Protein secretion plays an eminent role in cell maintenance and adaptation to the extracellular environment of microorganisms. Although protein secretion is an extremely efficient process in ...filamentous fungi, the mechanisms underlying protein secretion have remained largely uncharacterized in these organisms. In this study, we analyzed the effects of the D-xylose induction of cellulase and hemicellulase enzyme secretion on the protein composition of secretory organelles in Aspergillus niger. We aimed to systematically identify the components involved in the secretion of these enzymes via mass spectrometry of enriched subcellular microsomal fractions. Under each condition, fractions enriched for secretory organelles were processed for tandem mass spectrometry, resulting in the identification of peptides that originate from 1,081 proteins, 254 of which--many of them hypothetical proteins--were predicted to play direct roles in the secretory pathway. D-Xylose induction led to an increase in specific small GTPases known to be associated with polarized growth, exocytosis, and endocytosis. Moreover, the endoplasmic-reticulum-associated degradation (ERAD) components Cdc48 and all 14 of the 20S proteasomal subunits were recruited to the secretory organelles. In conclusion, induction of extracellular enzymes results in specific changes in the secretory subproteome of A. niger, and the most prominent change found in this study was the recruitment of the 20S proteasomal subunits to the secretory organelles.
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.
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•Cd content in sunflower stalks after A. niger leaching met the fertilizer standard.•A. niger exhibited the highest removal rate for insoluble phosphate-Cd in stalks.•Citric acid produced by A. niger played a dominant role in Cd removal of stalks.•The NPK elements in sunflower stalks were not be affected by A. niger leaching.•Physicochemical pretreatment reduced the recycling value of sunflower stalks.
•Downstream migration of the River Niger and River Benue confluence occurred over a 2.2 km wide zone.•We calculated a net migration of ∼ 880 m in 35 years.•Along with this migration, there was a ...drastic change in confluence angle from ca. 154° in 1987 to ca. 16° in 2022.•We observed a significant channel expansion along the tributary relative to the main river.
Analysis of 35 years (1987–2022) of time-lapse data derived from Landsat imagery and SRTM DEM has revealed significant changes in planform morphology at the confluence of the River Niger and River Benue in Lokoja, West Africa. In the study area, the Niger is flanked by high elevation plateaus of ca. 400 m altitude and low-lying floodplains on its western bank. The Benue is characterized by more abundant intra-channel and bank-attached bars relative to the Niger. Over the 35-year period, a net downstream migration of 880 m was observed at the junction, its angle decreased from ca. 175° in 1987 to 50° in 2006 and to ca. 16° in 2022 and showed varied segmentation patterns. We establish a linkage between this decrease in confluence angle and increase in annual runoff in the study area. Expansion along the banks of the Niger, Benue, and post-confluence channels was found to be low and non-uniform, suggesting varied resistance of the banks to erosion, which is linked to the abundance of vegetation. These decadal changes in confluence planform are important for understanding river confluence dynamics in major river systems around the world.
Phenotypic and genotypic changes in Aspergillus niger and Penicillium chrysogenum, spore forming filamentous fungi, with respect to central chitin metabolism were studied under low shear modeled ...microgravity, normal gravity and static conditions. Low shear modeled microgravity (LSMMG) response showed a similar spore germination rate with normal gravity and static conditions. Interestingly, high ratio of multiple germ tube formation of A. niger in LSMMG condition was observed. Confocal laser scanning microscopy images of calcofluor flurophore stained A. niger and P. chrysogenum showed no significant variations between different conditions tested. Transmission electron microscopy images revealed number of mitochondria increased in P. chrysogenum in low shear modeled microgravity condition but no stress related-woronin bodies in fungal hyphae were observed. To gain additional insight into the cell wall integrity under different conditions, transcription level of a key gene involved in cell wall integrity gfaA, encoding the glutamine: fructose-6-phosphate amidotransferase enzyme, was evaluated using qRT-PCR. The transcription level showed no variation among different conditions. Overall, the results collectively indicate that the LSMMG has shown no significant stress on spore germination, mycelial growth, cell wall integrity of potentially pathogenic fungi, A. niger and P. chrysogenum.
Genome mining approaches predict dozens of biosynthetic gene clusters in each of the filamentous fungal genomes sequenced so far. However, the majority of these gene clusters still remain cryptic ...because they are not expressed in their natural host. Simultaneous expression of all genes belonging to a biosynthetic pathway in a heterologous host is one approach to activate biosynthetic gene clusters and to screen the metabolites produced for bioactivities. Polycistronic expression of all pathway genes under control of a single and tunable promoter would be the method of choice, as this does not only simplify cloning procedures, but also offers control on timing and strength of expression. However, polycistronic gene expression is a feature not commonly found in eukaryotic host systems, such as Aspergillus niger.
In this study, we tested the suitability of the viral P2A peptide for co-expression of three genes in A. niger. Two genes descend from Fusarium oxysporum and are essential to produce the secondary metabolite enniatin (esyn1, ekivR). The third gene (luc) encodes the reporter luciferase which was included to study position effects. Expression of the polycistronic gene cassette was put under control of the Tet-On system to ensure tunable gene expression in A. niger. In total, three polycistronic expression cassettes which differed in the position of luc were constructed and targeted to the pyrG locus in A. niger. This allowed direct comparison of the luciferase activity based on the position of the luciferase gene. Doxycycline-mediated induction of the Tet-On expression cassettes resulted in the production of one long polycistronic mRNA as proven by Northern analyses, and ensured comparable production of enniatin in all three strains. Notably, gene position within the polycistronic expression cassette matters, as, luciferase activity was lowest at position one and had a comparable activity at positions two and three.
The P2A peptide can be used to express at least three genes polycistronically in A. niger. This approach can now be applied to heterologously express entire secondary metabolite gene clusters polycistronically or to co-express any genes of interest in equimolar amounts.
The current study was intended to identify Aspergillus niger isolated from different sources oil, peanut (pistachios, ground nut, walnuts, almonds and cashew), dried milk and factory waste water. ...Traditional methods were used to investigate the ability of Aspergillus niger for lipase production using T80 and T80 with phenol red agar and calculate Aspergillus niger efficiency in this enzyme production. The results revealed that all isolates were able to produce lipase, and the efficiency of lipase production ranged between (0.90-2.21) mm. A50 isolate showed the highest efficiency in lipase production, which was isolated from factory waste water factory.
•Three recombinant phyA mutant strains (PP-NPm-8, PP-NPep-6A and I44E/T252R-PhyA) were constructed.•Improving catalytic efficiency or thermostability of Aspergillus niger N25 phytase, by error-prone ...PCR or site-directed mutagenesis.•Directed evolution and site-directed mutagenesis were further applied to improve the modified phytase properties.•These mutations could produce cumulative or synergistic improvements in thermostability or catalytic efficiency of phytase.•It can do some for industrial production work.
We previously constructed three recombinant phyA mutant strains (PP-NPm-8, PP-NPep-6A and I44E/T252R-PhyA), showing improved catalytic efficiency or thermostability of Aspergillus niger N25 phytase, by error-prone PCR or site-directed mutagenesis. In this study, directed evolution and site-directed mutagenesis were further applied to improve the modified phytase properties. After one-round error-prone PCR for phytase gene of PP-NPep-6A, a single transformant, T195L/Q368E/F376Y, was obtained with the significant improvements in catalytic efficiency and thermostability. The phytase gene of T195L/Q368E/F376Y, combined with the previous mutant phytase genes of PP-NPep-6A, PP-NPm-8 and I44E/T252R-PhyA, was then sequentially modified by DNA shuffling. Three genetically engineered strains with desirable properties were then obtained, namedQ172R, Q172R/K432R andQ368E/K432R. Among them, Q172R/K432R showed the highest thermostability with the longest half-life and the greatest remaining phytase activity after heat treatment, while Q368E/K432R showed the highest catalytic activity. Five substitutions (Q172R, T195L, Q368E, F376Y, K432R) identified from random mutagenesis were added sequentially to the phytase gene of PP-NPep-6A to investigate how the mutant sites influence the properties of phytase. Characterization and structural analysis demonstrated that these mutations could produce cumulative or synergistic improvements in thermostability or catalytic efficiency of phytase.
PM2.5 has become a global challenge threatening human health, climate, and the environment. PM2.5 is ranked as the most common cause of premature mortality and morbidity. Therefore, the current study ...endeavors to probe the spatiodynamic characteristics of PM2.5 in the Republic of Niger and its impacts on human health from 1998 to 2019. Based on remotely sensed satellite datasets, the study found that the concentration of PM2.5 continued to rise in Niger from 68.85 μg/m3 in 1998 to 70.47 μg/m3 in 2019. During the study period, the annual average PM2.5 concentration is far above the WHO guidelines and the interim target-1 (35 μg/m3). The overall annual growth rate of PM2.5 concentration in Niger is 0.02 μg/m3/year. The health risk (HR) due to PM2.5 exposure is also escalated in Niger, particularly, in Southern Niger. The extent of the extremely high-risk areas corresponding to 1 × 104–9.4 × 105 μg.persons/m3 is increased from 0.9% (2000) to 2.8% (2019). Niamey, southern Dakoro, Mayahi, Tessaoua, Mirriah, Magaria, Matameye, Aguié, Madarounfa, Groumdji, Madaoua, Bouza, Keita, eastern Tahoua, eastern Illéla, Bkomnni, southern Dogon-Doutchi, Gaya, eastern Boboye, central Kollo, and western Tillabéry are experienced high HR due to long-term exposure to PM2.5. These findings indicate that PM2.5 causes a serious health risk across Niger. There is an immediate need to carry out its regional control. Therefore, policymakers and the Nigerien government should make conscious efforts to identify the priority target areas with radically innovative appropriate mitigation interventions.
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•PM2.5 continues to upsurge in Niger with a growth rate of 0.02 μg/m3/year.•The annual average PM2.5 concentrations are far above the WHO guidelines.•Southern Niger is under extremely-high health risk areas.•The health risk of the population to PM2.5 exposure rise from 2000 to 2019.
COVID-19 emerged in China in late 2019 and quickly spread worldwide. The severe immunomodulation and depletion of lymphocytes caused by the virus and its therapy led to an increase in the incidence ...of superinfections. COVID-19-associated pulmonary aspergillosis (CAPA) is a new entity with increasing incidence and high associated mortality. We present the case of a 68-year-old patient admitted to our ward after recovering from severe COVID-19 pneumonia. Due to worsening of her clinical condition, chest computed tomography was performed and a lung abscess was documented with the identification of
. Despite therapy with voriconazole, the patient's condition deteriorated, culminating in her death.
COVID-19-associated pulmonary aspergillosis (CAPA) is a new entity with an increasing incidence.It is a serious and life-threatening complication in patients with severe COVID-19 even in the absence of the classic risk factors for invasive pulmonary aspergillosis.Clinical suspicion is crucial since a timely diagnosis and treatment have a major impact on prognosis.
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