow of fumaric acid to L-malic acid. Furthermore, a promoter PmfsA that is exclusively activated in a fermentation medium by calcium carbonate was identified through RNA-sequencing screening. Utilizing PmfsA to regulate fumA expression led to a 9.0% increase in L-malic acid titer, an 8.75% increase in yield (glucose to L-malic acid), and an 8.86% enhancement in productivity. This research serves as a significant step toward expediting the industrialization of L-malic acid synthesis via biological fermentation. Additionally, it offers valuable insights for the biosynthesis of other organic acids.IMPORTANCEThis study focuses on enhancing L-malic acid synthesis by modifying the tricarboxylic acid cycle within the mitochondria of Aspergillus niger . We emphasize the significant role of fumarase in converting fumaric acid into L-malic acid, enhancing our understanding of metabolic pathways in A. niger . The precise regulation of fumA is highlighted as a key factor in enhancing L-malic acid production. Furthermore, this research introduces a stringent conditional promoter (PmfsA), exclusively activated by CaCO 3 . The utilization of PmfsA for fumA expression resulted in heightened L-malic acid titers. The progress in metabolic engineering and bioprocess optimization holds promise for expediting industrial L-malic acid synthesis via biological fermentation. Moreover, it carries implications for the biosynthesis of various other organic acids., Competing Interests: The authors declare no conflict of interest.

This study aimed to investigate the phytochemical profile, bioactivity, and release mechanism of bound polyphenols (BPs) released from Rosa roxburghii fruit pomace insoluble dietary fiber (RPDF) through solid-state fermentation (SSF) with Aspergillus niger . The results indicated that the amount of BPs released from RPDF through SSF was 17.22 mg GAE/g DW, which was significantly higher than that achieved through alkaline hydrolysis extraction (5.33 mg GAE/g DW). The BPs released through SSF exhibited superior antioxidant and α-glucosidase inhibitory activities compared to that released through alkaline hydrolysis. Chemical composition analysis revealed that SSF released several main compounds, including ellagic acid, epigallocatechin, p -hydroxybenzoic acid, quercetin, and 3,4-dihydroxyphenylpropionic acid. Mechanism analysis indicated that the disruption of tight structure, chemical bonds, and hemicellulose was crucial for the release of BPs from RPDF. This study provides valuable information on the potential application of SSF for the efficient release of BPs from RPDF, contributing to the utilization of RPDF as a functional food ingredient.

Genes flbA-E are involved in sporulation and vegetative growth in Aspergillus nidulans. Inactivation of either of these genes results in a fluffy phenotype with delayed or even abolished sporulation. Previously, a non-sporulating phenotype was obtained by inactivating flbA in Aspergillus niger, which was accompanied by lysis, thinner cell walls, and an increased secretome complexity. Here, we further studied the role of the flb genes of A. niger. Strains ΔflbA, ΔflbB and ΔflbE showed increased biomass formation, while inactivation of flbA-D reduced, or even abolished, formation of conidia. Strain ΔflbA was more sensitive to H 2 O 2 , DTT, and the cell wall integrity stress compounds SDS and Congo Red (CR). Also, ΔflbC was more sensitive to SDS, while ΔflbB, ΔflbD, and ΔflbE were more sensitive to CR. On the other hand, inactivation of flbE increased resistance to H 2 O 2 . Enzyme secretion was impacted when the Δflb strains were grown on xylose. Strain ΔflbE showed reduced xylanase, cellulase and amylase secretion. On the other hand, amylase secretion at the periphery of the ΔflbA colony was reduced but not in its center, while secretion of this enzyme was increased in the center of the ΔflbB colony but not at its periphery. Inactivation of flbC and flbD also impacted zonal cellulase and amylase activity. Together, the Flb protein family of A. niger function in biomass formation, sporulation, stress response, and protein secretion., (© 2024. The Author(s).)

The efficient production of l-malic acid using Aspergillus niger requires overcoming challenges in synthesis efficiency and excessive byproduct buildup. This study addresses these hurdles, improving the activity of NADH-dependent malate dehydrogenase (Mdh) in the early stages of the fermentation process. By employing a constitutive promoter to express the Escherichia coli sthA responsible for the transfer of reducing equivalents between NAD(H) and NADP(H) in A. niger , the l-malic acid production was significantly elevated. However, this resulted in conidiation defects of A. niger , limiting industrial viability. To mitigate this, we discovered and utilized the PmfsA promoter, enabling the specific expression of sthA during the fermentation stage. This conditional expression strain showed similar phenotypes to its parent strain while exhibiting exceptional performance in a 5 L fermenter. Notably, it achieved a 65.5% increase in productivity, reduced fermentation cycle by 1.5 days, and lowered succinic acid by 76.2%. This work marks a promising advancement in industrial l-malic acid synthesis via biological fermentation, showcasing the potential of synthetic biology in A. niger for broader applications.

Enzyme immobilized on magnetic nanomaterials is a promising biocatalyst with efficient recovery under applied magnets. In this study, a recombinant extracellular lipase from Aspergillus niger GZUF36 (PEXANL1) expressed in Pichia pastoris GS115 was immobilized on ionic liquid-modified magnetic nano ferric oxide (Fe 3 O 4 @SiO 2 @ILs) via electrostatic and hydrophobic interaction. The morphology, structure, and properties of Fe 3 O 4 @SiO 2 @ILs and immobilized PEXANL1 were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, x-ray diffraction, vibration sample magnetometer, and zeta potential analysis. Under optimized conditions, the immobilization efficiency and activity recovery of immobilized PEXANL1 were 52 ± 2% and 122 ± 2%, respectively. The enzymatic properties of immobilized PEXANL1 were also investigated. The results showed that immobilized PEXANL1 achieved the maximum activity at pH 5.0 and 45 °C, and the lipolytic activity of immobilized PEXANL1 was more than twice that of PEXANL1. Compared to PEXANL1, immobilized PEXANL1 exhibited enhanced tolerance to temperature, metal ions, surfactants, and organic solvents. The operation stability experiments revealed that immobilized PEXANL1 maintained 86 ± 3% of its activity after 6 reaction cycles. The enhanced catalytic performance in enzyme immobilization on Fe 3 O 4 @SiO 2 @ILs made nanobiocatalysts a compelling choice for bio-industrial applications. Furthermore, Fe 3 O 4 @SiO 2 @ILs could also benefit various industrial enzymes and their practical uses. KEY POINTS: • Immobilized PEXANL1 was confirmed by SEM, FT-IR, and XRD. • The specific activity of immobilized PEXANL1 was more than twice that of PEXANL1. • Immobilized PEXANL1 had improved properties with good operational stability., (© 2024. The Author(s).)

A chitinase (PbChi70) from Paenibacillus barengoltzii was engineered by directed evolution to enhance its hydrolysis efficiency towards powder chitin. Through two rounds of screening, a mutant (mPbChi70) with a maximum specific activity of 73.21 U/mg was obtained, which is by far the highest value ever reported. The mutant gene was further transformed into Aspergillus niger FBL-B (ΔglaA) which could secrete high level of endogenously β-N-acetylglucosaminidase (GlcNAcase), thus a two-enzyme expression system was constructed. The highest chitinase activity of 61.33 U/mL with GlcNAcase activity of 353.1 U/mL was obtained in a 5-L fermentor by high-cell density fermentation. The chitin-degrading enzyme cocktail was used for the bioconversion of GlcNAc from powder chitin directly, and the highest conversion ratio reached high up to 71.9 % (w/w) with GlcNAc purity ≥95 % (w/w). This study may provide an excellent chitinase as well as a double enzyme cocktail system for efficient biological conversion of chitin materials., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Excessive sodium significantly inhibits citric acid fermentation by Aspergillus niger during the recycling of citric acid wastewater. This study aimed to elucidate the inhibition mechanism at the interface of physiology and transcriptomics. The results showed that excessive sodium caused a 22.3 % increase in oxalic acid secretion and a 147.6 % increase in H + -ATPase activity at the 4 h fermentation compared to the control. Meanwhile, a 13.1 % reduction in energy charge level and a 15.2 % decline in NADH content were found, which implied the effects on carbon metabolism and redox balance. In addition, transcriptomic analysis revealed that excessive sodium altered the gene expression profiles related to ATPase, hydrolase, and oxidoreductase, as well as pathways like glyoxylate metabolism, and transmembrane transport. These findings gained insights into the metabolic regulation of A. niger response to environmental stress and provided theoretical guidance for the construction of sodium-tolerant A. niger for industrial application., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Ltd. All rights reserved.)

Six compounds were isolated and purified from the crude acetone extract of Aspergillus niger xj. Characterization of all compounds was done by NMR and MS. On the basis of chemical and spectral analysis structure, six compounds were elucidated as metazachlor (1), nonacosane (2), palmitic acid (3), 5,5'-oxybis(5-methylene-2-furaldehyde) (4), dimethyl 5-nitroisophthalate (5) and cholesta-3,5-dien-7-one (6), respectively, and compounds 1, 4, 5 and 6 were isolated for the first time from A. niger. To evaluate the antibacterial activity of compounds 1-6 against three plant pathogenic bacteria (Agrobacterium tumefaciens T-37, Erwinia carotovora EC-1 and Ralstonia solanacearum RS-2), and the minimum inhibitory concentrations (MICs) were determined by broth microdilution method in 96-well microtiter plates. Results of the evaluation of the antibacterial activity showed that T-37 strain was more susceptible to metazachlor with the lowest MIC of 31.25 µg/mL. The antibacterial activity of metazachlor has rarely been reported, thus the antibacterial mechanism of metazachlor against T-37 strain were investigated. The permeability of cell membrane demonstrated that cells membranes were broken by metazachlor, which caused leakage of ions in cells. SDS-PAGE of T-37 proteins indicated that metazachlor could damage bacterial cells through the destruction of cellular proteins. Scanning electron microscopy results showed obvious morphological and ultrastructural changes in the T-37 cells, further confirming the cell membrane damages caused by metazachlor. Overall, our findings demonstrated that the ability of metazachlor to suppress the growth of T-37 pathogenic bacteria makes it potential biocontrol agents., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Environmental hormones have attracted more attention because of their adverse impact on the health and ecological security of human. Biodegradation is still an efficient tactics to remove environmental hormones, but human intestinal microbes remain to be elucidated in the role of their degradation. In the present work, we intended to perform the in vitro experiment for investigating the degradation of 17β-estradiol, the main environmental estrogen, by human intestinal microflora Aspergillus niger RG13B1. Its degradation led to the production of eighteen metabolites characterized by 1 H, 13 C, and 2D NMR, and HRMS spectra, including nine new (1-9) and nine known metabolites (10-18). Based on their structures, the degradation pathway of 17β-estradiol mediated by A. niger RG13B1 involved hydroxylation, oxidation, methylation, acetylation, and dehydrogenation, especially infrequent lactylation, and the key degradation enzymes were found in the gene cluster of A. niger. In addition, we found that metabolite 12 interacted with amino acid residues Lys37, Gln39, Lys93, and Asn115 of NF-κB p65 to suppress expressions of inflammatory genes or proteins, exerting its anti-inflammatory effect. This study first illustrated the role of human gut microbe in 17β-estradiol degradation and provided new insights into its degradation mechanism by A. niger RG13B1., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Background: Plant growth-promoting bacteria (PGPR), while generally considered to aid plant growth with the provision of nutrients, can also be used as biocontrol agents for plant pathogens., Aim: The study assessed the protective potential of inoculums and metabolites of plant growthpromoting rhizobacterial strains against bacterial and fungal pathogens on soybean seedlings., Materials and Methods: Inoculums and metabolites of 15 rhizobacterial strains were used for the study. Five pathogens ( Alternaria sp., Aspergillus niger, Corynespora sp., Fusarium oxysporum and Xanthomonas campestris) were employed for the study. Four experimental setups: treated-only seeds, infected-only seeds, infected then inoculum or metabolite treated seeds, and infected then distilled water-treated seeds., Results: In the setup infected with Alternaria sp., final germination values of seeds in the presence of the respective inoculums showed no significant variation between the treated only and the infected then treated setup. In the case of seeds infected with Aspergillus niger, higher germination and vigor index values were observed in the treated-only seeds when compared with the infected then-treated seeds. For seeds infected with Corynespora sp., significantly lower germination and vigor index values were observed in the infected then-treated seeds than the treated-only seeds in the presence of the respective inoculums. With regards to setup infected with Fusarium oxysporum, significantly higher final germination and vigor index values were recorded for the treated only seeds when compared with the infected then treated setups. For the Xanthomonas campestris infected seeds, the majority of the infected then metabolite-treated seeds showed significantly lower final germination values when compared with the treated-only seeds., Conclusion: The study findings were able to establish the efficacy of some bacteria agents against economically important species of plant pathogens., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

Proline-specific endoproteases have been successfully used in, for example, the in-situ degradation of gluten, the hydrolysis of bitter peptides, the reduction of haze during beer production, and the generation of peptides for mass spectroscopy and proteomics applications. Here we present the crystal structure of the extracellular proline-specific endoprotease from Aspergillus niger (AnPEP), a member of the S28 peptidase family with rarely observed true proline-specific endoprotease activity. Family S28 proteases have a conventional Ser-Asp-His catalytic triad, but their oxyanion-stabilizing hole shows a glutamic acid, an amino acid not previously observed in this role. Since these enzymes have an acidic pH optimum, the presence of a glutamic acid in the oxyanion hole may confine their activity to an acidic pH. Yet, considering the presence of the conventional catalytic triad, it is remarkable that the A. niger enzyme remains active down to pH 1.5. The determination of the primary cleavage site of cytochrome c along with molecular dynamics-assisted docking studies indicate that the active site pocket of AnPEP can accommodate a reverse turn of approximately 12 amino acids with proline at the S1 specificity pocket. Comparison with the structures of two S28-proline-specific exopeptidases reveals not only a more spacious active site cavity but also the absence of any putative binding sites for amino- and carboxyl-terminal residues as observed in the exopeptidases, explaining AnPEP's observed endoprotease activity., (© 2023 The Authors. Protein Science published by Wiley Periodicals LLC on behalf of The Protein Society.)

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.)

Rhizosphere soil of aromatic rice inhabits different fungal species that produce many bioactive metabolites including 2-acetyl-1-pyrroline (2AP). The mechanism for the biosynthesis of 2AP in the fungal system is still elusive. Hence, the present study investigates the role of possible nitrogen (N) precursors such as some amino acids and polyamines as well as the enzymes involved in 2AP synthesis in the fungal species isolated from the rhizosphere of aromatic rice varieties. Three fungal isolates were found to synthesize 2AP (0.32-1.07 ppm) and maximum 2AP was synthesized by Aspergillus niger (1.07 ppm) isolated from rhizosphere of Dehradun Basmati (DB). To determine the N source for 2AP synthesis, various N sources such as proline, glutamate, ornithine putrescine, spermine, and spermidine were used in place of putrescine in the synthetic medium (Syn18). The results showed that maximum 2AP synthesis was found with putrescine (1.07 ppm) followed by spermidine (0.89 ppm) and spermine (0.84 ppm). Further, LC-QTOF-MS analysis revealed the mobilization of spermine and spermidine into the putrescine, indicating that putrescine is the key N source for 2AP synthesis. Moreover, higher enzyme activity of DAO, PAO, and ODC as well as higher content of methylglyoxal metabolite in the A. niger NFCCI 5060 as compared to A. niger NFCCI 4064 (control) suggests the prominent role of these enzymes in the synthesis of 2AP. In conclusion, this study showed evidence of the polyamines mediated 2AP biosynthesis in A. niger NFCCI 5060., (© 2023. The Author(s) under exclusive licence to Sociedade Brasileira de Microbiologia.)

Aflatoxin and other mycotoxin contamination are major threats to global food security and present an urgent need to secure the global food crop against spoilage by mycotoxigenic fungi. Cocoa material is noted for naturally low aflatoxin contamination. This study was designed to assess the potential for harnessing cocoa-associated filamentous fungi for the biocontrol of aflatoxigenic Aspergillus flavus. The candidate fungi were isolated from fermented cocoa beans collected from four cocoa-growing areas in Ghana. Molecular characterization included Internal Transcribed Spacer (ITS)-sequencing for identification and polymer chain reaction (PCR) to determine mating type. Effects of the candidate isolates on growth and aflatoxin-production by an aflatoxigenic A. flavus isolate (BANGA1) were assessed. Aflatoxin production was monitored by UV fluorescence and quantified by enzyme-linked immunosorbent assay (ELISA). Thirty-six filamentous fungi were cultured and identified as Aspergillus, Cladosporium, Lichtheimia, or Trichoderma spp. isolates. The isolates generally interacted negatively with BANGA1 growth and aflatoxin production. The Aspergillus niger and Aspergillus aculeatus biocontrol candidates showed the strongest colony antagonism (54%-94%) and reduction in aflatoxin production (12%-50%) on agar. In broth, the A. niger isolates reduced aflatoxin production by up to 97%. Metabolites from the A. niger isolates showed the strongest inhibition of growth by BANGA1 and inhibited aflatoxin production. Four of the candidate isolates belonged to the MAT1-1 mating type and 12 identified as MAT1-2. This may be indicative of the potential for genetic recombination events between fungi in the field, a finding which is particularly relevant to the risk posed by A. flavus biocontrol measures that rely on atoxigenic A. flavus strains., (© 2023 Wiley-VCH GmbH.)