Aspergillus niger ATCC 20611 is an industrially important fructooligosaccharides (FOS) producer since it produces the β-fructofuranosidase with superior transglycosylation activity, which is ...responsible for the conversion of sucrose to FOS accompanied by the by-product (glucose) generation. This study aims to consume glucose to enhance the content of FOS by heterologously expressing glucose oxidase and peroxidase in engineered A. niger.
Glucose oxidase was successfully expressed and co-localized with β-fructofuranosidase in mycelia. These mycelia were applied to synthesis of FOS, which possessed an increased purity of 60.63% from 52.07%. Furthermore, peroxidase was expressed in A. niger and reached 7.70 U/g, which could remove the potential inhibitor of glucose oxidase to facilitate the FOS synthesis. Finally, the glucose oxidase-expressing strain and the peroxidase-expressing strain were jointly used to synthesize FOS, which content achieved 71.00%.
This strategy allows for obtaining high-content FOS by the multiple enzymes expressed in the industrial fungus, avoiding additional purification processes used in the production of oligosaccharides. This study not only facilitated the high-purity FOS synthesis, but also demonstrated the potential of A. niger ATCC 20611 as an enzyme-producing cell factory.
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IZUM, KILJ, NUK, PILJ, PNG, SAZU, UL, UM, UPUK
A recombinant Aspergillus niger strain expressing the Hypocrea jecorina endoglucanase Cel7B was grown on spent hydrolysates (stillage) from sugarcane bagasse and spruce wood. The spent hydrolysates ...served as excellent growth media for the Cel7B-producing strain, A. niger D15egI, which displayed higher endoglucanase activities in the spent hydrolysates than in standard medium with a comparable monosaccharide content (e.g., 2,100 nkat/ml in spent bagasse hydrolysate compared to 480 nkat/ml in standard glucose-based medium). In addition, A. niger D15egI was also able to consume or convert other lignocellulose-derived compounds, such as acetic acid, furan aldehydes, and phenolic compounds, which are recognized as inhibitors of yeast during ethanolic fermentation. The results indicate that enzymes can be produced from the stillage stream as a high-value coproduct in second-generation bioethanol plants in a way that also facilitates recirculation of process water.
Cerebral vasculitis is a long-standing but flourishing and fadeless research topic. Infections are a frequent cause of cerebral vasculitis, vital to diagnose due to involvement of specific ...anti-infection treatments. A 65-year-old man visited the hospital for his neurological symptoms without obvious inducements. After admission, radiological examination and comprehensive conventional microbiological tests (CMTs) revealed suspected intracranial infectious vasculitis. Metagenomic next-generation sequencing (mNGS) and reverse transcription-polymerase chain reaction further confirmed that his cerebral vasculitis was caused by
Talaromyces marneffei
(
T. marneffei
) and
Aspergillus niger
(
A. niger
) co-infection. The patient’s final diagnosis changed from initial herpetic encephalitis, due to the past history of cephalosome and facial herpes and non-significant antiviral therapeutic effects, to fungal cerebral vasculitis. The patient was discharged after use of targeted antifungal therapies on day 18 of his admission, and his associated symptoms disappeared completely at follow-up 3 weeks later. We first illustrated the presence of uncommon cerebral vasculitis caused by
T. marneffei
and
A. niger
in a human immunodeficiency virus-positive patient. In clinically suspected patients with infectious cerebral vasculitis, mNGS should be performed to detect potential pathogens if CMTs may not provide useful pathogenic clues, highlighting the importance of mNGS in the diagnosis and treatment of infectious diseases.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
Abstract
Streptomyces sp. TD-1 was identified as Streptomyces alboflavus based on its morphological characteristics, physiological properties, and 16S rDNA gene sequence analysis. The antifungal ...activity of the volatile-producing S. alboflavus TD-1 was investigated. Results showed that volatiles generated by S. alboflavus TD-1 inhibited storage fungi Fusarium moniliforme Sheldon, Aspergillus flavus, Aspergillus ochraceus, Aspergillus niger, and Penicillum citrinum in vitro. GC/MS analysis revealed that 27 kinds of volatile organic compounds were identified from the volatiles of S. alboflavus TD-1 mycelia, among which the most abundant compound was 2-methylisoborneol. Dimethyl disulfide was proved to have antifungal activity against F. moniliforme by fumigation in vitro.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Chloroxylenol is a very toxic phenolic derivative and it represents potential hazard towards human health and to the environment. Aspergillus niger, local isolate, is an efficient fungus to degrade ...99.72% of 2 mg/L of chloroxylenol after 7 days of fermentation. It also has a high capacity to degrade 91.83% of higher chloroxylenol concentration of 20 mg/L after 6 days of incubation on mineral medium amended with 2 g/L of glucose. Statistical experimental designs were used to optimize the process of chloroxylenol degradation by the fungus. The most important factors influencing chloroxylenol degradation, as identified by a two-level Plackett-Burman design with 11 variables, were NaCl, (NH sub(4)) sub(2)SO sub(4), and inoculums size. Response surface analysis was adopted to further investigate the mutual interactions between these variables and to identify their optimal values that would generate maximum chloroxylenol degradation. Under the optimized medium compositions and culture conditions, A. niger was able to degrade completely (100%) chloroxylenol (20 mg/L) after 134.6 h of fermentation. The predicted values of Plackett-Burman conditions and response surface methodology were further verified by validation experiments. The excellent correlation between predicted and experimental values confirmed the validity and practicability of this statistical optimum strategy. Optimal conditions obtained in this work laid to a solid foundation for further use of A. niger in treatment of high strength chloroxylenol polluted effluents. So, the optimized conditions were applied to bioremediate crude sewage containing 27.8 mg/L of chloroxylenol by A. niger. The fungus efficiently degraded chloroxylenol after 8 days of fermentation.
Highlights • The survivability of Staphylococcus aureus and spores of Aspergillus niger was compared on 5 of the most common floor materials. • Microbial survivability differs for various floor ...materials. • Unlike carpets, smooth floor surface materials, such as vinyl tiles, porcelain tile, and wood, allow survival of S aureus and spores for A niger for at least 4 weeks.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Aspergillus niger forms conidia that contain melanin in their cell wall. This black pigment has been shown to protect fungi against UV radiation, and experimental evidence has indicated that it also ...protects against drought and high salt concentrations. In this study, growth of A. niger was evaluated at low water activity (aw) and after changes in relative humidity (RH). In addition, deletion strains of A. niger affected in the melanin synthesis pathway were compared. Germination of conidia of the wild‐type and deletion strains was observed at 0·81 aw and germ tubes continued growth at aw ≥ 0·83. Conidia and microcolonies of the different strains were incubated for 1 week at lowered RH (33–84%). Conidia of all strains germinated and formed colonies after exposure to RH ≥33% when transferred back to malt extract medium at aw 0·98. Conidia germinated and showed limited growth at 84% RH. Microcolonies of all strains did not survive an incubation of 1 week at RH ≤75%, but continued growth after exposure to 84% RH. Together, this is the first genetic evidence that melanin does not play a role during germination and radial extension of fungi at low water conditions.
Significance and Impact of the Study
Aspergillus niger, a cosmopolitan fungus with melanized conidia, is used here as a model system for fungal growth at low water activity (aw) and humidity dynamics. From this study it becomes clear that melanin, contrary to what has been suggested before, is not a key factor in survival and growth during situations that mimic indoor conditions. Indoor fungal growth can lead to cosmetic damage to building materials and health problems. This knowledge makes clear that novel ways to limit indoor fungal growth have to be based on interference with other cellular traits of fungi.
Significance and Impact of the Study: Aspergillus niger, a cosmopolitan fungus with melanized conidia, is used here as a model system for fungal growth at low water activity (aw) and humidity dynamics. From this study it becomes clear that melanin, contrary to what has been suggested before, is not a key factor in survival and growth during situations that mimic indoor conditions. Indoor fungal growth can lead to cosmetic damage to building materials and health problems. This knowledge makes clear that novel ways to limit indoor fungal growth have to be based on interference with other cellular traits of fungi.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
Kinetic parameters for the dephosphorylation of sodium phytate and a series of partially phosphorylated myo-inositol phosphates were determined at pH 3.0 and pH 5.0 for three phytase preparations ...(Aspergillus niger, Escherichia coli, rye). The enzymes showed lower affinity and turnover numbers at pH 3 compared to pH 5 toward all myo-inositol phosphates included in the study. The number and distribution of phosphate groups on the myo-inositol ring affected the kinetic parameters. Representatives of the individual phytate dephosphorylation pathways were identified as the best substrates of the phytases. Within the individual phytate dephosphorylation pathways, the pentakisphosphates were better substrates compared to the tetrakisphosphates or phytate itself. E. coli and rye phytase showed comparable activities at both pH values toward the tetrakis- and trisphosphate, whereas A. niger phytase exhibited a higher activity toward the tetrakisphosphate. A myo-inositol phosphate with alternate phosphate groups was shown to be not significantly dephosphorylated by the phytases.
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IJS, KILJ, NUK, PNG, UL, UM, UPUK
Feruloyl esterase (FAE)-encoding genes
AnfaeA
and
AnfaeB
were isolated from
Aspergillus niger
0913. For overexpression of the two genes in
Trichoderma reesei
, constitutive and inductive expression ...plasmids were constructed based on parental plasmid pAg1-H3. The constructed plasmids contained
AnfaeA
or
AnfaeB
gene under the control of glyceraldehyde-3-phosphate dehydrogenase A gene (
gpd
A) promoter (from
A. nidulans
) or cellobiohydrolases I (
cbh
I) gene promoter (from
T. reesei
), and
cbh
I terminator from
T. reesei
. The target plasmids were transferred into
T. reesei
D-86271 (Rut-C30) by
Agrobacterium tumefaciens-
mediated transformation (ATMT), respectively. A high level of feruloyl esterase was produced by the recombinant fungal strains under solid-state fermentation, and the
cbh
I promoter was more efficient than the
gpd
A promoter in the expression of
AnfaeA
. The optimum temperatures and pH values were 50 °C and 5.0 for AnFAEA, and 35 °C and 6.0 for AnFAEB. The maximum production levels were 20.69 U/gsd for AnFAEA and 15.08 U/gsd for AnFAEB. The recombinant fungal enzyme systems could release 62.9% (for AnFAEA) and 52.2% (for AnFAEB) of total ferulic acids from de-starched wheat bran, which was higher than the 46.3% releasing efficiency of
A. niger
0913. The supplement of xylanase from
T. longibrachiatum
in the enzymatic hydrolysis led to a small increment of the ferulic acids release.
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EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OBVAL, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
A cocktail of biomass hydrolytic enzymes was produced by solid-state fermentation (SSF) by the mutant strain Aspergillus niger 3T5B8, using as substrate a mixture of grape pomace and wheat bran, and ...compared to the production when wheat bran was used as the sole substrate. The two enzymatic cocktails were subsequently used for the extraction of bioactive compounds from grape pomace and the relationship between the activities of the cocktail and the release of phenolic compounds was evaluated. Although the wheat bran SSF process was more effective for enzyme production, the enzymatic cocktail produced by the grape pomace - wheat bran mixture was more effective for the extraction of compounds with higher proanthocyanidins content and higher antioxidant potential (p < 0.05). A significant correlation between the bioactive compounds and enzyme activity was observed.
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•SSF from wheat bran produced an enzymatic cocktail with high hydrolytic activity.•The addition of grape pomace induced the synthesis of the enzymes of interest.•In the presence of grape pomace, the enzymes had greater activity at 96 h.•Enzymatic cocktail increased the release of bioactive compounds from grape pomace.•The cocktail activities correlated with the content of the bioactive compounds.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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