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1.
Food Microbiol ; 109: 104142, 2023 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-36309457

RESUMO

This study aimed to isolate and identify fungal species involved in sliced bread spoilage, and to evaluate their susceptibility to antifungal proteins of fungal origin (AFPs). Proteins include PdAfpB from Penicillium digitatum and PeAfpA, PeAfpB and PeAfpC from Penicillium expansum. Based on morphological criteria, a group of sixteen fungal isolates were selected and subsequently identified at the species level using sequence analysis. Penicillium species, the predominant mycobiota, were identified based on a combined phylogenetic analysis using ITS and ß-tubulin sequences, being P. roqueforti, P. brevicompactum, P. chrysogenum and P. crustosum the most abundant species. Aspergillus versicolor, Aspergillus niger and Bissochlamys spectabilis were also identified. Regarding the antifungal activity of AFPs, PdAfpB and PeAfpA were the most potent proteins since the growth of most of tested fungi was completely inhibited by concentrations ranging from 2 to 32 µg/mL. PeAfpB showed moderate antifungal activity, whereas PeAfpC was the least active protein. The best in vitro AFPs, PdAfpB and PeAfpA, were also evaluated in in situ protection assays against P. roqueforti. PdAfpB provoked a clear reduction of P. roqueforti growth in sliced bread samples, suggesting that this AFP has a protective effect on bread. This study underlines the potential of the AFPs tested, in particular PdAfpB, as alternative antifungal agents for extending sliced bread shelf life.


Assuntos
Pão , Penicillium , Pão/microbiologia , Antifúngicos/metabolismo , Filogenia , Aspergillus niger , Fungos
2.
J Hazard Mater ; 442: 130106, 2023 01 15.
Artigo em Inglês | MEDLINE | ID: mdl-36209612

RESUMO

Fungus Cladosporium sp. strain F1 showed highly effective biosorption capacity to lead phosphate mineral and perovskite solar cells lead iodide compared to other fungi Aspergillus niger VKMF-1119 and Mucor ramannianus R-56. Scanning electron microscopy and transmission electron microscopy analyses shows that Cladosporium sp. strain F1, which previously showed high biosorption capacity to uranium phosphate nanorods and nanoplates, can accumulate lead phosphate mineral and lead iodide on the fungal hyphae surface in large amounts under a wide range of pH conditions, while A. niger VKMF-1119 and M. ramannianus R-56 adsorbed small amounts of minerals. After biosorption of lead iodide minerals on Cladosporium sp. strain F1, aqueous dimethyl sulfoxide (50%) at pH 2 (70 °C) released the mineral more than 99%. Based on the fungal surface analyses, hydrophobic properties on the surfaces of Cladosporium sp. strain F1 could affect the higher biosorption capacity of strain F1 to lead phosphate mineral and lead iodide as compared to other tested fungi. Cladosporium sp. strain F1 may be the novel biosorbents to remediate the phosphate rich environment and to recover lead from perovskite solar cells lead iodide.


Assuntos
Cladosporium , Urânio , Cladosporium/metabolismo , Adsorção , Fosfatos/metabolismo , Concentração de Íons de Hidrogênio , Biomassa , Iodetos , Urânio/metabolismo , Dimetil Sulfóxido , Chumbo/metabolismo , Aspergillus niger , Minerais/metabolismo
3.
Food Chem ; 400: 134087, 2023 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-36084599

RESUMO

Apergillus carbonarius and Aspergillus niger are the principal fungi that attack table grapes, and they are responsible for producing and contaminating these fruits with ochratoxin A. Packaging containing essential oils from Ocimum gratissimum L. and Ocimum basilicum L. encapsulated in poly(lactic acid) (PLA) nanofibers were produced, the antifungal and antiocratoxigenic activities against A. carbonarius and A. niger were evaluated in vitro and in vivo, and the effect of these packages on the quality of table grapes was determined. The nanofibers were produced by the Solution Blow Spinning technique and characterized by Scanning Electron Microscopy and Thermogravimetric Analysis. Fungal contamination and ochratoxin A production were significantly controlled by PLA nanofibers containing the essential oils and the physicochemical parameters of the grapes were preserved, preserving the quality and the shelf life of the fruit. Therefore, the active packaging developed herein has potential and may be suitable for application in fruits.


Assuntos
Nanofibras , Ocratoxinas , Ocimum basilicum , Ocimum , Óleos Voláteis , Vitis , Antifúngicos , Aspergillus , Aspergillus niger , Ocimum/química , Óleos Voláteis/química , Óleos Voláteis/farmacologia , Poliésteres , Vitis/química
4.
Microb Cell Fact ; 21(1): 238, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36376878

RESUMO

BACKGROUND: Our recent multi-omics analyses of glucoamylase biosynthesis in Aspergillus niger (A. niger) suggested that lipid catabolism was significantly up-regulated during high-yield period under oxygen limitation. Since the catabolism of fatty acids can provide energy compounds such as ATP and important precursors such as acetyl-CoA, we speculated that enhancement of this pathway might be beneficial to glucoamylase overproduction. RESULTS: Based on previous transcriptome data, we selected and individually overexpressed five candidate genes involved in fatty acid degradation under the control of the Tet-on gene switch in A. niger. Overexpression of the fadE, fadA and cyp genes increased the final specific enzyme activity and total secreted protein on shake flask by 21.3 ~ 31.3% and 16.0 ~ 24.2%, respectively. And a better inducible effect by doxycycline was obtained from early logarithmic growth phase (18 h) than stationary phase (42 h). Similar with flask-level results, the glucoamylase content and total extracellular protein in engineered strains OE-fadE (overexpressing fadE) and OE-fadA (overexpressing fadA) on maltose-limited chemostat cultivation were improved by 31.2 ~ 34.1% and 35.1 ~ 38.8% compared to parental strain B36. Meanwhile, intracellular free fatty acids were correspondingly decreased by 41.6 ~ 44.6%. The metabolomic analysis demonstrated intracellular amino acids pools increased 24.86% and 18.49% in two engineered strains OE-fadE and OE-fadA compared to B36. Flux simulation revealed that increased ATP, acetyl-CoA and NADH was supplied into TCA cycle to improve amino acids synthesis for glucoamylase overproduction. CONCLUSION: This study suggested for the first time that glucoamylase production was significantly improved in A. niger by overexpression of genes fadE and fadA involved in fatty acids degradation pathway. Harnessing the intracellular fatty acids could be a strategy to improve enzyme production in Aspergillus niger cell factory.


Assuntos
Aspergillus niger , Glucana 1,4-alfa-Glucosidase , Glucana 1,4-alfa-Glucosidase/metabolismo , Aspergillus niger/metabolismo , Acetilcoenzima A/metabolismo , Aminoácidos/metabolismo , Ácidos Graxos/metabolismo , Trifosfato de Adenosina/metabolismo
5.
Molecules ; 27(20)2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-36296608

RESUMO

This work presents a literature review on the biological activity of S-carvone, geraniol and derivatives of these compounds, which are formed in the process of isomerization (during the process of geraniol isomerization, oxidation products of this compound are also obtained). Moreover, this work presents preliminary microbiological tests of creams with the addition of these biologically active compounds: S-carvone, geraniol, carvacrol (an S-carvone isomerization product), nerol (a geraniol isomerization product), linalool (a geraniol isomerization product) and citral (a geraniol oxidation product). Because the post-reaction mixture obtained after the S-carvone isomerization has a relatively simple composition, it was also added to creams and tested without isolating pure compounds. This may be a cheaper alternative to creams prepared with the addition of pure compounds. The mixture obtained after the geraniol isomerization process has a very complex composition; therefore, only compounds with the lowest molecular weight and are easily commercially available were selected for studies. The content of the tested compounds in the creams ranged from 0.5 to 3 wet%. The following microorganisms were selected for microbiological tests: the Gram-negative bacterium Escherichia coli K12, the Gram-positive bacterium Staphylococcus epidermidis, and the fungi Candida albicans, Trichophyton rubrum, Aspergillus niger, and Penicillium chrysogenum. A content of 3% carvacrol, nerol, geraniol and citral inhibited the growth of E. coli, and attenuated the growth of C. albicans and T. rubrum. On the other hand, 3% carvacrol and citral only poorly attenuated the growth of the mould fungi P. chrysogenum and A. niger.


Assuntos
Monoterpenos , Terpenos , Monoterpenos/farmacologia , Terpenos/farmacologia , Isomerismo , Escherichia coli , Aspergillus niger
6.
Biochem Biophys Res Commun ; 634: 55-61, 2022 Dec 17.
Artigo em Inglês | MEDLINE | ID: mdl-36228545

RESUMO

Aspergillus niger ATCC 10864 phytase A was produced in Penicillium verruculosum. The enzyme was found to have two pH optima of 2.5 and 5.0, as well as a T-optimum of 50-55 °C. Two amino acid substitutions, A76M and S265P, were designed for improvement in thermostability, and two more, N300K and D363N, were designed for improvement in enzyme activity. The most thermostable variant, S265P, was characterized by a 3.8-fold increase in time of half-life at 55 °C and a 1.2-fold increase in residual activity at 90 °C compared to the wild-type. The most active variant, D363N, was 1.7-times more active at 40 °C and retained 1.3-times higher residual activity at 90 °C compared to the wild-type. The obtained results revealed the importance of substitutions with proline in α-helixes for the thermostability improvement of phytases. Also, the importance of sequence motif 361HDN363 was demonstrated with relevance to values of catalytic parameters.


Assuntos
6-Fitase , 6-Fitase/genética , 6-Fitase/química , 6-Fitase/metabolismo , Aspergillus niger , Estabilidade Enzimática , Concentração de Íons de Hidrogênio
7.
Artigo em Inglês | MEDLINE | ID: mdl-36231984

RESUMO

Cadmium toxicity is one of the deleterious abiotic factors that reduce wheat production. Two different cultivars (Akbar and Dilkash) were compared for their cadmium (0, 40 and 80 mg/kg) tolerance and responses towards Bacillus subtilis NA2, Aspergillus niger PMI-118 and L-proline. Both microbes were tested for heavy metal tolerance and production of various plant hormones and biological active enzyme characteristics under normal and cadmium stress. A completely randomized design (two cultivars × four treatments × three cadmium levels × three replicates) was adopted using distilled water as a control. The growth promotion potential of these strains under cadmium stress was determined by N-fixation, IAA synthesis, P-solubilization, amylase and proteases production. A pot experiment under controlled conditions was conducted to evaluate the effect of bacteria, fungi, and L-proline under cadmium stress. It was indicated from the result that plant biomass (46.43%), shoot length (22.40%), root length (25.06%), chlorophyll (17.17%), total sugars (27.07%), total proteins (86.01%) and ascorbic acid (83.27%) were improved with inoculation under control and cadmium stress. The accumulation of total flavonoids (48.64%), total phenolics (24.88%), hydrogen peroxide (53.96%) and activities of antioxidant enzymes CAT (26.37%) and APX (43.71%) were reduced in the plants treated with bacteria, fungi and L-proline than those under control. With parallel aids, Bacillus subtilis NA2 showed a higher cadmium tolerance and plant growth stability as compared to Aspergillus niger PMI-118 and L-proline and may be adopted in the future.


Assuntos
Metais Pesados , Poluentes do Solo , Amilases , Antioxidantes/metabolismo , Ácido Ascórbico/farmacologia , Aspergillus niger , Bacillus subtilis , Biodegradação Ambiental , Cádmio/metabolismo , Clorofila/metabolismo , Flavonoides/farmacologia , Peróxido de Hidrogênio/metabolismo , Metais Pesados/metabolismo , Peptídeo Hidrolases/metabolismo , Reguladores de Crescimento de Plantas/metabolismo , Reguladores de Crescimento de Plantas/farmacologia , Plantas/metabolismo , Prolina/metabolismo , Prolina/farmacologia , Poluentes do Solo/análise , Açúcares/metabolismo , Triticum/metabolismo , Água/metabolismo
8.
Sci Rep ; 12(1): 17323, 2022 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-36243776

RESUMO

The potential of the surface dielectric barrier discharge technique (SDBD) was evaluated to decontaminate the date palm fruit. Preliminary investigations emphasized that Aspergillus niger fungus was predominant in most date samples as a post-harvest infestation. The influence of SDBD techniques on the viability of A. niger isolated from date varieties was investigated and documented. Physical and chemical characterizations of treated dates were assessed, and statistical correlation coefficients were calculated and elucidated. A 4 log10 reduction of A. niger radial growth was observed at 3 min exposure/15 days of incubation. Simultaneous reductions in pH, water activity, and moisture content of treated dates were observed when compared to untreated dates. Statistical analysis showed a positive correlation between physical and chemical variables with the viability of A. niger in treated samples. Therefore, we believe that SDBD treatment will be a promising technique for decontaminating date fruits from attacked fungi, which will positively impact sustainable food security and consumer health.


Assuntos
Phoeniceae , Aspergillus niger , Descontaminação , Frutas/química , Phoeniceae/química , Água/análise
9.
Int J Biol Macromol ; 222(Pt B): 2353-2367, 2022 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-36209910

RESUMO

Cutinases are hydrolytic enzymes secreted by phytopathogens to degrade cutin, the main polymeric component of plant cuticles. The multifaceted functionality of cutinases has allowed for their exploitation for catalytic reactions beyond their natural purpose. To diversify and expand the cutinase enzyme class, we identified five cutinase homologs from the saprotroph Aspergillus niger. One of these cutinases, AnCUT3, was over-expressed in Pichia pastoris and its biophysicochemical properties characterized. The purified recombinant AnCUT3 possessed an optimum temperature of 25 °C, an optimum pH of 5, and was stable at temperatures up to 50 °C (1 h incubation, melting point of 45.6 °C) and in a wide pH range. Kinetic studies of AnCUT3 using pNP ester substrates showed the highest catalytic efficiency, kcat/Km of 859 mM-1 s-1 toward p-nitrophenyl decanoate (C10). Although its calculated molecular mass is 27 kDa, AnCUT3 was expressed as two glycosylated proteins of molecular weights 24 and 50 kDa. Glycan profiling detected the presence of atypical paucimannose N-glycans (≤Man1-5GlcNAc) from recombinant AnCUT3, suggesting protein-dependent glycan processing of AnCUT3 in P. pastoris. AnCUT3 was also able to degrade and modify the surface of polycaprolactone and polyethylene terephthalate. Taken together, these features poise AnCUT3 as a potential biocatalyst for industrial applications.


Assuntos
Aspergillus niger , Plásticos , Cinética , Plásticos/metabolismo , Proteínas Recombinantes/química , Concentração de Íons de Hidrogênio , Pichia/genética , Pichia/metabolismo , Temperatura , Clonagem Molecular
10.
Appl Microbiol Biotechnol ; 106(21): 6993-7011, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36149454

RESUMO

The biosynthesis of citric acid (CA) using Aspergillus niger as a carrier is influenced by mycelium morphology, which is determined by the expression level of morphology-related genes. As a key component of the fungal cell wall, chitin content has an important effect on morphogenesis, and to investigate the effects of this on fermentation performance, we used RNA interference to knockdown chitin synthase C (CHSC) and chitin synthase activator (CHS3) to obtain the single-gene mutant strains A. niger chs3 and chsC and the double mutant A. niger chs3C. We found that the CA fermentation performance of the two single mutants was significantly better than that of the double mutant. The mutant A. niger chs3-4 exhibited CA production potential compared to that of the parent strain in scale-up fermentation; we determined certain characteristics of CA high-yielding strain fermentation pellets. In addition, when chsC alone was silenced, there was very little change in chs3 mRNA levels, whereas those of chsC were significantly reduced when only chs3 was silenced. As this may be because of a synergistic effect between chsC and chs3, and we speculated that the latent activation target of CHS3 is CHSC, our results confirmed this hypothesis. This study is the first application of a separation and combination silence strategy of chitin synthase and chitin synthase activator in the morphology of A. niger CA fermentation. Furthermore, it provides new insights into the method for the morphological study of A. niger fermentation and the interaction of homologous genes. KEY POINTS: • The function of chitin synthase C (chsC) and chitin synthase activator (chs3) is tightly interrelated. • Mycelial morphology was optimized by knockdown of CHS3, resulting in the overproduction of citric acid. • The separation and combination silence strategies are promising tools for the interaction of homologous housekeeping genes.


Assuntos
Aspergillus niger , Quitina Sintase , Quitina Sintase/genética , Aspergillus niger/genética , Aspergillus niger/metabolismo , Ácido Cítrico , Fermentação , Quitina/metabolismo , RNA Mensageiro/metabolismo
11.
FEMS Microbiol Lett ; 369(1)2022 10 14.
Artigo em Inglês | MEDLINE | ID: mdl-36073760

RESUMO

Fungi often experience oxidative stress in response to the environment during growth. In this study, Aspergillus niger HY2, whose presence easily results in paddy mildew, was used to investigate the effects of different carbon sources on morphological development, reactive oxygen species (ROS) metabolites, and antioxidant enzymes activities. Morphological development mainly includes the changes in conidial production and colony diameter. ROS metabolites production include the content of hydrogen peroxide (H2O2), superoxide anion (O2·-), and malondialdehyde (MDA). The results indicated that A. niger HY2 adapted to H2O2 exposure by decreasing growth and increasing the activities of some antioxidant enzymes, including superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx). Different carbon sources also affected the expression of the developmental-specific gene flbA and the oxidative stress tolerance-related gene cat. When incubated with glucose, sucrose, and xylose as carbon sources, A. niger exhibited stronger oxidative stress tolerance, but when incubated with maltose as a carbon source, A. niger exhibited relatively poor oxidative stress tolerance. Our results can provide a theoretical basis for further understanding mechanisms of metabolic adaptation and developing targeted strategies to control the spoilage caused by A. niger.


Assuntos
Aspergillus niger , Peróxido de Hidrogênio , Antioxidantes/metabolismo , Aspergillus niger/genética , Carbono/metabolismo , Catalase/metabolismo , Glucose/metabolismo , Glutationa Peroxidase/metabolismo , Glutationa Peroxidase/farmacologia , Peróxido de Hidrogênio/metabolismo , Peróxido de Hidrogênio/farmacologia , Malondialdeído/metabolismo , Maltose/metabolismo , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , Sacarose/metabolismo , Superóxido Dismutase/genética , Superóxido Dismutase/metabolismo , Superóxidos/metabolismo , Xilose/metabolismo
12.
Water Res ; 223: 119039, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36084430

RESUMO

Melanin is a critical component of fungal cell wall which protect fungi from adverse environmental tress. However, the role of melanin for fungi during the disinfection with chlorine-based disinfectants has not been elucidated. The results showed that the inactivation rate constants of Aspergillus niger with chlorine and chlorine dioxide decreased from 0.08 to 2.10 min-1 to 0 after addition of 0.32 mg/L melanin. The results indicated addition of extracted fungal melanin inhibited the inactivation efficiency of chlorine and chlorine dioxide. In contrast, the k of Aspergillus niger after inactivation with monochloramine ranged from 1.50 to 1.78 min-1 after addition of melanin which indicated effect of melanin on the inactivation efficiency of monochloramine was negligible. In addition, the extracted fungal melanin exhibited high reactivity with chlorine and chlorine dioxide but very low reactivity with monochloramine. The different inactivation mechanisms of chlorine-based disinfectants and different reactivity of melanin with chlorine-based disinfectants led to the different protective mechanism of melanin for A. niger and A. flavus spores against disinfection with chlorine-based disinfectants. The chlorine and chlorine dioxide appeared to react with functional groups of melanin in cell wall of spores, so sacrificial reactions between melanin and disinfectants decreased the available disinfectants and limited the diffusion of disinfectants to the reactive site on cell membrane, which led to the decrease of the disinfection efficiency for chlorine and chlorine dioxide. The monochloramine could penetrate into cell and damage DNA without the effect of melanin due to its strong penetration and low reactivity with melanin. Our results systematically demonstrate the protective roles of melanin on the fungal spores against chlorine-based disinfectants and the underlying mechanisms in resisting the environmental stress caused by chlorine-based disinfectants, which provides important implications for the control of fungi, especially for fungi producing melanin.


Assuntos
Cloro , Desinfetantes , Aspergillus , Aspergillus flavus , Aspergillus niger , Cloraminas , Cloretos , Cloro/farmacologia , Compostos Clorados , DNA , Desinfetantes/farmacologia , Desinfecção/métodos , Melaninas , Óxidos
13.
J Am Chem Soc ; 144(37): 17110-17119, 2022 09 21.
Artigo em Inglês | MEDLINE | ID: mdl-36069714

RESUMO

Enzyme-like catalysts by design have been a long sought-after goal of chemists but difficult to realize due to the challenges in the construction of multifunctionalized active sites with accurately positioned catalytic groups for complex substrates. Hydrolysis of cellulose is a key step in biomass utilization and requires multiple enzymes to work in concert to overcome the difficulty associated with hydrolyzing the recalcitrant substrate. We here report methods to construct synthetic versions of these enzymes through covalent molecular imprinting and strategic postmodification of the imprinted sites. The synthetic catalysts cleave a cellulose chain endolytically at multiple positions or exolytically from the nonreducing end by one or three glucose units at a time, all using the dicarboxylic acid motif found in natural cellulases. By mimicking the endocellulase, exocellulase, and ß-glucosidase, the synthetic catalysts hydrolyze cellulose in a synergistic manner, with an activity at 90 °C in pH 6.5 buffer more than doubled that of Aspergillus niger cellulase at pH 5 and 37 °C and 44% of that of a commercial cellulase blend (from Novozyme). As robust cross-linked polymeric nanoparticles, the synthetic catalysts showed little changes in activity after preheating at 90 °C for 3 days and could be reused, maintaining 76% of activity after 10 reaction cycles.


Assuntos
Celulase , Nanopartículas , Aspergillus niger , Celulose/química , Glucose , Hidrólise , beta-Glucosidase
14.
Environ Monit Assess ; 194(10): 728, 2022 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-36064812

RESUMO

Previous studies have shown that the soil microbial population and soil enzyme activity are seriously affected by fracturing flow-back fluid (FFBF) from the shale gas mining process. However, the toxic effect of FFBF on specific bacteria, fungi, and plankton has not been systematically confirmed in detail. In this paper, a toxic effect evaluation of FFBF was conducted using the representative toxicity test organisms Vibrio fischeri, Daphnia, Aspergillus niger, and S. cerevisiae, indicating that FFBF can significantly decrease the survival rate of these species. The results also showed that there was a significant negative correlation between the concentration of some inorganic toxicity factors and the survival rate when Daphnia was used as the test organism, indicating that the toxicity degree order for these inorganic toxicity factors is Ba2+ > Li+ > As3+ > Cl- > Cu2+ > Rb2+ > Ga2+ > V2+ > Na+. In addition, other toxic factors, including polycyclic aromatic hydrocarbons (PAHs), were also determined, and the order of toxic effects with a negative correlation to the Daphnia survival rate was confirmed. These results showed that the biological toxicity of FFBF was caused not only by inorganic toxicity factors such as heavy metals but also by organic compounds such as PAHs. The results not only provide a significant reference value for the systematic assessment of biological toxicity by FFBF, but they also have great significance for developing approaches to appropriate FFBF treatment.


Assuntos
Aliivibrio fischeri , Hidrocarbonetos Policíclicos Aromáticos , Animais , Aspergillus , Aspergillus niger , Daphnia , Monitoramento Ambiental , Saccharomyces cerevisiae
15.
PLoS One ; 17(9): e0274731, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36121857

RESUMO

Plant microbiome engineering is a promising tool to unlock crop productivity potential and exceed the yield obtained with conventional chemical inputs. We studied the effect of Aspergillus niger inoculation on in-field lettuce (Lactuca sativa) growth in soils with limiting and non-limiting P concentrations. Lettuce plants originating from inoculated seeds showed increased plant diameter (6.9%), number of leaves (8.1%), fresh weight (23.9%), and chlorophyll content (3.8%) as compared to non-inoculated ones. Inoculation of the seedling substrate just before transplanting was equally efficient to seed inoculation, while application of a granular formulation at transplanting did not perform well. Plant response to P addition was observed only up to 150 kg P2O5 ha-1, but A. niger inoculation allowed further increments in all vegetative parameters. We also employed a high-throughput phenotyping method based on aerial images, which allowed us to detect changes in plants due to A. niger inoculation. The visible atmospherically resistant index (VARI) produced an accurate prediction model for chlorophyll content, suggesting this method might be used to large-scale surveys of croplands inoculated with beneficial microorganisms. Our findings demonstrate that A. niger inoculation surpasses the yield obtained with conventional chemical inputs, allowing productivity gains not reached by just increasing P doses.


Assuntos
Aspergillus niger , Alface , Clorofila , Plântula , Solo
16.
Environ Pollut ; 313: 120064, 2022 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-36055452

RESUMO

Soil receiving discharges from Pb-acid batteries dismantling and restoring units (PBS) can have a high concentration of phytoavailable Pb. Reducing Pb phytoavailability in PBS can decline Pb uptake in food crops and minimize the risks to humans and the environment. This pot study aimed to reduce the concentration of phytoavailable Pb in PBS through Aspergillus niger (A. niger)-mediated release of PO43- from fish bone [Apatite II (APII)] products. The PBS (Pb = 639 mg kg-1 soil) was amended with APII powder (APII-P), APII char (APII-C), and A. niger inoculum as separate doses, and combining A. niger with APII-P (APII-P + A. niger) and APII-C (APII-C + A. niger). The effects of these treatments on reducing the phytoavailability of Pb in PBS and its uptake in fenugreek were examined. Additionally, enzymatic activities and microbial biomass carbon (MBC) in the PBS and the indices of plant physiology, nutrition, and antioxidant defense machinery were scoped. Results revealed that the APII-C + A. niger treatment was the most efficient one. Compared to the control, it significantly reduced the Pb phytoavailability (DTPA-extractable Pb fraction) in soil and its uptake in plant shoots, roots, and grain, up to 61%, 83%, 74%, and 92%. The grain produced under APII-C + A. niger were safe for human consumption as Pb concentration in grain was 4.01 mg kg-1 DW, remaining within the permissible limit set by WHO/FAO (2007). The APII-C + A. niger treatment also improved soil pH, EC, CEC, MBC, available P content and enzymatic activities, and the fenugreek quality parameters. A. niger played a significant role in solubilizing PO43- from APII-C, which reacted with Pb and formed insoluble Pb-phosphates, thereby reducing Pb phytoavailability in PBS and its uptake in plants. This study suggests APII-C + A. niger can remediate Pb-polluted soils via reducing Pb phytoavailability in them.


Assuntos
Poluentes do Solo , Trigonella , Animais , Antioxidantes , Apatitas , Aspergillus , Aspergillus niger , Carbono , Humanos , Ácido Pentético , Fosfatos , Pós , Solo/química , Poluentes do Solo/análise
17.
Molecules ; 27(18)2022 Sep 09.
Artigo em Inglês | MEDLINE | ID: mdl-36144576

RESUMO

Magnetic nanoparticles (MNPs) are becoming important DNA nanocarriers for genetic engineering of industrial fungi. However, the biological effect of MNPs on industrial fungi remains unknown. In this study, we prepared three kinds of magnetic nanoparticles with different sizes (i.e., 10 nm, 20 nm, and 200 nm) to investigate their impact on the growth and sporulation of the important industrial fungus Aspergillus niger. Transmission electron microscopy, X-ray diffraction analysis and Zeta potential analysis revealed that the three kinds of MNPs, including MNP10, MNP20 and MNP200, had uniform size distribution, regular Fe3O4 X-ray diffraction (XRD) patterns and similar Zeta potentials. Interestingly, although the three kinds of MNPs did not obviously inhibit growth of the fungus, the MNP20 at 500 mg/L strongly attenuated sporulation, leading to a remarkable decrease in spore numbers on culturing plates. Further investigation showed that MNP20 at the high concentration led to drastic chitin accumulation in the cell wall, indicating cell wall disruption of the MNP20-treated fungal cells. Moreover, the MNPs did not cause unusual iron dissolution and reactive oxygen species (ROS) accumulation, and the addition of ferrous ion, ferric ion or the reactive oxygen species scavenger N-acetyl-L-cysteine (NAC) had no impact on the sporulation of the fungus, suggesting that both iron dissolution and ROS accumulation did not contribute to attenuated sporulation by MNP20. This study revealed the size-dependent effect of MNPs on fungal sporulation, which was associated with MNP-induced cell wall disruption.


Assuntos
Nanopartículas de Magnetita , Acetilcisteína , Aspergillus niger , Quitina , DNA , Ferro , Espécies Reativas de Oxigênio
18.
Appl Environ Microbiol ; 88(17): e0104622, 2022 09 13.
Artigo em Inglês | MEDLINE | ID: mdl-36000858

RESUMO

Exploring the potential functions of nonconserved residues on the outer side of α-helices and systematically optimizing them are pivotal for their application in protein engineering. Based on the evolutionary structural conservation analysis of GH5_5 cellulases, a practical molecular improvement strategy was developed. Highly variable sites on the outer side of the α-helices of the GH5_5 cellulase from Aspergillus niger (AnCel5A) were screened, and 14 out of the 34 highly variable sites were confirmed to exert a positive effect on the activity. After the modular combination of the positive mutations, the catalytic efficiency of the mutants was further improved. By using CMC-Na as the substrate, the catalytic efficiency and specific activity of variant AnCel5A_N193A/T300P/D307P were approximately 2.0-fold that of AnCel5A (227 ± 21 versus 451 ± 43 ml/s/mg and 1,726 ± 19 versus 3,472 ± 42 U/mg, respectively). The half-life (t1/2) of variant AnCel5A_N193A/T300P/D307P at 75°C was 2.36 times that of AnCel5A. The role of these sites was successfully validated in other GH5_5 cellulases. Computational analyses revealed that the flexibility of the loop 6-loop 7-loop 8 region was responsible for the increased catalytic performance. This work not only illustrated the important role of rapidly evolving positions on the outer side of the α-helices of GH5_5 cellulases but also revealed new insights into engineering the proteins that nature left as clues for us to find. IMPORTANCE A comprehensive understanding of the residues on the α-helices of the GH5_5 cellulases is important for catalytic efficiency and stability improvement. The main objective of this study was to use the evolutionary conservation and plasticity of the TIM-barrel fold to probe the relationship between nonconserved residues on the outer side of the α-helices and the catalytic efficiency of GH5_5 cellulases by conducting structure-guided protein engineering. By using a four-step nonconserved residue screening strategy, the functional role of nonconserved residues on the outer side of the α-helices was effectively identified, and a variant with superior performance and capability was constructed. Hence, this study proved the effectiveness of this strategy in engineering GH5_5 cellulases and provided a potential competitor for industrial applications. Furthermore, this study sheds new light on engineering TIM-barrel proteins.


Assuntos
Celulase , Celulases , Aspergillus niger/genética , Aspergillus niger/metabolismo , Catálise , Celulase/metabolismo , Celulases/metabolismo , Mutação
19.
J Microbiol ; 60(10): 998-1006, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35984613

RESUMO

Aspergillus section Nigri is a fungus used industrially because of its ability to produce enzymes such as cellulolytic, amylolytic and proteolytic enzymes. In this study, we obtained twenty-eight strains of Aspergillus section Nigri from the traditional Korean fermentation starter, nuruk, which is known as a mixed culture of enzymatic filamentous fungi and yeasts. All strains were identified as Aspergillus section Nigri through combined phylogenetic analysis using partial ß-tubulin and calmodulin gene sequences. The cellulase, amylase and protease activities of Korean strains were measured and compared with ten reference strains of Aspergillus niger. Most Korean strains showed higher cellulolytic activity than reference strains, and Aspergillus neoniger KCN5 showed the highest ß-glucosidase activity. Two-thirds of the Korean strains showed similar levels of α- and glucoamylase activity as the reference strains. The protease activity of Aspergillus section Nigri strains was the highest at pH 3.0, and A. niger KSJ2 showed the highest acidic protease activity. By comparing ten reference strains and twenty-eight Korean strains, our results suggested useful Aspergillus section Nigri strains from nuruk with high enzyme activity, such as KCN5 and KSJ2, and their potential for industrial applications as enzyme producers.


Assuntos
Celulases , Glucana 1,4-alfa-Glucosidase , Amilases , Aspergillus niger/genética , Calmodulina , Fermentação , Glucana 1,4-alfa-Glucosidase/metabolismo , Peptídeo Hidrolases/genética , Filogenia , República da Coreia , Tubulina (Proteína)
20.
Biosci Biotechnol Biochem ; 86(10): 1343-1348, 2022 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-35973685

RESUMO

One new compound and 13 known compounds were isolated from Aspergillus niger, a plant endophytic fungus of Pachysandra terminalis collected from Qinling Mountains, Xi'an, China. The structure of new compound 1 was classically determined by extensive spectroscopic analysis. Compounds 5, 6, 8, and 14 were first reported from Aspergillus, while compound 2 was isolated from A. niger for the first time. All isolated compounds were further evaluated for their antioxidant and α-glucosidase inhibitory activities. Compounds 2 and 3 exhibited significant antioxidant activities with IC50 values of 31.64 µm and 24.32 µm, respectively, similar to the positive control ascorbic acid. Additionally, compound 1 displayed remarkable inhibitory activity against α-glucosidase with an IC50 value of 96.25 µm, which was 3.4-fold more potent than that of the positive control acarbose. Compound 1 has great potential for development as a new lead compound owing to its simple structure and remarkable biological activity.


Assuntos
Pachysandra , alfa-Glucosidases , Acarbose , Antioxidantes/farmacologia , Ácido Ascórbico , Aspergillus , Aspergillus niger/metabolismo , Fungos/metabolismo , Estrutura Molecular , Pachysandra/metabolismo , alfa-Glucosidases/metabolismo
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