Showing papers on "Aspergillus niger published in 2014"
TL;DR: Chitosans markedly inhibited growth of most bacteria and fungi tested, although the inhibitory effect depends on the type of microorganism and on the chitosan characteristics (DA and MW).
284 citations
TL;DR: Biosorption and biodegradation of the azo dye Procion Red MX-5B in solutions with the filamentous fungi As pergillus niger and Aspergillus terreus were evaluated, finding that biosorption was effective in both decolorization and reducing the toxicity of the solutions.
149 citations
TL;DR: The higher capacity of medium acidification and the production of organic acids with stronger metal-complexation activity are characteristics that confer to A. niger FS1 a wider action on insoluble P sources, which qualifies as a promising candidate for application in the management of P fertilization.
Abstract: The use of phosphate-solubilizing fungi is a promising biotechnological strategy in the management of phosphorus (P) fertilization, as it enables the utilization of rock phosphates (RP) or the recovery of P fixed in soil particles. The objective of our study was to evaluate fungal isolates for mechanisms of solubilization of P-bearing compounds, such as AlPO4, FePO4, Ca3(PO4)2, Araxa RP, and Catalao RP. Four fungal isolates obtained from Brazilian soils were characterized in liquid media: Aspergillus niger FS1, Penicillium canescens FS23, Eupenicillium ludwigii FS27, and Penicillium islandicum FS30. A. niger FS1 was the only isolate able to solubilize all of the P sources, solubilizing 71, 36, 100, and 14 % of the P from AlPO4, FePO4, Ca3(PO4)2, and RPs, respectively. Medium acidification was an effective solubilization mechanism, particularly for Ca3(PO4)2. The other P sources were mainly solubilized through organic acids produced by the fungi. Oxalic acid, produced exclusively by A. niger FS1, and citric acid were decisive factors in the solubilization of AlPO4 and FePO4. Penicillium isolates produced more gluconic acid than A. niger FS1 in all treatments. However, this higher production did not result in higher solubilization for any of the P sources, showing that gluconic acid contributes little to the solubilization of the P sources evaluated. The higher capacity of medium acidification and the production of organic acids with stronger metal-complexation activity are characteristics that confer to A. niger FS1 a wider action on insoluble P sources. Consequently, this isolate qualifies as a promising candidate for application in the management of P fertilization.
145 citations
TL;DR: In this article, a maize treated with nanosilica (20-40 nm) is screened for resistance against phytopathogens such as Fusarium oxysporum and Aspergillus niger and compared with that of bulk silica.
Abstract: In this study, maize treated with nanosilica (20-40 nm) is screened for resistance against phytopathogens such as Fusarium oxysporum and Aspergillus niger and compared with that of bulk silica. The resistivity is measured for disease index and expression of plant responsive compounds such as total phenols, phenylalanine ammonia lyase, peroxidase and polyphenol oxidase. The results indicate that nanosilica-treated plant shows a higher expression of phenolic compounds (2056 and 743 mg/ml) and a lower expression of stress-responsive enzymes against both the fungi. Maize expresses more resistance to Aspergillus spp., than Fusarium spp. These results show significantly higher resistance in maize treated with nanosilica than with bulk, especially at 10 and 15 kg/ha. In addition, hydrophobic potential and silica accumulation percentage of nanosilica treated maize (86.18° and 19.14%) are higher than bulk silica treatment. Hence, silica nanoparticles can be used as an alternative potent antifungal agent against phytopathogens.
116 citations
TL;DR: Itaconic acid can be produced in A. niger by the introduction of the A. terreus cis- aconitate decarboxylase encoding cadA gene, and this results in strains that produce over twenty five-fold higher levels of itaconic Acid and show a twenty-fold increase in yield compared to a strain expressing only CadA.
Abstract: Aspergillus terreus is a natural producer of itaconic acid and is currently used to produce itaconic acid on an industrial scale. The metabolic process for itaconic acid biosynthesis is very similar to the production of citric acid in Aspergillus niger. However, a key enzyme in A. niger, cis-aconitate decarboxylase, is missing. The introduction of the A. terreus cadA gene in A. niger exploits the high level of citric acid production (over 200 g per liter) and theoretically can lead to production levels of over 135 g per liter of itaconic acid in A. niger. Given the potential for higher production levels in A. niger, production of itaconic acid in this host was investigated. Expression of Aspergillus terreus cis- aconitate decarboxylase in Aspergillus niger resulted in the production of a low concentration (0.05 g/L) of itaconic acid. Overexpression of codon-optimized genes for cis- aconitate decarboxylase, a mitochondrial transporter and a plasma membrane transporter in an oxaloacetate hydrolase and glucose oxidase deficient A. niger strain led to highly increased yields and itaconic acid production titers. At these higher production titers, the effect of the mitochondrial and plasma membrane transporters was much more pronounced, with levels being 5–8 times higher than previously described. Itaconic acid can be produced in A. niger by the introduction of the A. terreus cis- aconitate decarboxylase encoding cadA gene. This results in a low itaconic acid production level, which can be increased by codon-optimization of the cadA gene for A. niger. A second crucial requirement for efficient production of itaconic acid is the expression of the A. terreus mttA gene, encoding a putative mitochondrial transporter. Expression of this transporter results in a twenty-fold increase in the secretion of itaconic acid. Expression of the A. terreus itaconic acid cluster consisting of the cadA gene, the mttA gene and the mfsA gene results in A. niger strains that produce over twenty five-fold higher levels of itaconic acid and show a twenty-fold increase in yield compared to a strain expressing only CadA.
110 citations
TL;DR: The excellent performance of A. niger and P. chrysporium in the biodegradation of textile dyes of different chemical structures suggests and reinforces the potential of these fungi for environmental decontamination.
110 citations
TL;DR: Twenty-four samples including 14 functional foods and 10 spices obtained from Chinese markets were examined for their mould profile and the mycotoxin contamination levels were determined by an optimized HPLC-FLD method.
103 citations
TL;DR: Results showed the novel bioflocculant (PM-5) had high potential to treat river water from colloids and 63% of turbidity removal with the present of Ca(2+) ion.
97 citations
TL;DR: The genetic and biosynthetic pathway of the antibiotic yanuthone D from Aspergillus niger is deduced and another compound (yanuthone X1) is identified that defines a class of ynuthones that depend on several enzymatic activities encoded by genes in the yan cluster but that are not derived from 6-MSA.
89 citations
TL;DR: Fermentation broths of mixed cultures of T. reesei with different Aspergillus strains resulted in approx.
86 citations
TL;DR: It is shown, using proteomics, that carbon-starved cultures indeed release CAZymes with predicted activity on plant polysaccharides, and analysis of the enzymatic activity and the reaction products, indicates that these proteins are enzymes that can degrade various plant polySaccharides to generate both known, as well as potentially new, inducers of CAZ enzymes.
14 Oct 2014
TL;DR: This is the first report demonstrating that A. niger is a potent and promising expression host for nonribosomal peptides with titers high enough to become industrially attractive.
Abstract: Filamentous fungi can each produce dozens of secondary metabolites which are attractive as therapeutics, drugs, antimicrobials, flavour compounds and other high-value chemicals. Furthermore, they can be used as an expression system for eukaryotic proteins. Application of most fungal secondary metabolites is, however, so far hampered by the lack of suitable fermentation protocols for the producing strain and/or by low product titers. To overcome these limitations, we report here the engineering of the industrial fungus Aspergillus niger to produce high titers (up to 4,500 mg • l−1) of secondary metabolites belonging to the class of nonribosomal peptides. For a proof-of-concept study, we heterologously expressed the 351 kDa nonribosomal peptide synthetase ESYN from Fusarium oxysporum in A. niger. ESYN catalyzes the formation of cyclic depsipeptides of the enniatin family, which exhibit antimicrobial, antiviral and anticancer activities. The encoding gene esyn1 was put under control of a tunable bacterial-fungal hybrid promoter (Tet-on) which was switched on during early-exponential growth phase of A. niger cultures. The enniatins were isolated and purified by means of reverse phase chromatography and their identity and purity proven by tandem MS, NMR spectroscopy and X-ray crystallography. The initial yields of 1 mg • l−1 of enniatin were increased about 950 fold by optimizing feeding conditions and the morphology of A. niger in liquid shake flask cultures. Further yield optimization (about 4.5 fold) was accomplished by cultivating A. niger in 5 l fed batch fermentations. Finally, an autonomous A. niger expression host was established, which was independent from feeding with the enniatin precursor d-2-hydroxyvaleric acid d-Hiv. This was achieved by constitutively expressing a fungal d-Hiv dehydrogenase in the esyn1-expressing A. niger strain, which used the intracellular α-ketovaleric acid pool to generate d-Hiv. This is the first report demonstrating that A. niger is a potent and promising expression host for nonribosomal peptides with titers high enough to become industrially attractive. Application of the Tet-on system in A. niger allows precise control on the timing of product formation, thereby ensuring high yields and purity of the peptides produced.
TL;DR: The potential value of H2S in reducing postharvest loss and food spoilage caused by microbe propagation is suggested, and it is found that short time exposure of H1S showed a microbicidal role rather than just inhibiting the growth of microbes.
Abstract: In this research, the antifungal role of hydrogen sulfide (H2S) on the postharvest pathogens Aspergillus niger and Penicillium italicum growing on fruits and under culture conditions on defined media was investigated. Our results show that H2S, released by sodium hydrosulfide (NaHS) effectively reduced the postharvest decay of fruits induced by A. niger and P. italicum. Furthermore, H2S inhibited spore germination, germ tube elongation, mycelial growth, and produced abnormal mycelial contractions when the fungi were grown on defined media in Petri plates. Further studies showed that H2S could cause an increase in intracellular reactive oxygen species (ROS) in A. niger. In accordance with this observation we show that enzyme activities and the expression of superoxide dismutase (SOD) and catalase (CAT) genes in A. niger treated with H2S were lower than those in control. Moreover, H2S also significantly inhibited the growth of Saccharomyces cerevisiae, Rhizopus oryzae, the human pathogen Candida albicans, and several food-borne bacteria. We also found that short time exposure of H2S showed a microbicidal role rather than just inhibiting the growth of microbes. Taken together, this study suggests the potential value of H2S in reducing postharvest loss and food spoilage caused by microbe propagation.
TL;DR: Results show that the evaluated fungi are able to grow and produce OTA in a wide range of temperature, aw, and pH, however, the optimal conditions for toxin production are generally different from those optimal for fungal growth.
TL;DR: This study clearly shows that all the elicitors had the potential to increase the accumulation of psoralen but the A. niger elicitor at 1.0% v/v induced maximum accumulation.
DOI•
23 Jan 2014
TL;DR: Major differences in the percent of oil degrading fungi were evident among the time of biodegradation and dry weights and pH of utilizing Petroleum hydrocarbon as a carbon and energy source.
Abstract: This study investigated the abilities of four fungi isolated indigenously polluted soil to utilize Petroleum hydrocarbon. Of all the fungal isolates obtained in this study Aspergillus niger, Aspergillus fumigatus, Fusarium solani and Peniclllium funiculosum were found to be more predominant in the polluted soil. In the present study, significant differences in the percent of oil degrading fungi were evident among the time of biodegradation. Dry weights and pH of utilizing Petroleum hydrocarbon as a carbon and energy source. There was no significant increased in dry weights of fungi as the 7 days of incubation. The pH values decreased in fungal cells metabolized after 28 days of incubation. The PH value in F. solani culture was above when compare with another fungi and these PH reached to 5.8 after 28 days incubation. The highest percentage loss of Petroleum hydrocarbon concentration by the axenic cultures of fungi was 95% with A. niger after 28 days of treatment. The highest percentage loss of Petroleum hydrocarbon concentration by the mixed cultures of fungi were 90% with A. niger and A. fumigatus, but the lowest loss of Petroleum hydrocarbon calculated in mixed four fungal strains (A. niger, A. fumigatus, P. funiculosum and F. solani) to 70%.
TL;DR: Results indicated that, the enzymatic yield is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse, and maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs.
TL;DR: In this paper, the effect of essential oils on Aspergillus spore germination, growth and mycotoxin production was investigated using poisoned food techniques, including spore propagation, agar dilution, and aflatoxin arresting.
Abstract: Objective To investigate effect of essential oils on Aspergillus spore germination, growth and mycotoxin production. Method In vitro antifungal and antiaflatoxigenic activity of essential oils was carried out using poisoned food techniques, spore germination assay, agar dilution assay, and aflatoxin arresting assay on toxigenic strains of Aspergillus species. Results Cymbopogon martinii, Foeniculum vulgare and Trachyspermum ammi ( T. ammi ) essential oils were tested against toxicogenic isolates of Aspergillus species. T. ammi oil showed highest antifungal activity. Absolute mycelial inhibition was recorded at 1 μl/mL by essential oils of T. ammi . The oil also showed, complete inhibition of spore germination at a concentration of 2 μl/mL. In addition, T. ammi oil showed significant antiaflatoxigenic potency by totally inhibiting aflatoxin production from Aspergillus niger and Aspergillus flavus at 0.5 and 0.75 μl/mL, respectively. Cymbopogon martinii, Foeniculum vulgare and T. ammi oils as antifungal were found superior over synthetic preservative. Moreover, a concentration of 5 336.297 μl/kg body weight was recorded for LC50 on mice indicating the low mammalian toxicity and strengthening its traditional reputations. Conclusions In conclusion, the essential oils from T. ammi can be a potential source of safe natural food preservative for food commodities contamination by storage fungi.
TL;DR: Results indicated that aflatoxin B1 degradation of Aspergillus niger is enzymatic and this process occurs in the extracellular environment.
Abstract: Aflatoxin B1, a type of highly toxic mycotoxin produced by some species belonging to the Aspergillus genus, such as Aspergillus flavus and Aspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to screen microorganism strains that were isolated from types of feed ingredients. Only one isolate (ND-1) was able to degrade aflatoxin B1 after screening. ND-1 isolate, identified as a strain of Aspergillus niger using phylogenetic analysis on the basis of 18S rDNA, could remove 26.3% of aflatoxin B1 after 48 h of fermentation in nutrient broth (NB). Optimization of fermentation conditions for aflatoxin B1 degradation by selected Aspergillus niger was also performed. These results showed that 58.2% of aflatoxin B1 was degraded after 24 h of culture under the optimal fermentation conditions. The aflatoxin B1 degradation activity of Aspergillus niger supernatant was significantly stronger than cells and cell extracts. Furthermore, effects of temperature, heat treatment, pH, and metal ions on aflatoxin B1 degradation by the supernatant were examined. Results indicated that aflatoxin B1 degradation of Aspergillus niger is enzymatic and this process occurs in the extracellular environment.
TL;DR: The microalgae/fungi co-cultures at mixotrophic conditions obtained much higher total biomass than pure cultures of each individual strains; indicating the symbiotic relationship between two strains.
Abstract: Microalgae harvesting is a labor- and energy-intensive process and new approaches to harvesting microalgae need to be developed in order to decrease the costs. In this study; co-cultivatation of filamentous fungus (Aspergillus niger) and microalgae (Chlorella vulgaris) to form cell pellets was evaluated under different conditions, including organic carbon source (glucose; glycerol; and sodium acetate) concentration; initial concentration of fungal spores and microalgal cells and light. Results showed that 2 g/L of glucose with a 1:300 ratio of fungi to microalgae provided the best culturing conditions for the process to reach >90% of cell harvest efficiency. The results also showed that an organic carbon source was required to sustain the growth of fungi and form the cell pellets. The microalgae/fungi co-cultures at mixotrophic conditions obtained much higher total biomass than pure cultures of each individual strains; indicating the symbiotic relationship between two strains. This can benefit the microbial biofuel production in terms of cell harvest and biomass production.
TL;DR: Inactivation of the gene encoding this regulator resulted in down-regulation of genes involved in the release of l-rhamnose from the pectin substructure rhamnogalacturonan I, as well as catabolism of this monosaccharide.
Abstract: The genome of the filamentous fungus Aspergillus niger is rich in genes encoding pectinases, a broad class of enzymes that have been extensively studied due to their use in industrial applications. The sequencing of the A. niger genome provided more knowledge concerning the individual pectinolytic genes, but little is known about the regulatory genes involved in pectin degradation. Understanding regulation of the pectinolytic genes provides a tool to optimize the production of pectinases in this industrially important fungus. This study describes the identification and characterization of one of the activators of pectinase-encoding genes, RhaR. Inactivation of the gene encoding this regulator resulted in down-regulation of genes involved in the release of L-rhamnose from the pectin substructure rhamnogalacturonan I, as well as catabolism of this monosaccharide. The rhaR disruptant was unable to grow on L-rhamnose, but only a small reduction in growth on pectin was observed. This is likely caused by the presence of a second, so far unknown regulator that responds to the presence of D-galacturonic acid.
TL;DR: Morpholine and N-acetyl piperazine containing compounds 10c and 10e have shown promising activity against various bacterial strains and compounds 10e was found to be most active against Pseudomonas aeruginosa.
TL;DR: The production of sclerotia by certain strains of Aspergillus niger when grown on CYA agar with raisins, or on other fruits or on rice, is reported for the first time.
Abstract: Several species in Aspergillus section Nigri have been reported to produce sclerotia on well-known growth media, such as Czapek yeast autolysate (CYA) agar, with sclerotia considered to be an important prerequisite for sexual development. However Aspergillus niger sensu stricto has not been reported to produce sclerotia, and is thought to be a purely asexual organism. Here we report, for the first time, the production of sclerotia by certain strains of Aspergillus niger when grown on CYA agar with raisins, or on other fruits or on rice. Up to 11 apolar indoloterpenes of the aflavinine type were detected by liquid chromatography and diode array and mass spectrometric detection where sclerotia were formed, including 10,23-dihydro-24,25-dehydroaflavinine. Sclerotium induction can thus be a way of inducing the production of new secondary metabolites from previously silent gene clusters. Cultivation of other species of the black aspergilli showed that raisins induced sclerotium formation by A. brasiliensis, A. floridensis A. ibericus, A. luchuensis, A. neoniger, A. trinidadensis and A. saccharolyticus for the first time.
TL;DR: This study may provide the basis for the industrial use of this recombinant endoinulinase for the production of inulooligosaccharides and should reduce production costs distinctly, compared with the conditions used in previous studies.
Abstract: In the present study, the endoinulinase gene (EnInu) from Aspergillus niger CICIM F0620 was optimized according to the codon usage of Pichia pastoris and both the native and the optimized gene were expressed in P. pastoris. Use of the optimized gene resulted in the secretion of recombinant endoinulinase activity that reached 1,349 U ml−1, 4.18 times that observed using the native gene. This is the highest endoinulinase activity reported to date. The recombinant enzyme was optimally active at pH 6.0 and 60 °C. Moreover, inulooligosaccharides production from inulin was studied using the recombinant enzyme produced from the optimized gene. After 8 h under optimal conditions, which included 400 g l−1 inulin, an enzyme concentration of 40 U g−1 substrate, 50 °C and pH 6.0, the inulooligosaccharide yield was 91 %. The high substrate concentration and short reaction time described here should reduce production costs distinctly, compared with the conditions used in previous studies. Thus, this study may provide the basis for the industrial use of this recombinant endoinulinase for the production of inulooligosaccharides.
TL;DR: The recombinant protein is N-terminally truncated, thermostable, has optimal activity at pH ~6 and 66°C, and is more efficient in ochratoxin A hydrolysis than carboxypeptidase A and Y, the two previously known enzymes capable of degrading this mycotoxin.
Abstract: Ochratoxin, with ochratoxin A as the dominant form, is one of the five major mycotoxins most harmful to humans and animals. It is produced by Aspergillus and Penicillium species and occurs in a wide range of agricultural products. Detoxification of contaminated food is a challenging health issue. In the present paper we report the identification, characterization and crystal structure (at 2.2 angstrom) of a novel microbial ochratoxinase from Aspergillus niger. A putative amidase gene encoding a 480 amino acid polypeptide was cloned and homologously expressed in A. niger. The recombinant protein is N-terminally truncated, thermostable, has optimal activity at pH similar to 6 and 66 degrees C, and is more efficient in ochratoxin A hydrolysis than carboxypeptidase A and Y, the two previously known enzymes capable of degrading this mycotoxin. The subunit of the homo-octameric enzyme folds into a two-domain structure characteristic of a metal dependent amidohydrolase, with a twisted TIM (triosephosphateisomerase)-barrel and a smaller beta-sandwich domain. The active site contains an aspartate residue for acid base catalysis, and a carboxylated lysine and four histidine residues for binding of a binuclear metal centre.
TL;DR: The study revealed that highest clarification was achieved when raw banana juice was incubated for 60 min with 2 % concentration of partially purified pectinase and the absorbance obtained was 0.10, which is more than 3 times of polygalacturonase activity as compared to the crude enzyme.
Abstract: Optimization of substrate concentration, time of incubation and temperature for crude pectinase production from A niger was carried out using Bhimkol banana (Musa balbisiana) peel as substrate The crude pectinase produced was partially purified using ethanol and effectiveness of crude and partially purified pectinase was studied for banana juice clarification The optimum substrate concentration, incubation time and temperature of incubation were 807 %, 6582 h and 3237 °C respectively, and the polygalacturonase (PG) activity achieved was 66 U/ml for crude pectinase The partially purified enzyme showed more than 3 times of polygalacturonase activity as compared to the crude enzyme The SDS-PAGE profile showed that the molecular weight of proteins present in the different pectinases varied from 34 to 42 kDa The study further revealed that highest clarification was achieved when raw banana juice was incubated for 60 min with 2 % concentration of partially purified pectinase and the absorbance obtained was 010
TL;DR: Forty-six fungal species belonging to 26 genera were isolated from 125 legume seed samples on potato dextrose agar at 28 °C, with the most prevalent genera being Aspergillus, Emericella, Mucor, Mycosphaerella, Penicillium and Rhizopus.
TL;DR: It is found that heat shock at 42 °C in Saccharomyces cerevisiae and treatment of this yeast species and Candida albicans with the antifungal drug caspofungin resulted in 2- to 3-fold increase of chitin and in a reduction of β-(1,3)-glucan accompanied by an increase of β- glucan, whereas ethanol stress had apparently no effect on yeast cell wall composition.
Abstract: A reliable method to determine cell wall polysaccharides composition in yeast is presented, which combines acid and enzymatic hydrolysis. Sulphuric acid treatment is used to determine mannans, whereas specific hydrolytic enzymes are employed in a two sequential steps to quantify chitin and the proportion of β-(1, 3) and β-(1, 6)-glucan in the total β-glucan of the cell wall. In the first step, chitin and β-(1, 3)-glucan were hydrolysed into their corresponding monomers N -acetylglucosamine and glucose, respectively, by the combined action of a chitinase from Streptomyces griseus and a pure preparation of endo/exo-β-(1, 3)-glucanase from Trichoderma species . This step was followed by addition of recombinant endo-β-(1, 6)-glucanase from Trichoderma harzianum with β-glucosidase from Aspergillus niger to hydrolyse the remaining β-glucan. This latter component corresponded to a highly branched β-(1, 6)-glucan that contained about 75–80% of linear β-(1, 6)-glucose linked units as deduced from periodate oxidation. We validated this novel method by showing that the content of β-(1, 3), β-(1, 6)-glucan or chitin was dramatically decreased in yeast mutants defective in the biosynthesis of these cell wall components. Moreover, we found that heat shock at 42 °C in Saccharomyces cerevisiae and treatment of this yeast species and Candida albicans with the antifungal drug caspofungin resulted in 2- to 3-fold increase of chitin and in a reduction of β-(1, 3)-glucan accompanied by an increase of β-(1, 6)-glucan, whereas ethanol stress had apparently no effect on yeast cell wall composition.
TL;DR: The antifungal activity of the new L. brevis isolates seems to be a promising advantage of these four strains, suggesting their potential applications in different food technologies as bio-preservative agents against moulds.
TL;DR: The aim of this work was the development and application of an immobilized biocatalyst, due to the well-known advantages over soluble enzyme preparations: control of the reaction progress and preparation of enzyme-free products.