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Biodeterioration of mural paintings by Aspergillusniger and Aspergillusflavus Fungi has been proved in different mural paintings in Egypt nowadays. Several researches have studied the effect of fungi on mural paintings, the mechanism of interaction and methods of control. But none of these researches gives us the solution without causing a side effect. In this paper, for the first time, a recent treatment by antibiotic "6 penthyl ? pyrone phenol" was applied as a successful technique for elimination of Aspergillusniger and Aspergillusflavus. On the other hand, it is favorable for cleaning Surfaces of Murals executed by tembera technique from the fungi metabolism which caused a black pigments on surfaces.
In the present study Aspergillusniger and Aspergillusflavus isolated from paper mill effluent showed tolerance and accumulation of toxic metals Ni, Zn, Cd, Pb, Cr and Cu from synthetic medium and paper mill effluent. Physico-chemical and heavy metals characterization of industrially treated paper mill effluent showed insignificant reduction in BOD, hardness, TDS and heavy metals as compared to permissible limits of BIS and WHO. A. niger and A. flavus were treated with synthetic medium containing 100-1000 mg l(-1) of six heavy metals. A. niger was able to tolerate and grow in 1000 mg l(-1) Pb, 500 mg l(-1) Cu, 250 mg l(-1) Zn and 100 mg l(-1) Cr, Ni respectively. No growth of A. niger was observed in 100 mg l-(-1) of Cd. A. flavus was capable to tolerate and grow in 1000 mg l(-1) Pb, Zn and Ni, 100mg l(-1) Cu. A. flavus growth was completely inhibited in 100 mg l(-1) of Cd and Cr. The Cd, Zn, Cu and Pb reduction were found significant (p < 0.05) in the paper effluent inoculated with A. niger and A. flavus biomass compared to industrial treated effluent. A. niger and A. flavus accumulated maximum of Pb (75.82%) followed by Zn (49.40%) > Cu (45.34%) > Ni (25.20%), while only 41% Cr was accumulated by A. nigerfrom 100 mg l(-1) of Cr solution. PMID:23741802
Aspergillusflavus is saprophytic soil fungus that infects and contaminates preharvest and postharvest seed crops with the carcinogenic secondary metabolite aflatoxin. The fungus is also an opportunistic animal and human pathogen causing aspergillosis diseases with incidence increasing in the immunocompromised population. Whole genome sequences of A. flavus have been released and reveal 55 secondary metabolite clusters that are regulated by different environmental regimes and the global secondary metabolite regulators LaeA and VeA. Characteristics of A. flavus associated with pathogenicity and niche specialization include secondary metabolite production, enzyme elaboration, and a sophisticated oxylipin host crosstalk associated with a quorum-like development program. One of the more promising strategies in field control involves the use of atoxic strains of A. flavus in competitive exclusion studies. In this review, we discuss A. flavus as an agricultural and medical threat and summarize recent research advances in genomics, elucidation of parameters of pathogenicity, and control measures. PMID:21513456
The effects of incubation temperature (10–30°C), pH (3.0–4.0) and vanillin concentration (350–1200ppm) on the growth ofAspergillusflavus, Aspergillusniger, Aspergillus ochraceusandAspergillus parasiticuswere evaluated using potato–dextrose agar adjusted to water activity (aw) 0.98. The radial growth rates after a lag period followed zero-order kinetics with constants that varied from 0 (no growth) to 0.63mmh?1. The lag period depended on vanillin concentration,
This study compares two xylanases produced by filamentous fungi such as A. niger and A. flavus using agroindustrial residues as substract and evaluated the effect of these enzymes on cellulose pulp biobleaching process. Wheat bran was the best carbon source for xylanase production by A. niger and A. flavus. The production of xylanase was 18 and 21% higher on wheat bran when we compare the xylanase production with xylan. At 50°C, the xylanase of A. niger retained over 85% activity with 2 h of incubation, and A. flavus had a half-life of more than 75 minutes. At 55°C, the xylanase produced by A. niger showed more stable than from A. flavus showing a half-life of more than 45 minutes. The xylanase activity of A. niger and A. flavus were somehow protected in the presence of glycerol 5% when compared to the control (without additives). On the biobleaching assay it was observed that the xylanase from A. flavus was more effective in comparison to A. niger. The kappa efficiency corresponded to 36.32 and 25.93, respectively. That is important to emphasize that the cellulase activity was either analyzed and significant levels were not detected, which explain why the viscosity was not significantly modified. PMID:24010038
de Alencar Guimaraes, Nelciele Cavalieri; Sorgatto, Michele; Peixoto-Nogueira, Simone de Carvalho; Betini, Jorge Henrique Almeida; Zanoelo, Fabiana Fonseca; Marques, Maria Rita; de Moraes Polizeli, Maria de Lourdes Teixeira; Giannesi, Giovana C
...docket ID number EPA-HQ-OPP-2010-0101 at http://www.regulations.gov.). 2. U.S. EPA. 2003. Environmental Hazard Assessment for the Microbial Pesticide, Aspergillusflavus AF36 for Conditional Registration in Arizona and...
Ascomycetous fungi of the genus Aspergillus comprise a wide variety of species of biotechnological importance (e.g. A. sojae, A. oryzae, A. niger) as well as pathogens and toxin producers (e.g. A. flavus, A. parasiticus, A. fumigatus, A. nidulans). With the exception of A. nidulans, which is a homot...
Ethyl acetate extracts and hydrodistillated essential oils from five cultivars of tropical citrus epicarps were evaluated\\u000a for their inhibitory activities against Aspergillus fumigatus, Aspergillusniger, Aspergillusflavus, Aspergillus parasiticus, and Penicillium sp. using disk diffusion and broth microdilution assays. Essential oils prepared from kaffir lime (Citrus hystrix DC) and acid lime (Citrus aurantifolia Swingle) epicarps exhibited stronger antifungal activity to
The aspergilli show immense ecological and metabolic diversity. To date, the sequences of fifteen different Aspergillus genomes have been determined providing scientists with an exciting resource to improve the understanding of Aspergillus molecular genomics. Aspergillusflavus, one of the most wide...
A mixture of aminopeptidase and neutral protease from the Aspergillusflavus mold obtained by chromatography on DEAE-Sephadex was fractionated by chromatography on the hydroxyalkyl methacrylate gel with chemically bonded 1,6 hexamethylene diamine and D-leucine. Aminopeptidase thus obtained was electrophoretically homogeneous. Conditions for chromatography were worked out allowing a one stage isolation of a highly active aminopeptidase sample directly from the alcoholic precipitate of the culture medium of the Aspergillusflavus mold. PMID:814927
Aspergillus spp. cause disease in a broad range of organisms, but it is unknown if strains are specialized for particular hosts. We evaluated isolates of Aspergillusflavus, Aspergillus fumigatus, and Aspergillus nidulans for their ability to infect bean leaves, corn kernels, and insects (Galleria mellonella). Strains of A. flavus did not affect nonwounded bean leaves, corn kernels, or insects at 22°C, but they killed insects following hemocoelic challenge and caused symptoms ranging from moderate to severe in corn kernels and bean leaves injured during inoculation. The pectinase P2c, implicated in aggressive colonization of cotton bolls, is produced by most A. flavus isolates, but its absence did not prevent colonization of bean leaves. Proteases have been implicated in colonization of animal hosts. All A. flavus strains produced very similar patterns of protease isozymes when cultured on horse lung polymers. Quantitative differences in protease levels did not correlate with the ability to colonize insects. In contrast to A. flavus, strains of A. nidulans and A. fumigatus could not invade living insect or plant tissues or resist digestion by insect hemocytes. Our results indicate that A. flavus has parasitic attributes that are lacking in A. fumigatus and A. nidulans but that individual strains of A. flavus are not specialized to particular hosts.
St. Leger, Raymond J.; Screen, Steven E.; Shams-Pirzadeh, Bijan
SUMMARY Aspergillusflavus is an opportunistic pathogen of crops. It is important because it produces aflatoxin as a secondary metabolite in the seeds of a number of crops both before and after harvest. Aflatoxin is a potent carcinogen that is highly regulated in most countries. In the field, aflatoxin is associated with drought-stressed oilseed crops including maize, peanut, cottonseed and tree nuts. Under the right conditions, the fungus will grow and produce aflatoxin in almost any stored crop seed. In storage, aflatoxin can be controlled by maintaining available moisture at levels below that which will support growth of A. flavus. A number of field control measures are being utilized or explored, including: modification of cultural practices; development of resistant crops through molecular and proteomic techniques; competitive exclusion using strains that do not produce aflatoxin; and development of field treatments that would block aflatoxin production. Taxonomy: Aspergillusflavus Link (teleomorph unknown) kingdom Fungi, phyllum Ascomycota, order Eurotiales, class Eurotiomycetes, family Trichocomaceae, genus Aspergillus, species flavus. Host range: Aspergillusflavus has a broad host range as an opportunistic pathogen/saprobe. It is an extremely common soil fungus. The major concern with this fungus in agriculture is that it produces highly carcinogenic toxins called aflatoxins which are a health hazard to animals. In the field, A. flavus is predominantly a problem in the oilseed crops maize, peanuts, cottonseed and tree nuts. Under improper storage conditions, A. flavus is capable of growing and forming aflatoxin in almost any crop seed. It also is a pathogen of animals and insects. In humans it is predominantly an opportunistic pathogen of immunosuppressed patients. Useful websites: http://www.aspergillusflavus.org, http://www.aflatoxin.info/health.asp, plantpathology.tamu.edu/aflatoxin, http://www.aspergillus.org.uk. PMID:20507532
Aspergillus nomius is described and represents a new aflatoxigenic species phenotypically similar to A. flavus. Strains examined were isolated from insects and agricultural commodities. Separation from A. flavus is based on the presence of indeterminate sclerotia and a lower growth temperature. Comparisons of DNA relatedness show A. nomius to have only relatively recently evolved from A. flavus and A. tamarii.
Infections due to Aspergillus species cause significant morbidity and mortality. Most are attributed to Aspergillus fumigatus, followed by Aspergillusflavus and Aspergillus terreus. Aspergillusniger is a mould that is rarely reported as a cause of pneumonia. A 72-year-old female with chronic obstructive pulmonary disease and temporal arteritis being treated with steroids long term presented with haemoptysis and pleuritic chest pain. Chest radiography revealed areas of heterogeneous consolidation with cavitation in the right upper lobe of the lung. Induced bacterial sputum cultures, and acid-fast smears and cultures were negative. Fungal sputum cultures grew A. niger. The patient clinically improved on a combination therapy of empiric antibacterials and voriconazole, followed by voriconazole monotherapy. After 4 weeks of voriconazole therapy, however, repeat chest computed tomography scanning showed a significant progression of the infection and near-complete necrosis of the right upper lobe of the lung. Serum voriconazole levels were low-normal (1.0 microg ml(-1), normal range for the assay 0.5-6.0 microg ml(-1)). A. niger was again recovered from bronchoalveolar lavage specimens. A right upper lobectomy was performed, and lung tissue cultures grew A. niger. Furthermore, the lung histopathology showed acute and organizing pneumonia, fungal hyphae and oxalate crystallosis, confirming the diagnosis of invasive A. niger infection. A. niger, unlike A. fumigatus and A. flavus, is less commonly considered a cause of invasive aspergillosis (IA). The finding of calcium oxalate crystals in histopathology specimens is classic for A. niger infection and can be helpful in making a diagnosis even in the absence of conidia. Therapeutic drug monitoring may be useful in optimizing the treatment of IA given the wide variations in the oral bioavailability of voriconazole. PMID:20299503
Person, A K; Chudgar, S M; Norton, B L; Tong, B C; Stout, J E
Cyclopiazonic acid (CPA) is an indole-tetramic acid neurotoxin produced by some of the same strains of A. flavus that produce aflatoxins and by some Aspergillus oryzae strains. Despite its discovery 40 years ago, few reviews of its toxicity and biosynthesis have been reported. This review examines what is currently known about the toxicity of CPA to animals and humans, both by itself or in combination with other mycotoxins. The review also discusses CPA biosynthesis and the genetic diversity of CPA production in A. flavus/oryzae populations. PMID:22069533
Aspergillusflavus is one of the most widely known species of Aspergillus. It was described as a species in 1809 and first reported as a plant pathogen in 1920. More recently, A. flavus has emerged as an important opportunistic pathogen and is now rec¬ognized as the second leading cause of aspergill...
The genomic study of filamentous fungi has made significant advances in recent years, and the genomes of several species in the genus Aspergillus have been sequenced, including Aspergillusflavus. This ubiquitous mold is present as a saprobe in a wide range of agricultural and natural habits, and can function as an opportunistic animal and plant pathogen. A. flavus produces many
Jiujiang Yu; William C. Nierman; Natalie D. Fedorova; Deepak Bhatnagar; Thomas E. Cleveland; Joan W. Bennett
Aflatoxins, produced by Aspergillusflavus and A. parasiticus, are toxic and carcinogenic metabolites. They contaminate agricultural crops before harvest and post harvest grains during storage. In order to reduce and eliminate aflatoxin contamination of food and feed, Aspergillusflavus genomics p...
Conserved regions within the M1 family of metallo-aminopeptidases have been used to clone a zinc aminopeptidase from the industrially used fungus Aspergillusniger. The derived amino acid sequence of ApsA is highly similar to two yeast zinc aminopeptidases, LAPI and AAPI (53.3 and 50.9?verall similarity, respectively), two members of the M1 family of metallo-aminopeptidases. The encoding gene was successfully overexpressed
Streptomyces S24 has broad spectrum against Aspergillus spp. in food and feed, such as Aspergillusflavus, Aspergillusniger and Asperegillus alutacells. The objective of this study was to improve the production of antifungal substances produced by S24 and to test their inhibitory effects on Aspergillusflavus. By using one-factor-at-a-time experiment and orthogonal design method, we optimized the fermentation medium. The composition of an optimized medium for the production of antifungal substances contained (g/L): starch soluble, 10; Glucose, 40; yeast extract, 8; soybean powder, 24; KH2PO4 4; and CaCO3 0.8. As a result, the productivity of antifungal substances could reach to 10 235.45 microg/mL, and this value was 2.81 times higher than that of initial medium before optimization. Additionally, inhibitory effects of the products on Aspergillusflavus were analyzed. Antagonistic tests indicated that the antifungal substances greatly inhibited mycelium growth and spores germination of Aspergillusflavus. We observed through microscope that the mycelia grew abnormally, such as contorting, bulging, vacuole increasing and the cytoplasmic contents inside effusing and the spores appeared unusual, such as gathering, deforming, cytoplasmic contents inside effusing and fracturing. PMID:21650044
Aspergillar endaortitis does not seem to have been described before in the English literature. Our patient had undergone aortic valvotomy and subsequently developed leg pains, migratory arthralgias, periarticular swelling, and general malaise. Mild intermittent pyrexia, evanescent petechiae, splinter haemorrhages, and peripheral small artery occlusion characterized the early course in hospital. Dramatic popliteal artery occlusion led to surgical recovery of embolic material packed with mycelia of Aspergillusflavus, but the patient died despite intravenous amphotericin B therapy. Necropsy revealed endaortitis and aspergilli were demonstrated in the wall of a saccular dilatation of the ascending aorta close to non-absorbable sutures. The relevant literature is reviewed and attention is drawn to the current implications of knowledge relating to risk factors, diagnosis, and treatment. We suggest that cardiovascular aspergillosis will now be encountered more frequently and that a different therapeutic approach is justified. Images
Aspergillusflavus is a fungal pathogen of many agronomically important crops worldwide. We sampled A. flavus strains from a cornfield in Rocky Mount, NC. This field was planted in 2010 and plots were inoculated at tasselling with either AF36 or NRRL 21882 (=Afla-Guard) biocontrol strains, both of...
In a survey of the occurrence of ochratoxin A (OA)-positive strains isolated from feedstuffs, two of the 19 isolates of Aspergillusniger var. niger that were studied produced OA in 2% yeast extract-15% sucrose broth and in corn cultures. This is the first report of production of OA by this species.
Abarca, M L; Bragulat, M R; Castella, G; Cabanes, F J
Aspergillusflavus and Aspergillus oryzae belong to Aspergillus section Flavi. They are closely related and are of significant economic importance. The former species has the ability to produce harmful aflatoxins while the latter is widely used in food fermentation and industrial enzyme production. This review summarizes the current understanding of the similarity of the A. flavus and A. oryzae genomes, the genetic diversity in A. flavus and A. oryzae populations, the causes of this diversity, and the relatedness of nonaflatoxigenic A. flavus strains to A. oryzae. PMID:20163884
Aflatoxins are carcinogenic mycotoxins formed by a number of fungi in the genus Aspergillus. The major fungi responsible for aflatoxin formation in crop seeds in the field and in storage are Aspergillusflavus and A. parasiticus. This review emphasizes developmental, environmental, biological, and chemical factors that influence aflatoxin formation\\u000a by A. flavus and A. parasiticus.
Aspergillusflavus is a plant and animal pathogen that also produces the potent carcinogen aflatoxin. Aspergillus oryzae is a closely related species that has been used for centuries in the food fermentation industry and is Generally Regarded As Safe (GRAS). Whole genome sequences for these two fungi are now complete, providing us with the opportunity to examine any genomic differences
G. A. PAYNE; W. C. NIERMAN; Jennifer R. Wortman; B. L. PRITCHARD; D. BROWN; R. A. DEAN; D BHATNAGAR; T. E. CLEVELAND; MASAYUKI MACHIDA; J. YU
Aspergillusflavus is a plant and animal pathogen that also produces the potent carcinogen aflatoxin. Aspergillus oryzae is a closely related species that has been used for centuries in the food fermentation industry and is generally regarded as safe (GRAS). Whole genome sequences for these two fu...
Aspergillusniger is capable of removing heavy metals such as lead, cadmium and copper from aqueous solutions. The role played by various functional groups in the cell wall of A. niger in biosorption of lead, cadmium and copper was investigated. The biomass was subjected to chemical treatments to modify the functional groups, carboxyl, amino and phosphate, to study their role
Fungal species were isolated which utilize organophosphate pesticides, viz. phosphorothioic (pirimiphos-methyl and pyrazophos), phosphorodithioic (dimethoate and malathion), phosphonic (lancer) and phosphoric (profenfos) acid derivatives. Pesticide degradation was studied in vitro and in vivo (soil). Aspergillusflavus, A. fumigatus, A. niger, A. sydowii, A. terreus, Emericella nidulans, Fusarium oxysporum and Penicillium chrysogenum were isolated from pesticide-treated wheat straw. The number of A. sydowii colonies was significantly promoted by 1 mmol/L pirimiphos-methyl, pyrazophos, lancer, dimethoate and malathion when used as phosphorus sources and by pirimiphos-methyl and pyrazophos when used as carbon sources. The number of A. flavus colonies increased with 0.5 mmol/L lancer and malathion used as the only carbon sources. A. sydowii, A. niger, A. flavus, E. nidulans and F. oxysporum grew on, and utilized, 5 pesticides as phosphorus source and showed more than 50% mass growth. A. sydowii, A. flavus and F. oxysporum phosphatase hydrolyzed the pesticides suggesting that these species are important pesticide degraders. A. sydowii produced higher amounts of the phosphatase than A. flavus and F. oxysporum. The enzyme was highly active against pyrazophos, lancer and malathion used as the only sources of organic phosphate. A. flavus and A. sydowii phosphatases efficiently hydrolyzed pesticides at 300 ppm in soil, the degradation at 1000 ppm was lower. Mineralization of 1000 ppm pesticides in soil amended with wheat straw was higher than in nonamended soil. All added pesticides except profenfos were degraded within 3 weeks. Lyophilized adapted biomass of A. flavus and A. sydowii could thus be used for field biodegradation of these pesticides. PMID:10489696
Immature fig fruits did not support colonization and aflatoxin production by Aspergillusflavus Lk. but became susceptible when ripe. While sun-drying on the tree, fruits were particularly vulnerable to fungal infection and colonization. Aflatoxin accumulation equaled levels frequently reported for such seeds as peanuts and cereal grains.
The objective of this experiment was to identify differentially expressed genes for Aspergillusflavus resistance in the Va35 (susceptible) and Mp313E (resistant) maize (Zea mays L.) lines using cDNA microarray analysis. Out of the 5065 ESTs analyzed, 2.4% of the total ESTs analyzed were significant...
Aspergillusflavus is a common saprophyte and opportunistic pathogen that produces numerous secondary metabolites. The primary objectives of the A. flavus genomics program are to reduce and eliminate aflatoxin contamination in food and feed and to discover genetic factors that contribute to plant and animal pathogenicity. A. flavus expressed sequence tags (ESTs) and whole-genome sequencing have been completed. Annotation of the A. flavus genome has revealed numerous genes and gene clusters that are potentially involved in the formation of aflatoxin and other secondary metabolites, as well as in the degradation of complex carbohydrate polymers. Analysis of putative secondary metabolism pathways might facilitate the discovery of new compounds with pharmaceutical properties, as well as new enzymes for biomass degradation. PMID:19195728
Cleveland, Thomas E; Yu, Jiujiang; Fedorova, Natalie; Bhatnagar, Deepak; Payne, Gary A; Nierman, William C; Bennett, Joan W
Blasticidin S, a protein synthesis inhibitor, inhibits aflatoxin production of Aspergillusflavus without affecting fungal growth. Analysis of metabolites in blasticidin S-treated A. flavus using quadrupole time-of-flight liquid chromatography-mass spectrometry showed that blasticidin S was metabolized into a novel metabolite, N-acetyldeaminohydroxyblasticidin S. Conversion of blasticidin S to N-acetyldeaminohydroxyblasticidin S via deaminohydroxyblasticidin S or N-acetylblasticidin S was observed in in vivo and in vitro A. flavus systems. Blasticidin S and N-acetylblasticidin S inhibited the growth of Aspergillusniger strongly and weakly, respectively, but deaminohydroxyblasticidin S and N-acetyldeaminohydroxyblasticidin S did not inhibit its growth. On the other hand, deaminohydroxyblasticidin S sustained the inhibition of aflatoxin production whereas N-acetylblasticidin S and N-acetyldeaminohydroxyblasticidin S did not. These results suggest that the free amino group at C-13 of blasticidin S and deaminohydroxyblasticidin S may be important for the inhibitory activity of aflatoxin production. PMID:23879927
Aspergillusflavus and Aspergillus parasiticus produced ethylene during early growth. However, the onset of toxin biosynthesis was marked by the absence of ethylene evolution. 2-Chloroethyl phosphonic acid, an ethylene-generating compound, inhibited aflatoxin biosynthesis in vivo. The reciprocal relationship between the production of aflatoxin and ethylene by the organism may indicate the involvement of the latter in the regulation of aflatoxin biogenesis.
Aflatoxins are the most toxic and carcinogenic naturally occurring mycotoxins. They are produced primarily by Aspergillusflavus and A. parasiticus. In order to better understand the molecular mechanisms that control aflatoxin production, identification of genes using A. flavus expressed sequence ...
Acute aortic occlusion caused by a saddle embolus is a rare vascular emergency. Associated sudden paraplegia secondary to spinal cord ischemia is even more uncommon. Aspergillus surgical site infection is typically linked to cardiac surgery but is exceptional. Here we present a case that combines all of these factors. A 67-year-old man presented with sudden paraplegia from acute aortic occlusion with a saddle embolus from Aspergillusniger aortitis 4 months after aortic valve replacement and aortoplasty. We believe this to be the second reported case of Aspergillusniger aortitis and the first presenting as aortic occlusion with paraplegia. PMID:21715126
Jamieson, Russell W; Wallace, William A; Din, Jehangir N; Raza, Zahid
...and cellulase derived from Aspergillusniger. 173.120 Section 173.120 ...and cellulase derived from Aspergillusniger. Carbohydrase and cellulase enzyme preparation derived from Aspergillusniger may be safely used in food in...
...and cellulase derived from Aspergillusniger. 173.120 Section 173.120 ...and cellulase derived from Aspergillusniger. Carbohydrase and cellulase enzyme preparation derived from Aspergillusniger may be safely used in food in...
Experiments were conducted to evaluate the effects of relative humidity (r.h.; 75%, 80%, 85%, 97%) and temperature (10, 13, 15, 25, 30°C) on aflatoxin production in previously dried (3.5% moisture content; m.c.) Brazil nuts. Initially Aspergillus spp. were isolated from the surfaces of whole in-shell (WIS) Brazil nuts imported from Peru using A. flavus and A. parasiticus agar (AFPA). Isolates
K. Arrus; G. Blank; D. Abramson; R. Clear; R. A. Holley
Aspergillusflavus is a cosmopolitan fungus able to respond to external stimuli and to shift both its trophic behaviour and the production of secondary metabolites, including that of the carcinogen aflatoxin (AF). To better understand the adaptability of this fungus, we examined genetic and phenotypic responses within the fungus when grown under four conditions that mimic different ecological niches ranging from saprophytic growth to parasitism. Global transcription changes were observed in both primary and secondary metabolism in response to these conditions, particularly in secondary metabolism where transcription of nearly half of the predicted secondary metabolite clusters changed in response to the trophic states of the fungus. The greatest transcriptional change was found between saprophytic and parasitic growth, which resulted in expression changes in over 800 genes in A. flavus. The fungus also responded to growth conditions, putatively by adaptive changes in conidia, resulting in differences in their ability to utilize carbon sources. We also examined tolerance of A. flavus to oxidative stress and found that growth and secondary metabolism were altered in a superoxide dismutase (sod) mutant and an alkyl-hydroperoxide reductase (ahp) mutant of A. flavus. Data presented in this study show a multifaceted response of A. flavus to its environment and suggest that oxidative stress and secondary metabolism are important in the ecology of this fungus, notably in its interaction with host plant and in relation to changes in its lifestyle (i.e. saprobic to pathogenic). PMID:23894339
Reverberi, Massimo; Punelli, Marta; Scala, Valeria; Scarpari, Marzia; Uva, Paolo; Mentzen, Wieslawa I; Dolezal, Andrea L; Woloshuk, Charles; Pinzari, Flavia; Fabbri, Anna A; Fanelli, Corrado; Payne, Gary A
Purpose To report the clinical, microbiologic, confocal scan and histopathologic features of Aspergillusflavus keratitis which developed immediately after deep anterior lamellar keratoplasty (DALK). Case Report A 28-year-old woman underwent DALK using the big-bubble technique for keratoconus. The operation was uneventful, yielding a bare Descemet’s membrane (DM) followed by transplantation of a corneal graft devoid of DM and endothelium. Four days after keratoplasty, mild infiltrates were noticed in the inferonasal margin of the graft, which rapidly progressed to involve the adjacent recipient cornea. Confocal scan findings suggested filamentous fungal keratitis, leading to initiation of topical and systemic antifungal medications followed by immediate replacement of the graft. Histopathologic examination disclosed keratitis caused by a filamentous fungus, which was determined by microbiologic cultures to be Aspergillusflavus. Early diagnosis and appropriate management resulted in complete recovery from this potentially devastating infection. Conclusion AspergillusFlavus can cause graft ulcers immediately after DALK. Confocal scan proved to be a valuable tool for early diagnosis and prompt intervention to control this otherwise devastating infection.
Aspergillusflavus and Aspergillus parasiticus cause perennial infection of agriculturally important crops in tropical and subtropical areas. Invasion of crops by these\\u000a fungi may result in contamination of food and feed by potent carcinogenic aflatoxins. Consumption of aflatoxin contaminated\\u000a foods is a recognised risk factor for human hepatocellular carcinoma (HCC) and may contribute to the high incidence of HCC\\u000a in
Four agar media used to isolate aflatoxin producing fungi were compared for utility in isolating fungi in theAspergillusflavus group from agricultural soils collected in 15 fields and four states in the southern United States. The four media wereAspergillusflavus andparasiticus Agar (AFPA, 14), the rose bengal agar described by Bell and Crawford (BCRB; 3), a modified rose bengal agar
Alfatoxins are toxic metabolites with demonstrated carcinogenic activity in vertebrate systems produced by Aspergillusflavus and A. parasiticus when these fungi infect corn, cotton, peanuts and tree nuts. Lipid metabolism has been demonstrated to be utilized by fungi to as nutrition for growth and...
In filamentous fungi, peroxisomes are crucial for the primary metabolism and play a pivotal role in the formation of some secondary metabolites. Further, peroxisomes are important site for fatty acids ?-oxidation, the formation of reactive oxygen species and for their scavenging through a complex of antioxidant activities. Oxidative stress is involved in different metabolic events in all organisms and it occurs during oxidative processes within the cell, including peroxisomal ?-oxidation of fatty acids. In Aspergillusflavus, an unbalance towards an hyper-oxidant status into the cell is a prerequisite for the onset of aflatoxin biosynthesis. In our preliminary results, the use of bezafibrate, inducer of both peroxisomal ?-oxidation and peroxisome proliferation in mammals, significantly enhanced the expression of pex11 and foxA and stimulated aflatoxin synthesis in A. flavus. This suggests the existence of a correlation among peroxisome proliferation, fatty acids ?-oxidation and aflatoxin biosynthesis. To investigate this correlation, A. flavus was transformed with a vector containing P33, a gene from Cymbidium ringspot virus able to induce peroxisome proliferation, under the control of the promoter of the Cu,Zn-sod gene of A. flavus. This transcriptional control closely relates the onset of the antioxidant response to ROS increase, with the proliferation of peroxisomes in A. flavus. The AfP33 transformant strain show an up-regulation of lipid metabolism and an higher content of both intracellular ROS and some oxylipins. The combined presence of a higher amount of substrates (fatty acids-derived), an hyper-oxidant cell environment and of hormone-like signals (oxylipins) enhances the synthesis of aflatoxins in the AfP33 strain. The results obtained demonstrated a close link between peroxisome metabolism and aflatoxin synthesis.
In order to gain insight into the causal agents of aflatoxin contamination of maize in Italy, populations of Aspergillusflavus on maize produced in the most affected area were characterized. Forty-six percent of A. flavus, isolated from maize kernels collected in 5 districts of northern Italy betwe...
Repetitive DNA sequences have proven useful and reliable characters in evaluating genetic relatedness of strains at different levels of taxonomic classification. A DNA probe was constructed to distinguish among strains of Aspergillusflavus by DNA fingerprinting techniques. Chromosomal DNA of A. flavus var. flavus NRRL 6541 was partially digested with EcoRI and ligated to a Lambda Dash bacteriophage vector. Four lambda clones were identified which displayed multiple and distinct bands when hybridized with chromosomal DNA from seven strains of A. flavus var. flavus digested with either EcoRI or PstI. One of these clones was chosen for further analysis and was subcloned into pUC19. The subclone, pAF28, contained a 6.2-kb chromosomal DNA insert and was able to distinguish among strains characterized by K. E. Papa (Mycologia 78:98-101, 1986) as belonging to 22 different vegetative compatibility groups. The subclone identified unique banding patterns when hybridized to genomic DNA digested with PstI. The cloned probe may be species specific as it hybridized with the DNA of all isolates of A. flavus tested in addition to strains recognized as varieties of A. flavus (e.g., A. flavus var. oryzae, A. flavus var. parasiticus, and A. flavus var. sojae). pAF28 hybridized to a single band on a Southern blot with Aspergillus nomius DNA but did not hybridize with the DNA of other fungal species tested including Aspergillus ochraceus, Aspergillus auricomus, Aspergillus alliaceus, Fusarium moniliforme, and Penicillium thomii.
Four soil temperature and moisture treatment regimens were imposed on Florunner peanuts 94 days after planting in experimental plots in 1980. At harvest (145 days after planting), the incidence of the Aspergillusflavus group and the aflatoxin concentration were greatest in damaged kernels. Extensive colonization of sound mature kernels (SMK) by the A. flavus group occurred with the drought stress treatment (56% kernels colonized); colonization was less in the irrigated plot (7%) and the drought stress plot with cooled soil (11%) and was intermediate in the irrigated plot with heated soil (26%). Aflatoxin was virtually absent from SMK with the last three treatments, but it was found at an average concentration of 244 ppb (ng/g) in drought-stressed SMK. Colonization of SMK by the A. flavus group and aflatoxin production were greater with hot dry conditions. Neither elevated temperature alone nor drought stress alone caused aflatoxin contamination in SMK. When the ratio of SMK colonized by A. flavus compared with A. niger was greater than 19:1, there was aflatoxin contamination, but there was none if this ratio was less than 9:1. Irrigation caused a higher incidence of A. niger than drought did. This may have prevented the aflatoxin contamination of undamaged peanuts.
Hill, R A; Blankenship, P D; Cole, R J; Sanders, T H
An effective selective medium for the enumeration of Aspergillusflavus and Aspergillus parasiticus has been developed by modification of Bothast and Fennell's Aspergillus Differential Medium. Results can be obtained with the new medium, Aspergillusflavus and parasiticus Agar (AFPA), after 42 h incubation at 30 degrees C. The medium is thus suitable for use in quality control as a guide to the presence of A. flavus and, potentially, of aflatoxins. AFPA has been extensively tested on peanuts and soils. Results were reproducible and comparable with those on standard fungal enumeration media incubated for much longer periods. A very low percentage of false positive or negatives was found. PMID:6406419
An elastinolytic proteinase of Aspergillusflavus has been isolated to homogeneity, and its physical and biochemical properties have been characterized. Two purification protocols were compared; an initial step of ion-exchange chromatography was found to be equivalent to ammonium sulfate precipitation at neutral pH. A combination of gel filtration and adsorption chromatographies on the resultant crude enzyme produced highly purified elastase with yields of 5 to 10%. The enzyme is a 23-kilodalton protein with a pI of 7.6. The enzyme activity is markedly inhibited by numerous metal ions. Aspergillus elastase appears to be a metalloproteinase EC 3.4.24.X), as determined by its sensitivity to 1,10-phenanthroline. Images
Aflatoxins are toxic and carcinogenic secondary metabolites produced by the fungi Aspergillusflavus and A. parasiticus. In order to better understand the molecular mechanisms that regulate aflatoxin production, the biosynthesis of the toxin in A. flavus and A. parasiticus grown in yeast extract su...
Summary Queens ofLasius flavus (F.) andL. niger (L.) were observed to choose sunlit bare areas for colony foundation and shading was found to reduce their success in founding colonies. Large colonies of these species killed queens of the opposite species first thus favouring the co-existence brought about by their habitat selection.
Evidence is presented for the simultaneous induction of sorbitol dehydrogenase along with fructokinase and repression of glucokinase by sorbitol in Aspergillusniger. Fructose is the first product of sorbitol catabolism.
Aflatoxin contamination resulting from maize infection by Aspergillusflavus is both an economic concern and public health concern. Therefore, strategies for controlling maize contamination are being investigated. Abilities of 11 naturally occurring atoxigenic strains in Nigeria to reduce aflatox...
... (b) An exemption from the requirement of a tolerance is established for residues of Aspergillusflavus AF36 in or on pistachio when applied as an antifungal agent and used in accordance with good agricultural practices. (c) An exemption from...
...cotton, undelinted seed. (b) Aspergillusflavus AF36 is temporarily exempt from the requirement of a tolerance on pistachio when used in accordance with the Experimental Use Permit, EPA File Symbol 71693-EUP-1. This temporary exemption...
Aflatoxins are toxic and carcinogenic polyketide metabolites produced by certain fungal species, including Aspergillusflavus and A. parasiticus. Because many internal and external factors, such as nutrition and environment affect aflatoxin biosynthesis, we have analyzed the transcriptome of A. fla...
...the requirement of a tolerance is established for residues of Aspergillusflavus NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob...
...the requirement of a tolerance is established for residues of Aspergillusflavus NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob...
Aspergillusflavus, like approximately one- third of ascomycete fungi, is thought to be cosmopolitan and clonal because it has uniform asexual morphology. A. flavus produces af latoxin on nuts, grains, and cotton, and assump- tions about its life history are being used to develop strategies for its biological control. We tested the assumptions of clonality and conspecificity in a sample
The maize endophyte Acremonium zeae Gams and Sumner is antagonistic to kernel rotting and mycotoxin producing fungi Aspergillusflavus and Fusarium verticillioides in cultural tests for antagonism and interferes with A. flavus infection and aflatoxin contamination of preharvest maize kernels. Chemi...
A genomic clone of the aflatoxin-producing fungus Aspergillusflavus, designated pAF28, has been used as a probe for Southern blot fingerprinting of fungal strains. A large number of A. flavus strains isolated from corn fields and tree-nut orchards can be distinguished because the DNA fingerprint p...
Six non-aflatoxigenic Aspergillusflavus isolates were tagged with enhanced green fluorescent protein. All transformed A. flavus strains exhibit consistent individual growth compared to their wild type parents, though the intensities of their fluorescence were variable. The transformants, as competi...
Aims: To find an agar medium ingredient that significantly promotes conidial production in small sclerotia (S strain) Aspergillusflavus isolates that normally produce lower numbers of conidia than large sclerotia (L strain) A. flavus isolates on routinely used growth media. Methods and Results: ...
The ability of two non-aflatoxin producing strains of Aspergillusflavus (NRRL 32354; NRRL 29269) to interfere with aflatoxin production by A. flavus NRRL 32355 was examined using a replacement series with the suspended disc culture method (R.A. Norton, 1995). Individual glass fiber discs, affixed ...
Toxigenic and atoxigenic strains of Aspergillusflavus were grown on potato dextrose agar (PDA) and wetted sterile, cracked corn for 21 and 14 days, respectively. Volatile compounds produced by A. flavus, as well as those present in the PDA controls and sterile cracked corn, were collected using sol...
The potential for two non-toxigenic isolates of Aspergillusflavus CT3 and K49 isolated from the Mississippi Delta to reduce aflatoxin contamination of corn was assessed in a field study. These two isolates exhibited comparable growth and aggressiveness as the toxigenic A. flavus isolate F3W4. The...
Two different humanized immunoglobulin G1() antibodies and an Fab fragment were produced by Aspergillusniger. The antibodies were secreted into the culture supernatant. Both light and heavy chains were initially synthesized as fusion proteins with native glucoamylase. After antibody assembly, cleavage by A. niger KexB protease allowed the release of free antibody. Purification by hydrophobic charge induction chromatog- raphy proved
Michael Ward; Cherry Lin; Doreen C. Victoria; Bryan P. Fox; Judith A. Fox; David L. Wong; Hendrik J. Meerman; Jeff P. Pucci; Robin B. Fong; Meng H. Heng; Naoya Tsurushita; Christine Gieswein; Minha Park; Huaming Wang
The distribution of total aflatoxin (AFT) and cyclopiazonic acid (CPA) between conidia and mycelial matrix was studied in five isolates of Aspergillusflavus Link cultured on maize grain for 20 days at 30°C. Total aflatoxin and CPA production differed between the isolates with Aspergillusflavus F2R4FP 1–5 producing the most AFT (conidia—0.245 ?g\\/g; mycelial matrix—83 ?g\\/g) and CPA (conidia—0.091 ?g\\/g;
Repetitive DNA sequences have proven useful and reliable characters in evaluating genetic relatedness of strains at different levels of taxonomic classification. A DNA probe was constructed to distinguish among strains of Aspergillusflavus by DNA fingerprinting techniques. Chromosomal DNA of A. flavus var. flavus NRRL 6541 was partially digested with EcoRI and ligated to a Lambda Dash bacteriophage vector. Four lambda clones were identified which displayed multiple and distinct bands when hybridized with chromosomal DNA from seven strains of A. flavus var. flavus digested with either EcoRI or PstI. One of these clones was chosen for further analysis and was subcloned into pUC19. The subclone, pAF28, contained a 6.2-kb chromosomal DNA insert and was able to distinguish among strains characterized by K. E. Papa (Mycologia 78:98-101, 1986) as belonging to 22 different vegetative compatibility groups. The subclone identified unique banding patterns when hybridized to genomic DNA digested with PstI. The cloned probe may be species specific as it hybridized with the DNA of all isolates of A. flavus tested in addition to strains recognized as varieties of A. flavus (e.g., A. flavus var. oryzae, A. flavus var. parasiticus, and A. flavus var. sojae). pAF28 hybridized to a single band on a Southern blot with Aspergillus nomius DNA but did not hybridize with the DNA of other fungal species tested including Aspergillus ochraceus, Aspergillus auricomus, Aspergillus alliaceus, Fusarium moniliforme, and Penicillium thomii. PMID:7793909
Aflatoxins (AFs) are the main contaminants in pistachio nuts. AFs production in pistachio has been attributed to Aspergillusflavus. The aim of this study was to apply existing models to predict growth and AFs production by an A. flavus isolated from pistachios as a function of moisture content and storage temperature of pistachios in order to test their usefulness and complementarities. A full factorial design was used: the moisture content levels assayed were 10, 15, 20, 25 and 30% and incubation temperatures were 10, 15, 20, 25, 30, 37 and 42 °C. Both kinetic and probability models were built to predict growth of the strain under the assayed conditions. Among the assayed models, cardinal ones gave a good quality fit for radial growth rate data. Moreover, the progressive approach, which was developed based on a reduced number of experimental points led to an improved prediction in the validation step. This is quite significant as may allow for improved experimental designs, less costly than full factorial ones. Probability model proved to be concordant in 91% of the calibration set observations. Even though the validation set included conditions around the growth/no-growth interface, there was a 100% agreement in the predictions from the data set (n = 16, cut off = 0.5) after 60 days. Similarly, the probability for AF presence was rightly predicted in 89% of the cases. According to our results EC maximum aflatoxin levels would be surpassed in a period as short as 1 month if pistachio nuts reach 20 °C, unless %mc is ?10%. PMID:22986204
Mitochondrial DNA restriction fragment length polymorphisms were identified that clearly distinguish Aspergillusflavus, A. parasiticus, and A. nomius. Mitochondrial DNAs of A. flavus and A. parasiticus were found to be circular, and their size was estimated size to be 32 kilobases. A restriction map was constructed for the mitochondrial genome of an A. parasiticus isolate by using four restriction endonucleases. Four genes tested were found to have the same order as in the mitochondrial genome of A. nidulans. The mitochondrial genome of A. nomius was estimated to be 33 kilobases. Images
...PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms Â§ 173...Aspergillusniger. Carbohydrase and cellulase enzyme preparation derived from Aspergillusniger... from the carbohydrase and cellulase enzyme product. (d) The additive is...
Aspergillusflavus is a weak pathogen that infects plants, animals and humans. When it infects agricultural crops, however, it produces one of the most potent carcinogens known (aflatoxins). To devise strategies to control aflatoxin contamination of pre-harvest agricultural crops and post-harvest grains during storage, we launched the A. flavus genomics program. The major objective of this program is the identification of genes involved in aflatoxin biosynthesis and regulation, as well as in pathogenicity, to gain a better understanding of the mechanism of aflatoxin formation. The sequencing of A. flavus whole genome has been completed. Initial annotation of the sequence revealed that there are about 13,071 genes in the A. flavus genome. Genes which potentially encode for enzymes involved in secondary metabolite production in the A. flavus genome have been identified. Preliminary comparative genome analysis of A. flavus with A. oryzae is summarized here. PMID:19238624
Yu, Jiujiang; Payne, Gary A; Nierman, William C; Machida, Masayuki; Bennett, Joan W; Campbell, Bruce C; Robens, Jane F; Bhatnagar, Deepak; Dean, Ralph A; Cleveland, Thomas E
The transcription factors NsdC and NsdD have been shown to be necessary for sexual development in Aspergillus nidulans. Herein we examine the role of these proteins in development and aflatoxin production of the agriculturally important, aflatoxin-producing fungus, Aspergillusflavus. We found tha...
Background: Aspergillusflavus is the second most important Aspergillus species causing human infections particularly fungal sinusitis. Since little is known about aflatoxin producing ability of clinical isolates, this study was undertaken to de- tect the aflatoxigenic isolates amongst these isolates. Methods: A total of 23 isolates of A. spp. which were recovered from patients proved to have fungal sinusitis by
P Dehghan; F Zaini; S Rezaei; A Jebali; P Kordbacheh; M Mahmoudi
A multi-species Affymetrix GeneChip array was developed to study development, metabolism and pathogenicity of A. flavus. This chip based on the whole genome sequence of A. flavus, contains 13,000 A. flavus genes, 8,000 maize genes and 25 human and mouse innate immune response genes, as well as the ...
Aspergillusniger is a filamentous ascomycete fungus that is ubiquitous in the environment and has been implicated in opportunistic infections of humans. In addition to its role as an opportunistic human pathogen, A. niger is economically important as a fermentation organism used for the production of citric acid. Industrial citric acid production by A. niger represents one of the most efficient, highest yield bioprocesses in use currently by industry. The genome size of A. niger is estimated to be between 35.5 and 38.5 megabases (Mb) divided among eight chromosomes/linkage groups that vary in size from 3.5 - 6.6 Mb. Currently, there are three independent A. niger genome projects, an indication of the economic importance of this organism. The rich amount of data resulting from these multiple A. niger genome sequences will be used for basic and applied research programs applicable to fermentation process development, morphology and pathogenicity.
An unusual mutation at the afl-1 locus, affecting aflatoxin biosynthesis in Aspergillusflavus 649, was investigated. The inability of strain 649 to produce aflatoxin was found to be the result of a large (greater than 60 kb) deletion that included a cluster of aflatoxin biosynthesis genes. Diploids formed by parasexual crosses between strain 649 and the aflatoxigenic strain 86 did not produce aflatoxin, indicating the dominant nature of the afl-1 mutation in strain 649. In metabolite feeding experiments, the diploids did not convert three intermediates in the aflatoxin pathway to aflatoxin. Northern (RNA blot) analysis of the diploids grown in medium conducive for aflatoxin production indicated that the aflatoxin pathway genes nor1, ver1, and omt1 were not expressed; however, there was low-level expression of the regulatory gene aflR. Pulsed-field electrophoresis gels indicated a larger (6 Mb) chromosome in strain 649 than the apparently homologous (4.9 Mb) chromosome in strain 86. The larger chromosome in strain 649 suggests that a rearrangement occurred in addition to the deletion. From these data, we proposed that a trans-sensing mechanism in diploids is responsible for the dominant phenotype associated with the afl-1 locus in strain 649. Such a mechanism is known in Drosophila melanogaster but has not been described for fungi.
Woloshuk, C P; Yousibova, G L; Rollins, J A; Bhatnagar, D; Payne, G A
The production and characterization of a bioflocculant, IH-7, by Aspergillusflavus was investigated. About 0.4 g of purified bioflocculant with an average molecular weight of 2.574 × 10(4)Da could be obtained from 1L of fermentation medium. The bioflocculant mainly consisted of protein (28.5%) and sugar (69.7%), including 40% of neutral sugar, 2.48% of uronic acid and 1.8% amino sugar. The neutral sugar components are sucrose, lactose, glucose, xylose, galactose, mannose and fructose at a molar ratio of 2.4:4.4:4.1:5.8:9.9:0.8:3.1. Fourier-transform infrared spectroscopy analysis revealed that purified IH-7 contained hydroxyl, amide, carboxyl and methoxyl groups. The elemental analysis of purified IH-7 showed that the weight fractions of the elements C, H, O, N and S were 29.9%, 4.8%, 34.7%, 3.3%, and 2.0%, respectively. IH-7 had good flocculating rate in kaolin suspension without cation addition and stable over wide range of pH and temperature. PMID:23159465
Aljuboori, Ahmad H Rajab; Idris, Azni; Abdullah, Norhafizah; Mohamad, Rosfarizan
Lactobacillus casei KC-324 was tested for its ability to inhibit aflatoxin production and mycelial growth of Aspergillusflavus ATCC 15517 in liquid culture. Aflatoxin B1 biosynthesis and mycelial growth were inhibited in both simultaneous culture and individual antagonism assays,suggesting that the inhibitory activity was due to extracellular metabolites produced in cell-free supernatant fluids of the cultured broth of L. casei KC-324. In cell-free supernatant fluids of all media tested,deMan,Rogosa and Sharpe broth,potato dextrose broth,and Czapek-Dox broth + 1% yeast extract showed higher antiaflatoxigenic activity. In these case, fungal growths, however, was not affected as measured by mycelial dry weight. The antiaflatoxigenic metabolites from L. casei KC-324 were produced over wide range of temperatures between 25? and 37?. However, these metabolites were not thermostable since the inhibitory activity of the supernatant was inactivated within 30 minutes at 100? and 121?. The inhibitory activity was not influenced by changing pH of supernatant between 4 and 10. However,the antiaflatoxigenic activity was slightly reduced at pH 10. PMID:24015075
Lactobacillus casei KC-324 was tested for its ability to inhibit aflatoxin production and mycelial growth of Aspergillusflavus ATCC 15517 in liquid culture. Aflatoxin B1 biosynthesis and mycelial growth were inhibited in both simultaneous culture and individual antagonism assays,suggesting that the inhibitory activity was due to extracellular metabolites produced in cell-free supernatant fluids of the cultured broth of L. casei KC-324. In cell-free supernatant fluids of all media tested,deMan,Rogosa and Sharpe broth,potato dextrose broth,and Czapek-Dox broth + 1% yeast extract showed higher antiaflatoxigenic activity. In these case, fungal growths, however, was not affected as measured by mycelial dry weight. The antiaflatoxigenic metabolites from L. casei KC-324 were produced over wide range of temperatures between 25? and 37?. However, these metabolites were not thermostable since the inhibitory activity of the supernatant was inactivated within 30 minutes at 100? and 121?. The inhibitory activity was not influenced by changing pH of supernatant between 4 and 10. However,the antiaflatoxigenic activity was slightly reduced at pH 10.
Aspergillusflavus produced approximately 50 U/mL of amylolytic activity when grown in liquid medium with raw low-grade tapioca starch as substrate. Electrophoretic analysis of the culture filtrate showed the presence of only one amylolytic enzyme, identified as an alpha-amylase as evidenced by (i) rapid loss of color in iodine-stained starch and (ii) production of a mixture of glucose, maltose, maltotriose and maltotetraose as starch digestion products. The enzyme was purified by ammonium sulfate precipitation and ion-exchange chromatography and was found to be homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The purified enzyme had a molar mass of 52.5 +/- 2.5 kDa with an isoelectric point at pH 3.5. The enzyme was found to have maximum activity at pH 6.0 and was stable in a pH range from 5.0 to 8.5. The optimum temperature for the enzyme was 55 degrees C and it was stable for 1 h up to 50 degrees C. The Km and V for gelatinized tapioca starch were 0.5 g/L and 108.67 mumol reducing sugars per mg protein per min, respectively. PMID:7729774
Khoo, S L; Amirul, A A; Kamaruzaman, M; Nazalan, N; Azizan, M N
A 52-year-old woman was hospitalized because of severe cough in August 1994. She had engaged in culturing roses in greenhouses since 1968, and had developed a cough during the summer of 1990. Chest radiography showed diffuse ground-glass opacity in both lung fields, and she suffered from hypoxemia (PaO2 = 45.6 torr) while breathing room air. The lymphocyte count in the bronchoalveolar lavage fluid was increased, and transbronchial lung biopsy specimens showed lymphocyte alveolitis in the alveolar spaces. After admission, the patient's symptoms improved rapidly without medication. However, on her return to work, the cough and hypoxemia reappeared. In her rose culture, she had used Rockwool, and Aspergillusniger was detected predominantly in the Rockwool. Precipitins against the extracts of Aspergillusniger were detected with the double immunodiffusion test and the inhalation provocation test yielded clinical symptoms. Our diagnosis was hypersensitivity pneumonitis caused by Aspergillusniger. PMID:15357273
To get insight into the limiting factors existing for the efficient production of fungal peroxidase in filamen- tous fungi, the expression of the Phanerochaete chrysosporium lignin peroxidase H8 (lipA) and manganese peroxidase (MnP) H4 (mnp1) genes in Aspergillusniger has been studied. For this purpose, a protease-deficient A. niger strain and different expression cassettes have been used. Northern blotting experiments
ANA CONESA; CEES A. M. J. J. VAN DEN HONDEL; PETER J. PUNT
Resistance to the morpholine-fungicide fenpropimorph was studied in Aspergillusniger and A. nidulans. Mass selection of conidia of A. nidulans on agar amended with the fungicide at different concentrations did not yield of resistant mutants, even after UV-treatment\\u000a of the conidia. In contrast, similar experiments with A. niger generated many fenpropimorph-resistant mutants. The mutants displayed cross-resistance to fenpropidin and generally
A. J. G. Engels; E. F. Holub; K. Swart; M. A. De Waard
Single cell profiling was performed to assess differences in RNA accumulation in neighboring hyphae of the fungus Aspergillusniger. A protocol was developed to isolate and amplify RNA from single hyphae or parts thereof. Microarray analysis resulted in a present call for 4 to 7% of the A. niger genes, of which 12% showed heterogeneous RNA levels. These genes belonged to a wide range of gene categories.
There is a need to develop technologies that can remove toxic heavy metal ions found in wastewaters. Microorganisms are known to remove heavy metal ions from water. In this study the potential of the fungus Aspergillusniger to remove lead, cadmium, copper and nickel ions was evaluated. A. niger biomass pretreated by boiling in 0.1N NaOH solution for 15 min
D-Mannitol is the predominant carbon compound in conidiospores of the filamentous fungus Aspergillusniger and makes up 10 to 15?f the dry weight. A number of physiological functions have been ascribed to mannitol, including serving as a reserve carbon source, as an antioxidant, and to store reducing power. In this study, we cloned and characterized the A. niger mpdA gene,
George J. G. Ruijter; Maarten Bax; Hema Patel; Simon J. Flitter; Vondervoort van de P. J. I; Vries de R. P; Kuyk van P. A; Jaap Visser
Orum, T. V., Bigelow, D. M., Nelson, M. R., Howell, D. R., and Cotty, P. J. 1997. Spatial and temporal patterns of Aspergillusflavus strain composition and propagule density in Yuma County, Arizona, soils. Plant Dis. 81:911-916. Aspergillusflavus isolates from Arizona can be divided into S and L strains on the basis of scle- rotial morphology. These genetically distinct
Thomas V. Orum; Donna M. Bigelow; Merritt R. Nelson; Donald R. Howell; Peter J. Cotty
Neutralized electrolyzed oxidizing water (NEW) and acidic electrolyzed oxidizing water (AcEW) are electrolyzed oxidizing waters (EOW) that have significantly different fungicidal efficiencies against Aspergillusflavus (A. flavus) (The actuation durations of no survival population to NEW and AcEW were 90s and 120s, respectively.), even when used at the same available chlorine concentration (30ppm). It has been verified by our previous
Twenty-two aflatoxin B1 (AFB1) producing Aspergillusflavus strains were isolated from 1,200 discolored rice grain samples collected from 20 states across India and tested their potential\\u000a to produce AFB1 on different agar media. Further these isolates were characterized through randomly amplified polymorphic\\u000a DNA method. All the strains of A. flavus were produced AFB1 on yeast extract sucrose agar media and
K. R. N. Reddy; Ch. Surendhar Reddy; P. Nataraj Kumar; K. Muralidharan
Different polymorphs of rasburicase, a recombinant urate oxidase enzyme (Uox) from Aspergillusflavus, were obtained as a series of polycrystalline precipitates. Different crystallization protocols were followed in which the salt type, pH and polyethylene glycol 8000 (PEG 8000) concentration were varied. The related crystalline phases were characterized by means of high-resolution synchrotron X-ray powder diffraction. In all cases, Uox complexed with the inhibitor 8-azaxanthine (AZA) was not altered from its robust orthorhombic I222 phase by variation of any of the factors listed above. However, in the absence of AZA during crystallization ligand-free Uox was significantly affected by the type of salt, resulting in different crystal forms for the four salts tested: sodium chloride, potassium chloride, ammonium chloride and ammonium sulfate. Remarkable alterations of some of these phases were observed upon gradual increase of the exposure time of the sample to the synchrotron beam in addition to variation of the PEG 8000 concentration. When Uox was crystallized in Tris buffer or pure water in the absence of salt, a distinct polymorph of orthorhombic symmetry (P2(1)2(1)2) was obtained that was associated with significantly altered lattice dimensions in comparison to a previously reported isosymmetrical structure. The latter form of Uox exhibits enhanced stability to variation of pH and PEG 8000 concentration accompanied by minor modifications of the unit-cell dimensions in the ranges under study. Accurate lattice parameters were extracted for all crystalline phases. This study reveals the rich phase diagram of Uox, a protein of high pharmaceutical importance, which is associated with an enhanced degree of polymorphism. The outcome of our analysis verifies previously reported results as well as demonstrating polymorphs that have altered unit-cell dimensions with respect to known structural models. PMID:20445229
Collings, Ines; Watier, Yves; Giffard, Marion; Dagogo, Sotonye; Kahn, Richard; Bonneté, Francoise; Wright, Jonathan P; Fitch, Andrew N; Margiolaki, Irene
Four agar media used to isolate aflatoxin producing fungi were compared for utility in isolating fungi in the Aspergillusflavus group from agricultural soils collected in 15 fields and four states in the southern United States. The four media were Aspergillusflavus and parasiticus Agar (AFPA, 14), the rose bengal agar described by Bell and Crawford (BCRB; 3), a modified rose bengal agar (M-RB), and Czapek's-Dox Agar supplemented with the antibiotics in BC-RB (CZ-RB). M-RB was the most useful for studying the population biology of this group because it permitted both identification of the greatest number of A. flavus group strains and growth of the fewest competing fungi. M-RB supported an average of 12% more A. flavus group colonies than the original rose bengal medium while reducing the number of mucorales colonies and the number of total fungi by 99% and 70%, respectively. M-RB was successfully employed to isolate all three aflatoxin producing species, A. flavus, A. parasiticus and A. nomius, and both the S and L strains of A. flavus. M-RB is a defined medium without complex nitrogen and carbon sources (e.g. peptone and yeast extract) present in BC-RB. M-RB should be useful for studies on the population biology of the A. flavus group. PMID:8047107
Aflatoxin contaminated corn is dangerous for domestic animals when used as feed and cause liver cancer when consumed by human beings. Therefore, the ability to detect A. flavus and its toxic metabolite, aflatoxin, is important. The objective of this study is to measure A. flavus growth using hyper...
Aflatoxin contaminated corn is dangerous for domestic animals when used as feed and cause liver cancer when consumed by human beings. Therefore, the ability to detect A. flavus and its toxic metabolite, aflatoxin, is important. The objective of this study is to measure A. flavus growth using hyperspectral technology and develop spectral signatures for A. flavus. Based on the research group's previous experiments using hyperspectral imaging techniques, it has been confirmed that the spectral signature of A. flavus is unique and readily identifiable against any background or surrounding surface and among other fungal strains. This study focused on observing changes in the A. flavus spectral signature over an eight-day growth period. The study used a visible-near-infrared hyperspectral image system for data acquisition. This image system uses focal plane pushbroom scanning for high spatial and high spectral resolution imaging. Procedures previously developed by the research group were used for image calibration and image processing. The results showed that while A. flavus gradually progressed along the experiment timeline, the day-to-day surface reflectance of A. flavus displayed significant difference in discreet regions of the wavelength spectrum. External disturbance due to environmental changes also altered the growth and subsequently changed the reflectance patterns of A. flavus.
DiCrispino, Kevin; Yao, Haibo; Hruska, Zuzana; Brabham, Kori; Lewis, David; Beach, Jim; Brown, Robert L.; Cleveland, Thomas E.
In this study, urease production was investigated among thirteen strains of Aspergillusniger; seven strains isolated from soils of Semnan province in Iran and six strains obtained from Persian Type Culture Collection (PTCC). The enzyme production was screened in two submerged media quantitatively. The registered PTCC 5011 and the native S31 strains showed more urease production than the other eleven
Mohammad Faezi Ghasemi; Mohammad Reza Bakhtiari; Masoud Fallahpour; Ashrafossadat Noohi; Nasrin Moazami; Zohreh Amidi
Citric acid was produced using Aspergillusniger immobilized on polyurethane foam in a bubble column reactor. Most of the adsorbed cells remained on the support and, as a result, high oxygen tension was maintained during the reactor operation. However, uncontrolled growth of the pellets made continuous reactor operation difficult. The citric acid productivity obtained from 15 vol.% foam particles containing
Color elimination by Aspergillusniger from wastewater from molasses alcoholic fermentation was studied. The influences of the nutrient concentrations, initial pH and carbon source on this color elimination were analyzed. It worked in a discontinuous process in shaken cultures and in a continuous process in a bubble reactor. During the batch process, through all experiments the maximal color elimination was
M. Peńa Miranda; G. González Benito; N. San Cristobal; C. Heras Nieto
Cultures of Aspergillusniger NRRL-599 in fluid Sabouraud medium were grown with quinazoline and phthalazine for 7 days. Metabolites were purified by high-performance liquid chromatography and identified by mass spectrometry and proton nuclear magnetic resonance spectroscopy. Quinazoline was oxidized to 4-quinazolinone and 2,4-quinazolinedione, and phthalazine was oxidized to 1-phthalazinone. PMID:21169055
Sutherland, John B; Heinze, Thomas M; Schnackenberg, Laura K; Freeman, James P; Williams, Anna J
Aspergillusniger was found capable of rapidly converting about 97% of the sugar from brewery spent grain liquor to fungal mass. The yield of dry mycelium, based on the sugar consumed, was approximately 57%. This fungus produced 1.10% titratable acid calculated as citric acid and reduced the biochemical oxygen demand by 96%.
Hang, Y. D.; Splittstoesser, D. F.; Woodams, E. E.
Aflatoxins are a family of highly toxic and carcinogenic toxins produced by several Aspergillus species. Aflatoxin contamination of agricultural commodities both pre- and postharvest is a serious food safety issue and a significant economic concern. Using nonaflatoxigenic A. flavus isolates to competitively exclude toxigenic A. flavus isolates in agricultural fields has become an adopted approach to reduce aflatoxin contamination. From screening subgroups of nonaflatoxigenic A. flavus, we identified an A. flavus isolate, TX9-8, which competed well with three A. flavus isolates producing low, intermediate, and high levels of aflatoxins, respectively. TX9-8 has a defective polyketide synthase gene (pksA), which is necessary for aflatoxin biosynthesis. Co-inoculating TX9-8 at the same time with large sclerotial (L strain) A. flavus isolates at a ratio of 1:1 or 1:10 (TX9-8:toxigenic) prevented aflatoxin accumulation. The intervention of TX9-8 on small sclerotial (S strain) A. flavus isolates varied and depended on isolate and ratio of co-inoculation. At a ratio of 1:1 TX9-8 prevented aflatoxin accumulation by A. flavus CA28 and reduced aflatoxin accumulation 10-fold by A. flavus CA43. No decrease in aflatoxin accumulation was apparent when TX9-8 was inoculated 24 h after toxigenic L- or S strain A. flavus isolates started growing. The competitive effect likely is due to TX9-8 outgrowing toxigenic A. flavus isolates. PMID:17140692
Forty-seven isolates of Aspergillus parasiticus were analyzed for production of aflatoxins B1, B2, G1, G2, and cyclopiazonic acid. None produced cyclopiazonic acid, whereas 46 of 47 produced aflatoxins B1 and G1. These data are related to previous studies pertaining to A. flavus and illustrate species validity from a biochemical standpoint.
Changes in aflatoxin biosynthesis in Aspergillusflavus and A. parasticus grown in yeast extract sucrose medium were compared to yeast extract sucrose media supplemented with several common amino acids. Yeast extract sucrose media supplemented with 50 mM tryptophan was found to significantly reduce...
Aspergillusflavus first gained scientific attention for its production of aflatoxin. The underlying regulation of aflatoxin biosynthesis has been serving as a theoretical model for biosynthesis of other microbial secondary metabolites. Nevertheless, for several decades, the DNA methylation status, one of the important epigenomic modifications involved in gene regulation, in A. flavus remains to be controversial. Here, we applied bisulfite sequencing in conjunction with a biological replicate strategy to investigate the DNA methylation profiling of A. flavus genome. Both the bisulfite sequencing data and the methylome comparisons with other fungi confirm that the DNA methylation level of this fungus is negligible. Further investigation into the DNA methyltransferase of Aspergillus uncovers its close relationship with RID-like enzymes as well as its divergence with the methyltransferase of species with validated DNA methylation. The lack of repeat contents of the A. flavus' genome and the high RIP-index of the small amount of remanent repeat potentially support our speculation that DNA methylation may be absent in A. flavus or that it may possess de novo DNA methylation which occurs very transiently during the obscure sexual stage of this fungal species. This work contributes to our understanding on the DNA methylation status of A. flavus, as well as reinforces our views on the DNA methylation in fungal species. In addition, our strategy of applying bisulfite sequencing to DNA methylation detection in species with low DNA methylation may serve as a reference for later scientific investigations in other hypomethylated species.
Aflatoxin contamination in cottonseed, caused primarily by Aspergillusflavus, is a global concern in terms of food safety and economy. Current strategies to reduce the risk of aflatoxin contamination rely mostly upon biological control with non-aflatoxigenic strains and chemical control measures. ...
Aflatoxins are toxic and extremely carcinogenic compounds produced by the molds Aspergillusflavus and A. parasiticus. The aflatoxin biosynthetic pathway and its genetic regulation have been studied for decades, revealing a well organized aflatoxin pathway gene cluster consisting of 25 genes within...
Aflatoxins contamination by Aspergillusflavus is a matter of great concern for oil rich crops among which hazelnuts represent economically important agricultural commodities of Mediterranean countries, mainly used as mixed nuts or as ingredients in the bakery and confectionery industries. Since the biosynthetic pathway of aflatoxin biosynthesis has been elucidated in detail, expression analysis of the genes along the pathway
The European corn borer (ECB), Ostrinia nubilalis, is a major pest of corn in Europe and in several agricultural areas of the USA. In addition to direct yield losses, the ECB is expected to act as a vector for carrying spores of the aflatoxin-producing fungus Aspergillusflavus. Therefore the object...
Bacterial isolates from Mississippi maize field soil and maize rhizosphere samples were evaluated for their potential as biological control agents against Aspergillusflavus and Fusarium verticillioides. Isolated strains were screened for antagonistic activities in liquid co-culture against A. flav...
Aspergillusflavus is a filamentous fungus that produces mycotoxins in many food and feed crops, such as maize (Zea mays L.). Isolates were analyzed for toxin production by nucleic acid profiles in an attempt to differentiate toxigenic from atoxigenic isolates. A total of 41 toxigenic and 34 atox...
Aflatoxin contamination caused by Aspergillus fungi is a great concern in peanut production world wide. Pre-harvest A. flavus infection usually happens in peanuts that are grown under less-irrigation, drought stressed condition. However, drought resistant peanut lines displayed less aflatoxin contam...
Trans-2-hexenal, a volatile aldehyde, is produced by soybean [Glycine max (L.) Merr] and other plants via the lipoxygenase pathway. In vitro tests showed it significantly (p< 0.001) reduced Aspergillusflavus germinating conidial viability at 10 µM, with approximately 95% viability reduction observ...
Cotty, P. J. 1989. Virulence and cultural characteristics of two Aspergillusjlavus strains pathogenic on cotton. Phytopathology 79:808-814. Seventy Aspergillusflavus isolates from Arizona desert valleys were sorted into two distinct strains on the basis of sclerotial size, cultural characteristics, and virulence to cotton. Strain L isolates produced large sclerotia (over 400 \\/lm in diameter), and strain S isolates produced small
The aim of this study was to verify the effects of gamma radiation process on the fungal DNA and the application of PCR in the detection of Aspergillusflavus in irradiated maize grains. The samples were inoculated with a toxigenic strain and incubated under controlled conditions of relative humidity, water activity, and temperature for 15 days. After incubation, the samples
Simone Aquino; Ralf Greiner; Ursula Konietzny; Regina H. Hassegawa; Tatiana Alves dos Reis; Benedito Corręa; Anna Lucia C. H. Villavicencio
The aflatoxigenic ability of 300 strains of Aspergillusflavus (Link) was examined employing thin layer chromatography (TLC) of plugs of cultures on agar media incubated for two weeks. The strains were isolated from 185 samples of various feeds and grains used in Norway. They were cultivated on yeast extract sucrose agar (YES) and a synthetic low salts agar medium containing
Aflatoxins are toxic and the most carcinogenic compounds produced by Aspergillusflavus and A. parasiticus that contaminate food and feed commodities when these fungi infect crops such as cotton, corn, peanuts, and tree nuts. Molecular studies on the genetics of aflatoxin biosynthesis established a...
Aflatoxins are extremely toxic and carcinogenic compounds produced primarily by the fungi Aspergillusflavus and A. parasiticus. Molecular studies on the genetics of aflatoxin biosynthesis established a well organized aflatoxin pathway gene cluster consisting of 25 genes within 70 kb DNA region. M...
Aflatoxins are carcinogenic fungal secondary metabolites produced by Aspergillusflavus and other closely related species. Levels of aflatoxins in agricultural commodities are stringently regulated by many countries and thus aflatoxins are a major concern to both producers and consumers. A cluster...
Distribution of trace element levels in corn germ fractions from kernels naturally infected with Aspergillusflavus and from kernels free of the fungus demonstrated an association between the presence of A. flavus and higher levels of metals. A. flavus production of aflatoxin on various autoclaved corn media showed that ground, whole corn was an excellent substrate; similar high levels of toxin were observed on full-fat corn germ but endosperm and defatted corn germ supported reduced yields. The influence of trace elements and their availability in defatted corn germ to A. flavus-mediated aflatoxin biosynthesis were measured. Enrichment of the substrate with 5 to 10 ?g of manganese, copper, cadmium, or chromium per g of germ increased toxin yields. Addition of lead or zinc (50 to 250 ?g/g) also enhanced toxin accumulation. Aflatoxin elaboration was reduced by the addition of 25 ?g of cadmium per g or 500 ?g of copper per g of germ.
In Kanagawa Prefecture, located in central Japan, aflatoxin-producingAspergillusflavus was isolated in 4 (2.5%) of 160 field soil samples. In the 4 fields, whose soil contained aflatoxin-producingA. flavus, the annual average temperature of the sampling sites of the soil ranged from 13.8 to 15.1°C. Of all the isolated strains of aflatoxin-producingA. flavus, 4 strains, isolated from a single soil sample,
Aspergillusniger FCBP-198 was genetically modified for its ability to reveal extra cellular ?-amylase enzyme activity. From 76 efficient mutants isolated after ultraviolet (UV) irradiation, An-UV-5.6 was selected as the most efficient UV mutant, with 76.41 units mL of ?-amylase activity compared to wild (34.45 units mL). In case of ethyl methane sulphonate (EMS), among 242 survivors, 74 were assayed
The antifungal effects of lauric acid and four lauric acid derivatives (monolauroylglycerol, D-laurate A, T-laurate A, 6-O-lauroysucrose) were tested on the spore germination and the growth rate of Aspergillusniger DMF 0801. The results showed that the tested substances varied in their antifungal activity and they also confirmed the relation of the structure of tested substances and their antifungal effects.
Zde?ka ?iháková; Milada Plocková; Vladimír Filip; Jan Šmidrkal
Adaptation of filamentous fungi to short-term salt stress has been analysed by a continuous measurement system. Spores of Aspergillusniger were immobilized on the polylysine-coated glass bottom of a culture vessel, which enabled the exchange of a medium containing salt (NaCl) without disturbing continuous observation. Repeated contacts with 0.75% NaCl produced hypha insensitive to this concentration of NaCl. When the
A comprehensive approach of bioprocess design at various levels was used to optimize microbial production of extracellular\\u000a fructofuranosidase, important as biocatalyst to derive fructooligosaccharides with broad application in food or pharmaceutical\\u000a industry. For production, the recombinant strain Aspergillusniger SKAn1015 was used, which expresses the fructofuranosidase encoding gene suc1 under control of a strong constitutive promoter. In a first screening
Habib Driouch; Andreas Roth; Petra Dersch; Christoph Wittmann
..beta..-Xylosidase from a commercial Aspergillusniger preparation was purified by differential ammonium sulfate precipitation and either gel permeation or cation exchange chromatography, giving 16-fold purification in 32% yield for the first technique or 27-fold purification in 19% yield for the second. Enzyme prepared by this method was immobilized to 10 different carriers, but only when it was bound to alumina with TiCl/sub 4/ and to alkylamine porous silica with glutaraldehyde were substantial efficiencies and stabilities achieved.
Purpose To document transcriptional activation (expression) of key aflatoxin biosynthetic pathway genes in corneal isolates of Aspergillusflavus. Methods The expression of certain regulatory (aflatoxin regulatory [aflR] and aflatoxin J [aflJ]) and structural (polyketide synthase acetate [pksA] and norsolonic acid-1 [nor-1]) genes in four corneal A. flavus isolates was evaluated by reverse transcription PCR. The aflatoxin-producing potential of each strain was determined by thin-layer chromatography and quantified by spectrophotometry. Four environmental isolates were used for comparison. The mean expression levels of these genes were compared in the corneal and environmental A. flavus isolates. In addition, the mean expression levels were also correlated with the aflatoxin production levels. Results All isolates expressed aflJ, nor-1, and pksA, while all but one expressed aflR. Overall, significantly higher mean expression levels occurred in aflatoxigenic than in non-aflatoxigenic corneal isolates. A significant positive correlation was noted between the mean expression level of aflR and the quantum of aflatoxin production by the corneal isolates. Essentially similar patterns of expression of these genes were noted in four environmental A. flavus isolates used for comparison. Conclusions For the first time, isolates of A. flavus from human keratitis patients have been shown to express regulatory and structural aflatoxin biosynthetic pathway genes. Further studies are needed to clarify the precise influence of the corneal microenvironment on expression of these genes and aflatoxin production by A. flavus infecting the cornea.
Leema, George; Chou, Duen-Suey; Jesudasan, Christadoss A. Nelson; Geraldine, Pitchairaj
Aspergillusflavus, a haploid organism found worldwide in a variety of crops, including maize, cottonseed, almond, pistachio, and peanut, causes substantial and recurrent worldwide economic liabilities. This filamentous fungus produces aflatoxins (AFLs) B1 and B2, which are among the most carcinogenic compounds from nature, acutely hepatotoxic and immunosuppressive. Recent efforts to reduce AFL contamination in crops have focused on the use of nonaflatoxigenic A. flavus strains as biological control agents. Such agents are applied to soil to competitively exclude native AFL strains from crops and thereby reduce AFL contamination. Because the possibility of genetic recombination in A. flavus could influence the stability of biocontrol strains with the production of novel AFL phenotypes, this article assesses the diversity of vegetative compatibility reactions in isolates of A. flavus to identify heterokaryon self-incompatible (HSI) strains among nonaflatoxigenic isolates, which would be used as biological controls of AFL contamination in crops. Nitrate nonutilizing (nit) mutants were recovered from 25 A. flavus isolates, and based on vegetative complementation between nit mutants and on the microscopic examination of the number of hyphal fusions, five nonaflatoxigenic (6, 7, 9 to 11) and two nontoxigenic (8 and 12) isolates of A. flavus were phenotypically characterized as HSI. Because the number of hyphal fusions is reduced in HSI strains, impairing both heterokaryon formation and the genetic exchanges with aflatoxigenic strains, the HSI isolates characterized here, especially isolates 8 and 12, are potential agents for reducing AFL contamination in crops. PMID:23726204
Rosada, L J; Sant'anna, J R; Franco, C C S; Esquissato, G N M; Santos, P A S R; Yajima, J P R S; Ferreira, F D; Machinski, M; Corręa, B; Castro-Prado, M A A
We used computational and mass spectrometric approaches to characterize the Aspergillusniger secretome. The 11,200 gene models predicted in the genome of A. niger strain ATCC 1015 were the data source for the analysis. Depending on the computational methods used, 691 to 881 proteins were predicted to be secreted proteins. We cultured A. niger in six different media and analyzed the extracellular proteins produced using mass spectrometry. A total of 222 proteins were identified, with 39 proteins expressed under all six conditions and 74 proteins expressed under only one condition. The secreted proteins identified by mass spectrometry were used to guide the correction of about 20 gene models. Additional analysis focused on extracellular enzymes of interest for biomass processing. Of the 63 glycoside hydrolases predicted to be capable of hydrolyzing cellulose, hemicellulose or pectin, 94% of the exo-acting enzymes and only 18% of the endo-acting enzymes were experimentally detected.
Tsang, Adrian; Butler, Gregory D.; Powlowski, Justin; Panisko, Ellen A.; Baker, Scott E.
Genetic tools for the fine-tuning of gene expression levels are a prerequisite for rational strain optimization through metabolic engineering. While Aspergillusniger is an industrially important fungus, widely used for production of organic acids and heterologous proteins, the available genetic tool box for this organism is still rather limited. Here, we characterize six novel constitutive promoters of A. niger providing different expression levels. The selection of the promoters was based on published transcription data of A. niger. The promoter strength was determined with the ?-glucuronidase (gusA) reporter gene of Escherichia coli. The six promoters covered a GUS activity range of two to three orders of magnitude depending on the strain background. In order to demonstrate the power of the newly characterized promoters for metabolic engineering, they were used for heterologous expression of the cis-aconitate decarboxylase (cad1) gene of Aspergillus terreus, allowing the production of the building block chemical itaconic acid with A. niger. The CAD activity, dependent on the choice of promoter, showed a positive correlation with the specific productivity of itaconic acid. Product titers from the detection limit to up to 570 mg/L proved that the set of constitutive promoters is a powerful tool for the fine-tuning of metabolic pathways for the improvement of industrial production processes. PMID:22707054
Two Aspergillusflavus inoculation techniques were compared to the standard inoculation technique, the side-needle technique, on aflatoxin resistant and susceptible corn hybrids. The first study evaluated the use of A. flavus infested corn cob grits as a dry inoculum carrier. The side-needle and...
Aspergillusflavus produces toxic and the most carcinogenic mycotoxins, the aflatoxins. The primary objectives of our A. flavus genomics program are to reduce and eliminate aflatoxin contamination in food and feed and control fungal infection in preharvest crops such as corn, cotton, peanut and tre...
Aspergillosis is a common disease of the silkworm Bombyx mori Linn., caused by an insect mycopathogen Aspergillusflavus Link : Fries. The present study reveals the germination, penetration and conidial development of A. flavus on the larval integument of B. mori under SEM. Four different strains (NB18, KA, NB4D2 and NB7) of B. mori was surface inoculated with ca. of
Non-toxigenic strains of Aspergillusflavus offer the potential to control aflatoxin contamination by competitive displacement of indigenous populations of A. flavus colonizing corn grain. Two sets of experiments were conducted to assess the competitiveness of strain K49 when challenged against two...
Aspergillusflavus was grown on maize and rice extract agars and on irradiated viable cracked maize and rice grains, either in pure culture or in dual culture with wild strains of either Hyphopichia burtonii or Bacillus amyloliquefaciens. Aflatoxin production by A. flavus and its growth and interactions with the other microorganisms were studied at three water activities (a\\/sub w\\/) (0.98,
Aflatoxins (AF), among the most potent carcinogens known, are produced by some, but not all, strains of Aspergillusflavus and A. parasiticus. The higher percent toxigenic strains in the soil reservoir of A. flavus than in naturally-infected crop plants lends support to strategies for reducing AF co...
Maize (Zea mays L.) is a major crop susceptible to Aspergillusflavus infection and subsequent contamination with aflatoxins, the potent carcinogenic secondary metabolites of the fungus. Protein profiles of maize genotypes resistant and susceptible to A. flavus infection and/or aflatoxin contaminati...
AFPA culture medium, which is used for recognition of Aspergillusflavus and A. parasiticus, has been validated in a collaborative study including nine laboratories located in Australia, Brazil, Denmark, The Netherlands, Sweden and United Kingdom. Three freeze-dried fungal mixtures, containing A. flavus\\/A. parasiticus and background fungi, were produced and checked for homogeneity. The coefficients of variance were low, ranging from
Background Considering that the costs of cellulases and hemicellulases contribute substantially to the price of bioethanol, new studies aimed at understanding and improving cellulase efficiency and productivity are of paramount importance. Aspergillusniger has been shown to produce a wide spectrum of polysaccharide hydrolytic enzymes. To understand how to improve enzymatic cocktails that can hydrolyze pretreated sugarcane bagasse, we used a genomics approach to investigate which genes and pathways are transcriptionally modulated during growth of A. niger on steam-exploded sugarcane bagasse (SEB). Results Herein we report the main cellulase- and hemicellulase-encoding genes with increased expression during growth on SEB. We also sought to determine whether the mRNA accumulation of several SEB-induced genes encoding putative transporters is induced by xylose and dependent on glucose. We identified 18 (58% of A. niger predicted cellulases) and 21 (58% of A. niger predicted hemicellulases) cellulase- and hemicellulase-encoding genes, respectively, that were highly expressed during growth on SEB. Conclusions Degradation of sugarcane bagasse requires production of many different enzymes which are regulated by the type and complexity of the available substrate. Our presently reported work opens new possibilities for understanding sugarcane biomass saccharification by A. niger hydrolases and for the construction of more efficient enzymatic cocktails for second-generation bioethanol.
Most fungal species from marine environments also live on land. It is not clear whether these fungi reach the sea from terrestrial sources as spores or other propagules, or if there are separate ecotypes that live and reproduce in the sea. The emergence of marine diseases has created an urgency to understand the distribution of these fungi. Aspergillusflavus is ubiquitous in both terrestrial and marine environments. This species is an opportunistic pathogen in many hosts, making it a good model to study the relationship between genetic diversity and specificity of marine fungi. In this study, an intraspecific phylogeny of A. flavus isolates based on Amplified Fragment Length Polymorphisms (AFLPs) was used to determine if terrestrial and marine isolates form discrete populations, and to determine if phylogeny predicts substratum specificity. Results suggest lack of population structure in A. flavus. All isolates may compose a single population, with no clade particular to marine environments.
ZULUAGA-MONTERO, Anabella; RAMIREZ-CAMEJO, Luis; RAUSCHER, Jason; BAYMAN, Paul
We investigated the in vitro interaction of terbinafine with itraconazole, fluconazole, ampho- tericin B and 5-flucytosine, against Aspergillus spp. We tested three isolates of Aspergillus fumi- gatus (one resistant to itraconazole), and two each of Aspergillusflavus, Aspergillusniger and Aspergillus terreus. We employed a broth microdilution-based method derived from an in vivo validated method capable of detecting itraconazole resistance
J. Mosquera; A. Sharp; C. B. Moore; P. A. Warn; D. W. Denning
A new diketopiperazine dimer, 1'-(2-phenyl-ethylene)-ditryptophenaline , was isolated together with ditryptophenaline  from the fungus Aspergillusflavus. The structure of 1 was determined by analysis of spectroscopic data. In contrast to the structurally related substance-P antagonist WIN 64821 , both 1 and 2 are weak substance-P inhibitors, indicating that stereochemistry at the position of dimerization is an important determinant of biological potency for these molecules. PMID:7528269
Aspergillusflavus mycelium-bound lipase demonstrates high preference towards short chain triacylglycerols and discriminates against triunsaturated triacylglycerols e.g. triolein. The great discriminating power of its lipase against triolein was shown in comparison with its ability to catalyse the hydrolysis of shorter chain triacylglycerols e.g. tricaprin and less was shown when hydrolysing tripalmitin. A similar phenomenon was noted when the mycelium-bound lipase
Kamariah Long; Hasanah M. Ghazali; Arbakariya Ariff; Yaakob Che Man; Christopher Bucke
The genetic diversity of Aspergillusflavus populations isolated from the peanut-cropped soils in the peanut-growing region at Cordoba Province was evaluated by analysis of vegetative compatibility group (VCG). VCGs were determined through complementation assays between nitrate-nonutilizing (NNO) mutants. Fifty-six VCGs were identified from 100 isolates. Twenty-five VCGs contained two or more isolates and 31 VCGs contained only a single isolate.
G. G. Barros; A. M. Torres; M. I. Rodriguez; S. N. Chulze
Two new compounds, 4-(hydroxymethyl)-5-hydroxy-2H-pyran-2-one (1) and (5-hydroxy-2-oxo-2H-pyran-4-yl) methyl acetate (2), have been isolated from a marine-derived fungus Aspergillusflavus. Their structures were determined by spectroscopic data. Compound 1 induced the production of cAMP on GPR12 transfected CHO and HEK293 cells in a dose-dependent manner, which indicated 1 might be a possible ligand for GPR12. PMID:18503205
Two new compounds, 4-(hydroxymethyl)-5-hydroxy-2H-pyran-2-one (1) and (5-hydroxy-2-oxo-2H-pyran-4-yl) methyl acetate (2), have been isolated from a marine-derived fungus Aspergillusflavus. Their structures were determined by spectroscopic data. Compound 1 induced the production of cAMP on GPR12 transfected CHO and HEK293 cells in a dose-dependent manner, which indicated 1 might be a possible ligand for GPR12.
The effects of selected concentrations of antimicrobials from natural (vanillin, thymol, eugenol, carvacrol or citral) or synthetic (potassium sorbate or sodium benzoate) origin on Aspergillusflavus lag time inoculated in laboratory media formulated at water activity (aw) 0.99 and pH 4.5 or 3.5, were evaluated. Time to detect a colony with a diameter >0.5 mm was determined. Mold response was
Aurelio López-Malo; Stella M Alzamora; Enrique Palou
Aspergillusflavus K49 secreted at least two xylanase activities when grown on a medium containing larch (wood) xylan as a sole carbon source.\\u000a Enzyme activity was assayed using an agar medium containing Remazol Brilliant Blue R conjugated oat spelt xylan as substrate.\\u000a Crude enzyme preparations were inhibited by Hg+2, with an ED50 of 17.5 mM and maximum inhibition of 83% at
Jay E. MellonPeter; Peter J. Cotty; Kenneth A. Callicott; Hamed Abbas
UV photography in glucose, yeast extract (GY) agar medium was tested as a simple and rapid method for the distinction of afiatoxin-positive from aflatoxin-negative strains ofAspergillusflavus andA. parasiticus. In the UV photographs aflatoxin-producing moulds were identified as grey or black colonies, whereas aflatoxin-non-producing moulds appeared as white colonies. Of the afiatoxin-positive strains detected by the UV photographic method, 10%
The fungal flora of 6 Asian medicinal plants, Aerva lanata (Linn.) Juss. Alyssicarpus vaginalis D.C., Tribulus terrestris Linn. Adhatoda vasica Nees., Centella asciatica (L.) Urb., Cardiospermum halicacabum Linn. was determined. After surface disinfection Aspergillus spp. were most frequently observed. Aspergillusflavus, isolated from Alyssicarpus vaginalis and Aerva lanata produced aflatoxins in culture. Aflatoxin B1 was also detected in a sample of Aerra lanata at a level of 0.5 micrograms/g. Plant material destined for medicinal use should be stored carefully prior to its use to prevent growth of naturally occurring toxigenic mold fungi. PMID:1906136
Background Worldwide, Aspergillusflavus is the second leading cause of allergic, invasive and colonizing fungal diseases in humans. However, it is the most common species causing fungal rhinosinusitis and eye infections in tropical countries. Despite the growing challenges due to A. flavus, the molecular epidemiology of this fungus has not been well studied. We evaluated the use of microsatellites for high resolution genotyping of A. flavus from India and a possible connection between clinical presentation and genotype of the involved isolate. Methodology/Principal Findings A panel of nine microsatellite markers were selected from the genome of A. flavus NRRL 3357. These markers were used to type 162 clinical isolates of A. flavus. All nine markers proved to be polymorphic displaying up to 33 alleles per marker. Thirteen isolates proved to be a mixture of different genotypes. Among the 149 pure isolates, 124 different genotypes could be recognized. The discriminatory power (D) for the individual markers ranged from 0.657 to 0.954. The D value of the panel of nine markers combined was 0.997. The multiplex multicolor approach was instrumental in rapid typing of a large number of isolates. There was no correlation between genotype and the clinical presentation of the infection. Conclusions/Significance There is a large genotypic diversity in clinical A. flavus isolates from India. The presence of more than one genotype in clinical samples illustrates the possibility that persons may be colonized by multiple genotypes and that any isolate from a clinical specimen is not necessarily the one actually causing infection. Microsatellites are excellent typing targets for discriminating between A. flavus isolates from various origins.
Rudramurthy, Shivaprakash M.; de Valk, Hanneke A.; Chakrabarti, Arunaloke; Meis, Jacques F. G. M.; Klaassen, Corne H. W.
An efficient gene-targeting system based on impairment of the nonhomologous end-joining pathway and the orotidine monophosphate decarboxylase gene (pyrG) in Aspergillusflavus was established. It was achieved by replacing the ku70 gene with the Aspergillus oryzae pyrithiamine resistance (ptr) gene and by inserting the Aspergillus parasiticus cypA gene into the pyrG locus. The utility of this system was demonstrated by disruption of nine candidate genes for conidial pigment biosynthesis. The gene-targeting frequencies ranged from 80 to 100%. Two linked genes on chromosome 4, wA and olgA, were confirmed to be involved in pigment formation. In contrast to the parental strain which produced yellowish-green conidia, the knockout mutants produced white and olive-green conidia, respectively. The system was further refined by restoring the pyrithiamine sensitivity and uracil auxotrophy in the A. flavus transformation recipient with an engineered pyrG marker. The improvement allowed gene manipulation using the reusable pyrG marker as shown by the restoration of laeA-mediated aflatoxin production in an A. flavus laeA-deleted mutant. PMID:20298723
The filamentous fungus Aspergillusniger is used extensively for the production of enzymes and organic acids. A major problem in industrial fermentations with this fungus is to ensure sufficient supply of oxygen required for respiratory metabolism of the fungus. In case of oxygen limitation, the fungus will produce various by-products like organic acids and polyols. In order to circumvent this problem we here study the effects of the expression of a bacterial hemoglobin protein on the metabolism of A. niger. We integrated the vgb gene from Vitreoscilla sp. into the genome at the pyrA locus behind the strong gpdA promoter from Aspergillus nidulans. Analysis of secreted metabolites, oxygen uptake, CO(2) evolution and biomass formation points towards a relief of stress in the mutant expressing VHB when it is exposed to oxygen limitation. Our findings therefore point to an interesting strategy to attenuate unwanted side effects resulting from oxygen limitation during industrial fermentations with A. niger. PMID:18694843
Soil is presumed to be a major source of inoculum for Aspergillusflavus which contaminates cottonseed and produces the potent carcinogen, aflatoxin. Little is known about the mycoflora of the low desert soils of cotton fields where aflatoxin is a chronic problem. In this study, soils from cotton fields in southwestern Arizona and south-eastern California were assayed for filamentous fungi. Forty-two taxa, predominantly in the genera Aspergillus, Penicillium and Fusarium, were isolated. To determine whether or not compounds produced by these fungi could be potential inhibitors of A. flavus, extracts of strains of each taxon were tested for their ability to inhibit growth of A. flavus. Twelve taxa produced compounds inhibitory to A. flavus, including several strains of Fusarium solani, Penicillium vinaceum and Aspergillus auricomus. PMID:9926421
Citric acid production by Aspergillusniger NCIM 548 and Candida lipolytica NCIM 3472 has been studied in shake culture using glucose and molasses as carbon sources. Methanol addition (3% v\\/v) at 40 h of fermentation enhanced the production of citric acid by Aspergillusniger whereas a reduction in citric acid production by Candida lipolytica was observed with addition of methanol.
d-Mannitol is the predominant carbon compound in conidiospores of the filamentous fungus Aspergillusniger and makes up 10 to 15% of the dry weight. A number of physiological functions have been ascribed to mannitol, including serving as a reserve carbon source, as an antioxidant, and to store reducing power. In this study, we cloned and characterized the A. niger mpdA gene, which encodes mannitol 1-phosphate dehydrogenase (MPD), the first enzyme in the mannitol biosynthesis pathway. The mpdA promoter contains putative binding sites for the development-specific transcription factors BRLA and ABAA. Furthermore, increased expression of mpdA in sporulating mycelium suggests that mannitol biosynthesis is, to a certain extent, developmentally regulated in A. niger. Inactivation of mpdA abolished mannitol biosynthesis in growing mycelium and reduced the mannitol level in conidiospores to 30% that in the wild type, indicating that MPD and mannitol 1-phosphate phosphatase form the major metabolic pathway for mannitol biosynthesis in A. niger. The viability of spores after prolonged storage and germination kinetics were normal in an mpdA null mutant, indicating that mannitol does not play an essential role as a reserve carbon source in A. niger conidia. However, conidiospores of a ?mpdA strain were extremely sensitive to a variety of stress conditions, including high temperature, oxidative stress and, to a lesser extent, freezing and lyophilization. Since mannitol supplied in the medium during sporulation repaired this deficiency, mannitol appears to be essential for the protection of A. niger spores against cell damage under these stress conditions.
Ruijter, George J. G.; Bax, Maarten; Patel, Hema; Flitter, Simon J.; van de Vondervoort, Peter J. I.; de Vries, Ronald P.; vanKuyk, Patricia A.; Visser, Jaap
Chitosanase, a new class of enzymes with antifungal properties was induced by toxigenic Aspergillusflavus in both germinating corn and peanut seeds. The enzyme was partially purified and fractioned by SDS?Polyacrylamide Gel Electrophoresis activity and copolymerized with chitosan or glycolchitosan as substrate, then quantified by scanning densitometry and a 2?dimensional analysis software program. Chitosanase enzyme was markedly induced by toxigenic
Aflatoxins are a family of highly toxic and carcinogenic toxins produced by several Aspergillus species. Aflatoxin contamination of agricultural commodities, both pre- and post-harvest, is a serious food safety issue and a significant economic concern. Using aflatoxin non-producing A. flavus isola...
Chitosanase, a new class of enzymes with antifungal properties was induced by toxigenic Aspergillusflavus in both germinating corn and peanut seeds. The enzyme was partially purified and fractioned by SDS-Polyacrylamide Gel Electrophoresis activity and copolymerized with chitosan or glycolchitosan as substrate, then quantified by scanning densitometry and a 2-dimensional analysis software program. Chitosanase enzyme was markedly induced by toxigenic A. flavus growing in germinating corn and peanut seeds, as compared to control (water) which showed the lowest activity (almost nil in corn). However, chitosanase induction was higher in seeds treated with chitosan from crustacea. Overall, enzyme activity was higher in peanut than in corn seeds. However, electrophoresed gels from peanut treated with A. flavus or water showed more polypeptides (three and one, respectively) than gels from corn seeds, which only showed one polypeptide for both A. flavus and water treatment. The enzyme molecular weight was estimated to be between 36,000 and 45,000. PMID:7664946
The fungus Aspergillusflavus is a ubiquitous pathogen of corn, figs, pistachio, cotton and nut trees. On corn, aspergillus causes an ear and kernel rot especially when the plants are stressed by drought, heat or insect injuries. Fungal infections result in the production of aflatoxins, a series of structurally related compounds known to be carcinogenic. In an attempt to identify
Cyclopiazonic acid (CPA), an indole-tetramic acid toxin, is produced by many species of Aspergillus and Penicillium. In addition to CPA Aspergillusflavus produces polyketide-derived carcinogenic aflatoxins (AFs). AF biosynthesis genes form a gene cluster in a subtelomeric region. Isolates of A. fla...
Salmonella cycles between host and nonhost environments, where it can become an active member of complex microbial communities. The role of fungi in the environmental adaptation of enteric pathogens remains relatively unexplored. We have discovered that S. enterica Typhimurium rapidly attaches to and forms biofilms on the hyphae of the common fungus, Aspergillusniger. Several Salmonella enterica serovars displayed a similar interaction, whereas other bacterial species were unable to bind to the fungus. Bacterial attachment to chitin, a major constituent of fungal cell walls, mirrored this specificity. Pre-incubation of S. Typhimurium with N-acetylglucosamine, the monomeric component of chitin, reduced binding to chitin beads by as much as 727-fold and inhibited attachment to A. niger hyphae considerably. A cellulose-deficient mutant of S. Typhimurium failed to attach to chitin beads and to the fungus. Complementation of this mutant with the cellulose operon restored binding to chitin beads to 79% of that of the parental strain and allowed for attachment and biofilm formation on A. niger, indicating that cellulose is involved in bacterial attachment to the fungus via the chitin component of its cell wall. In contrast to cellulose, S. Typhimurium curli fimbriae were not required for attachment and biofilm development on the hyphae but were critical for its stability. Our results suggest that cellulose–chitin interactions are required for the production of mixed Salmonella-A. niger biofilms, and support the hypothesis that encounters with chitinaceous alternate hosts may contribute to the ecological success of human pathogens.
Brandl, Maria T.; Carter, Michelle Q.; Parker, Craig T.; Chapman, Matthew R.; Huynh, Steven; Zhou, Yaguang
Individual and combined effects of aw and incorporation of selected concentrations of Mexican oregano essential oil on the time to growth (TTG) of Aspergillusniger intentionally inoculated into dried tomatoes were studied during storage at 25°C for 100 days. For aw 0.96, 1,000 ppm of Mexican oregano essential oil inhibited A. niger growth during 100 days, whereas 500 ppm were sufficient at aw 0.91 and 250 ppm for tomatoes with aw 0.78. A. niger growth was evident at different incubation times depending on tested tomato aw and concentration of essential oil; these data were utilized to model TTG. Regression analysis revealed good agreement between experimental and predicted data with a correlation coefficient higher than 0.98. Analysis of mold growth data through TTG models makes possible to include observations detected as no growth and can be utilized to predict mold time to growth for specific preservation factor combinations or to select preservation factor levels for an expected shelf-life based on A. niger growth. PMID:23587709
Gómez-Ramírez, C; Sosa-Morales, M E; Palou, E; López-Malo, A
Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillusflavus has been postulated to be a mechanism to relieve oxidative stress. The msnA gene, the ortholog of Saccharomyces cerevisiae MSN2 associated with multi-stress response, of the two species was disrupted....
The mineral requirements of a strain ofAspergillusniger for the production of citric acid in a synthetic medium were studied. It was observed that K2HPO4 and MgSO4.7 H2O were required at concentrations of 0.1% and 0.02% respectively. The optimum level of each of the trace elements Fe, Mn and\\u000a Zn was 1.0 ?g\\/ml. NaCl and CaCl2 at lower concentrations had
Aspergillusniger ..beta..-xylosidase was characterized when in soluble form and when immobilized to alkylamine porous silica with glutaraldehyde and to alumina with titanium tetrachloride. Energies of activation averaged 13.4 kcal/mol for the soluble enzyme, 9.0 kcal/mol when immobilized to alumina, and 8.0 kcal/mol when bound to silica. The highest activity of all forms of ..beta..-xylosidase was found near pH 3. The soluble enzyme was highly stable at pH 4, where lowest rates of decay occurred, and temperatures of 65/sup 0/C and below.
Phytase from Aspergillusniger increases the availability of phosphorus from feed for monogastric animals by releasing phosphate from the substrate phytic acid. A phytase cDNA was constitutively expressed in transgenic tobacco (Nicotiana tabacum) plants. Secretion of the protein to the extracellular fluid was established by use of the signal sequence from the tobacco pathogen-related protein S. The specific phytase activity in isolated extracellular fluid was found to be approximately 90-fold higher than in total leaf extract, showing that the enzyme was secreted. This was confirmed by use of immunolocalization. Despite differences in glycosylation, specific activities of tobacco and Aspergillus phytase were identical. Phytase was found to be biologically active and to accumulate in leaves up to 14.4% of total soluble protein during plant maturation. Comparison of phytase accumulation and relative mRNA levels showed that phytase stably accumulated in transgenic leaves during plant growth.
Verwoerd, T C; van Paridon, P A; van Ooyen, A J; van Lent, J W; Hoekema, A; Pen, J
Background Within the genus Aspergillus, A. flavus is the second most important species of clinical significance. It is predominantly associated with infections involving sinuses, eye and skin, mostly in geographic regions with hot and arid climate, including the Middle East. Recent reports on emergence of resistance to triazoles among Aspergillus spp. is a cause of concern for treatment of patients with invasive aspergillosis. In this study we present data on genetic characterization and antifungal susceptibility profile of clinical and environmental isolates of A. flavus. Methods Ninety-nine Aspergillus section Flavi isolates, originating from clinical (n=92) and environmental (n=7) sources, initially identified by morphological characteristics, were analyzed by partial sequencing of ?-tubulin and calmodulin gene fragments and their susceptibilities to six antifungal agents was determined by Etest on RPMI1640 and Muller-Hinton agar media. Etest minimum inhibitory concentrations (MICs) of amphotericin B and voriconazole were also compared with zone of inhibition diameters obtained by disc diffusion test on RPMI agar medium. Results The identity of all clinical and environmental isolates was confirmed as A. flavus species by combined analysis of ?-tubulin and calmodulin genes. The mean MIC90 (?g/ml) values on RPMI medium for amphotericin B, voriconazole, posaconazole, anidulafungin, micafungin and caspofungin were 3, 0.25, 0.25, 0.002, 0.002 and 0.032, respectively. No environmental isolate exhibited MIC value of >2 ?g/ml for amphotericin B. For clinical isolates, the zone of inhibition diameters for amphotericin B and voriconazole ranged from 7–16 mm and 24–34 mm, respectively. Linear regression analysis between Etest MIC values and disk diffusion diameters revealed a significant inverse correlation with amphotericin B (p <0.001) and voriconazole (p<0.003). Conclusions The ?-tubulin and calmodulin gene sequences confirmed that all 92 clinical isolates identified phenotypically belonged to A. flavus taxon, thus suggesting that the other species within Aspergillus section Flavi are of little clinical significance. Triazoles and echinocandins showed very good in vitro activity against the A. flavus, however, 10% clinical isolates showed MICs of >2 ?g/ml for amphotericin B.
Twelve species belonging to six fungal genera were found to be associated with wheat (Triticum aestivum L.) grain samples collected from three main regions in Saudi Arabia. The most common genera (average frequency) were Aspergillus (14.3%), Fusarium (29.1%), Penicillium (9.3%), and Alternaria (8.2%). Nineteen isolates of Aspergillusflavus were screened for their ability to produce aflatoxins using HPLC. Thirteen isolates produced aflatoxins ranging from 0.5 to 2.6 µg/kg. Inter-simple sequence repeats (ISSR), and random amplified polymorphic DNA (RAPD) molecular markers were used, with the aim of genetically characterizing strains of A. flavus to discriminate between aflatoxigenic and non-aflatoxigenic isolates. RAPD and ISSR analysis revealed a high level of genetic diversity in the A. flavus population, useful for genetic characterization. Clustering based on RAPD and ISSR dendograms was unrelated to geographic origin. RAPD and ISSR markers were not suitable to discriminate aflatoxigenic and non-aflatoxigenic isolates, but ISSR primers were better compared to RAPD. PMID:24065675
Al-Wadai, A S; Al-Othman, M R; Mahmoud, M A; Abd El-Aziz, A R M
The inoculation of Aspergillusflavus spores into a culture of Streptococcus lactis in Lablemco tryptone broth medium resulted in little or no aflatoxin accumulation even though the growth of the fungus was not hindered. The drop in pH and reduced nutrient levels in the medium as a result of the S. lactis growth were not the cause of the observed inhibition. The inhibition was not eliminated by the addition of carbohydrate equal to the amount used by the bacterium before the inoculation with the fungus. Aflatoxin levels were also markedly reduced when S. lactis was inoculated into a growing A. flavus culture. In addition to inhibiting the synthesis of aflatoxin, S. lactis also degraded preformed toxin. A. flavus, on the other hand, not only reduced the growth of S. lactis but also affected the morphology of the bacterial cell; the cells became elongated and formed long chains. S. lactis produced and excreted the inhibitor into the medium late in its growth phase. The inhibitor was a heat-stable low-molecular-weight compound. Chloroform extracts of A. flavus grown in the presence of S. lactis were toxic to Bacillus megaterium but did not exhibit mutagenic or carcinogenic activity in the Salmonella/mammalian microsome mutagenicity test.
Headspace volatiles from eight strains of Aspergillusflavus (four aflatoxigenic strains and four nonaflatoxigenic strains), grown for 1, 2, 3, 4, 8, and 10 days in submerged cultures, were collected in Tenax GC traps. The traps were desorbed onto a 50-m gas-liquid chromatography capillary column by heat and gas purge from an external direct injector device. The column was interfaced with a mass spectrometer data acquisition system. Peaks were identified by comparing retention times and mass spectra with those obtained from authentic compounds and by using a computer-assisted mass spectral data base. Aflatoxigenic strains of A. flavus produced several C15H24 compounds (e.g., alpha-gurjunene, trans-caryophyllene, and cadinene) which peaked in 3-day cultures and were not present in earlier (1- and 2-day) or later (8- and 10-day) cultures. None of these volatiles were detected in nonaflatoxigenic strains of A. flavus. There was an apparent correlation between the release of C15H24 volatile compounds and the initiation of aflatoxin biosynthesis, and a correlation between decline of aflatoxin synthesis and the disappearance of the C15H24 compounds unique to aflatoxigenic A. flavus also existed.
Strains of Aspergillusflavus often degenerate with serial transfers on culture media, resulting in morphological changes and loss of aflatoxin production. However, degeneration does not readily occur in nature as indicated by the wild-type morphological characters of newly isolated strains and the high percentage of aflatoxigenic A. flavus from soil and crops in some geographic regions. In this study, three aflatoxin-producing strains of A. flavus were serially transferred using conidia for 20 generations (three independent generation lines per strain) on potato dextrose agar at 30 C. The rate of degeneration was compared to that of cultures grown in the presence of competing fungi (A. terreus, Penicillium funiculosum, and the yeast, Pichia guilliermondii) and under adverse conditions of elevated temperature, reduced water activity, low pH, and nutrient deprivation. Formation of morphological variants and the associated loss of aflatoxin production over generations varied considerably according to strain and the generation line within each strain. In the strain most sensitive to degeneration on potato dextrose agar, aflatoxin-producing ability was maintained to varying degrees under adverse culture conditions, but not when A. flavus was competing with other fungi. PMID:21156547
Effects of chitosan and Aspergillusflavus to enhance elicitation of phenolic compounds in viable peanut seeds were conducted at two water activity levels. In vitro effects of phenolic acids on A. flavus growth and aflatoxin B1 production were also studied. Chitosan enhanced elicitation of free phenolic compounds (FPC) at Aw .85 and .95 levels. A. flavus initially decreased and subsequently
J. E. Fajardo; R. D. Waniska; R. G. Cuero; R. E. Pettit
Effects of chitosan and Aspergillusflavus to enhance elicitation of phenolic compounds in viable peanut seeds were conducted at two water activity levels. In vitro effects of phenolic acids on A. flavus growth and aflatoxin B1 production were also studied. Chitosan enhanced elicitation of free phenolic compounds (FPC) at Aw .85 and .95 levels. A. flavus treatment initially decreased and
J. E. Fajardol; R. D. Waniska; R. G. Cuero; R. E. Pettit
With an initial microbial level of ca. 10/sup 7/ microorganisms per g of Ivory Coast cacao beans, 5 kGy of gamma radiation from a Co/sup 60/ source under an atmosphere of air reduced the microflora per g by 2.49 and 3.03 logs at temperatures of 35 and 50/sup 0/C, respectively. Bahia cacao beans were artificially contaminated with dried spores of Aspergillusflavus and Penicillium citrinum, giving initial fungal levels of 1.9 x 10/sup 4/ and 1.4 x 10/sup 3/ spores per g of whole Bahia cacao beans, respectively. The average D/sub 10/ values for A. flavus and P. citrinum spores on Bahia cacao beans were 0.66 and 0.88 kGy, respectively. 12 references.
Restaino, L.; Myron, J.J.J.; Lenovich, L.M.; Bills, S.; Tscherneff, K.
The present study deals with the isolation of fungi from soil with the ability to degrade polyurethane (PU). A pure fungal isolate was analyzed for its ability to utilize PU as a sole carbon source in shaking culture for 30 days. Incubation of PU with Aspergillusflavus resulted in 60.6% reduction in weight of PU. The scanning electron microscopy and Fourier transform infrared spectroscopy (FTIR) results showed certain changes on the surface of PU film and formation of some new intermediate products after polymer breakdown. Thermogravimetric curves showed changes between the thermal behavior of the samples that were inoculated with A. flavus and control. FTIR spectra showed detectable changes in control and incubated samples, suggesting that degradation occurs, with the decreased intensity of band at 1,715 cm(-1), corresponding to ester linkages. We have identified an extracellular esterase activity which might be responsible for the polyurethanolytic activity. PMID:22367637
Manipulation of the fungal epigenome is hypothesized to be an effective method for accessing natural products from silent biosynthetic pathways. A library of epigenetic modifiers was tested using the fungus Aspergillusniger to determine the impact of small-molecule inhibitors on reversing the transcriptional suppression of biosynthetic genes involved in polyketide (PKS), non-ribosomal peptide (NRPS), and hybrid PKS-NRPS (HPN) production. Examination of expressed sequence tag libraries from A. niger demonstrated that >70% of its PKS-, NRPS-, and HPN-encoding gene clusters were transcriptionally suppressed under standard laboratory culture conditions. Using a chemical epigenetic methodology, we showed that treatment of A. niger with suberoylanilide hydroxamic acid and 5-azacytidine led to the transcriptional upregulation of many secondary-metabolite-encoding biosynthetic gene clusters. Chemical epigenetic modifiers exhibited positional biases for upregulating chromosomally distal gene clusters. In addition, a phylogenetic-based preference was noted in the upregulation of reducing clade I PKS gene clusters, while reducing clade IV PKS gene clusters were largely unaffected. Manipulating epigenetic features in fungi is a powerful method for accessing the products of silent biosynthetic pathways. Moreover, this approach can be readily incorporated into modern microbial screening operations. PMID:19521728
Fisch, K M; Gillaspy, A F; Gipson, M; Henrikson, J C; Hoover, A R; Jackson, L; Najar, F Z; Wägele, H; Cichewicz, R H
A recombinant Aspergillusniger 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 D15[egI], 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 D15[egI] 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.
Alriksson, Bjorn; Rose, Shaunita H.; van Zyl, Willem H.; Sjode, Anders; Nilvebrant, Nils-Olof; Jonsson, Leif J.
The colony reverse of aflatoxin (AF)-producing strains ofAspergillusflavus andA. parasiticus turned pink when their cultures were exposed to ammonia vapor. The color change was visible for colonies grown on media suitable\\u000a for AF production such as potato dextrose, coconut, and yeast extract sucrose agars after 2 d incubation at 25°C. Of the 120\\u000a strains ofA. flavus, A. parasiticus, and
Aspergillusflavus causes an ear rot of maize, often resulting in the production of aflatoxin, a potent liver toxin and carcinogen that impacts the health of humans and animals. Many aspects of kernel infection and aflatoxin biosynthesis have been studied but the precise effects of the kernel environment on A. flavus are poorly understood. The goal of this research was to study the fungal response to the kernel environment during colonization. Gene transcription in A. flavus was analyzed by microarrays after growth on kernels of the four developmental stages: blister (R2), milk (R3), dough (R4), and dent (R5). Five days after inoculation, total RNA was isolated from kernels and hybridized to Affymetrix Gene Chip arrays containing probes representing 12,834 A. flavus genes. Statistical comparisons of the expression profile data revealed significant differences that included unique sets of upregulated genes in each kernel stage and six patterns of expression over the four stages. Among the genes expressed in colonized dent kernels were a phytase gene and six putative genes involved in zinc acquisition. Disruption of the phytase gene phy1 resulted in reduced growth on medium containing phytate as the sole source of phosphate. Furthermore, growth of the mutant (?phy1) was 20% of the wild-type strain when wound inoculated into maize ears. In contrast, no difference was detected in the amount of aflatoxin produced relative to fungal growth, indicating that phy1 does not affect aflatoxin production. The study revealed the genome-wide effects of immature maize kernels on A. flavus and suggest that phytase has a role in pathogenesis. PMID:21341988
Reese, Brittiney N; Payne, Gary A; Nielsen, Dahlia M; Woloshuk, Charles P
Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillusflavus has been postulated to be a mechanism to relieve oxidative stress. The msnA gene of A. parasiticus and A. flavus is the ortholog of Saccharomyces cerevisiae MSN2 that is associated with multi-stress response. Compared to wild type strains, the msnA deletion (?msnA) strains of A. parasiticus and A. flavus exhibited retarded colony growth with increased conidiation. The ?msnA strains also produced slightly higher amounts of aflatoxins and elevated amounts of kojic acid on mixed cereal medium. Microarray assays showed that expression of genes encoding oxidative stress defense enzymes, i.e., superoxide dismutase, catalase, and cytochrome c peroxidase in A. parasiticus ?msnA, and the catalase A gene in A. flavus ?msnA, was up-regulated. Both A. parasiticus and A. flavus ?msnA strains produced higher levels of reactive oxygen species (ROS), and ROS production of A. flavus msnA addback strains was decreased to levels comparable to that of the wild type A. flavus. The msnA gene appears to be required for the maintenance of the normal oxidative state. The impairment of msnA resulted in the aforementioned changes, which might be used to combat the increased oxidative stress in the cells. PMID:22069691
Chang, Perng-Kuang; Scharfenstein, Leslie L; Luo, Meng; Mahoney, Noreen; Molyneux, Russell J; Yu, Jiujiang; Brown, Robert L; Campbell, Bruce C
The minimal fungicidal concentrations (MFCs) of voriconazole and itraconazole for five clinical isolates each of Aspergillus terreus, Aspergillus fumigatus, Aspergillusflavus, and Aspergillusniger were determined by a broth macrodilution method. Conidial suspensions as inocula were compared to hyphae as inocula since the invasive form of aspergillosis is manifested by the appearance of hyphal structures. In addition, cell viability staining
CORNELIA LASS-FLORL; MARKUS NAGL; CORNELIA SPETH; HANNO ULMER; MANFRED P. DIERICH; REINHARD WURZNER
In order to gain insight into the causal agents of aflatoxin contamination of maize in Italy, populations of Aspergillusflavus on maize produced in the most affected area were characterized. Forty-six percent of A. flavus, isolated from maize kernels collected in 5 districts of northern Italy between 2003 and 2010, were unable to produce detectable levels of aflatoxins. The genetic diversity of the population was assessed by analysis of vegetative compatibility groups (VCGs) and presence or absence of several aflatoxin biosynthesis genes. Forty-eight VCGs were identified through complementation between nitrate non-utilizing mutants. Twenty-five VCGs contained only atoxigenic isolates, and the remaining 23 only aflatoxin producers. Members of the largest atoxigenic VCG (IT6) were found in 4 of the 5 districts sampled. Six deletion patterns of genes in the aflatoxin biosynthesis gene cluster were detected. No deletions in the cluster were detected for twelve atoxigenic isolates and 10 had the entire cluster deleted. One isolate had a deletion pattern only seen once before in Nigeria. The basis for initial selection of endemic atoxigenic strains of A. flavus for biological control of aflatoxin contamination of maize in Italy is provided. PMID:23340386
Aspergillusflavus is second only to A. fumigatus in causing invasive aspergillosis and it is the major agent responsible for fungal sinusitis, keratitis and endophthalmitis in many countries in the Middle East, Africa and Southeast Asia. Despite the growing challenge due to A. flavus, data on the molecular epidemiology of this fungus remain scarce. The objective of the present study was to develop a new typing method based on the detection of VNTR (Variable number tandem repeat) markers. Eight VNTR markers located on 6 different chromosomes (1, 2, 3, 5, 7 and 8) of A. flavus were selected, combined by pairs for multiplex amplifications and tested on 30 unrelated isolates and six reference strains. The Simpson index for individual markers ranged from 0.398 to 0.818. A combined loci index calculated with all the markers yielded an index of 0.998. The MLVA (Multiple Locus VNTR Analysis) technique proved to be specific and reproducible. In a second time, a total of 55 isolates from Chinese avian farms and from a Tunisian hospital have been evaluated. One major cluster of genotypes could be defined by using the graphing algorithm termed Minimum Spanning Tree. This cluster comprised most of the isolates collected in an avian farm in southern China. The MLVA technique should be considered as an excellent and cost-effective typing method that could be used in many laboratories without the need for sophisticated equipment.
Development of a method for the purification and partial characterization of endoxylanase obtained from the fungus Aspergillusniger is reported. This xylanase hydrolyzes xylan, a component of the hemicellulose complex found in large amounts in cereal. He...
Terpenes are present in the essential oils obtained from herbs and spices. They are produced by these plant species as a chemical defense mechanism against phytopathogenic microorganisms. Therefore, terpenes have attracted great attention in the food industry, e.g., they have been used in foods such as cheese as natural preservatives to prevent fungal growth. Herein, we describe the microbial transformation of onopordopicrin (1) by Aspergillusniger. Four product 11? H-dihydroonopordopicrin (2), 11? H-dihydroonopordopicrin (3), 3?-hydroxy-11? H-dihydroonopordopicrin (4), and 14-hydroxy-11? H-dihydroonopordopicrin (5) were obtained. Their structures were identified on the basis of chemical and spectroscopic data. All the four compounds were novel. PMID:22186324
A fungal tannase was produced, recovered, and immobilized by entrapment in calcium alginate beads. Catalytical properties of the immobilized enzyme were compared with those of the free one. Tannase was produced intracellularly by the xerophilic fungus Aspergillusniger GH1 in a submerged fermentation system. Enzyme was recovered by cell disruption and the crude extract was partially purified. The catalytical properties of free and immobilized tannase were evaluated using tannic acid and methyl gallate as substrates. K(M) and V(max) values for free enzyme were very similar for both substrates. But, after immobilization, K(M) and V(max) values increased drastically using tannic acid as substrate. These results indicated that immobilized tannase is a better biocatalyst than free enzyme for applications on liquid systems with high tannin content, such as bioremediation of tannery or olive-mill wastewater. PMID:21918717
Flores-Maltos, Abril; Rodríguez-Durán, Luis V; Renovato, Jacqueline; Contreras, Juan C; Rodríguez, Raúl; Aguilar, Cristóbal N
A fungal tannase was produced, recovered, and immobilized by entrapment in calcium alginate beads. Catalytical properties of the immobilized enzyme were compared with those of the free one. Tannase was produced intracellularly by the xerophilic fungus Aspergillusniger GH1 in a submerged fermentation system. Enzyme was recovered by cell disruption and the crude extract was partially purified. The catalytical properties of free and immobilized tannase were evaluated using tannic acid and methyl gallate as substrates. KM and Vmax values for free enzyme were very similar for both substrates. But, after immobilization, KM and Vmax values increased drastically using tannic acid as substrate. These results indicated that immobilized tannase is a better biocatalyst than free enzyme for applications on liquid systems with high tannin content, such as bioremediation of tannery or olive-mill wastewater.
Flores-Maltos, Abril; Rodriguez-Duran, Luis V.; Renovato, Jacqueline; Contreras, Juan C.; Rodriguez, Raul; Aguilar, Cristobal N.
Indole and its derivatives form a class of toxic recalcitrant environmental pollutants. The growth of Aspergillusniger was inhibited by very low concentrations (0.005 to 0.02%) of indole, even when 125- to 500-fold excess glucose was present in the medium. When 0.02% indole was added, the fungus showed a lag phase for about 30 h and the uptake of glucose was inhibited. Indole was metabolized by a new pathway via indoxyl (3-hydroxyindole), N-formylanthranilic acid, anthranilic acid, 2,3-dihydroxybenzoic acid, and catechol, which was further degraded by ortho cleavage. The enzymes N-formylanthranilate deformylase, anthranilate hydroxylase, 2,3-dihydroxybenzoate decarboxylase, and catechol dioxygenase were induced by indole as early as after 5 h of growth, and their activities were demonstrated in a cell-free system.
Low levels of glucoamylase are produced when Aspergillusniger is grown on sorbitol, but substitution of the latter by glucose, maltose, or starch results in greater formation of glucoamylase as measured by enzymatic activity. Both glucoamylase I and glucoamylase II are formed in a yeast extract medium; however, glucoamylase I appears to be the only form produced when ammonium chloride is the nitrogen source. Maltose or isomaltose (1.4 × 10?4m), but no other disaccharides or monosaccharides, dextrins, dextrans, or starches, stimulated glucoamylase formation when added to mycelia pregrown on sorbitol-ammonium salts. The induction of glucoamylase by maltose was independent of sulfate concentration but showed a dependency on low pH and the absence of utilizable carbon sources.
Barton, Larry L.; Georgi, Carl E.; Lineback, David R.
One strategy to reduce aflatoxin contamination of corn and cottonseed is to introduce spores of atoxigenic strains as competitors. Using isogenic mutants we show that, upon 5 or 20 min exposure to 302 nm (UVB) light, the viability of conidia of A. parasiticus and A. flavus mutants lacking the abilit...
Aspergillusniger and A. tubingensis, species belonging to section Nigri, are commonly found in plant products and processed food, such as grapes, cereals, coffee, and derived products. These two species are very difficult to differentiate by classical morphological criteria and some isolates are known to produce ochratoxin A. The exact identification of these two species is very important to avoid the overestimation of toxicological contamination and related risks. A polymerase chain reaction (PCR)-based identification and detection assay was developed as a tool to identify A. niger and A. tubingensis, using molecular differences obtained by sequencing the calmodulin gene. Two pairs of species-specific primers were designed and empirically evaluated for PCR identification of A. niger and A. tubingensis. Species-specific PCR products generated by each primer set were 505 bp (A. tubingensis) and 245 bp (A. niger) in length, which could be potentially useful for a multiplex PCR assay. The sensitivity of this assay was about 10 pg DNA in a 25-microl PCR reaction volume, using pure total DNA of the two species. The method described in this study represents a rapid and reliable procedure to assess the presence in food products of two ochratoxigenic species of section Nigri. PMID:17886188
Combined with u.v. irradiation and the nitrosoguanidine method, selection of biochemical mutants resistant to metabolic inhibitors (2-deoxy-D-glucose, antimycin A, sodium orthovanadate and sodium azide) was a very efficient method for improvement of ribonuclease production by Aspergillusniger. Resistance to sodium azide produced highest RNase production, greatest frequency of positive mutation and shortest sporulation time. The most active strain, Aspergillusniger
Ya-Hong Xiong; Jian-Zhong Liu; Hai-Yan Song; Li-Ping Weng; Liang-Nian Ji
Background The degradation of plant materials by enzymes is an industry of increasing importance. For sustainable production of second generation biofuels and other products of industrial biotechnology, efficient degradation of non-edible plant polysaccharides such as hemicellulose is required. For each type of hemicellulose, a complex mixture of enzymes is required for complete conversion to fermentable monosaccharides. In plant-biomass degrading fungi, these enzymes are regulated and released by complex regulatory structures. In this study, we present a methodology for evaluating the potential of a given fungus for polysaccharide degradation. Results Through the compilation of information from 203 articles, we have systematized knowledge on the structure and degradation of 16 major types of plant polysaccharides to form a graphical overview. As a case example, we have combined this with a list of 188 genes coding for carbohydrate-active enzymes from Aspergillusniger, thus forming an analysis framework, which can be queried. Combination of this information network with gene expression analysis on mono- and polysaccharide substrates has allowed elucidation of concerted gene expression from this organism. One such example is the identification of a full set of extracellular polysaccharide-acting genes for the degradation of oat spelt xylan. Conclusions The mapping of plant polysaccharide structures along with the corresponding enzymatic activities is a powerful framework for expression analysis of carbohydrate-active enzymes. Applying this network-based approach, we provide the first genome-scale characterization of all genes coding for carbohydrate-active enzymes identified in A. niger.
Secreted yields of foreign proteins may be enhanced in filamentous fungi through the use of translational fusions in which the target protein is fused to an endogenous secreted carrier protein. The fused proteins are usually separated in vivo by cleavage of an engineered Kex2 endoprotease recognition site at the fusion junction. We have cloned the kexin-encoding gene of Aspergillusniger (kexB). We constructed strains that either overexpressed KexB or lacked a functional kexB gene. Kexin-specific activity doubled in membrane-protein fractions of the strain overexpressing KexB. In contrast, no kexin-specific activity was detected in the similar protein fractions of the kexB disruptant. Expression in this loss-of-function strain of a glucoamylase human interleukin-6 fusion protein with an engineered Kex2 dibasic cleavage site at the fusion junction resulted in secretion of unprocessed fusion protein. The results show that KexB is the endoproteolytic proprotein processing enzyme responsible for the processing of (engineered) dibasic cleavage sites in target proteins that are transported through the secretion pathway of A. niger.
Jalving, Ruud; van de Vondervoort, Peter J. I.; Visser, Jaap; Schaap, Peter J.
Xylan constitutes the second most abundant source of renewable organic carbon on earth and is located in the cell walls of hardwood and softwood plants in the form of hemicellulose. Based on its availability, there is a growing interest in production of xylanolytic enzymes for industrial applications. ?-1,4-xylan xylosidase (EC 188.8.131.52) hydrolyses from the nonreducing end of xylooligosaccharides arising from endo-1,4-?-xylanase activity. This work reports the partial characterization of a purified ?-xylosidase from the native strain Aspergillusniger GS1 expressed by means of a fungal system. A gene encoding ?-xylosidase, xlnD, was successfully cloned from a native A. niger GS1 strain. The recombinant enzyme was expressed in A. niger AB4.1 under control of A. nidulans gpdA promoter and trpC terminator. ?-xylosidase was purified by affinity chromatography, with an apparent molecular weight of 90 kDa, and showed a maximum activity of 4,280 U mg protein(-1) at 70°C, pH 3.6. Half-life was 74 min at 70°C, activation energy was 58.9 kJ mol(-1), and at 50°C optimum stability was shown at pH 4.0-5.0. ?-xylosidase kept residual activity >83% in the presence of dithiothreitol (DTT), ?-mercaptoethanol, sodium dodecyl sulfate (SDS), ethylenediaminetetraacetate (EDTA), and Zn(2+). Production of a hemicellulolytic free xylosidase showed some advantages in applications, such as animal feed, enzymatic synthesis, and the fruit-juice industry where the presence of certain compounds, high temperatures, and acid media is unavoidable in the juice-making process. PMID:21116681
Amaro-Reyes, A; García-Almendárez, B E; Vázquez-Mandujano, D G; Amaya-Llano, S; Castańo-Tostado, E; Guevara-González, R G; Loera, O; Regalado, C
Aflatoxins are carcinogenic fungal secondary metabolites produced by Aspergillusflavus and other closely related species. Levels of aflatoxins in agricultural commodities are stringently regulated by many countries because of the health hazard, and thus, aflatoxins are of major concern to both producers and consumers. A cluster of genes responsible for aflatoxin biosynthesis has been identified; however, expression of these genes is a complex and poorly understood phenomenon. To better understand the molecular events that are associated with aflatoxin production, three separate nonaflatoxigenic A. flavus strains were produced through serial transfers of aflatoxigenic parental strains. The three independent aflatoxigenic/nonaflatoxigenic pairs were compared via transcription profiling by microarray analyses. Cross comparisons identified 22 features in common between the aflatoxigenic/nonaflatoxigenic pairs. Physical mapping of the 22 features using the Aspergillus oryzae genome sequence for reference identified 16 unique genes. Aflatoxin biosynthetic and regulatory gene expression levels were not significantly different between the aflatoxigenic/nonaflatoxigenic pairs, which suggests that the inability to produce aflatoxins is not due to decreased expression of known biosynthetic or regulatory genes. Of the 16 in common genes, only one gene homologous to glutathione S-transferase genes showed higher expression in the nonaflatoxigenic progeny relative to the parental strains. This gene, named hcc, was selected for over-expression in an aflatoxigenic A. flavus strain to determine if it was directly responsible for loss of aflatoxin production. Although hcc transformants showed six- to ninefold increase in expression, no discernible changes in colony morphology or aflatoxin production were detected. Possible roles of hcc and other identified genes are discussed in relation to regulation of aflatoxin biosynthesis. PMID:17955191
Chang, Perng-Kuang; Wilkinson, Jeffery R; Horn, Bruce W; Yu, Jiujiang; Bhatnagar, Deepak; Cleveland, Thomas E
Oxylipins, a class of oxygenase-derived unsaturated fatty acids, are important signal molecules in many biological systems. Recent characterization of an Aspergillusflavus lipoxygenase gene, lox, revealed its importance in maintaining a density-dependent morphology switch from sclerotia to conidia as population density increased. Here, we present evidence for the involvement of four more oxylipin-generating dioxygenases (PpoA, PpoB, PpoC, and PpoD) in A. flavus density-dependent phenomena and the effects of loss of these genes on aflatoxin production and seed colonization. Although several single mutants showed alterations in the sclerotia-to-conidia switch, the major effect was observed in a strain downregulated for all five oxygenases (invert repeat transgene [IRT] strain IRT4 = ppoA, ppoB, ppoC, ppoD, and lox). In strain IRT4, sclerotia production was increased up to 500-fold whereas conidiation was decreased down to 100-fold and the strain was unable to switch into conidial production. Aflatoxin (AF) production for all mutant strains and the wild type was greatest at low population densities and absent in high populations except for strain IRT4, which consistently produced high levels of the mycotoxin. Growth on host seed by both IRT4 and IRT2 (downregulated in ppoA, ppoB, and ppoD) was marked by decreased conidial but increased AF production. We propose that A. flavus oxygenases and the oxylipins they produce act in a highly interdependent network with some redundancy of biological function. These studies provide substantial evidence for oxylipin-based mechanisms in governing fungus-seed interactions and in regulating a coordinated quorum-sensing mechanism in A. flavus. PMID:19522570
Brown, Sigal Horowitz; Scott, James B; Bhaheetharan, Jeyanthi; Sharpee, William C; Milde, Lane; Wilson, Richard A; Keller, Nancy P
5,6-Epoxycholestan-3?-ol derivatives were hydrolyzed in a diastereoconvergent manner by growing and resting cells of several strains of Aspergillusniger, particularly A. niger ATCC 11394. These strains displayed opposite regioselectivity toward each isomer in an ? and ? epoxide mixture, thus, the nucleophilic attack took place at the less substituted and the most substituted carbon atom on each diasteromer, respectively. These
Fabricio R. Bisogno; Alejandro A. Orden; Celeste Aguirre Pranzoni; Diego A. Cifuente; Oscar S. Giordano; Marcela Kurina Sanz
Aspergillusniger produces a wide variety of carbohydrate hydrolytic enzymes which have potential applications in the baking, starch, textile, food and feed industries. The goal of this thesis is to unravel the molecular mechanisms of starch and inulin modifying network of A. niger, in order to improve the enzyme production and substrate utilization as well as to find novel enzyme
Summary Cultural studies onRhizoctonia solani, the causal agent of damping-off of cotton, as well as on two fungi of its antagonistic rhizospheric microflora, namelyAspergillus terreus andAspergillusflavus have shown coincidence of some of their cultural characteristics. However,R. solani produced mycelial growth far ahead both antagonists except at 37° C and at pH 4, at its optimum temperature. It is expected
The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillusflavus and aflatoxin contamination levels within the kernels. The choice of methodology was based on the principle that many biological materials exhibit fluorescenc...
...Gagliardi, Ph.D. and J.L. Kough, Ph.D. to S. Bacchus dated September 29, 2011. 3. U.S. EPA. 2003b. Environmental Hazard Assessment for the Microbial Pesticide, Aspergillusflavus AF36 for Conditional Registration in Arizona and...
We used a GFP-transformed Aspergillusflavus strain to needle inoculate mid-maturation ears and follow the path of fungal invasion in resistant and susceptible hybrids of Zea mays. In all ear cross-sections examined, the level of fluorescence was higher in susceptible compared to resistant lines. ...
Pseudomonas chlororaphis strain JP1015 and Pseudomonas fluorescens strain JP2175 were previously isolated from Mississippi cornfield soil samples and selected for their growth inhibition of Aspergillusflavus in laboratory culture. In this study, the antifungal activity of these bacterial strains a...
The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillusflavus and aflatoxin contamination levels within the kernels. Aflatoxin contamination in corn has been a long-standing problem plaguing the grain industry with potentially devastating consequences to corn growers. In this study, aflatoxin-contaminated corn kernels were produced through artificial inoculation of corn
H. Yao; Z. Hruska; R. Kincaid; R. Brown; T. Cleveland; D. Bhatnagar
We report the case of a child affected by acute myeloid leukaemia who was treated with allogeneic haematopoietic stem cell\\u000a transplantation and developed cervicothoracic spinal osteomyelitis due to Aspergillusflavus. The diagnosis was difficult on a clinical basis, but made possible by conventional radiography and MRI.
Infection of peanut seeds by Aspergillusflavus and A. parasiticus is a serious problem that can result in aflatoxin contamination in the seeds. Breeding resistant cultivars would be an effective approach to reduce aflatoxin accumulation. The objective of this study was to investigate the expressio...
Strains of Aspergillusflavus often degenerate with serial transfers on culture media, resulting in morphological changes and loss of aflatoxin production. However, degeneration does not readily occur in nature as indicated by the wild-type morphological characters of newly isolated strains and the...
The aim of this study was to determine the effect of some pre-harvest fungicides on growth and aflatoxin (AF) production of three Aspergillusflavus strains found in Capsicum powder. Each isolate, previously isolated from paprika, chilli and smoked paprika, was inoculated on yeast extract sucrose agar and on a 3% paprika extract agar medium supplemented with different fungicides and incubated
This study compared the effect of temperature and water activity and their interactions on the rate of mycelial growth of Penicillium aurantiogriseum, P. chrysogenum, P. corylophilum and Aspergillusflavus on a sponge cake analogue. As expected, growth rates showed dependence on aw and temperature. However, no significant differences were observed in the growth rates of different isolates. The minimum aw
The mycoparasite Humicola fuscoatra NRRL 22980 was isolated from a sclerotium of Aspergillusflavus that had been buried in a cornfield near Tifton, Ga. When grown on autoclaved rice, this fungus produced the antifungal metabolites monorden, monocillin IV, and a new monorden analog. Each metabolite produced a clear zone of inhibition surrounding paper assay disks on agar plates seeded with conidia of A. flavus. Monorden was twice as inhibitory to A. flavus mycelium extension (MIC > 28 ?g/ml) as monocillin IV (MIC > 56 ?g/ml). Cerebrosides C and D, metabolites known to potentiate the activity of cell wall-active antibiotics, were separated from the ethyl acetate extract but were not inhibitory to A. flavus when tested as pure compounds. This is the first report of natural products from H. fuscoatra.
Wicklow, Donald T.; Joshi, Biren K.; Gamble, William R.; Gloer, James B.; Dowd, Patrick F.
Contamination of food and feedstuffs by Aspergillus species and their toxic metabolites is a serious problem as they have adverse effects on human and animal health. Hence, food contamination monitoring is an important activity, which gives information on the level and type of contamination. A PCR-based method of detection of Aspergillus species was developed in spiked samples of sterile maize flour. Gene-specific primers were designed to target aflR gene, and restriction fragment length polymorphism (RFLP) of the PCR product was done to differentiate Aspergillusflavus and Aspergillus parasiticus. Sterile maize flour was inoculated separately with A. flavus and A. parasiticus, each at several spore concentrations. Positive results were obtained only after 12-h incubation in enriched media, with extracts of maize inoculated with A. flavus (101 spores/g) and A. parasiticus (104 spores/g). PCR products were subjected to restriction endonuclease (HincII and PvuII) analysis to look for RFLPs. PCR-RFLP patterns obtained with these two enzymes showed enough differences to distinguish A. flavus and A. parasiticus. This approach of differentiating these two species would be simpler, less costly and quicker than conventional sequencing of PCR products. PMID:15135586
The maize endophyte Acremonium zeae is antagonistic to kernel rotting and mycotoxin producing fungi Aspergillusflavus and Fusarium verticillioides in cultural tests for antagonism, and interferes with A. flavus infection and aflatoxin contamination of preharvest maize kernels. Chemical studies of an organic extract from maize kernel fermentations of Acremonium zeae (NRRL 13540), which displayed significant antifungal activity against Aspergillusflavus and F. verticillioides, revealed that the metabolites accounting for this activity were two newly reported antibiotics pyrrocidines A and B. Pyrrocidines were detected in fermentation extracts for 12 NRRL cultures of Acremonium zeae isolated from maize kernels harvested in Illinois (4/4 cultures), North Carolina (5/5), Georgia (1/2) and unrecorded locations within the USA (2/2). Pyrrocidine B was detected by LCMSMS in whole symptomatic maize kernels removed at harvest from ears of a commercial hybrid that were wound-inoculated in the milk stage with A. zeae (NRRL 13540) or (NRRL 13541). The pyrrocidines were first reported from the fermentation broth of an unidentified filamentous fungus LL-Cyan426, isolated from a mixed Douglas Fir hardwood forest on Crane Island Preserve, Washington, in 1993. Pyrrocidine A exhibited potent activity against most Gram-positive bacteria, including drug-resistant strains, and was also active against the yeast Candida albicans. In an evaluation of cultural antagonism between 13 isolates of A. zeae in pairings with A. flavus (NRRL 6541) and F. verticillioides (NRRL 25457), A. zeae (NRRL 6415) and (NRRL 34556) produced the strongest reaction, inhibiting both organisms at a distance while continuing to grow through the resulting clear zone at an unchanged rate. Maximum colony diameters for A. zeae (NRRL 6415) and (NRRL 13540), on potato dextrose agar after 14 d, were attained within the range of 25-30 degrees C, with less growth recorded at 15 degrees and 37.5 degrees and no growth at 5 degrees. Potential interactions between A. zeae and other maize endophytes are considered and the significance of these interactions relative to the aflatoxin and fumonisin contamination of preharvest maize is presented. This is the first report of natural products from Acremonium zeae. PMID:16018316
Wicklow, Donald T; Roth, Shoshannah; Deyrup, Stephen T; Gloer, James B
The sC sequence from Aspergillusniger was cloned and developed into a homologous marker system for genetic transformation. The coding region of the sC gene amplified by PCR from the A. niger genome was provided with Aspergillus nidulans expression signals (gpdA promoter and trpC terminator). This chimeric construct was used to successfully transform a spontaneous sC- isolate of A. niger to prototrophy. The transformants analyzed by Southern analysis showed integration of multiple copies of the transforming DNA. They also exhibited much higher ATP sulfurylase activity than the wild-type A. niger strain reinforcing the molecular data. This demonstrates the usefulness of the sCniger construct, driven by PgpdA, as a marker for A. niger transformation. PMID:15722148
Cyclopiazonic acid (CPA), an indole-tetramic acid mycotoxin, is produced by many species of Aspergillus and Penicillium. In addition to CPA Aspergillusflavus produces polyketide-derived carcinogenic aflatoxins. Aflatoxin biosynthesis genes form a gene cluster in a subtelomeric region. Isolates of A. flavus lacking aflatoxin production due to the loss of the entire aflatoxin gene cluster and portions of the subtelomeric region are often unable to produce CPA, which suggests a physical link of genes involved in CPA biosynthesis to the aflatoxin gene cluster. Examining the subtelomeric region in A. flavus isolates of different chemotypes revealed a region possibly associated with CPA production. Disruption of three of the four genes present in this region predicted to encode a monoamine oxidase, a dimethylallyl tryptophan synthase, and a hybrid polyketide non-ribosomal peptide synthase abolished CPA production in an aflatoxigenic A. flavus strain. Therefore, some of the CPA biosynthesis genes are organized in a mini-gene cluster that is next to the aflatoxin gene cluster in A. flavus. PMID:19038354
Essential oils are aromatic oily liquids obtained from some aromatic plant materials. Certain essential oils such as citronella oil contain antifungal activity, but the antifungal effect is still unknown. In this study, we explored the antifungal effect of citronella oil with Aspergillusniger ATCC 16404. The antifungal activity of citronella oil on conidia of A. niger was determined by poisoned food technique, broth dilution method, and disc volatility method. Experimental results indicated that the citronella oil has strong antifungal activity: 0.125 (v/v) and 0.25 % (v/v) citronella oil inhibited the growth of 5?×?10? spore/ml conidia separately for 7 and 28 days while 0.5 % (v/v) citronella oil could completely kill the conidia of 5?×?10? spore/ml. Moreover, the fungicidal kinetic curves revealed that more than 90 % conidia (initial concentration is 5?×?10? spore/ml) were killed in all the treatments with 0.125 to 2 % citronella oil after 24 h. Furthermore, with increase of citronella oil concentration and treatment time, the antifungal activity was increased correspondingly. The 0.5 % (v/v) concentration of citronella oil was a threshold to kill the conidia thoroughly. The surviving conidia treated with 0.5 to 2 % citronella oil decreased by an order of magnitude every day, and no fungus survived after 10 days. With light microscope, scanning electron microscope, and transmission electron microscope, we found that citronella oil could lead to irreversible alteration of the hyphae and conidia. Based on our observation, we hypothesized that the citronella oil destroyed the cell wall of the A. niger hyphae, passed through the cell membrane, penetrated into the cytoplasm, and acted on the main organelles. Subsequently, the hyphae was collapsed and squashed due to large cytoplasm loss, and the organelles were severely destroyed. Similarly, citronella oil could lead to the rupture of hard cell wall and then act on the sporoplasm to kill the conidia. Nevertheless, the citronella oil provides a potential of being a safe and environmentally friendly fungicide in the future. PMID:23081773
A new aflatoxin, aflatoxin B(2b) (1), together with six known compounds, were isolated from the marine-derived fungus Aspergillusflavus 092008 endogenous with the mangrove plant Hibiscus tiliaceus (Malvaceae). The structure of 1 was determined by the spectroscopic and chemical methods. Compound 1 exhibited a moderate antimicrobial activity against Escherichia coli, Bacillus subtilis and Enterobacter aerogenes, with MIC values of 22.5, 1.7 and 1.1 M, respectively. Compound 1 also showed a weak cytotoxicity against A549, K562 and L-02 cell lines, with IC(50) values of 8.1, 2.0 and 4.2 M, respectively. The results showed that hydration and hydrogenation of (8)-double bond significantly reduces the cytotoxicity of aflatoxins, while the esterification at C-8 increases the cytotoxicity. PMID:22941481
A new oxylipin, (8E,12Z)-10,11-dihydroxyoctadeca-8,12-dienoic acid (1), a new steroid, 3?,4?-dihydroxy-26-methoxyergosta-7,24(28)-dien-6-one (2), and four known steroids, episterol (3), (22E,24R)-ergosta-7,22-dien-3?,5?,6?-triol (4), (22E,24R)-ergosta-5,22-dien-3?-ol (5), and (22E,24R)-ergosta-4,6,8(14),22-tetraen-3-one (6), were isolated from the cultures of Aspergillusflavus, an endophytic fungus isolated from the marine red alga Corallina officinalis. Their structures and relative stereochemistry were elucidated by 1D, 2D NMR and mass spectroscopic techniques. 1 and 2 exhibited low activity to inhibit acetylcholinesterase and no activity against plant pathogenic fungi Colletotrichum lagenarium and Fusarium oxysporum. PMID:21452344
Qiao, Ming-Feng; Ji, Nai-Yun; Miao, Feng-Ping; Yin, Xiu-Li
Extracellular keratinase isolated from Aspergillusflavus K-03 was immobilized on calcium alginate. The properties and reaction activities of free and immobilized keratinase with calcium alginate were characterized. The immobilized keratinase showed proteolytic activity against soluble azo-casein and azo-keratin, and insoluble feather keratin. Heat stability and pH tolerance of keratinase were greatly enhanced by immobilization. It also displayed a higher level of heat stability and an increased tolerance toward alkaline pHs compared with free keratinase. During the durability test at 40?, 48% of the original enzyme activity of the immobilized keratinase was remained after 7 days of incubation. The immobilized keratinase exhibited better stability, thus increasing its potential for use in industrial application.
A 3,5-disubstituted furan, named flufuran, was isolated from a culture filtrate of a strain of Aspergillusflavus obtained from a chestnut compost created in the same orchard. Flufuran was identified by spectroscopic methods, and its structure was confirmed through the preparation of some key derivatives, also used to test the antifungal activity. At a concentration of 0.2 mg/ml, assayed against three Phytophthora species, pathogenic of some forest and agrarian plants, flufuran and especially its acetyl derivative showed significant antifungal activity. Although flufuran appears to be identical to a fungal metabolite isolated previously from some Polyporus spp., its interesting antifungal activity has never been reported before. PMID:19319868
The present study demonstrates an eco-friendly and low cost protocol for synthesis of silver nanoparticles using the cell-free filtrate of Aspergillusflavus NJP08 when supplied with aqueous silver (Ag+) ions. Identification of the fungal isolate was based on nuclear ribosomal DNA internal transcribed spacer (ITS) identities. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) revealed the formation of spherical metallic silver nanoparticles. The average particle size calculated using Dynamic Light Scattering measurements (DLS) was found to be 17 +/- 5.9 nm. UV-Visible and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of extracellular proteins. SDS-PAGE profiles of the extracellular proteins showed the presence of two intense bands of 32 and 35 kDa, responsible for the synthesis and stability of silver nanoparticles, respectively. A probable mechanism behind the biosynthesis is discussed, which leads to the possibility of using the present protocol in future ``nano-factories''.
The present study demonstrates an eco-friendly and low cost protocol for synthesis of silver nanoparticles using the cell-free filtrate of Aspergillusflavus NJP08 when supplied with aqueous silver (Ag+) ions. Identification of the fungal isolate was based on nuclear ribosomal DNA internal transcribed spacer (ITS) identities. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) revealed the formation of spherical metallic silver nanoparticles. The average particle size calculated using Dynamic Light Scattering measurements (DLS) was found to be 17±5.9 nm. UV-Visible and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of extracellular proteins. SDS-PAGE profiles of the extracellular proteins showed the presence of two intense bands of 32 and 35 kDa, responsible for the synthesis and stability of silver nanoparticles, respectively. A probable mechanism behind the biosynthesis is discussed, which leads to the possibility of using the present protocol in future "nano-factories". PMID:21088776
Aspergillusflavus and other pathogenic fungi display typical infrared spectra which differ significantly from spectra of substrate materials such as corn. On this basis, specific spectral features have been identified which permit detection of fungal infection on the surface of corn kernels by photoacoustic infrared spectroscopy. In a blind study, ten corn kernels showing bright greenish yellow fluorescence (BGYF) in the germ or endosperm and ten BGYF-negative kernels were correctly classified as infected or not infected by Fourier transform infrared photoacoustic spectroscopy. Earlier studies have shown that BGYF-positive kernels contain the bulk of the aflatoxin contaminating grain at harvest. Ten major spectral features, identified by visual inspection of the photoacoustic spectra of A. flavus mycelium grown in culture versus uninfected corn, were interpreted and assigned by theoretical comparisons of the relative chemical compositions of fungi and corn. The spectral features can be built into either empirical or knowledge-based computer models (expert systems) for automatic infrared detection and segregation of grains or kernels containing aflatoxin from the food and feed supply. PMID:9105926
Gordon, S H; Schudy, R B; Wheeler, B C; Wicklow, D T; Greene, R V
The plant pathogenic fungus Aspergillusflavus produces several types of mycotoxins. The most well known are the carcinogenic compounds called aflatoxins. In addition,\\u000a A. flavus produces cyclopiazonic acid and aflatrem mycotoxins, contributing to the toxicity of A. flavus infected crops. Cyclopiazonic acid is a specific inhibitor of calcium-dependent ATPase in the sarcoplasmic reticulum that\\u000a results in altered cellular Ca++ levels.
AFPA culture medium, which is used for recognition of Aspergillusflavus and A. parasiticus, has been validated in a collaborative study including nine laboratories located in Australia, Brazil, Denmark, The Netherlands, Sweden and United Kingdom. Three freeze-dried fungal mixtures, containing A. flavus/A. parasiticus and background fungi, were produced and checked for homogeneity. The coefficients of variance were low, ranging from 0.81% to 1.09% for total fungal counts and between 2.50% and 2.72% for counts of A. flavus/A. parasiticus. The laboratories analysed the contents of two vials of each mixture on commercial A. flavus and A. parasiticus agar (AFPA), in-house-made AFPA, and on a standard media, dichloran 18% glycerol agar (DG18). Reproducibility values for counts of A. flavus/A. parasiticus indicated no differences between the commercial AFPA and the in-house-made AFPA. Variation between laboratories was low, indicating that the medium was effective in use. Reproducibility values for DG18 were higher. There were no differences in counts of A. flavus/A. parasiticus on AFPA and DG18. However, DG18 gave slightly higher total fungal counts compared to AFPA. PMID:14580978
Cotton bolls were inoculated with a green fluorescent protein (GFP)-expressing Aspergillusflavus (strain 70) to monitor fungal growth, mode of entry, colonization of cottonseeds, and production of aflatoxins. The GFP strain and the wild-type did not differ significantly in pathogen aggressiveness as indicated by similar reductions in inoculated locule weight. GFP fluorescence was at least 10 times higher than the blue green yellow fluorescence (BGYF) produced in response to infection by A. flavus. The GFP produced by the strain made it possible to identify and monitor specific plant tissues colonized by the fungus. For example, the inner seed coat and cotyledon were colonized by the fungus within 72 h of inoculation and the mode of entry was invariably through the porous chalazal cap in intact seeds. The amount of GFP fluorescence was shown to be an indicator of fungal growth, colonization and, to some extent, aflatoxin production. The A. flavus strain expressing GFP should be very useful for rapidly identifying cotton lines with enhanced resistance to A. flavus colonization developed through genetic engineering or traditional plant breeding. In addition, development of GFP expressing A. flavus strain provides an easy and rapid assay procedure for studying the ecology, etiology, and epidemiology of cotton boll rot caused by A. flavus resulting in aflatoxin contamination. PMID:18266076
Rajasekaran, Kanniah; Cary, Jeffrey W; Cotty, Peter J; Cleveland, Thomas E
Aflatoxins are a family of fungal secondary metabolites. They are produced by species in the genus Aspergillus. Within the last decade, significant advances have been made in understanding the biochemistry, genetics, and gene regulation of aflatoxin biosynthesis. Many scientists have used aflatox...
Traditional storage of maize in tropical countries such as Ghana results in the rapid development of numerous fungi, including potential mycotoxin producers such as Aspergillusflavus (aflatoxins), A. ochraceus (ochratoxins, penicillic acid), Fusarium mon...
Hydrolysable tannins containing gallic acid moieties and certain other phenolic acids are antioxidants that possess potent antiaflatoxigenic activity against Aspergillusflavus Link. The antiaflatoxigenic activity of these compounds is initiated upstream from the aflatoxin biosynthetic pathway. To...
Aspergillusflavus is a saprophytic fungus which can grow on corn and produce aflatoxins which render it unsafe for food and feed consumption. In this study, aflatoxin and non-aflatoxin producing isolates of A. flavus were grown separately on wet (20% water added), sterile or non-sterile cracked co...
This study investigated the potential of Aspergillusniger strains for the production of citric acid from oil palm empty fruit bunches (EFB) through solid state bioconversion (SSB). Twenty six wild strains of Aspergillusniger isolated from lemon, orange, and sewage treatment plant sludge were evaluated. Factors considered in the study were citric acid production, sugar consumption, and protein content as
Zahangir Alam; Niamul Bari; Suleyman A. Muyibi; Parveen Jamal; Abdullah-Al-Mamun
Humans and animals are exposed to aflatoxins, toxic carcinogenic fungal metabolites, through consumption of contaminated food and feed. Aspergillusflavus, the primary causal agent of crop aflatoxin contamination, is composed of phenotypically and genotypically diverse vegetative compatibility groups (VCGs). Molecular data suggest that VCGs largely behave as clones with certain VCGs exhibiting niche preference. VCGs vary in aflatoxin-producing ability, ranging from highly aflatoxigenic to atoxigenic. The prevalence of individual VCGs is dictated by competition during growth and reproduction under variable biotic and abiotic conditions. Agronomic practices influence structures and average aflatoxin-producing potentials of A. flavus populations and, as a result, incidences and severities of crop contamination. Application of atoxigenic strains has successfully reduced crop aflatoxin contamination across large areas in the United States. This strategy uses components of the endemic diversity to alter structures of A. flavus populations and improve safety of food, feed, and the overall environment. PMID:23230832
Mehl, Hillary L; Jaime, Ramon; Callicott, Kenneth A; Probst, Claudia; Garber, Nicholas P; Ortega-Beltran, Alejandro; Grubisha, Lisa C; Cotty, Peter J
A two-step bioconversion process of ferulic acid to vanillin was elaborated combining two filamentous fungi, Aspergillusniger and Pycnoporus cinnabarinus. In the first step, A. niger transformed ferulic acid to vanillic acid and in the second step vanillic acid was reduced to vanillin by P. cinnabarinus. Ferulic acid metabolism by A. niger occurred essentially via the propenoic chain degradation to
Proteins with a Zn(II)?Cys? domain, Cys-X?-Cys-X?-Cys-X????-Cys-X?-Cys-X???-Cys (hereafter, referred to as the C6 domain), form a subclass of zinc finger proteins found exclusively in fungi and yeast. Genome sequence databases of Saccharomyces cerevisiae and Candida albicans have provided an overview of this family of genes. Annotation of this gene family in most fungal genomes is still far from perfect and refined bioinformatic algorithms are urgently needed. Aspergillusflavus is a saprophytic soil fungus that can produce the carcinogenic aflatoxin. It is the second leading causative agent of invasive aspergillosis. The 37-Mb genome of A. flavus is predicted to encode 12,000 proteins. Two and a half percent of the total proteins are estimated to contain the C6 domain, more than twofold greater than those estimated for yeast, which is about 1 %. The variability in the spacing between cysteines, C?-C? and C?-C?, in the zinc cluster enables classification of the domains into distinct subgroups, which are also well conserved in Aspergillus nidulans. Sixty-six percent (202/306) of the A. flavus C6 proteins contain a specific transcription factor domain, and 7 % contain a domain of unknown function, DUF3468. Two A. nidulans C6 proteins containing the DUF3468 are involved in asexual conidiation and another two in sexual differentiation. In the anamorphic A. flavus, a homolog of the latter lacks the C6 domain. A. flavus being heterothallic and reproducing mainly through conidiation appears to have lost some components involved in homothallic sexual development. Of the 55 predicted gene clusters thought to be involved in production of secondary metabolites, only about half have a C6-encoding gene in or near the gene clusters. The features revealed by the A. flavus C6 proteins likely are common for other ascomycete fungi. PMID:23563886
The filamentous fungus Aspergillusniger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of
Herman J Pel; Johannes H de Winde; David B Archer; Paul S Dyer; Gerald Hofmann; Peter J Schaap; Geoffrey Turner; Ronald P de Vries; Richard Albang; Kaj Albermann; Mikael R Andersen; Jannick D Bendtsen; Jacques A E Benen; Marco van den Berg; Stefaan Breestraat; Mark X Caddick; Roland Contreras; Michael Cornell; Pedro M Coutinho; Etienne G J Danchin; Alfons J M Debets; Peter Dekker; Piet W M van Dijck; Alard van Dijk; Lubbert Dijkhuizen; Arnold J M Driessen; Christophe d'Enfert; Steven Geysens; Coenie Goosen; Gert S P Groot; Piet W J de Groot; Thomas Guillemette; Bernard Henrissat; Marga Herweijer; Johannes P T W van den Hombergh; Cees A M J J van den Hondel; Rene T J M van der Heijden; Rachel M van der Kaaij; Frans M Klis; Harrie J Kools; Christian P Kubicek; Patricia A van Kuyk; Jürgen Lauber; Xin Lu; Marc J E C van der Maarel; Rogier Meulenberg; Hildegard Menke; Martin A Mortimer; Jens Nielsen; Stephen G Oliver; Maurien Olsthoorn; Karoly Pal; Arthur F J Ram; Ursula Rinas; Johannes A Roubos; Cees M J Sagt; Monika Schmoll; Jibin Sun; David Ussery; Janos Varga; Wouter Vervecken; Holger Wedler; Han A B Wösten; An-Ping Zeng; Albert J J van Ooyen; Jaap Visser; Hein Stam
The biochemical rationale for the inhibition of citric acid fermentation by Aspergillusniger in the presence of Mn2+ ions has been investigated using high citric acid-yielding, Mn2+ ion-sensitive as well as Mn2+ ion-tolerant mutant strains of A. niger. In the presence of Mn2+ (1.5 mg\\/l), citric acid production by the Mn2+ ion-sensitive strain (KCU 520) was reduced by about 75%
The ability of Aspergillusniger GH1 in converting creosote bush ellagitannins into ellagic acid (EA) was evaluated in solid state culture. Creosote bush\\u000a leaves were used to extract the ellagitannins fraction, which was impregnated in polyurethane foam used as support of solid\\u000a state culture. Ellagitannins content, EA accumulation, and the related enzymatic activities were evaluated. A. niger GH1 was able
Antonio Aguilera-Carbo; Juan S. Hernández; Christopher Augur; Lilia A. Prado-Barragan; Ernesto Favela-Torres; Cristóbal N. Aguilar
Two extracellular ß-glucosidases (EC 184.108.40.206) were isolated from Aspergillusniger USDB 0827 and A. niger USDB 0828, and their physical and kinetic properties studied. Both enzymes were very similar in terms of molecular size (230000 Da), pH optimum (pH 4.6), temperature optimum (65° C), stability at high temperatures and substrate preferences. They were capable of hydrolysing ß-linked disaccharides, phenyl ß-d-glucoside,
A number of nutritional factors influencing glucose oxidase (EC 220.127.116.11) production by Aspergillusniger NCIM 545 were studied. The synthesis of glucose oxidase by A. niger was investigated in two steps using submerged fermentation at 30?±?2 °C and 180 rpm for 96 h. Primarily, nutritional components\\u000a were selected by one-factor-at-a-time method, and the significance of each component with respect to glucose oxidase
Sandip B. Bankar; Mahesh V. Bule; Rekha S. Singhal; Laxmi Ananthanarayan
The present study deals with the direct production of citric acid from raw starch by Aspergillusniger. Shake flask and semi solid culture methods were compared using A. niger GCB-47 (parental strain) and GCMC-7 (mutant strain). When cultivated in shaking culture with 150 g\\/l soluble starch as a carbon source, the mutant strain GCMC-7 produced 69.5 g\\/l citric acid, which
With the availability of the genome sequence of the filamentous fungus Aspergillusniger, the use of targeted genetic modifications has become feasible. This, together with the fact that A. niger is well established industrially, makes this fungus an attractive micro-organism for creating a cell factory platform for\\u000a production of chemicals. Using molecular biology techniques, this study focused on metabolic engineering
Susan Meijer; Michael Lynge Nielsen; Lisbeth Olsson; Jens Nielsen
The effects of cotton–corn rotation and glyphosate use on levels of soil-borne Aspergillusflavus, aflatoxin and fumonisin contamination in corn and cotton seed were determined during 2002–2005 in Stoneville, Mississippi (USA). There were four rotation systems (continuous cotton, continuous corn, cotton–corn and corn–cotton) for both glyphosate-resistant (GR) and non-GR cultivars–herbicide system arranged in a randomized complete block design with four
K. N. Reddy; H. K. Abbas; R. M. Zablotowicz; C. A. Abel; C. H. Koger
Antifungal activity of essential oils of thyme, summer savory and clove were evaluated in culture medium and tomato paste. Aspergillusflavus were inoculated in Sabouraud Dextrose Broth and tomato paste and then 0, 50, 200, 350 and 500ppm of essential oils were added to each sample and then kept at 25±0.5°C for 2 months. Results showed that all essential oils
Soil is presumed to be a major source of inoculum for Aspergillusflavus which contaminates cottonseed and produces the potent\\u000a carcinogen, aflatoxin. Little is known about the mycoflora of the low desert soils of cotton fields where aflatoxin is a chronic\\u000a problem. In this study, soils from cotton fields in southwestern Arizona and southeastern California were assayed for filamentous\\u000a fungi.
Culture filtrates of Trichoderma viride and Trichoderma harzianum were inhibitory of Fusarium moniliforme and, to a lesser\\u000a extent, Aspergillusflavus. The degree of inhibition was, however, dependent on the carbon or nitrogen source incorporated\\u000a into the medium. Scanning electron microscopy revealed the development of abnormal fruiting structures on exposure to some\\u000a Trichoderma culture filtrate, while macroscopically, growth restriction and, in
Previous research demonstrated that aflatoxin contamination in corn is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillusflavus strain NRRL 30797. To facilitate field applications of this biocontrol isolate, a series of laboratory studies were conducted on the reliability and efficiency of replacing wheat grains with the novel bioplastic formulation Mater-Bi® to serve as a carrier
Cesare Accinelli; M. Ludovica Saccŕ; Hamed K. Abbas; Robert M. Zablotowicz; Jeffery R. Wilkinson
The effect of Zataria multiflora Boiss. essential oil (EO) against growth, spore production and aflatoxin formation by Aspergillusflavus ATCC 15546 was investigated in synthetic media as well as Iranian ultra-filtered white cheese in brine. EO effectively inhibited radial growth and spore production on potato dextrose agar (PDA) in a dose-dependent manner. At 200ppm, the radial growth and sporulation reduced
Aspergillusflavus was grown on maize and rice extract agars and on irradiated viable cracked maize and rice grains, either in pure culture or in dual culture with wild strains of either Hyphopichia burtonii or Bacillus amyloliquefaciens. Aflatoxin production by A. flavus and its growth and interactions with the other microorganisms were studied at three water activities (aw) (0.98, 0.95, and 0.90) and two temperatures (25 and 16 degrees C). Both H. burtonii and B. amyloliquefaciens markedly stimulated growth and aflatoxin production by A. flavus on cracked maize, especially at 25 degrees C and 0.95 and 0.98 aw. No aflatoxin was detected in pure cultures of A. flavus on cracked rice after 12 days of incubation at 25 degrees C, but some was produced by mixed cultures at 16 degrees C and 0.98 aw. The morphological interactions among A. flavus, H. burtonii, and B. amyloliquefaciens were also examined on maize and rice extract agars under similar controlled conditions. PMID:3111368
Aspergillusflavus was grown on maize and rice extract agars and on irradiated viable cracked maize and rice grains, either in pure culture or in dual culture with wild strains of either Hyphopichia burtonii or Bacillus amyloliquefaciens. Aflatoxin production by A. flavus and its growth and interactions with the other microorganisms were studied at three water activities (aw) (0.98, 0.95, and 0.90) and two temperatures (25 and 16 degrees C). Both H. burtonii and B. amyloliquefaciens markedly stimulated growth and aflatoxin production by A. flavus on cracked maize, especially at 25 degrees C and 0.95 and 0.98 aw. No aflatoxin was detected in pure cultures of A. flavus on cracked rice after 12 days of incubation at 25 degrees C, but some was produced by mixed cultures at 16 degrees C and 0.98 aw. The morphological interactions among A. flavus, H. burtonii, and B. amyloliquefaciens were also examined on maize and rice extract agars under similar controlled conditions.
Aspergillusflavus K49 secreted at least two xylanase activities when grown on a medium containing larch (wood) xylan as a sole carbon source. Enzyme activity was assayed using an agar medium containing Remazol Brilliant Blue R conjugated oat spelt xylan as substrate. Crude enzyme preparations were inhibited by Hg(+2), with an ED(50) of 17.5 mM and maximum inhibition of 83% at 50 mM. A concentrated sample of A. flavus K49 xylanase preparation was subjected to gel filtration chromatography on a P-30 column. A small protein peak coinciding with the major peak of xylanase activity was separated from the other secreted fungal proteins. An additional peak of xylanase activity was observed in fractions containing multiple fungal proteins. Analysis by denaturing sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) of fractions containing the smaller molecular weight xylanase revealed a major and minor protein band in the vicinity of 14 kD. Analysis of these same fractions by acidic native PAGE revealed a single band. Confirmation of identity for the isolated xylanase was provided by isolation of a protein band from a SDS-PAGE gel, followed by trypsin digestion/analysis by tandem mass spectrometry. Comparison of the peptide library derived from this protein band with sequence data from the A. oryzae genomic data base provided a solid match with an endo-1,4-?-xylanase, XlnA. This identification is consistent with a low molecular weight protein associated with the major xylanolytic activity. XlnA may be a highly mobile (diffusible), plant wall hemicellulose degrading factor with significant activity during plant infection. PMID:21479830
Mellon, Jay E; Cotty, Peter J; Callicott, Kenneth A; Abbas, Hamed
Aspergillusflavus, a mycotoxigenic filamentous fungus, colonizes several important agricultural crops, such as maize and peanuts. Two proteins, VeA and LaeA, known to form a nuclear complex in Aspergillus nidulans have been found to positively regulate developmental processes in several Aspergillus species. Here, an examination of near-isogenic A. flavus mutants differing in copy number of veA and laeA alleles (0, 1, or at least 2 each) revealed critical roles for VeA and LaeA in A. flavus development and seed colonization. In contrast to the wild type, both null mutants were unable to metabolize host cell lipid reserves and were inhibited by oleic acid in growth assays. The copy number of LaeA but not VeA appeared critical for a density-dependent sclerotial-to-conidial shift, since the multicopy laeA (MClaeA) strain produced relatively constant sclerotial numbers with increasing population size rather than showing the decrease in sclerotia seen in both the wild-type and MCveA strains. The MCveA-laeA strain yielded an intermediate phenotype. This study revealed unique roles of VeA and LaeA in seed pathogenesis and fungal biology, distinct from their cooperative regulatory functions in aflatoxin and sclerotial development.
Members of the Aspergillus section Nigri, known as black-spored aspergilli, can contaminate several substrates including maize. Although some species within the group can produce plant disease symptoms such as black mold in onions and maize ear rot, the main concern with A. niger aggregate contamina...
We isolated and characterized a new type of endopolygalacturonase (PG)-encoding gene, pgaD, from Aspergillusniger. The primary structure of PGD differs from that of other A. niger PGs by a 136 amino acid residues long N-terminal extension. Biochemical analysis demonstrated extreme processive behavior of the enzyme on oligomers longer than five galacturonate units. Furthermore, PGD is the only A. niger PG capable of hydrolyzing di-galacturonate. It is tentatively concluded that the enzyme is composed of four subsites. The physiological role of PGD is discussed. PMID:10675564
Studies were carried out on the removal of alumina from iron ore slime containing (%) Fe(2)O(3) 75.7, Al(2)O(3) 9.95, SiO(2) 6.1, Fe (total) 52.94 with the help of Bacillus circulans and Aspergillusniger. B. circulans and A. niger showed 39% and 38% alumina removal after six and 15 days of in situ leaching at 10% pulp density, respectively. Culture filtrate leaching with A. niger removed 20% alumina at 2% pulp density with 13 day old culture filtrate. B. circulans was more efficient than A. niger for selective removal of alumina. In case of A. niger in situ leaching rather than culture filtrate leaching was found to be more effective. PMID:16531043
Pradhan, N; Das, B; Gahan, C S; Kar, R N; Sukla, L B
The photoprotective potential of fungus pigments was investigated by irradiating conidiospores of three Aspergillusniger strains possessing the same genetic background, but differing in their degree of pigmentation with pulsed light (PL) and monochromatic (254 nm) UV-C radiation. Spores of A. niger MA93.1 and JHP1.1 presenting, respectively, a fawn and a white pigmentation were more sensitive to PL and continuous UV-C radiation than the wild-type A. niger strain N402 possessing a dark pigment. Both spores of the dark A. niger N402 and the fawn-color mutant were equally resistant to moist heat at 56°C while spores of the white-color mutant were highly sensitive. These results indicate that melanin protects pigmented spores of A. niger from PL. PMID:23278805
Esbelin, Julia; Mallea, Sabine; J Ram, Arthur F; Carlin, Frédéric
Efficient production of recombinant barley ?-amylase has been achieved in Aspergillusniger. The cDNA encoding ?-amylase isozyme 1 (AMY1) and its signal peptide was placed under the control of the Aspergillus nidulans glyceraldehyde-3-phosphate dehydrogenase (gpd) promoter and the A. nidulans trpC gene terminator. Secretion yields up to 60?mg\\/l were obtained in media optimised for ?-amylase activity and low protease\\u000a activity.
Aflatoxins are toxic polyketides produced by several Aspergillus species that contaminate food crops worldwide. Aspergillusflavus and A. parasiticus are the most common agents of aflatoxin contamination of oil-rich crops. The genes involved in aflatoxin biosynthesis are clustered and convert acetat...
Aspergillus isolates (n 103) collected from cancer patients were screened to determine the taxonomic distribution and quantity of gliotoxin production. Gliotoxin was detected in 93% of Aspergillus fumigatus, 75% of A. niger, 25% of A. terreus, and 4% of A. flavus cultures. Gliotoxin concentrations were highest in cultures of A. fumigatus. Aspergillus fumigatus produces several secondary metabo- lites during invasive
Russell E. Lewis; Nathan P. Wiederhold; Michail S. Lionakis; Randall A. Prince; Dimitrios P. Kontoyiannis
Antifungal activity and minimal fungicidal concentration (MFC) of extracts of garlic, bakeri garlic, Chinese leek, Chinese chive, scallion, onion bulb and shallot bulb against Aspergillusniger, A. flavus and A. fumigatus were examined. These Allium plants possessed antifungal activity, with garlic showing the lowest MFC. With the exception of scallion, the inhibitory effect of Allium plants against three Aspergillus species
Figs in an orchard were inoculated with an aflatoxigenic Aspergillusflavus strain in two ways by spore injection or by dusting at three maturation stages: firm ripe, shrivelled, and dried. Fruits were individually examined for fungal development and analyzed for aflatoxin B1 (AF B1) after 2, 4, 6, 8 and 10 days. Fruit injected at the first stage showed fungal development and AF B1 contamination within two days. The toxin level increased sharply to 1 ppm after 10 days. The mean level of AF B1 (284.75 ng/g) was significantly higher than those observed in other conditions. Figs dusted at the first stage showed only a tiny fungal growth even after 10 days. AF B1 appeared after 6 days with a low frequency (35%), mean level (7.6 ng/g) and a great variation among figs (0.22-15 ng/g). Among fruits inoculated during the shrivelled fig and dried fruit stages, no fungal growth was observed and AF B1 was detected with a lower incidence in association with low mean levels (less than 1.25 ng/g). Methods of prevention of aflatoxin contamination at the critical step, the firm ripe stage, are discussed. PMID:7935736
All the varieties, advanced breeding lines, germplasm lines, and wild species used in the experiments differed significantly for their ability to allow invasion and aflatoxin production by an aflatoxigenicAspergillusflavus strain. Infection and colonisation were strongly correlated (r = 0.82), while there was no relation between infection and aflatoxin content or colonisation and aflatoxin content (r = 0.15). The varieties ICGS11 and S 206 supported less infection and colonisation (range 35 to 40%). Lowest aflatoxin content was recorded in Chitra (3,200 ppb), while it was highest in Kaushal (38,250 ppb). A cross derivative of GAUG1 × NC Ac 17133 R F showed lowest infection and colonisation (86,3 and 25,28%, respectively), and also supported moderate aflatoxin production (4,000 ppb). Among germplasm lines spancross supported lowest aflatoxin production (2,026 ppb) while both the wild species vz. ICG 8127 and ICG 8128 were highly susceptible to infection, colonisation, and aflatoxin production. PMID:23605654
Desai, S; Ghewande, M P; Nagaraj, G; Narayan, P; Chauhan, S; Singh, H
A crude 2S albumin fraction was separated from peanut (Arachis hypogaea L.) cotyledons. Untreated 2S albumin had little inhibitory activity against trypsin, spore germination, or hyphal growth of Aspergillusflavus. However, following treatment of 2S albumin with SDS, increased inhibitory activity was demonstrated. We further purified 2S albumin using Sephadex G-100 and DEAE cellulose (DE-32) chromatography. HPLC analysis showed that the partially pure 2S albumin consisted of two polypeptides, whereas SDS-PAGE analyzes exhibited six polypeptides. One of the polypeptides, 2S-1, was found to contain the same molecular weight and enzymatic properties as the peanut protease inhibitor (PI); however, the N-terminal amino acid sequence of 2S-1 differed from that of PI. An NCBI database search revealed that the 2S-1 polypeptide is homologous to the pathogenesis-related proteins from soybean, cowpea, chickpea, and Lupinus luteus. We hypothesize that the 2S-1 polypeptide might represent a novel antifungal protein. PMID:23500710
Quantitative losses in various biochemical constituents like capsaicin, carotenes, ascorbic acid, polyphenols, mineral matter, sugars (soluble and insoluble), protein and fat were estimated after the successful growth of Aspergillusflavus for 30 days on powdered red pepper. The fungal biomass was measured by ergosterol content and Aflatoxin B1 by HPLC. Amongst the various nutritional constituents evaluated for nutritional losses and changes the highest nutritional loss was reported in total carotenoids (88.55%) followed by total sugars (85.5%). The protein content of the infected sample increased from 18.01% to 23%. The nutritional profile of chilli powder (Capsicum annum var. sannam L.) shows highest share of total soluble sugars (32.89%) and fiber content (21.05%), followed by protein (18.01%) and fat (13.32%) making it an ideal solid- substrate for mould growth. At the end of incubation the fungal biomass was 192. 25 mg / 100 gram powder, total plate count 17.5 X 10 (4) CFU/g and Aflatoxin B1 content was 30.06 ?g / kg. PMID:24031333
Quantitative losses in various biochemical constituents like capsaicin, carotenes, ascorbic acid, polyphenols, mineral matter, sugars (soluble and insoluble), protein and fat were estimated after the successful growth of Aspergillusflavus for 30 days on powdered red pepper. The fungal biomass was measured by ergosterol content and Aflatoxin B1 by HPLC. Amongst the various nutritional constituents evaluated for nutritional losses and changes the highest nutritional loss was reported in total carotenoids (88.55%) followed by total sugars (85.5%). The protein content of the infected sample increased from 18.01% to 23%. The nutritional profile of chilli powder (Capsicum annum var. sannam L.) shows highest share of total soluble sugars (32.89%) and fiber content (21.05%), followed by protein (18.01%) and fat (13.32%) making it an ideal solid- substrate for mould growth. At the end of incubation the fungal biomass was 192. 25 mg / 100 gram powder, total plate count 17.5 X 10 4 CFU/g and Aflatoxin B1 content was 30.06 ?g / kg.
Feruloyl esterases are key enzymes involved in the complete hydrolysis of hemicellulose. In the present study, the encoding sequence of putative feruloyl esterase A (AfFaeA) was cloned from genomic DNA from Aspergillusflavus and expressed in Pichia pastoris. The purified recombinant AfFaeA had apparent relative molecular mass of about 40,000 and had an optimum pH of 6.0, although it was stable at pH values ranging from 4.5 to 8.0. The optimum temperature for AfFaeA was 58°C. AfFaeA had hydrolytic activity toward methyl caffeate, methyl p-coumarate, methyl ferulate and methyl sinapate. Substrate specificity profiling of AfFaeA demostrated it is a type-A feruloyl esterase. The good performance of AfFaeA to release ferulic acid from steam exploded corn stalk in concert with Geobacillus stearothermophilus xylanase mutant indicated it is a promising biocatalyst for biomass degradation. PMID:23981381
Two series of new chitosan derivatives were synthesized by reaction of deacetylated chitosan (CH) with propyl (CH-Propyl) and pentyl (CH-Pentyl) trimethylammonium bromides to obtain derivatives with increasing degrees of substitution (DS). The derivatives were characterized by (1)H NMR and potentiometric titration techniques and their antifungal activities on the mycelial growth of Aspergillusflavus were investigated in vitro. The antifungal activities increase with DS and the more substituted derivatives of both series, CH-Propyl and CH-Pentyl, exhibited antifungal activities respectively three and six times higher than those obtained with commercial and deacetylated chitosan. The minimum inhibitory concentrations (MIC) were evaluated at 24, 48 and 72 h by varying the polymer concentration from 0.5 to 16 g/L and the results showed that the quaternary derivatives inhibited the fungus growth at polymer concentrations four times lower than that obtained with deacetylated chitosan (CH). The chitosans modified with pentyltrimethylammonium bromide exhibited higher activity and results are discussed taking into account the degree of substitution (DS). PMID:22819383
de Oliveira Pedro, Rafael; Takaki, Mirelle; Gorayeb, Teresa Cristina Castilho; Del Bianchi, Vanildo Luiz; Thomeo, Joăo Cláudio; Tiera, Marcio José; de Oliveira Tiera, Vera Aparecida
Aspergillusniger produced a proteinaceous hemolysin, nigerlysinTM when incubated on sheep's blood agar at both 23Â° C and 37Â°C. Nigerlysin was purified from tryptic soy broth culture filtrate. Purified nigerlysin has a molecular weight of approximately 72 kDa, with an...
ABSTRACT: BACKGROUND: The filamentous fungus Aspergillusniger is an exceptionally efficient producer of organic acids, which is one of the reasons for its relevance to industrial processes and commercial importance. While it is known that the mechanisms regulating this production are tied to the levels of ambient pH, the reasons and mechanisms for this are poorly understood. METHODS: To cast
Under otherwise identical fermentation conditions, the sugar source has been shown to have a marked effect on citric acid production by Aspergillusniger. Sucrose was the most favourable source, followed by glucose and fructose and then lactose. No citric acid was produced from galactose. Strong relationships were observed between citric acid production and the activities of certain enzymes in myccelial
In this work, we investigated the role of bacteria from the genera Bacillus and Pseudomonas and fungi from the genera Aspergillus and Penicillium in the leaching process of two different silicates (calamine and garnierite). Since the results obtained with A. niger were better than those with different bacteria, a more detailed investigation of the leaching process with this microorganism was
I. M Castro; J. L. R Fietto; R. X Vieira; M. J. M Trópia; L. M. M Campos; E. B Paniago; R. L Brandăo
. The initial moisture content, cultivation time, inoculum size and concentration of basal medium were optimized in solid state fermentation (SSF) for the production of xylanase by an Aspergillusniger mutant using statistical experimental designs. The cultivation time and concentration of basal medium were the most important factors affecting xylanase activity. An inoculum size of 5쎹 spores\\/g, initial moisture content
Y. S. Park; S. W. Kang; J. S. Lee; S. I. Hong; S. W. Kim
The biosorption of copper oxychloride fungicide particulates(~1 µm diameter), at concentrations ranging from 25 to 500 ppm active ingredient (ai), by pelleted mycelium of Aspergillusniger grown on Czapek Dox medium was evaluated. The concentration of the fungicide adsorbed to the mycelium, remaining suspended or solubilized in the medium, was determined by analysis of its copper content (CuF)using atomic absorption
This study was to compare three phytase activity assays and kinetics of Aspergillusniger PhyA and Escherichia coli AppA2 phytases expressed in Pichia pastoris at the observed stomach pH of 3.5. In Experiment 1, equivalent phytase activities in the crude preparations of PhyA and AppA2 were tested ...
Aims: To study the morphological patterns of Aspergillusniger during biofilm formation on polyester cloth by using cryo-scanning electron microscopy rela- ted to lignocellulolytic enzyme productivity. Methods and Results: Biofilm and pellet samples obtained from flask cultures were examined at )80? C in a LEO PV scanning electron microscope. Spore adhesion depends on both its rough surface and adhesive substances
A transposable element has been isolated from the industrially important fungus Aspergillusniger (strain N402). The element was identified as an insertion sequence within the coding region of the nitrate reductase gene. It had inserted at a TA site and appeared to have duplicated the target site upon insertion. The isolated element was found to be 4798 by in length
Dianne C. Glayzer; Ian N. Roberts; David B. Archer; Richard P. Oliver
Pure strain of Aspergillusniger was isolated and cultured using potato dextrose agar and broth, respectively. This was subsequently used to ferment six portions of 1 kg each of cassava pulp for 72 h. Three portions of the fermented cassava were each sieved and fried in a hot pan to gari, while the other three portions were each sun-dried and
BACKGROUND: Proteomic data is a potentially rich, but arguably unexploited, data source for genome annotation. Peptide identifications from tandem mass spectrometry provide prima facie evidence for gene predictions and can discriminate over a set of candidate gene models. Here we apply this to the recently sequenced Aspergillusniger fungal genome from the Joint Genome Institutes (JGI) and another predicted protein
James C Wright; Deana Sugden; Sue Francis-McIntyre; Isabel Riba-Garcia; Simon J Gaskell; Igor V Grigoriev; Scott E Baker; Robert J Beynon; Simon J Hubbard
Natural oils with high unsaturated fatty acids content when added at concentrations of 2% and 4% (v\\/v) to beet molasses (BM) medium caused a considerable increase in citric acid yield from Aspergillusniger. The fermentation capacities were also examined for production of citric acid using BM-oil media under different fermentation conditions. Maximum citric acid yield was achieved in surface culture
Phytate is an important plant constituent and can be found in the seeds of cereals and legumes. Phytic acid has 12 replaceable protons in the phytic molecule, giving it the ability to complex with multivalent cations. In this study, the phytate was used as an additive to enhance citric acid production by Aspergillusniger from an untreated beet molasses. The
Summary Production of citric acid from beet molasses at a varying pH profile using cell recycle ofAspergillusniger was investigated. Best results in terms of citric acid concentration, yield, productivity and specific citric acid productivity were obtained with a substrate pH of 3.0.
During the solid state fermentation (SSF) of cassava starch by Aspergillusniger estimations were made of total water, consumed water and the residual water remaining in small quantities after 23 h. A theoretical calculation based on the Ross equation showed that the water activity (aw) of the substrate decreased to 0.85 towards the end of the culture. Such low values
Eric Oriol; Maurice Raimbault; Sevastianos Roussos; Gustavo Viniegra-Gonzales
Simultaneous saccharification and fermentation of Jerusalem artichoke tubers were conducted batchwise at 30°C using Aspergillusniger 817 and Saccharomyces cerevisiae 1200. Ethanol concentrations obtained were 10.4% (v\\/v) from the ground tubers after 15 h, 15.0% from the juice concentrate after 72 h, and 20.1% from the flour after 120 h.
Aspergillusflavus and A. parasiticus infect peanut seeds and produce aflatoxins, which are associated with various diseases in domestic animals and humans throughout the world. The most cost-effective strategy to minimize aflatoxin contamination involves the development of peanut cultivars that are resistant to fungal infection and/or aflatoxin production. To identify peanut Aspergillus-interactive and peanut Aspergillus-resistance genes, we carried out a large scale peanut Expressed Sequence Tag (EST) project which we used to construct a peanut glass slide oligonucleotide microarray. The fabricated microarray represents over 40% of the protein coding genes in the peanut genome. For expression profiling, resistant and susceptible peanut cultivars were infected with a mixture of Aspergillusflavus and parasiticus spores. The subsequent microarray analysis identified 62 genes in resistant cultivars that were up-expressed in response to Aspergillus infection. In addition, we identified 22 putative Aspergillus-resistance genes that were constitutively up-expressed in the resistant cultivar in comparison to the susceptible cultivar. Some of these genes were homologous to peanut, corn, and soybean genes that were previously shown to confer resistance to fungal infection. This study is a first step towards a comprehensive genome-scale platform for developing Aspergillus-resistant peanut cultivars through targeted marker-assisted breeding and genetic engineering. PMID:22069737
Biosynthesis of the highly toxic and carcinogenic aflatoxins in select Aspergillus species from the common intermediate O-methylsterigmatocystin (OMST) has been postulated to require only the cytochrome P450 monooxygenase, OrdA (AflQ). We now provide evidence that the aryl alcohol dehydrogenase NorA (AflE) encoded by the aflatoxin biosynthetic gene cluster in A. flavus affects the accumulation of aflatoxins in the final steps of aflatoxin biosynthesis. Mutants with inactive norA produced reduced quantities of aflatoxin B1 (AFB1), but elevated quantities of a new metabolite, deoxyAFB1. To explain this result, we suggest that, in the absence of NorA, the AFB1 reduction product, aflatoxicol, is produced and is readily dehydrated to deoxyAFB1 in the acidic medium, enabling us to observe this otherwise minor toxin produced in wild-type A. flavus.
Ehrlich, Kenneth C.; Chang, Perng-Kuang; Scharfenstein, Lester L.; Cary, Jeffrey W.; Crawford, Jason M.; Townsend, Craig A.
Background Aspergillusflavus infection and aflatoxin contamination of maize pose negative impacts in agriculture and health. Commercial maize hybrids are generally susceptible to this fungus. Significant levels of host plant resistance have been observed in certain maize inbred lines. This study was conducted to identify maize genes associated with host plant resistance or susceptibility to A. flavus infection and aflatoxin accumulation. Results Genome wide gene expression levels with or without A. flavus inoculation were compared in two resistant maize inbred lines (Mp313E and Mp04?86) in contrast to two susceptible maize inbred lines (Va35 and B73) by microarray analysis. Principal component analysis (PCA) was used to find genes contributing to the larger variances associated with the resistant or susceptible maize inbred lines. The significance levels of gene expression were determined by using SAS and LIMMA programs. Fifty candidate genes were selected and further investigated by quantitative RT-PCR (qRT-PCR) in a time-course study on Mp313E and Va35. Sixteen of the candidate genes were found to be highly expressed in Mp313E and fifteen in Va35. Out of the 31 highly expressed genes, eight were mapped to seven previously identified quantitative trait locus (QTL) regions. A gene encoding glycine-rich RNA binding protein 2 was found to be associated with the host hypersensitivity and susceptibility in Va35. A nuclear pore complex protein YUP85-like gene was found to be involved in the host resistance in Mp313E. Conclusion Maize genes associated with host plant resistance or susceptibility were identified by a combination of microarray analysis, qRT-PCR analysis, and QTL mapping methods. Our findings suggest that multiple mechanisms are involved in maize host plant defense systems in response to Aspergillusflavus infection and aflatoxin accumulation. These findings will be important in identification of DNA markers for breeding maize lines resistant to aflatoxin accumulation.
Kelley, Rowena Y.; Williams, W. Paul; Mylroie, J. Erik; Boykin, Deborah L.; Harper, Jonathan W.; Windham, Gary L.; Ankala, Arunkanth; Shan, Xueyan
The workforce at a biotechnology plant producing citric acid by fermentation of molasses with a strain of Aspergillusniger was studied. A combination of a respiratory questionnaire and clinical assessment identified 18 subjects (4.9% of the workforce) with work related bronchospasm. In nine of these evidence of sensitisation to A niger was obtained by skin prick tests and radioallergosorbent test (RAST) using as an antigen an extract of the A niger culture fluid from the process. Of the 325 subjects without work related bronchospasm, only nine (2.7%) had a positive prick test. There were no subjects with symptoms of extrinsic allergic alveolitis. Investigation into the source of the antigen showed that whereas, in some areas of the plant, A niger spores were present, in others there were no detectable spores. In these areas, however, extracts of filters from air samplers were shown by RAST inhibition to contain A niger antigens, indicating that the culture fluid was generating airborne antigen. RAST inhibition studies showed that the A niger culture fluid used in the process contained antigens that were not present in a commercially available A niger extract, thus emphasising the importance in this type of investigation of using antigens prepared from material to which the workers are exposed.
Topping, M D; Scarisbrick, D A; Luczynska, C M; Clarke, E C; Seaton, A
Maize is one of the more important agricultural crops in the world and, under certain conditions, prone to attack from pathogenic\\u000a fungi. One of these, Aspergillusflavus, produces toxic and carcinogenic metabolites, called aflatoxins, as byproducts of its infection of maize kernels. The ?-amylase\\u000a of A. flavus is known to promote aflatoxin production in the endosperm of these infected kernels,
Young-Hwa Kim; Charles P. Woloshuk; Eun Hee Cho; Jung Myung Bae; Young-Sun Song; Gyung Hye Huh
The growth of a toxigenic strain (Saktiman 3Nst) of Aspergillusflavus decreased progressively with increasing concentration of essential oils from leaves of Cinnamomum camphora and rhizome of Alpinia galanga incorporated into SMKY liquid medium. The oils significantly arrested aflatoxin B1 elaboration by A. flavus. The oil of C. camphora completely checked aflatoxin B1 elaboration at 750 ppm (mg\\/L) while that of A. galanga showed
Two anionic isoperoxidases were isolated from media of Aspergillusflavus-inoculated cotton (Gossypium hirsutum L.) ovule cultures and purified about 150-fold to apparent homogeneity by treatment with Cell Debris Remover and ion exchange chromatography on Accell QMA medium. These isoperoxidases were present in noninoculated cotton ovule cultures at low levels. The major activity peak (B) represented 90% of the recovered peroxidase activity and was electrophoretically homogeneous. The minor activity peak (A) was about 95% pure. Isoelectric focusing analysis showed that B was greater than 95% pure with respect to other peroxidase isozymes, while the enzyme in A was about 90% isozymically pure. Each isoperoxidase displayed a molecular mass of 56 kilodaltons by interpolation from denaturing gel electrophoresis. The B isozyme displayed a molecular mass of 55 kilodaltons by gel filtration chromatography. The pH optima for the cotton ovule isoperoxidases were similar, 5.0 for isozyme A and 6.0 for isozyme B. The isoelectric points for isozymes A and B were 4.2 and 4.4, respectively. Eugenol, guaiacol, and 3,3?,5,5?-tetramethylbenzidine were good electron donor substrates, whereas 4-aminoantipyrine was a poor substrate. The absorption spectrum of the material in B revealed a major peak at 400 nanometers and a minor peak at 280 nanometers. The molar extinction coefficient at 400 nanometers (pH 7.0) was calculated to be 1.07 × 105 per square centimeter per mole. Amino acid analysis of isozyme B confirmed the acidic nature of this protein and identified a number of similarities to the anionic peroxidases from tobacco and potato. This glycoprotein was found to contain 12 to 14% sugar (by weight), mainly in the form of galactose and mannose. Images Figure 2 Figure 3
Pistachio is a popular snack food. Aflatoxin contamination of pistachio nuts is a serious problem for many producing countries. The development of biological control methods based on ecological parameters is an environmentally friendly approach. Thirty-eight Aspergillusflavus isolates collected from a pistachio orchard in California (CA) were analyzed for production of aflatoxin (AF), cyclopiazonic acid (CPA), vegetative compatibility groups (VCGs), and mating types. All aflatoxigenic isolates produced both AFB1 and CPA. The most toxigenic one was CA28 which produced 164 ?g AFB1 per 5 ml PDA fungal culture and small sclerotia (S strain, sclertoium size less than 400 ?m). The other aflatoxigenic strains produce AFB1 ranging from 1.2 ?g to 80 ?g per 5 ml fungal culture. Twenty-one percent of the CA isolates produced AFB1, 84% produced CPA and half formed sclerotia on at least one of three tested media. The 38 CA isolates formed 26 VCGs, 6 of which had two or more isolates and 20 contained single isolates. The S strain isolates belong to 4 different VCGs. Genomic profiling by a retrotransposon DNA probe revealed fingerprint patterns that were highly polymorphic. The predicted VCGs (Pred-VCGs) based on a similarity coefficient >80% matched the VCGs of multiple isolates determined by complementation. All isolates within a VCG had the same mating-type gene of either MAT1-1 or MAT1-2. Uncorrected and VCG-corrected MAT1-1 and MAT1-2 among the isolates were equally distributed. PMID:23605984
Hua, Sui Sheng T; McAlpin, Cesaria E; Chang, Perng-Kuang; Sarreal, Siov Bouy L
Two different extracellular proteases, protease I (P-I), an alkaline protease, and protease II (P-II) a neutral protease, from Aspergillusflavus var. columnaris were partially purified by using (NH4)2SO4 precipitation, diethylaminoethyl-Sephadex A-50 chromatography, carboxymethylcellulose CM-52 chromatography, and Sephadex G-100 gel filtration. The degree of purity was followed using polyacrylamide gel electrophoresis. The activity of P-I was completely inhibited by 0.1 mM phenylmethylsulfonyl fluoride, and that of P-II was completely inhibited by 1 mM ethylenediaminetetraacetate. By using these inhibitors with extracts of wheat bran koji, the proportions of total activity that could be assigned to P-I and P-II were 80 and 20%, respectively. This compared favorably with activities estimated by using polyacrylamide gel electrophoresis slices (82 and 18%, respectively). Extracts from factory-run soybean koji gave comparable results. Both enzymes demonstrated maximum activity at 50 to 55°C and only small changes in activity between pH 6 and 11. For P-I, activity was somewhat higher from pH 8.0 to 11.0, whereas for P-II it was somewhat higher from pH 6 to 9. In the presence of 18% NaCl, the activities of both P-I and P-II dropped by approximately 90 and 85%, respectively. P-I was inferred to possess aminopeptidase activity since it could hydrolyze l-leucyl-p-nitroanilide hydrochloride. P-II was devoid of such activity. The ramifications of the results for factory-produced soy sauce koji are discussed. Images
Impoolsup, Attawut; Bhumiratana, Amaret; Flegel, Timothy W.
Two different extracellular proteases, protease I (P-I), an alkaline protease, and protease II (P-II) a neutral protease, from Aspergillusflavus var. columnaris were partially purified by using (NH(4))(2)SO(4) precipitation, diethylaminoethyl-Sephadex A-50 chromatography, carboxymethylcellulose CM-52 chromatography, and Sephadex G-100 gel filtration. The degree of purity was followed using polyacrylamide gel electrophoresis. The activity of P-I was completely inhibited by 0.1 mM phenylmethylsulfonyl fluoride, and that of P-II was completely inhibited by 1 mM ethylenediaminetetraacetate. By using these inhibitors with extracts of wheat bran koji, the proportions of total activity that could be assigned to P-I and P-II were 80 and 20%, respectively. This compared favorably with activities estimated by using polyacrylamide gel electrophoresis slices (82 and 18%, respectively). Extracts from factory-run soybean koji gave comparable results. Both enzymes demonstrated maximum activity at 50 to 55 degrees C and only small changes in activity between pH 6 and 11. For P-I, activity was somewhat higher from pH 8.0 to 11.0, whereas for P-II it was somewhat higher from pH 6 to 9. In the presence of 18% NaCl, the activities of both P-I and P-II dropped by approximately 90 and 85%, respectively. P-I was inferred to possess aminopeptidase activity since it could hydrolyze l-leucyl-p-nitroanilide hydrochloride. P-II was devoid of such activity. The ramifications of the results for factory-produced soy sauce koji are discussed. PMID:16345858
BACKGROUND: The filamentous fungus Aspergillusniger is well-known as a producer of primary metabolites and extracellular proteins. For example, glucoamylase is the most efficiently secreted protein of Aspergillusniger, thus the homologous glucoamylase (glaA) promoter as well as the glaA signal sequence are widely used for heterologous protein production. Xylose is known to strongly repress glaA expression while maltose is
Primary cutaneous aspergillosis is a rare entity, usually caused by A. fumigatus and A. flavus . Here, we present such a case, manifested by ulceration due to A. niger, which remained undiagnosed for a prolonged period. The immunological status was intact, although the patient had associated severe fungal infection. Recurrence of the lesion occurred despite repeated anti-fungal therapies. Anti fungal testing was done based on the broth dilution (M-38A, NCCLS, USA) method. The culture isolate was found to be sensitive to fluconazole and amphotericin B. Continuation of antifungal therapy improved the symptoms, reducing the size of the lesion. PMID:19736412
Mohapatra, S; Xess, I; Swetha, J V; Tanveer, N; Asati, D; Ramam, M; Singh, M K
Citric acid is nowadays produced by submerged fermentation of Aspergillusniger. The process yield depends on the composition of the medium, as well as on the microorganism strain. In this work, the effect\\u000a of Fe+3, Zn+2, and Mn+2 on citric acid production by A. niger NRRL 2001 is presented. The culture medium composition was glucose (120 g\\/L) KH2PO4 (1.0 g\\/L); K2HPO4 (1.0 g\\/L),
Aspergillusniger infection of an exenterated orbit is a very rare occurrence. Treatment includes extensive surgical debridement with socket lavage with 0.6% hydrogen peroxide, oral itraconazole, and local amphotericin B. We describe a case of A. niger infection in an exenterated orbit, unresponsive to local amphotericin B, that was successfully treated with weekly boric acid irrigation. We conclude that local and conservative therapy with 2.5% boric acid solution in 70% ethanol is a useful option in the management of these cases. PMID:18209660
Avińó-Martínez, Juan A; Espańa-Gregori, Enrique; Peris-Martínez, Cristina P; Blanes, Marino
The antifungal effects of essential oils from Thymus eriocalyx and Thymus x-porlock were studied with special reference to the mechanism of inhibition of Aspergillusniger growth at ultrastructural level. Minimal inhibitory (MIC), minimal fungicidal (MFC) concentrations, and fungicidal kinetics of the oils were determined. Transmission electron microscopy (TEM) of A. niger exposed to MIC levels of the oils showed irreversible
Iraj Rasooli; Mohammad Bagher Rezaei; Abdolamir Allameh
The antifungal efficacy of Ficus sycomorus and Pergularia tomentosa plant extracts on Bufo regularis experimentally infected with Aspergillusniger was studied. After an oral administration of the pathogen for 15 days, the blood, kidney and liver were examined. Treatment with A. niger produced a reduction in red blood count cells and hemoglobin content. Also, both livers and kidneys revealed marked
Souad H. M. Bekheet; Fatma F. Abdel-Motaal; Usama A. Mahalel
Aspergillusniger NII-08121\\/MTCC 7956 exhibited differences in expression of ?-glucosidase (BGL) in response to carbon sources provided in the medium. Activity staining with methyl umbelliferyl ?-d-glucopyranoside (MUG) indicated that four different isoforms of BGL were expressed when A. niger was grown under submerged fermentation with either lactose or cellulose, whereas only two were expressed when wheat bran or rice straw
Reeta Rani Singhania; Rajeev Kumar Sukumaran; Kuni Parambil Rajasree; Abraham Mathew; Lalithadevi Gottumukkala; Ashok Pandey
The filamentous fungus Aspergillusniger exhibits great diversity in its phenotype. It is found globally, both as marine and terrestrial strains, produces both organic acids and hydrolytic enzymes in high amounts, and some isolates exhibit pathogenicity. Although the genome of an industrial enzyme-producing A. niger strain (CBS 513.88) has already been sequenced, the versatility and diversity of this species compel
Mikael R. Andersen; Margarita Salazar; P. J. Schaap; Peter van de Vondervoort; David E. Culley; Peter J. I. van de Vondervoot; Jens C. Frisvad; Kristian F. Nielsen; Richard Albang; Kristen F. Nielsen; Gerhard Braus; Susanna A. Braus-Stromeyer; Luis Corrochano; Gerald Hofmann; Piet W. M. van Dijck; Hildegard Menke; Jon K. Magnusson; Susan L. Meijer; Jakob B. Nielsen; Michael L. Nielsen; Albert J. J. van Ooyen; Kathyrn S. Panther; Lars Poulsen; Rob A. Samson; Adrian Tsang; Johannes M. van den Brink; Andrea Aerts; Harris Shapiro; Jasmyn Pangilinan; Asaf Salamov; Erika Lindquist; Jane Grimwood; Igor V. Grigoriev; Christian P. Kubicek; Diego Martinez; Johannes A. Roubos; Jens B. Nielsen; Scott E. Baker
The fungus Aspergillusniger is an industrial producer of pectin degrading enzymes. The recent solving of the genomic sequence of A. niger allowed an inventory of the entire genome of the fungus for potential carbohydrate degrading enzymes. By applying bioinformatics tools 12 new genes putatively encoding family 28 glycoside hydrolases were identified. Seven of the newly discovered genes form a
The recent discovery of fumonisin production in Aspergillusniger, raises concerns about the presence of these mycotoxins in grapes and raisins as well as other commodities where A. niger is a frequent contaminant. Here we investigate the potential production of fumonisins in A. niger cultured on grapes and raisins. Sixty-six A. niger, 4 A. tubingensis, and 16 A. acidus strains isolated from raisins were tested for fumonisin production on laboratory media. Neither A. tubingensis nor A. acidus strains produced fumonisins, but 77% of A. niger strains did. None of the strains produced ochratoxin A. Ten selected fumonisin producing A. niger strains were further able to produce fumonisin B(2) and fumonisin B(4) on grapes in the range 171-7841 microg fumonisin B(2)/kg and 14-1157 microg fumonisin B(4)/kg. Four selected strains were able to produce fumonisin B(2) (5-6476 microg/kg) and fumonisin B(4) (12-672 microg/kg) on raisins. PMID:20014861
Mogensen, Jesper M; Frisvad, Jens C; Thrane, Ulf; Nielsen, Kristian F
Filamentous fungi are important producers of plant polysaccharide degrading enzymes that are used in many industrial applications. These enzymes are produced by the fungus to liberate monomeric sugars that are used as carbon source. Two of the main components of plant polysaccharides are L-arabinose and D-xylose, which are metabolized through the pentose catabolic pathway (PCP) in these fungi. In Aspergillusniger, the regulation of pentose release from polysaccharides and the PCP involves the transcriptional activators AraR and XlnR, which are also present in other Aspergilli such as Aspergillus nidulans. The comparative analysis revealed that the regulation of the PCP by AraR differs in A. nidulans and A. niger, whereas the regulation of the PCP by XlnR was similar in both species. This was demonstrated by the growth differences on L-arabinose between disruptant strains for araR and xlnR in A. nidulans and A. niger. In addition, the expression profiles of genes encoding L-arabinose reductase (larA), L-arabitol dehydrogenase (ladA) and xylitol dehydrogenase (xdhA) differed in these strains. This data suggests evolutionary changes in these two species that affect pentose utilisation. This study also implies that manipulating regulatory systems to improve the production of polysaccharide degrading enzymes, may give different results in different industrial fungi. PMID:21484208
Battaglia, Evy; Hansen, Sara Fasmer; Leendertse, Anne; Madrid, Susan; Mulder, Harm; Nikolaev, Igor; de Vries, Ronald P
Aspergillusflavus is a fungal pathogen of maize causing an important ear rot disease when plants are exposed to drought and heat stress. Associated with the disease is the production of aflatoxins, which are a series of structurally related mycotoxins known to be carcinogenic. Previous research has suggested that the alpha-amylase of A. flavus promotes aflatoxin production in the endosperm of infected maize kernels. We report here the isolation and characterization of a 36-kDa alpha-amylase inhibitor from Lablab purpureus (AILP). AILP inhibited the alpha-amylases from several fungi but had little effect on those from animal and plant sources. The protein inhibited conidial germination and hyphal growth of A. flavus. The amino acid sequence indicated that AILP is similar to lectin members of a lectin-arcelin-alpha-amylase inhibitor family described in common bean and shown to be a component of plant resistance to insect pests. AILP also agglutinated papain-treated red blood cells from human and rabbit. These data indicate that AILP represents a novel variant in the lectin-arcelin-alpha-amylase inhibitor family of proteins having lectin-like and alpha-amylase inhibitory activity. PMID:11497467
Previous research demonstrated that aflatoxin contamination in corn is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillusflavus strain NRRL 30797. To facilitate field applications of this biocontrol isolate, a series of laboratory studies were conducted on the reliability and efficiency of replacing wheat grains with the novel bioplastic formulation Mater-Bi to serve as a carrier matrix to formulate this fungus. Mater-Bi granules were inoculated with a conidial suspension of NRRL 30797 to achieve a final cell density of approximately log 7 conidia/granule. Incubation of 20-g soil samples receiving a single Mater-Bi granule for 60-days resulted in log 4.2-5.3 propagules of A. flavus/g soil in microbiologically active and sterilized soil, respectively. Increasing the number of granules had no effect on the degree of soil colonization by the biocontrol fungus. In addition to the maintenance of rapid vegetative growth and colonization of soil samples, the bioplastic formulation was highly stable, indicating that Mater-Bi is a suitable substitute for biocontrol applications of A. flavus NRRL 30797. PMID:19349167
Accinelli, Cesare; Saccŕ, M Ludovica; Abbas, Hamed K; Zablotowicz, Robert M; Wilkinson, Jeffery R
The mycelial growth of Aspergillusflavus Link was completely inhibited using 1.5 (microl/ml or 2.0 (microl/ml of Cymbopogon citratus essential oil applied by fumigation or contact method in Czapek's liquid medium, respectively. This oil was found also to be fungicidal at the same concentrations. The sublethal doses 1.0 and 1.5 (microl/ml inhibited about 65% of fungal growth after five days of incubation and delayed conidiation as compared with the control. Microscopic observations using Light Microscope (LM), Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM) were carried out to determine the ultra structural modifications of A. flavus hyphae after treatment with C. citratus essential oil. The hyphal diameter decreased and hyphal wall appeared as precipitates and disappeared in some regions. This oil also caused plasma membrane disruption and mitochondrial structure disorganization. Moreover, Ca(+2), K(+) and Mg(+2) leakages increased from the fumigated mycelium and its total lipid content decreased, while the saturated and unsaturated fatty acids increased. One of the most important results obtained during this study was the ability of C. citratus essential oil at its sublethal dose to completely inhibit aflatoxin B(1) production from A. flavus. These findings increase the possibility of exploiting C. citratus essential oil as an effective inhibitor of biodegradation and storage contaminating fungi and also in fruit juice preservation. PMID:17304618
Helal, G A; Sarhan, M M; Abu Shahla, A N K; Abou El-Khair, E K
Background The antifungal activity of selenium nanoparticles (Se NPs) prepared by Klebsiella pneumoniae has been reported previously for different fungi. In the present study, freshly prepared Se NPs produced by K. pneumoniae were purified and characterized by transmission electron microscopy and Energy-Dispersive X-ray spectroscopy (EDS) and its post antifungal effects for two fungi were evaluated. Materials and Methods The minimum inhibitory concentrations (MICs) of Se NPs, determined by serial dilution were 250 µg/ml for Aspergillusniger and 2,000 µg/ml for Candida albicans. The effect of exposure of A. niger and C. albicans to Se NPs on later growth was evaluated by incubating the fungi for 1 hour at 25 °C in media containing 0, 1, 2 and 4 x MIC of Se NPs and diluting the cultures 100 times with Se free medium. The kinetics of growth of the fungi in control cultures and in non-toxic Se NPs concentration of, 0.01 × MIC, 0.02 × MIC or 0.04 × MIC were measured. Results The exposure of A. niger and C. albicans to 2 and 4 x MIC of Se NPs stimulated the growth of both fungi in the absence of toxic concentrations of Se. The strongest stimulation was observed for A. niger. Conclusion It is concluded that exposure to high concentration of the Se NPs did not have any post-inhibitory effect on A. niger and C. albicans and that trace amounts of this element promoted growth of both fungi in a dose- dependent-manner. The role of nanoparticles serving as needed trace elements and development of microorganism tolerance to nanoparticles should not be dismissed while considering therapeutic potential.
Kazempour, Zahra Bahri; Yazdi, Mohammad Hossein; Rafii, Fatemeh; Shahverdi, Ahmad Reza
The aflatoxin biosynthetic pathway regulatory gene, aflR, encodes a putative 47-kDa protein containing a zinc cluster DNA binding motif. It is required for the transcription of all of the characterized aflatoxin pathway genes in both Aspergillusflavus and Aspergillus parasiticus. The objective of this study was to examine the effects of aflR overexpression on temporal gene expression, aflatoxin production, and nitrate inhibition of aflatoxin biosynthesis in A. flavus. An inducible expression construct was made by fusing the coding region of aflR to the promoter region of the A. flavus adh1 gene. This construct was transformed into A. flavus 656-2 (FGSC A1010), a strain mutated at the aflR locus. Strain 656-2 containing the adh1(p)::aflR construct had induced transcription of two early aflatoxin pathway genes, nor-1 and pksA, and produced wild-type concentrations of aflatoxin in a temporal pattern similar to that of wild-type strains of A. flavus. Strains 656-2 and 86-10 (FGSC A1009) an aflatoxigenic strain, were transformed with a construct containing the constitutive promoter gpdA driving aflR. Transformants of these strains constitutively expressed aflR, fas-1A, pksA, nor-1, and omtA but did not constitutively produce aflatoxin. Strain 86-10 containing the gpdA(p)::aflR construct produced 50 times more aflatoxin than 86-10, but the temporal pattern of aflatoxin production was the same as for 86-10, and aflatoxin production was also induced by sucrose. The addition of 10 g of nitrate per liter to sucrose low salts medium inhibited aflatoxin production by both strain 86-10 and a transformant of 86-10 containing the gpdA(p)::aflR construct, indicating that nitrate inhibition of aflatoxin biosynthesis does not occur solely at the level of aflR transcription. These studies show that constitutive overexpression of the pathway transcriptional regulatory gene aflR leads to higher transcript accumulation of pathway genes and increased aflatoxin production but that the initiation of aflatoxin biosynthesis is not solely regulated by the transcriptional activities of the biosynthetic pathway. PMID:16535712
Aspergillus species are the most frequent cause of invasive mold infections in immunocompromised patients. Although over 180 species are found within the genus, 3 species, Aspergillusflavus, A. fumigatus, and A. terreus, account for most cases of invasive aspergillosis (IA), with A. nidulans, A. niger, and A. ustus being rare causes of IA. The ability to distinguish between the various
In the present investigation, Aspergillusniger isolated from pistachio shell was applied to remove iron impurities from an Iranian kaolin sample. In order to study the effects of initial pH, sucrose and spore concentration on oxalic and citric acid production, and consequently iron dissolution, response surface methodology based on a five-level, three-variable central composite design of experiments was employed. Three
E. Aghaie; M. Pazouki; M. R. Hosseini; M. Ranjbar; F. Ghavipanjeh
The mycelia of Aspergillusniger, cultivated in a medium containing 45 g l?1 maltose, 66 g l?1 yeast extract, and 5 g l?1 K2HPO4 at 30°C and 200 rpm, were used as a biocatalyst in the glucosylation of ascorbic acid. Free mycelia from 3-day-old culture,\\u000a when used in a 6-h reaction with maltose as the acyl donor, gave 16.07 g l?1 ascorbic acid glucoside corresponding
Fungi occurring in Egyptian fruits in the City of Qena were studied. Results from the examination of 25 replicated samples of plums, pears and apples are reported. Examinations were carried out by direct plating after surface disinfection in a 0.5% (w\\/v) calcium hypochlorite solution on Czapek's-Dox agar. The dominant fungus found in the three types of fruit was Aspergillusniger,
A well-known industrial fungus for enzyme production, Aspergillusniger, was selected to produce the feruloyl esterase FAEA by homologous overexpression for pulp bleaching application. The gpd gene promoter was used to drive FAEA expression. Changing the nature and concentration of the carbon source nature (maltose to glucose; from 2.5 to 60 g l -1), improved FAEA activity 24.5-fold and a yield of
E. Record; M. Asther; C. Sigoillot; S. Pagčs; P. J. Punt; M. Delattre; M. Haon; C. A. M. J. J. van den Hondel; J.-C. Sigoillot; L. Lesage-Meessen
Summary Phosphofructokinase 2 (PFK 2) was isolated from mycelia of the citric-acid-accumulating fungus Aspergillusniger, and partially purified by Trisacryl-Blue chromatography and Mono Q fast protein liquid chromatography. The appearance of a 96\\/94-kDa double band correlated with PFK 2 activity during purification. Purified PFK 2 had a half-life of 240 min at 4° C. The enzyme exhibited Michaelis-Menten type kinetics
Hermie J. M. Harmsenl; Eva M. Kubicek-Pranz; Max Röhr; Jaap Visser; Christian P. Kubicek
The aim of the present study was to investigate the effect of low-intensity static magnetic fields (SMFs) on invertase activity and growth on different newly identified moulds. The most positive effect of SMFs on invertase activity and growth was observed forAspergillusniger OZ–3. The submerged production of invertase was performed with the spores obtained at the different exposure times (120,
Inulinase activity produced by a mixed culture of Aspergillusniger and Kluyveromyces marxianus growing on Jerusalem artichoke powder was investigated. Inulinase produced by this mixed culture had a higher invertase-type activity than inulinase from respective monocultures. When hydrolysis was carried out at 50°C with Jerusalem artichoke exctract (total sugar 16% w\\/v) at pH 5.0, 90% hydrolysis was achieved after 4
Two new phenethyl-?-pyrone derivatives including, isopyrophen (1) and aspergillusol (2), were characterised from the culture extract of Aspergillusniger EN–13, an endophytic fungus isolated from the inner tissue of the marine brown alga Colpomenia sinuosa. In addition, four known compounds, including a phenethyl-?-pyrone derivative (pyrophen, 3) and three cyclodipeptides (4–6), were also isolated and identified. The structures of these compounds
The Caldariomyces fumago chloroperoxidase was suc- cessfully expressed in Aspergillusniger. The recombi- nant enzyme was produced in the culture medium as an active protein and could be purified by a three-step purification procedure. The catalytic behavior of recom- binant chloroperoxidase (rCPO) was studied and com- pared with that of native CPO. The specific chlorination activity (47 units\\/nmol) of rCPO
Ana Conesa; Fred van de Velde; Fred van Rantwijk; Roger A. Sheldon; Cees A. M. J. J. van den Hondel; Peter J. Punt
A constitutive level of a mycelium-bound lipolytic activity from Aspergillusniger MYA 135 was strongly increased by 97% in medium supplemented with 2% olive oil. The constitutive lipase showed an optimal\\u000a activity in the pH range of 3.0–6.5, while the mycelium-bound lipase activity produced in the presence of olive oil had two\\u000a pH optima at pH 4 and 7. Interestingly, both
An extracellular acid phosphatase isolated from the culture of a wild strainAspergillusniger, producing the dephosphorylating 3-phytase, was obtained in a homogeneous form by sequential application of ultrafiltration\\u000a through PS 50 membrane, gel filtration on Sephadex G-100 and ion exchange chromatography on DEAE-Sepharose CL 6B and CM-Sepharose\\u000a CL 6B. The enzyme showed a maximum catalytic value in a strongly acidic
Background: Carbohydrate-binding domains are usually small and physically separate from the catalytic domains of hydrolytic enzymes. Glucoamylase 1 (G1) from Aspergillusniger, an enzyme used widely in the food and brewing industries, contains a granular starch binding domain (SBD) which is separated from the catalytic domain by a semi-rigid linker. The aim of this study was to determine how the
Kay Sorimachi; Marie-Françoise Le Gal-Coëffet; Gary Williamson; David B Archer; Michael P Williamson
Cultural conditions for the production of lipase by Aspergillusniger strain MTCC 2594 by solid-state fermentation using gingelly oil cake were standardized. A lipase activity of 363·6 U\\/g of dry substrate was obtained at 72 h under optimum conditions. Addition of various nitrogen sources, carbohydrates and inducers to the substrate was found to be ineffective. The enzyme was optimally active
Cellulase production by Aspergillusniger was compared in three different culture systems: biofilm, solid-state, and submerged fermentation. Biofilm and solid-state\\u000a fermentations were carried out on perlite as inert support, and lactose was used as a carbon source in the three culture systems.\\u000a In cryo-scanning electron microscopy, biofilm and solid-state cultures gave similar morphological patterns and confirmed that\\u000a both spore first
Norma N. Gamarra; Gretty K. Villena; Marcel Gutiérrez-Correa
We have constructed an Aspergillusniger cDNA library with a yeast expression vector. The library DNA complemented a leucine auxotroph of Saccharomyces cerevisiae (strain BWG1-7a) at a frequency of 4×10-4. Plasmids rescued from the yeast prototrophs also complemented Escherichia coli (strain MC1066) deficient in leucine biosynthesis. Sequence determination of the rescued plasmids revealed two genes for\\u000a ?-isopropylmalate dehydrogenase, which we
Using synthetic oligonucleotide probes, we cloned genomic DNA sequences encoding an a-amylase gene from Aspergillusniger var. awamori (A. awamori) on a 5.8 kb EcoRI fragment. Hybridization experiments, using a portion of this cloned fragment to probe DNA from A. awamori, suggested the presence of two a-amylase gene copies which were subsequently cloned as 7 kb (designated as amyA) and
David R. Korman; Frank T. Bayliss; Christopher C. Barnett; Cynthia L. Carmona; Katherine H. Kodama; Theresa J. Royer; Sheryl A. Thompson; Michael Ward; Lori J. Wilson; Randy M. Berka
Inulinase is a hydrolase used for inulin hydrolysis to produce functional fructooligosaccharides and fructose. The objective of the research was to obtain the optimum fermentation conditions of inulinase from Aspergillusniger X-6 mutated by microwave treatment with the Plackett-Burmen design and response surface methodology. The content of wheat bran, inulin, peptone, yeast extract, fermentation time, temperature, pH, and inoculum affecting
The continuous production of citric acid from dairy wastewater was investigated using calcium-alginate immobilizedAspergillusniger ATCC 9142. The citric acid productivity and yield were strongly affected by the culture conditions. The optimal pH, temperature,\\u000a and dilution rate were 3.0, 30°C, and 0.025 h?1, respectively. Under optimal culture conditions, the maximum productivity, concentration, and yield of citric acid produced\\u000a by the
Synthesis of amylase and protease by Aspergillusniger strain UO-1 was followed in media prepared with brewery (BW) and meat (MPW) wastewaters supplemented with different starch concentrations. The highest amylase (70.29 and 60.12EU\\/mL) and protease (6.11 and 6.03EU\\/mL) production were, respectively, obtained in the BW and MPW media supplemented with 40g of starch\\/L of medium after 88h of fermentation. In
Mabel Salas Hernández; Marilú Rodríguez Rodríguez; Nelson Pérez Guerra; Renato Pérez Rosés
Elicitors derived from the cell wall of fungi are shown to be active in eliciting resistance in plants against a wide range\\u000a of pathogens. In the present study carbohydrate components from the autoclaved spore cell wall ofAspergillusniger were prepared as aqueous suspensions and tested for defense response in pearl millet (Pennisetum glaucum (L.) R.Br.) against the oomycetous downy mildew
C. K. Hindumathy; S. Shailasree; K. Ramachandra Kini; H. Shekar Shetty
Cutaneous aspergillosis is a rare infection most often seen in immunocompromised patients. We report a case of primary cutaneous aspergillosis infection in a nonhealing scalp wound of an immunocompetent elderly patient. The patient had a cutaneous malignancy of the scalp treated with surgical excision but complicated by poor wound healing. Fungal culture of the nonhealing wound revealed Aspergillusniger. The nonhealing wound subsequently resolved with retapamulin ointment 1% and ketoconazole gel 2%. PMID:21644495
Tracheal or bronchial aspergillar locations are rare. They are mainly found in patients with general or localised immune deficiency. The authors report the case of a 53-year-old Vietnamese immunocompetent patient without any factors of risk who suddenly came down with a perforation syndrome indicating a tracheo-oesophageal fistula. The bronchial samples helped identify Aspergillusniger as the agent incriminated. Surgical treatment associated with an antifungal treatment provided a cure without any recurrence for 3 years. PMID:19878804
When synthetic wastewater containing Cr(VI) was placed in contact with the dead fungal biomass of Aspergillusniger, the Cr(VI) was completely removed from aqueous solution, whereas Cr(III), which was not initially present, appeared in aqueous solution. Desorption and X-ray photoelectron spectroscopy (XPS) studies showed that most of the Cr bound on the biomass was in trivalent form. These results indicated
Donghee Park; Yeoung-Sang Yun; Ji Hye Jo; Jong Moon Park
Natural oils with high unsaturated fatty acids content when added at concentrations of 2% and 4% (v/v) to beet molasses (BM) medium caused a considerable increase in citric acid yield from Aspergillusniger. The fermentation capacities were also examined for production of citric acid using BM-oil media under different fermentation conditions. Maximum citric acid yield was achieved in surface culture in the presence of 4% olive oil after 12 days incubation. PMID:12137276
The effect of water activity (aw) (0.82–0.99) on growth and ochratoxin A (OTA) production by twelve Aspergillusniger aggregate strains, cultured in Czapek Yeast Autolysate agar (CYA) and Yeast Extract Sucrose agar (YES), was studied for an incubation period of 30 days. The strains were selected to include diverse sources, different reported abilities to produce OTA and different ITS-5.8 S
A. Esteban; M. L. Abarca; M. R. Bragulat; F. J. Cabańes
The effect of pH (2–10) on growth and ochratoxin A (OTA) production by 12 Aspergillusniger aggregate strains was studied in two culture media: Czapek yeast autolysate agar (CYA) and yeast extract sucrose agar (YES), over 30 days. The strains were selected to include different sources, different reported abilities to produce OTA and different ITS-5.8S rDNA RFLP patterns. YES was
A. Esteban; M. L. Abarca; M. R. Bragulat; F. J. Cabańes
An isopullulanase (IPU) from Aspergillusniger ATCC9642 hydrolyzes ?-1,4-glucosidic linkages of pullulan to produce isopanose. Although IPU does not hydrolyze dextran, it is classified into glycoside hydrolase family 49 (GH49), major members of which are dextran-hydrolyzing enzymes. IPU is highly glycosylated, making it difficult to obtain its crystal. We used endoglycosidase Hf to cleave the N-linked oligosaccharides of IPU, and
A local isolate of Aspergillusniger was cultivated under optimal growth conditions on wheat bran in solid state fermentation. ?-endoglucanase from fermented\\u000a bran was separately extracted with different solvents to test recovery of enzyme. Among solvents tested, distilled water served\\u000a the best leachate. Conditions were further optimized with this leachate. Two washes of fermented bran with the leachate for\\u000a 30
M. Subhosh Chandra; Buddolla Viswanath; B. Rajasekhar Reddy
There is a wide range of biotechnological applications for amylases, including the textile, pharmaceutical, food and laundry industries. Hydrolytic enzymes are 100% biodegradable and enzymatic detergents can achieve effective cleaning with lukewarm water. Microorganisms and culture media were tested for amylase production and the best producer was Aspergillusniger L119 (3.9Uml?1±0.2) in submerged culture and its amylase demonstrated excellent activity
Sydnei Mitidieri; Anne Helene Souza Martinelli; Augusto Schrank; Marilene Henning Vainstein
The efficacy of lipase from Aspergillusniger MTCC 2594 as an additive in laundry detergent formulations was assessed using response surface methodology (RSM). A five-level four-factorial central composite design was chosen to explain the washing protocol with four critical factors, viz. detergent concentration, lipase concentration, buffer pH and washing temperature. The model suggested that all the factors chosen had a
N. Saisubramanian; N. G. Edwinoliver; N. Nandakumar; N. R. Kamini; R. Puvanakrishnan
ATP:citrate lyase (EC 18.104.22.168) has been identified in cell-free extracts from the filamentous fungus Aspergillusniger. The enzyme was located in the cytosol. It exhibits an activity at least ten times that of acetate-CoA-kinase (EC 22.214.171.124) during growth on carbohydrates as carbon sources, and is thus considered responsible for acetyl-CoA formation under these conditions. It is formed constitutively and its
Summary \\u000a Aspergillusniger produced extracellular cellobiase when grown on different lignocellulosic substrates in solid state fermentation. The enzyme activity and yield were variable according to the carbon source. In Vogel’s medium, the cellobiase productivity was significantly higher on wheat bran, followed by Leptochloa fusca (kallar grass) straw augmented with corn steep liquor. Maximum yield of cellobiase\\/g wheat bran was significantly
Muhammad Ibrahim Rajoka; Muhammad Waheed Akhtar; Atif Hanif; A. M. Khalid
The thermotolerant fungus, Aspergillusniger NCIM 563, was used for production of extracellular phytase on agricultural residues: wheat bran, mustard cake, cowpea meal,\\u000a groundnut cake, coconut cake, cotton cake and black bean flour in solid state fermentation (SSF). Maximum enzyme activity\\u000a (108?U?g?1 dry mouldy bran, DMB) was obtained with cowpea meal. During the fermentation phytic acid was hydrolysed completely with
Air pressure pulsation solid state fermentation (APP-SSF) was applied to produce feruloyl esterase (FAE) by Aspergillusniger. With the optimization of some variables by orthogonal design, the optimal condition obtained was 0.2MPa (gauge pressure) of high pressure intensity, 30min of low pressure duration and 20s of high pressure duration. Based on the optimized condition, the APP-SSF achieved the reasonable enzyme
The filamentous fungus Aspergillusniger is widely used in biotechnological applications. Strain CBS513.88 is known to harbor 21 copies of the nonautonomous transposon Vader. Upon selection of chlorate-resistant A. niger colonies, one Vader copy was found integrated in the nirA gene. This copy was used for vector construction and development of a transposon-tagging method. Vader showed an excision frequency of about 1 in 2.2 × 105 conidiospores. A total of 95 of 97 colonies analyzed exhibited an excision event at the DNA level, and Vader footprints were found. By employing thermal asymmetric interlaced (TAIL)-PCR, the reintegration sites of 21 independent excision events were determined. All reintegration events occurred within or very close to genes. Therefore, this method can be used for transposon mutagenesis in A. niger.
Hihlal, Elkbir; Braumann, Ilka; van den Berg, Marco; Kempken, Frank
The filamentous fungus Aspergillusniger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of the 14,165 open reading frames identified. A detailed description of the components of the protein secretion pathway was made and striking differences in the hydrolytic enzyme spectra of aspergilli were observed. A reconstructed metabolic network comprising 1,069 unique reactions illustrates the versatile metabolism of A. niger. Noteworthy is the large number of major facilitator superfamily transporters and fungal zinc binuclear cluster transcription factors, and the presence of putative gene clusters for fumonisin and ochratoxin A synthesis. PMID:17259976
Pel, Herman J; de Winde, Johannes H; Archer, David B; Dyer, Paul S; Hofmann, Gerald; Schaap, Peter J; Turner, Geoffrey; de Vries, Ronald P; Albang, Richard; Albermann, Kaj; Andersen, Mikael R; Bendtsen, Jannick D; Benen, Jacques A E; van den Berg, Marco; Breestraat, Stefaan; Caddick, Mark X; Contreras, Roland; Cornell, Michael; Coutinho, Pedro M; Danchin, Etienne G J; Debets, Alfons J M; Dekker, Peter; van Dijck, Piet W M; van Dijk, Alard; Dijkhuizen, Lubbert; Driessen, Arnold J M; d'Enfert, Christophe; Geysens, Steven; Goosen, Coenie; Groot, Gert S P; de Groot, Piet W J; Guillemette, Thomas; Henrissat, Bernard; Herweijer, Marga; van den Hombergh, Johannes P T W; van den Hondel, Cees A M J J; van der Heijden, Rene T J M; van der Kaaij, Rachel M; Klis, Frans M; Kools, Harrie J; Kubicek, Christian P; van Kuyk, Patricia A; Lauber, Jürgen; Lu, Xin; van der Maarel, Marc J E C; Meulenberg, Rogier; Menke, Hildegard; Mortimer, Martin A; Nielsen, Jens; Oliver, Stephen G; Olsthoorn, Maurien; Pal, Karoly; van Peij, Noël N M E; Ram, Arthur F J; Rinas, Ursula; Roubos, Johannes A; Sagt, Cees M J; Schmoll, Monika; Sun, Jibin; Ussery, David; Varga, Janos; Vervecken, Wouter; van de Vondervoort, Peter J J; Wedler, Holger; Wösten, Han A B; Zeng, An-Ping; van Ooyen, Albert J J; Visser, Jaap; Stam, Hein
Direct fermentation of unhydrolyzed potato starch to ethanol by monocultures of an amylolytic fungus, Aspergillusniger, and cocultures of A. niger and Saccharomyces cerevisiae was investigated. Amylolytic activity, rate and amount of starch utilization, and ethanol yields increased several-fold in coculture versus the monoculture due to the synergistic metabolic interactions between the species. Optimal ethanol yields were obtained in the pH range 5 to 6 and amylolytic activity was obtained in the pH range 5 to 8. Ethanol yields were maximal when fermentations were conducted anaerobically. Increasing S. cerevisiae inoculum in the coculture from 4 to 12% gave a dramatic increase in the rate of ethanol production, and ethanol yields of greater than 96% of the theoretical maximum were obtained within 2 days of fermentation. These results indicate that simultaneous fermentation of starch to ethanol can be conducted efficiently by using cocultures of the amylolytic fungus A. niger and a nonamylolytic sugar fermenter, S. cerevisiae.
Background Laccase-like multicopper oxidases have been reported in several Aspergillus species but they remain uncharacterized. The biocatalytic potential of the Aspergillusniger fungal pigment multicopper oxidases McoA and McoB and ascomycete laccase McoG was investigated. Results The laccase-like multicopper oxidases McoA, McoB and McoG from the commonly used cell factory Aspergillusniger were homologously expressed, purified and analyzed for their biocatalytic potential. All three recombinant enzymes were monomers with apparent molecular masses ranging from 80 to 110 kDa. McoA and McoG resulted to be blue, whereas McoB was yellow. The newly obtained oxidases displayed strongly different activities towards aromatic compounds and synthetic dyes. McoB exhibited high catalytic efficiency with N,N-dimethyl-p-phenylenediamine (DMPPDA) and 2,2-azino-di(3-ethylbenzthiazoline) sulfonic acid (ABTS), and appeared to be a promising biocatalyst. Besides oxidizing a variety of phenolic compounds, McoB catalyzed successfully the decolorization and detoxification of the widely used textile dye malachite green. Conclusions The A. niger McoA, McoB, and McoG enzymes showed clearly different catalytic properties. Yellow McoB showed broad substrate specificity, catalyzing the oxidation of several phenolic compounds commonly present in different industrial effluents. It also harbored high decolorization and detoxification activity with the synthetic dye malachite green, showing to have an interesting potential as a new industrial biocatalyst.
After harvest, maize is dried artificially to halt fungal growth and mycotoxin production while in postharvest storage. The process often limits harvest capacity and has been a frequent cause of seed injury. Higher drying temperatures could lead to shorter drying periods and faster turnover; however, there is often a deterioration of the physical grain quality, including increased breakage susceptibility and loss of viability. The goals of this study were to determine the effect of different postharvest drying temperatures on Aspergillus filavus and Fusarium verticillioides survival and aflatoxin content in maize and to determine the viability of the seed. Five corn hybrids varying in resistance to A. flavus were side needle-inoculated with A. flavus, harvested at physiological maturity, and dried at temperatures ranging from 40 to 70 degrees C. Kernels were evaluated for aflatoxin, stress cracks, germination, and kernel infection by A. flavus and a natural infestation of F. verticillioides. Drying temperature had no effects on aflatoxin concentration given the heat stability of the toxin. With increased temperatures from 40 to 70 degrees C, germination decreased significantly, from 96 to 27%, and stress cracks increased significantly (1.4 up to 18.7). At temperatures above 60 degrees C, F. verticillioides kernel infection was significantly reduced to less than 18%. At 70 degrees C, there was a significant reduction in A. flavus kernel infection, from 11 to 3%. This information is useful in determining a range of temperatures that can be used for drying seed when fungal infection, stress cracks, and seed viability are of interest. PMID:16013400
Hawkins, Leigh K; Windham, Gary L; Williams, W Paul
The present study was aimed at optimization, production and partial purification of lipases from Pseudomonas aeruginosa, Candida albicans and Aspergillusflavus. Various nutritional and physical parameters affecting lipase production such as carbon and nitrogen supplements, pH, temperature, agitation speed and incubation time were studied. Refined sunflower oil (1% v/v) and tryptone at a pH of 6.2 favored maximum lipase production in Pseudomonas at 30 degrees C and 150 rpm, when incubated for 5 days. In C. albicans refined sunflower oil (3% v/v) and peptone resulted in maximum lipase production at pH 5.2, 30 degrees C and 150 rpm, when incubated for 5 days. In A. flavus coconut oil (3% v/v) and peptone yielded maximum lipase at pH 6.2, 37 degrees C, 200 rpm after an incubation period of 5 days. The lipases were partially purified by ammonium sulphate precipitation and dialysis. In P. aeruginosa enzyme activity of the dialyzed fraction was found to be 400 U mL-' and for C. albicans 410 U mL(-1). The dialysed lipase fraction from A. flavus demonstrated an activity of 460 U mL(-1). The apparent molecular weights of the dialyzed lipases were determined by sodium dodecyl sulphate polyacrylamide gel electrophoresis (SDS-PAGE). The dialyzed lipase fraction obtained from P. aeruginosa revealed molecular weights of 47, 49 and 51 kDa, whereas, lipases from C. albicans and A. flavus demonstrated 3 bands (16.5, 27 and 51 kDa) and one band (47 kDa), respectively. These extracellular lipases may find wide industrial applications. PMID:22514878
Research conducted at the USDA-ARS (Stoneville, MS) demonstrated that aflatoxin contamination in maize is dramatically reduced by inoculation with the atoxigenic Aspergillusflavus strain K49. To facilitate storage for field applications a series of studies were conducted on the reliability and effi...
The ability of mites of the species Tyrophagus putrescentiae to spread the toxigenic fungus Aspergillusflavus from contaminated maize to sterile grains was studied under controlled conditions. Maize samples were distributed among boxes, each divided into two compartments by a barrier of polystyrene and having restricted access from one compartment to the other. One box contained only uncontaminated maize (negative
Marcia R Franzolin; Walderez Gambale; Raul G Cuero; Benedito Correa
Jasmonic acid (JA), produced by the octadecanoid pathway, is a phytohormone that triggers induced resistance against certain pathogens and arthropod herbivores. The octadecanoid pathway has been implicated in playing a role in the Aspergillusflavus-maize seed interaction. In field studies, the ef...
Aflatoxins are carcinogens produced by Aspergillusflavus and A. parasiticus during infection of susceptible crops such as maize. Several resistant maize genotypes have been identified and the kernel proteins have been suggested to play an important role in resistance. Through comparisons of kerne...
The enantioselective hydrolysis of racemic epichlorohydrin for the production of enantiopure (S)-epichlorohydrin using whole cells of Aspergillusniger ZJB-09173 in organic solvents was investigated. Cyclohexane was used as the reaction medium based on the excellent enantioselectivity of epoxide hydrolase from A. niger ZJB- 09173 in cyclohexane. However, cyclohexane had a negative effect on the stability of epoxide hydrolase from A. niger ZJB-09173. In the cyclohexane medium, substrate inhibition, rather than product inhibition of catalysis, was observed in the hydrolysis of racemic epichlorohydrin using A. niger ZJB-09173. The racemic epichlorohydrin concentration was markedly increased by continuous feeding of substrate without significant decline of the yield. Ultimately, 18.5% of (S)-epichlorohydrin with 98 percent enantiomeric excess from 153.6 mM of racemic epichlorohydrin was obtained by the dry cells of A. niger ZJB-09173, which was the highest substrate concentration in the production of enantiopure (S)-epichlorohydrin by epoxide hydrolases using an organic solvent medium among the known reports. PMID:22922194
The presence of a mannitol cycle in fungi has been subject to discussion for many years. Recent studies have found no evidence for the presence of this cycle and its putative role in regenerating NADPH. However, all enzymes of the cycle could be measured in cultures of Aspergillusniger. In this study we have analyzed the localization of two enzymes from the pathway, mannitol dehydrogenase and mannitol-1-phosphate dehydrogenase, and the expression of their encoding genes in nonsporulating and sporulating cultures of A. niger. Northern analysis demonstrated that mpdA was expressed in both sporulating and nonsporulating mycelia, while expression of mtdA was expressed only in sporulating mycelium. More detailed studies using green fluorescent protein and dTomato fused to the promoters of mtdA and mpdA, respectively, demonstrated that expression of mpdA occurs in vegetative hyphae while mtdA expression occurs in conidiospores. Activity assays for MtdA and MpdA confirmed the expression data, indicating that streaming of these proteins is not likely to occur. These results confirm the absence of the putative mannitol cycle in A. niger as two of the enzymes of the cycle are not present in the same part of A. niger colonies. The results also demonstrate the existence of spore-specific genes and enzymes in A. niger.
Aguilar-Osorio, Guillermo; vanKuyk, Patricia A.; Seiboth, Bernhard; Blom, Dirk; Solomon, Peter S.; Vinck, Arman; Kindt, Frits; Wosten, Han A. B.; de Vries, Ronald P.
Background Infectious Bursal Disease Virus (IBDV) causes a highly immunosuppressive disease in chickens and is a pathogen of major economic importance to the poultry industry worldwide. The VP2 protein is the major host-protective immunogen of IBDV and has been considered as a potential subunit vaccine against the disease. VP2 coding sequence was cloned in an inducible fungal vector and the protein was expressed in Aspergillusniger (A. niger). Methods Aiming at a high level of expression, a multicopy AMA1-pyrG-based episomal construct driven by a strong inducible promoter, glaA, was prepared and used in transformation of A. niger pyrG-protoplasts. SDS-PAGE and western blot analysis was carried out to confirm the expression of the protein. Results A number of pyrG + positive transformants were isolated and the presence of expression cassette was confirmed. Western blot analysis of one of these recombinant strains using monospecific anti-VP2 antibodies demonstrated the successful expression of the protein. The recombinant protein was also detected by serum obtained from immunized chicken. Conclusion In the present study, we have generated a recombinant A. niger strain expressing VP2 protein intracellulary. This recombinant strain of A. niger may have potential applications in oral vaccination against IBDV in poultry industry.
In order to investigate the influence of different hyphal inoculum sizes on minimal inhibition concentrations (MICs) and minimum fungicidal concentrations (MFCs) of amphotericin B (AMB), voriconazole and itraconazole, five isolates each of Aspergillus fumigatus, Aspergillusflavus, Aspergillusniger and Aspergillus terreus were studied using a broth microdilution method. Three inoculum sizes were used: 1×103–5×103, 1×104–5×104 and 1×105–5×105 cfu\\/ml. MICs and
Cornelia Lass-Flörl; C Speth; G Kofler; M. P Dierch; E Gunsilius; R Würzner
Indirect fluorescent antibody technique was used for the detection of A. flavus entry in pistachio nuts where the kernel is protected with a hard, usually nonsplit, shell. Sound nuts were inoculated with a toxigenic species of A. flavus and stored at 88% RH for three weeks at 29 degrees C. Aflatoxins could be detected in the kernels at a level of 65 micrograms/kg at the end of this period. Antisera for A. flavus was produced using female New Zealand white rabbits. Cross sections of various parts of the shell were treated using indirect fluorescent antibody technique. Microscopic examinations revealed mycelial fragments only in sections taken from the vascular system. Presence of fluorescent mycelial fragments in the vascular bundles indicate that fungal invasion of tree nuts which are protected with a hard shell take place through the vascular system. PMID:1573560
A novel endoprotease Endo-Pro-Aspergillusniger (endoprotease EPR) was first successfully expressed at high level in the methylotrophic yeast Pichia pastoris and the purification procedure was established. The endoprotease EPR is 95 % identity with proline specific endopeptidase from A. niger CBS513.88 (EMBL; AX458699), while sharing low identity with those from other microorganisms. The purified endoprotease EPR was a monomer of 60 kDa. Furthermore, the peptide mass fingerprinting (PMF) analysis confirmed that the purified protein was an endoprotease Endo-Pro-Aspergillusniger. A three-dimensional model revealed that the active site of the enzyme was located in Ser(179)-Asp(458)-His(491), based on template 3n2zB with sequence identity of 17.6 %. The optimum pH and temperature of the endoprotease EPR were pH 4-5 and 35 °C, and the stabilities were pH 3-7 and 15-60 °C, respectively. Furthermore, the endoprotease EPR had the ability to digest peptides with the C-terminal of proline as well as alanine, and was also capable of hydrolyzing larger peptides. The properties of the endoprotease EPR made it a highly promising candidate for future application in the field of brewing and food process. PMID:23685896
Aspergillusniger is a fungus of the genus Aspergillus. It has caused a disease called black mold on certain fruits and vegetables. The culture filtrates released from the A. niger ATCC 66566 were grown in Czapek dox broth (CDB) then filtered with flash chromatograph and were used for the bioassay after a growth of thirty days. The result demonstrated these mortalities with LC50, LC90, and LC99 values of Culex quinquefasciatus 0.76, 3.06, and 4.75, Anopheles stephensi 1.43, 3.2, and 3.86, and Aedes aegypti 1.43, 2.2, and 4.1??l/cm2, after exposure of seven hours. We have calculated significant LT90 values of Cx. quinquefasciatus 4.5, An. stephensi 3.54, and Ae. aegypti 6.0?hrs, respectively. This liquid spray of fungal culture isolate of A. niger can reduce malaria, dengue, and filarial transmission. These results significantly support broadening the current vector control paradigm beyond chemical adulticides.
Chlorimuron-ethyl, ethyl-2-[[[[(4-methoxy-6-chloro-pyrimidin-2-yl)amino]carbonyl]amino] sulfonyl]benzoate, is used as a pre- and postemergence herbicide for the control of important broadleaved weeds in soybean and maize. Due to its phytotoxicity to rotation crops, concerns regarding chlorimuron contamination of soil and water have been raised. Although it is degraded in the agricultural environment primarily via pH- and temperature-dependent chemical hydrolysis, microbial transformation also has an important role. Fungi such as Fusarium and Alternaria are unable to survive in artificial media containing chlorimuron-ethyl at 25 mg L(-1) . However, Aspergillusniger survived in minimal broth containing chlorimuron at 2 mg mL(-1) . Aspergillusniger degraded the herbicide to harvest energy through two major routes of degradation. One route involves the cleavage of the sulfonylurea bridge, resulting in the formation of two major metabolites, namely ethyl-2-aminosulfonylbenzoate (I) and 4-methoxy-6-chloro-2-amino-pyrimidine (II). The other route is the cleavage of sulfonylamide linkage, which generates the metabolite N-(4-methoxy-6-chloropyrimidin-2-yl) urea (III). Two other metabolites, saccharin (IV) and N-methyl saccharin (V), formed from metabolite II, were also identified. A metabolic pathway for the degradation of chlorimuron-ethyl by A. niger has been proposed. PMID:22967225
Sharma, Seema; Banerjee, Kaushik; Choudhury, Partha P
The fluG gene is a member of a family of genes required for conidiation and sterigmatocystin production in Aspergillus nidulans. We examined the role of the Aspergillusflavus fluG orthologue in asexual development and aflatoxin biosynthesis. Deletion of fluG in A. flavus yielded strains with an approximately 3-fold reduction in conidiation but a 30-fold increase in sclerotial formation when grown on potato dextrose agar in the dark. The concurrent developmental changes suggest that A. flavus FluG exerts opposite effects on a mutual signaling pathway for both processes. The altered conidial development was in part attributable to delayed expression of brlA, a gene controlling conidiophore formation. Unlike the loss of sterigmatocystin production by A. nidulans fluG deletion strains, aflatoxin biosynthesis was not affected by the fluG deletion in A. flavus. In A. nidulans, FluG was recently found to be involved in the formation of dehydroaustinol, a component of a diffusible signal of conidiation. Coculturing experiments did not show a similar diffusible meroterpenoid secondary metabolite produced by A. flavus. These results suggest that the function of fluG and the signaling pathways related to conidiation are different in the two related aspergilli.
Scharfenstein, Leslie L.; Mack, Brian; Ehrlich, Kenneth C.
Background Aspergillusniger, a saprophyte commonly found on decaying vegetation, is widely used and studied for industrial purposes. Despite its place as one of the most important organisms for commercial applications, the lack of available information about its genetic makeup limits research with this filamentous fungus. Results We present here the analysis of 12,820 expressed sequence tags (ESTs) generated from A. niger cultured under seven different growth conditions. These ESTs identify about 5,108 genes of which 44.5% code for proteins sharing similarity (E ? 1e -5) with GenBank entries of known function, 38% code for proteins that only share similarity with GenBank entries of unknown function and 17.5% encode proteins that do not have a GenBank homolog. Using the Gene Ontology hierarchy, we present a first classification of the A. niger proteins encoded by these genes and compare its protein repertoire with other well-studied fungal species. We have established a searchable web-based database that includes the EST and derived contig sequences and their annotation. Details about this project and access to the annotated A. niger database are available. Conclusion This EST collection and its annotation provide a significant resource for fundamental and applied research with A. niger. The gene set identified in this manuscript will be highly useful in the annotation of the genome sequence of A. niger, the genes described in the manuscript, especially those encoding hydrolytic enzymes will provide a valuable source for researchers interested in enzyme properties and applications.
Posaconazole and/or amphotericin B was given to mice pretreated with a steroid and then infected by inhalation of Aspergillusflavus conidia. Two laboratories conducted studies using almost identical protocols to evaluate both survival and lung tissue burdens 8 days after infection. The results of the in vivo studies performed at both laboratories were consistent. We found that (i) up to 5 mg of amphotericin B per kg of body weight was poorly effective in treating invasive aspergillosis; (ii) posaconazole at 2 or 10 mg/kg/dose prolonged survival and reduced lung tissue CFU; and (iii) there was generally no antagonistic interaction of the drugs in combination, even when the experiments were designed to maximize the likelihood of antagonism. These studies do not confirm the antagonistic interaction of triazoles and polyenes reported by others.
Najvar, Laura K.; Cacciapuoti, Anthony; Hernandez, Steve; Halpern, Judith; Bocanegra, Rosie; Gurnani, Maya; Menzel, Frederick; Loebenberg, David; Graybill, John R.
An immune response is triggered in host cells when host receptors recognize conserved molecular motifs, pathogen-associated molecular patterns (PAMPs), such as ?-glucans, and chitin at the cell surface of a pathogen. Effector-triggered immunity occurs when pathogens deliver effectors into the host cell to suppress the first immune signaling. Using a differential proteomic approach, we identified an array of proteins responding to aflatoxins in cotyledons of peanut (Arachis hypogaea) infected with aflatoxin-producing (toxigenic) but not nonaflatoxin-producing (atoxigenic) strains of Aspergillusflavus. These proteins are involved in immune signaling and PAMP perception, DNA and RNA stabilization, induction of defense, innate immunity, hypersensitive response, biosynthesis of phytoalexins, cell wall responses, peptidoglycan assembly, penetration resistance, condensed tannin synthesis, detoxification, and metabolic regulation. Gene expression analysis confirmed the differential abundance of proteins in peanut cotyledons supplemented with aflatoxins, with or without infection with the atoxigenic strain. Similarly, peanut germination and A. flavus growth were altered in response to aflatoxin B1. These findings show an additional immunity initiated by aflatoxins. With the PAMP- and effector-triggered immune responses, this immunity constitutes the third immune response of the immune system in peanut cotyledon cells. The system is also a three-grade coevolution of plant-pathogen interaction. PMID:22424419
Wang, Zizhang; Yan, Shijuan; Liu, Chunming; Chen, Fang; Wang, Tai
Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and during storage, and also a concern in many other crops, such as peanuts, cottonseed, tree nuts, and rice. Although a number of resistant maize lines with low aflatoxin c...
Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and through storage. Previous studies have highlighted the constitutive production of proteins involved in maize kernel resistance against A. flavus’ infection. However, little is known about induced resistance nor about defense gene expression and regulation in kernels. In this study, maize oligonucleotide arrays and a pair of closely-related maize lines varying in aflatoxin accumulation were used to reveal the gene expression network in imbibed mature kernels in response to A. flavus’ challenge. Inoculated kernels were incubated 72 h via the laboratory-based Kernel Screening Assay (KSA), which highlights kernel responses to fungal challenge. Gene expression profiling detected 6955 genes in resistant and 6565 genes in susceptible controls; 214 genes induced in resistant and 2159 genes induced in susceptible inoculated kernels. Defense related and regulation related genes were identified in both treatments. Comparisons between the resistant and susceptible lines indicate differences in the gene expression network which may enhance our understanding of the maize-A. flavus interaction.
Crude ethanolic extracts of kaffir lime leaf, bitter cucumber fruit and tobacco leaf were examined for their ability to control the growth of A. flavus on PDA. The results showed that the ethanolic extracts of all herbs had an inhibitory effect on fungal growth. Kaffir lime at 10 % and tobacco at 8-10 % showed significantly higher inhibition than at
Because aflatoxins are toxic and extremely carcinogenic to animals, they pose a serious risk to human health. In order to better understand the molecular mechanisms that control or regulate aflatoxin production, identification of genes (gene profiling) using A. flavus expressed sequence tags (ESTs)...
...flavus AF36 in or on pistachio when applied as an antifungal agent and used in accordance with good agricultural practices...and corn, pop, stover, when applied/used as an antifungal agent. [68 FR 41541, July 14, 2003, as...
A transposable element has been isolated from the industrially important fungus Aspergillusniger (strain N402). The element was identified as an insertion sequence within the coding region of the nitrate reductase gene. It had inserted at a TA site and appeared to have duplicated the target site upon insertion. The isolated element was found to be 4798 bp in length and contained 37-bp inverted, imperfect, terminal repeats (ITRs). The sequence of the central region of the element revealed an open reading frame (designated ORF1) which showed similarity, at the amino acid level, to the transposase of the Tc1/mariner class of DNA transposons. Another sequence within the central region of the element showed similarity to the 3' coding and downstream untranslated region of the amyA gene of A. niger. Sequence homology and structural features indicate that this element, which has been named Ant1 (A. niger transposon 1), is related to the Tc1/mariner group of DNA transposons. Ant1 is apparently present as a single copy in strain N402 of A. niger. PMID:8552048
Glayzer, D C; Roberts, I N; Archer, D B; Oliver, R P
Aspergillus carbonarius and A. niger aggregate are the main fungal contaminants of table grapes. Besides their ability to cause black rot, they can produce ochratoxin A (OTA), a mycotoxin that has attracted increasing attention worldwide. The objective of this work was to set up a simple and rapid molecular method for the early detection of both fungi in table grapes before fungal development becomes evident. Polymerase chain reaction (PCR)-based assays were developed by designing species-specific primers based on the polyketide synthases (PKS(S)) sequences of A. carbonarius and A. niger that have recently been demonstrated to be involved in OTA biosynthesis. Three table grape varieties (Red globe, Crimson seedless, and Italia) were inoculated with A. carbonarius and A. niger aggregate strains producing OTA. The extracted DNA from control (non-inoculated) and inoculated grapes was amplified by PCR using ACPKS2F-ACPKS2R for A. carbonarius and ANPKS5-ANPKS6 for A. niger aggregate. Both primers allowed a clear detection, even in symptomless samples. PCR-based methods are considered to be a good alternative to traditional diagnostic means for the early detection of fungi in complex matrix for their high specificity and sensitivity. The results obtained could be useful for the definition of a 'quality label' for tested grapes to improve the safety measures taken to guarantee the production of fresh table grapes. PMID:20582777
Ayoub, F; Reverberi, M; Ricelli, A; D'Onghia, A M; Yaseen, T
We report the cloning and characterization of a gene encoding a ferulic acid esterase, faeA, from Aspergillusniger and Aspergillus tubingensis. The A. niger and A. tubingensis genes have a high degree of sequence identity and contain one conserved intron. The gene product, FAEA, was overexpressed in wild-type A. tubingensis and a protease-deficient A. niger mutant. Overexpression of both genes in wild-type A. tubingensis and an A. niger protease-deficient mutant showed that the A. tubingensis gene product is more sensitive to degradation than the equivalent gene product from A. niger. FAEA from A. niger was identical to A. niger FAE-III (C. B. Faulds and G. Williamson, Microbiology 140:779-787, 1994), as assessed by molecular mass, pH and temperature optima, pI, N-terminal sequence, and activity on methyl ferulate. The faeA gene was induced by growth on wheat arabinoxylan and sugar beet pectin, and its gene product (FAEA) released ferulic acid from wheat arabinoxylan. The rate of release was enhanced by the presence of a xylanase. FAEA also hydrolyzed smaller amounts of ferulic acid from sugar beet pectin, but the rate was hardly affected by addition of an endo-pectin lyase.
de Vries, R P; Michelsen, B; Poulsen, C H; Kroon, P A; van den Heuvel, R H; Faulds, C B; Williamson, G; van den Hombergh, J P; Visser, J
Background Aflatoxins (AFs) are highly carcinogenic compounds produced by Aspergillus species in seeds with high lipid and protein contents. It has been known for over 30?years that peptone is not conducive for AF productions, although reasons for this remain unknown. Results In this study, we showed that when Aspergillusflavus was grown in peptone-containing media, higher initial spore densities inhibited AF biosynthesis, but promoted mycelial growth; while in glucose-containing media, more AFs were produced when initial spore densities were increased. This phenomenon was also observed in other AF-producing strains including A. parasiticus and A. nomius. Higher peptone concentrations led to inhibited AF production, even in culture with a low spore density. High peptone concentrations did however promote mycelial growth. Spent medium experiments showed that the inhibited AF production in peptone media was regulated in a cell-autonomous manner. mRNA expression analyses showed that both regulatory and AF biosynthesis genes were repressed in mycelia cultured with high initial spore densities. Metabolomic studies revealed that, in addition to inhibited AF biosynthesis, mycelia grown in peptone media with a high initial spore density showed suppressed fatty acid biosynthesis, reduced tricarboxylic acid (TCA) cycle intermediates, and increased pentose phosphate pathway products. Additions of TCA cycle intermediates had no effect on AF biosynthesis, suggesting the inhibited AF biosynthesis was not caused by depleted TCA cycle intermediates. Conclusions We here demonstrate that Aspergillus species grown in media with peptone as the sole carbon source are able to sense their own population densities and peptone concentrations to switch between rapid growth and AF production. This switching ability may offer Aspergillus species a competition advantage in natural ecosystems, producing AFs only when self-population is low and food is scarce.
Chromium (VI) tolerance and removal efficiency of facultative marine fungus Aspergillusniger/ in the absence and presence of MnZn ferrite magnetic fluid (MF) has been studied. The fungus exhibits a luxuriant growth in the presence of hexavalent chromium at the concentration 25 mg/L. The MF also exhibits a positive effect on biomass accumulation. Percentage removal of chromium ranged 32-87%, while that in the presence of MF ranged 42-83%. Temporal effect studies on chromium removal revealed more than 50% Cr removal in the presence of MF on the fifth day. These preliminary observations indicate a possibility of harnessing young cultures of A. niger with nanoparticles dispersed in the magnetic fluid for chromium removal. Figs 2, Refs 17.
Davariya, V.; Vala, A. K.; Desai, R.; Upadhyay, R. V.
The enzymatic hydrolysis of cellulose to glucose involves the formation of cellobiose as an intermediate. It has been found necessary to add cellobiase from Aspergillusniger (NOVO) to the cellobiase component of Trichoderma reesei mutant Rut C-30 (Natick) cellulase enzymes in order to obtain after 48 h complete conversion of the cellobiose formed in the enzymatic hydrolysis of biomass. This study of the cellobiase activity of these two enzyme sources was undertaken as a first step in the formation of a kinetic model for cellulose hydrolysis that can be used in process design. In order to cover the full range of cellobiose concentrations, it was necessary to develop separate kinetic parameters for high- and low-concentration ranges of cellobiose for the enzymes from each organism. Competitive glucose inhibition was observed with the enzymes from both organisms. Substrate inhibition was observed only with the A. niger enzymes.
One single glucoamylase gene could be identified in the chromosomal DNA of Aspergillusniger by Southern blot analysis. This glucoamylase gene was isolated from a genomic library of A. niger DNA. The glucoamylase gene is situated on a 2.5-kb EcoRI-EcoRV fragment and contains five intervening sequences in the coding region. One 169-bp intron is involved in differential mRNA processing leading to the two different glucoamylase enzymes G1 and G2; the other four introns are all very small ranging from 55 to 75 bp in length. One intron has a significant homology to the coding region which immediately follows, and it contains the internal conserved sequence TACTAAC, which is also found in yeast chromosomal gene introns, and is thought to participate in mRNA splicing. Two transcription initiation sites and a typical eukaryotic promoter region with TATAAT and CAAT boxes are located upstream from the gene. Images Fig. 3. Fig. 4.
Boel, E; Hansen, M T; Hjort, I; H?egh, I; Fiil, N P
Aspergillusniger hyphae were found to grow with unliquefied potato starch under aerobic conditions, but did not grow under anaerobic conditions.\\u000a The raw culture ofA. niger catalyzed saccharification of potato starch to glucose, producing approximately 12 g glucose\\/L\\/day\\/ The extracellular enzyme\\u000a activity was decreased in proportion to incubation time, and approximately 64% of initial activity was maintained after 3\\u000a days.
Bo Young Jeon; Soo Jin Kim; Dae Hee Kim; Byung Kwan Na; Doo Hyun Park; Hung Thuan Tran; Ruihong Zhang; Dae Hee Ahn
The effect of growth temperature on the lipid fatty acid composition was studied over a temperature range from 35 to 10° C\\u000a with 5° C intervals in four exponentially growing fungi:Aspergillusniger, Neurospora crassa, Penicillium chrysogenum, andTrichoderma reesei. Fatty acid unsaturation increased inA. niger, P. chrysogenum, andT. reesei when the temperature was lowered to 20–15, 20, and 26–20° C, respectively.
Citric acid production from sugar cane molasses byAspergillusniger NIAB 280 was studied in a batch cultivation process. A maximum of 90 g\\/L total sugar was utilized in citric acid production\\u000a medium. From the parental strainA. niger, mutant strains showing resistance to 2-deoxyglucose in Vogal's medium containing molasses as a carbon source were induced\\u000a by ?-irradiation. Among the new series
S. Parvez; M. I. Rajoka; M. N. Ahmed; F. Latif; R. Shahid; K. A. Malik
The unfolded protein response (UPR) involves a complex signalling pathway in which the transcription factor HACA plays a central role. Here we report the cloning and characterisation of the hacA gene and its product from Aspergillusniger. ER (endoplasmic reticulum) stress results in the splicing of an unconventional 20-nt intron from the A. niger hacA mRNA, and is associated with
H. J. Mulder; M. Saloheimo; M. Penttilä; S. M. Madrid
The effects of various metal ions on the simultaneous production of glucose oxidase and catalase by Aspergillusniger were investigated. Calcium carbonate induced synthesis of both enzymes. The induction of calcium carbonate was accompanied by a metabolic shift from the glycolytic pathway (EMP, Embden-Meyerhof-Parnas) to direct oxidation of glucose by glucose oxidase. The time course of the biosynthesis of both enzymes is reported. The logistic model was in good agreement with the experimental growth results. The production of both enzymes was growth-associated. Finally, a model of growth and product formation was also proposed. PMID:11169035
Submicron particles of amorphous SiO(2) have been used to grow Ag(2)S nanophases at their surfaces. SEM and TEM analysis showed morphological well-defined nanocomposite particles consisting of Ag(2)S nanocrystals dispersed over the silica surfaces. These SiO(2)/Ag(2)S nanocomposites were investigated as anti-fungal agents against Aspergillusniger in different experimental conditions, including as nanofillers in cellulosic fibres. The anti-fungal activity in these composite systems is suggested to result from a synergistic effect due to Ag(2)S anti-fungal centres and the SiO(2) surfaces in promoting the adsorption of the fungus. PMID:19709863
Eight chemically modified cellulose supports were tested for their ability to adsorb components of the Aspergillusniger cellulase system. At least two of the most effective adsorbents, aminoethyl cellulose and carboxymethyl cellulose, were shown to be useful for the fractionation of cellulases. These supports apparently owe their resolving capacity to both ion exchange and biospecific binding effects; however, the relative importance of each effect is unknown. These observations form the basis for a new cellulase fractionation technique, combined ion exchange-affinity chromatography. 22 references.
The endo-polygalacturonase II from Aspergillusniger has been crystallized from an ammonium sulfate solution by the hanging drop method. The crystals belong to the monoclinic space group P2(1), with cell dimensions a = 69.6 A, b = 152.6 A, c = 74.0 A and beta = 91.2 degrees with four molecules per asymmetric unit. The crystals diffract to at least 2.8 A resolution and are suitable for X-ray analysis. PMID:7932761
Schröter, K H; Arkema, A; Kester, H C; Visser, J; Dijkstra, B W
The interaction of tannase (TAH) with chitosan, polyethyleneimine and Eudragit(®)E100 was studied. It was found that TAH selectively binds to these polycations (PC), probably due to the acid nature of the target protein. TAH could interact with these PC depending on the medium conditions. The effect of the interaction on the secondary and tertiary structure of TAH was assayed through circular dichroism and fluorescence spectroscopy. TAH was recovered from Aspergillusniger culture broth by means of precipitation and adsorption using chitosan. PMID:23706551
Durán, Luis V Rodríguez; Spelzini, Darío; Boeris, Valeria; Aguilar, Cristóbal N; Picó, Guillermo A
The ability of immobilized cell cultures of Aspergillusniger FETL FT3 to produce extracellular tannase was investigated. The production of enzyme was increased by entrapping the fungus in scouring mesh cubes compared to free cells. Using optimized parameters of six scouring mesh cubes and inoculum size of 1 × 10(6) spores/mL, the tannase production of 3.98 U/mL was obtained from the immobilized cells compared to free cells (2.81 U/mL). It was about 41.64% increment. The immobilized cultures exhibited significant tannase production stability of two repeated runs. PMID:21347668
Glucose oxidase from Aspergillusniger (EC 126.96.36.199) is able to catalyze the oxidation of -D-glucose with p-benzoquinone, methyl-1,4-benzoquinone, 1,2-naphthoquinone, 1,2-naphthoquinone-4-sulfonic acid, potassium ferricyanide, phenazine methosulfate, and 2,6-dichloroindophenol. In this work, the steady-state kinetic parameters, V\\u000a1\\/K\\u000a\\u000aB\\u000a, for reactions of these substrates were collected from pH 2.5–8. Further, the molecular models of the enzyme's active site were constructed for
Gerd Wohlfahrt; Svetlana Trivi?; Jasmina Zeremski; Draginja Peri?in; Vladimir Leskovac
Determination of the apparent pK\\u000a a's of purified carboxymethylcellulases fromAspergillusniger andCellulomonas biazotea at different temperatures and in the presence of dioxane indicated two side chain carboxyl groups which controlled the limiting\\u000a rate in both organisms. The thermostability of both enzymes slightly decreased with increasing pH from 5 to 7.5 but was unaffected\\u000a in the presence of 0.5 mmol\\/L Mn2+.
K. S. Siddiqui; M. J. Azhar; M. H. Rashid; M. I. Rajoka
In this study, rare ginsenoside Rf was transformed into 20(S)-protopanaxatriol (PPT(S)) by glycosidase from Aspergillusniger. By investing the reaction conditions, the optimal conditions were obtained, as follows: pH 5.0, temperature 55 degrees C, and substrate concentration 1.25 mmol/l. Under optimal conditions, PPT(S) (1.13 micromol) prepared from 1.25 mumol Rf showed a higher yield (90.4%). The enzymatic reaction was analyzed by reversed-phase HPLC, suggesting the transformation pathway: Rf-->Rh1(S)-->PPT(S). PMID:20057152
The enzyme oxaloacetate hydrolase (EC 188.8.131.52), which is involved in oxalate formation, was purified from Aspergillusniger. The native enzyme has a molecular mass of 360–440?kDa, and the denatured enzyme has a molecular mass of 39?kDa, as determined\\u000a by gel electrophoresis. Enzyme activity is maximal at pH?7.0 and 45?°C. The fraction containing the enzyme activity contained\\u000a at least five proteins.
Schizophillum commune (S. commune) is a rare type of basidiomycetous fungus that has being reported as a cause of allergic fungal rhinosinusitis (AFRS), invasive type of fungal sinusitis and allergic bronchopulmonary mycosis (ABPM). However, it is believed that S. commune was often misdiagnosed to Aspergillus sp. We report a case of bilateral nasal polyps and maxillary, ethmoidal and sphenoidal involvement within the context of S. commune and Aspergillusniger associated AFRS. Our patient was suffering from a chronic disease with periods of remission and exacerbation and was treated successfully by a combination of surgical and antifungal treatment. In our experience, S. commune may be found frequently in patients with AFRS. AFRS, including the S. commune-associated type, usually runs a prolonged course and can affect any paranasal sinus. Surgical treatment alone is not sufficient and must be combined with medical treatment. PMID:19593982
A novel antifungal peptide (termed as Anafp) was isolated from the culture supernatant of the filamentous fungi, Aspergillusniger. The whole amino acid sequence of Anafp was determined and the peptide was found to be composed of a single polypeptide chain with 58 amino acids including six cysteine residues. The peptide shows some degree of sequence homology to a cysteine-rich antifungal peptides reported from the seeds of Sinapis alba and Arabidopsis thaliana or the extracellular media of Aspergillus giganteus and Penicillium chrysogenumsome. Cysteine-spacing pattern of Anafp was similar to that of the antifungal peptide from Penicillium chrysogenum. The Anafp exhibited potent growth inhibitory activities against yeast strains as well as filamentous fungi at a range from 4 to 15 microM. In contrast, Anafp did not show antibacterial activity against Escherichia coli and Bacillus subtilis even at 50 microM. PMID:10512732
Gun Lee, D; Shin, S Y; Maeng, C Y; Jin, Z Z; Kim, K L; Hahm, K S
Clinical isolates of fifty strains of A. fumigatus and 30 stra- ins of A. flavus from immmunocompromised patients from the hematological unit were analyzed for mycotoxin pro- duction and compared with the same number of environ- mental isolates (from soil, compost, and air). Only 9 (18%) strains of A. fumigatus produced gliotoxin in a mean con- centration 2.22 mg mL-1
The full-length gene that encodes the chlorogenic acid hydrolase from Aspergillusniger CIRM BRFM 131 was cloned by PCR based on the genome of the strain A. niger CBS 513.88. The complete gene consists of 1,715 bp and codes for a deduced protein of 512 amino acids with a molecular mass of 55,264 Da and an acidic pI of 4.6. The gene was successfully cloned and overexpressed in A. niger to yield 1.25 g liter?1, i.e., 330-fold higher than the production of wild-type strain A. niger CIRM BRFM131. The histidine-tagged recombinant ChlE protein was purified to homogeneity via a single chromatography step, and its main biochemical properties were characterized. The molecular size of the protein checked by mass spectroscopy was 74,553 Da, suggesting the presence of glycosylation. ChlE is assembled in a tetrameric form with several acidic isoforms with pIs of around 4.55 and 5.2. Other characteristics, such as optimal pH and temperature, were found to be similar to those determined for the previously characterized chlorogenic acid hydrolase of A. niger CIRM BRFM 131. However, there was a significant temperature stability difference in favor of the recombinant protein. ChlE exhibits a catalytic efficiency of 12.5 × 106 M?1 s?1 toward chlorogenic acid (CGA), and its ability to release caffeic acid from CGA present in agricultural by-products such as apple marc and coffee pulp was clearly demonstrated, confirming the high potential of this enzyme.
Benoit, Isabelle; Asther, Michele; Bourne, Yves; Navarro, David; Canaan, Stephane; Lesage-Meessen, Laurence; Herweijer, Marga; Coutinho, Pedro M.; Asther, Marcel; Record, Eric
The removal of hexavalent chromium from aqueous solution was studied in batch experiments using dead biomass of three different\\u000a species of marine Aspergillus after alkali treatment. All the cultures exhibited potential to remove Cr(VI), out of which, Aspergillusniger was found to be the most promising one. This culture was further studied employing variation in pH, temperature, metal ion\\u000a concentration
Aspergillus, a mycotoxicogenic fungal genus, produces carcinogenic aflatoxins in crops like peanuts and maize. Development of fungal resistant maize cultivars is one strategy used to decrease contamination. Successful development and identification of resistant maize genotypes requires evaluation o...
By using agar well diffusion assay, antifungal activity of aqueous extract prepared from Egyptian garlic (Allium sativum L.) was evaluated in vitro against two strains of Aspergillusflavus (OC1 and OC10) causing human ocular infection. The recorded minimum inhibitory concentration (MIC) for growth inhibition of both strains was 3.60 mg/ml. Aqueous garlic extract (AGE) was used in successive in vivo tests as an attempt to cure rabbit’s fungal keratitis caused by A. flavus OC1. Findings showed that diluted preparation of AGE was effective topical antifungal agent and succeeded to cure severe A. flavus keratitis in a time course less than 10 days without any observable side effects. Microscopic examination showed that AGE induced deleterious cyto-morphological aberrations in A. flavus target cells. AGE applied to Czapek’s broth via contact method was more effective on growth, spores and aflatoxin B1 production than AGE applied to the same broth at the same concentration via fumigation method.
Ismaiel, Ahmed A.; Rabie, Gamal H.; Kenawey, Saied E.M.; Abd EL-Aal, Marwa A.
Interactions between bacteria and fungi cover a wide range of incentives, mechanisms and outcomes. The genus Collimonas consists of soil bacteria that are known for their antifungal activity and ability to grow at the expense of living fungi. In non-contact confrontation assays with the fungus Aspergillusniger, Collimonas fungivorans showed accumulation of biomass concomitant with inhibition of hyphal spread. Through microarray analysis of bacterial and fungal mRNA from the confrontation arena, we gained new insights into the mechanisms underlying the fungistatic effect and mycophagous phenotype of collimonads. Collimonas responded to the fungus by activating genes for the utilization of fungal-derived compounds and for production of a putative antifungal compound. In A. niger, differentially expressed genes included those involved in lipid and cell wall metabolism and cell defense, which correlated well with the hyphal deformations that were observed microscopically. Transcriptional profiles revealed distress in both partners: downregulation of ribosomal proteins and upregulation of mobile genetic elements in the bacteria and expression of endoplasmic reticulum stress and conidia-related genes in the fungus. Both partners experienced nitrogen shortage in each other's presence. Overall, our results indicate that the Collimonas/Aspergillus interaction is a complex interplay between trophism, antibiosis and competition for nutrients.
Mela, Francesca; Fritsche, Kathrin; de Boer, Wietse; van Veen, Johannes A; de Graaff, Leo H; van den Berg, Marlies; Leveau, Johan H J
Optimal agitation and aeration conditions (assuring O/sub 2/ transfer rates (OTR) of 12-179 mmol/L-h) were determined for pectin lyase (PL) synthesis of an Aspergillusniger strain. Components of the pectolytic enzyme complex were also investigated in order to determine whether their O/sub 2/ demand is identical with or different from that of pectin lyase. Should the latter be the case, a possibility would be given to produce enzyme complexes of different agitation and aeration conditions. The mycelium yield of Aspergillusniger was maximum at an OTR of 100 mmol/L-h. The yields of the various pectolytic enzymes reached maximum at different OTRs. PL production was highest (0.555 mumol/min-mL) at an OTR of 60 mmol/L-h. Endopolygalacturonase (PG) production has a maximum at OTR 49 mmol/L-h, with a 2nd peak at 100-135 mmol O2/L-h. Pectin esterase (PE) synthesis showed a maximum at an OTR of 12-14 mmol/L-h, while both apple juice clarifying and macerating activities gave 2 maximum at 14 and 60 mmol/L-h due to the optima of PE and endo-PG. Macerating activity showed a high value at OTR optimal for PL production as well.
The objective of this study was to determine the influence of natural biowaste substrates such as banana peel powder and coir powder at varying environmental parameters of pH (4-9) and temperature (20-50 degrees C) on the cellulase enzyme production by Aspergillusniger. The cellulase enzyme production was analyzed by measuring the amount of glucose liberated in IU ml(-1) by using the dinitrosalicylic acid assay method. The substrates were pretreated with 1% NaOH (alkaline treatment) and autoclaved. The maximum activity of the enzyme was assayed at varying pH with temperatures being constant and varying temperatures with pH being constant. The highest activity of the enzyme at varying pH was recorded at pH 6 for banana peel powder (0.068 +/- 0.002 IU ml) and coir powder (0.049 +/- 0.002 IU ml(-1)) and the maximum activity of the enzyme at varying temperature was recorded at 35 degrees C for both banana peel powder (0.072 +/- 0.001 IU ml(-1)) and coir powder (0.046 +/- 0.003 IU ml(-1)). At varying temperatures and pH the high level of enzyme production was obtained at 35 degrees C and pH 6 by using both the substrates, respectively. However among the two substrates used for the production of cellulases by Aspergillusniger banana peel powder showed maximum enzymatic activity than coir powder as substrate. PMID:22471203
Kiranmayi, M Usha; Poda, Sudhakar; Vijayalakshmi, M; Krishna, P V
The interaction force between single cells in contact is of high interest in various interdisciplinary fields of biotechnology, for instance, in cultivation or biofilm formation. A method for the determination of adhesion forces between two single Aspergillusniger spores in different aqueous solutions was established in this study. Adhesion force distributions were determined at three different sodium chloride concentrations and two different pH values using an atomic force microscope (AFM). It was pointed out that adhesion data can be described by log-normal density functions, of which corresponding parameters have been estimated. Using the knowledge of distribution shape, the influence of the environmental condition on the mean values of adhesion force could be studied quantitatively. The highest value of 0.95 nN was observed at pH 2.5 and an ionic strength of 0.5 mol L(-1). Decreasing the ionic strength to 0.05 mol L(-1) decreases the adhesion force mean for about 25%. Increasing the pH value to pH 5 at a sodium chloride concentration of 0.154 mol L(-1) entails a decrease of adhesion from 0.88 to 0.56 nN. These results qualitatively agree with the absolute value of the expected surface potential of Aspergillusniger spores, which is much higher at pH 5 and should take more effect at lower concentrations of counterions. PMID:20387816
The immobilized Aspergillusniger powder beads were obtained by entrapping nonviable A. niger powder into Ca-alginate gel. The effects of pH, contact time, initial uranium (VI) concentration and biomass dosage on the biosorption of uranium (VI) onto the beads from aqueous solutions were investigated in a batch system. Biosorption equilibrium data were agreeable with Langmuir isotherm model and the maximum biosorption capacity of the beads for uranium (VI) was estimated to be 649.4 mg/g at 30 °C. The biosorption kinetics followed the pseudo-second-order model and intraparticle diffusion equation. The variations in enthalpy (26.45 kJ/mol), entropy (0.167 kJ/mol K) and Gibbs free energy were calculated from the experimental data. SEM and EDS analysis indicated that the beads have strong adsorption capability for uranium (VI). The adsorbed uranium (VI) on the beads could be released with HNO(3) or HCl. The results showed that the immobilized A. niger powder beads had great potential for removing and recovering uranium (VI) from aqueous solutions. PMID:22580796
Antagonistic yeasts were isolated from the epiphytic flora associated with grape berries cv. Negroamaro and identified at species level using molecular methods. A total of 144 yeast isolates were tested in a preliminary screening on agar to select isolates showing a killer activity against Aspergillus carbonarius and A. niger, the main species responsible for the accumulation of ochratoxin A in grape. Twenty-eight yeast isolates were selected for their inhibitory effects on the above fungal species and assayed by an in vitro nutritional competition test for their antagonistic capacity towards three selected ochratoxigenic strains. Six yeast isolates belonging to five species, namely 2 isolates of Issatchenkia orientalis and one each of Metschnikowia pulcherrima, Kluyveromyces thermotolerans, Issatchenkia terricola and Candida incommunis, were finally selected and screened on wounded grape berries for their ability to inhibit infection by ochratoxigenic moulds. With the exception of the K. thermotolerans isolate, when inoculated at 10(9) CFU/wound, the other five challenger yeasts reduced the A. carbonarius and A. niger colonization on grape berry (P<0.05). In particular, the best antagonistic activity was shown by the two I. orientalis isolates. Results suggest that antagonist yeasts with the potential to control A. carbonarius and A. niger on grape can be found among the microflora associated with the berries. PMID:16443300
Two Aspergillusniger strains (GH1 and PSH) previously isolated from a semiarid region of Mexico were characterized for their effectiveness in converting pomegranate ellagitannins (ET) into ellagic acid (EA) in a solid state fermentation (SSF). Pomegranate seeds and husk were used as support for the SSF. Released EA was evaluated by liquid chromatography. Yields of 6.3 and 4.6 mg of EA per gram of dried pomegranate husk were obtained with A. niger GH1 and PSH, respectively. Total hydrolyzable polyphenols of pomegranate husk were degraded during the first 72 h of culture (71 and 61%, by GH1 and PSH strains, respectively). Tannin acyl hydrolase activity was not clearly associated with EA production. EA that accumulated in cultures of A. niger GH1 was remarkably pure after a simple extraction process. Pomegranate husk is a good support, and at the same time an excellent substrate in the production of high commercial interest metabolites like EA due the degradation of its ET content. PMID:18228068
Robledo, Armando; Aguilera-Carbó, Antonio; Rodriguez, Raúl; Martinez, José Luis; Garza, Yolanda; Aguilar, Cristobal N
Aspergillusniger represents a promising host for the expression of recombinant proteins, but only a few expression systems are available for this organism. In this study, the inducible catalase promoter (PcatR) from A. niger was characterized. For this, constructs were developed and checked for the expression of the alkaline xylanase gene transcriptionally fused under the cat R promoter. Two versions of the catalase (catR) promoter sequence from A. niger (P(cat300,) P(cat924)) were isolated and tested for their ability to drive expression of the alkaline xylanase (alx) gene. P(cat924) showed better efficiency (more than 10-fold increase in AlX activity compared to P(cat300)) under the optimized culture conditions. Induction of the catR promoter with 0.20% H(2)O(2) and 1.5% CaCO(3) in the culture medium, further increased expression of AlX 2.61- and 2.20-fold, respectively, clarifying its inducible nature. Specific induction or repression of the catR promoter provides the possibility for utilization of this promoter in heterologous protein production. PMID:22092890
Sharma, Ruchika; Katoch, Meenu; Govindappa, Nagraj; Srivastava, P S; Sastry, Kedarnath N; Qazi, Ghulam Nabi
In the genome sequence of Aspergillusniger CBS 513.88, three genes were identified with high similarity to fungal ?-amylases. The protein sequences derived from these genes were different in two ways from all described fungal ?-amylases: they were predicted to be glycosylphosphatidylinositol anchored, and some highly conserved amino acids of enzymes in the ?-amylase family were absent. We expressed two of these enzymes in a suitable A. niger strain and characterized the purified proteins. Both enzymes showed transglycosylation activity on donor substrates with ?-(1,4)-glycosidic bonds and at least five anhydroglucose units. The enzymes, designated AgtA and AgtB, produced new ?-(1,4)-glycosidic bonds and therefore belong to the group of the 4-?-glucanotransferases (EC 184.108.40.206). Their reaction products reached a degree of polymerization of at least 30. Maltose and larger maltooligosaccharides were the most efficient acceptor substrates, although AgtA also used small nigerooligosaccharides containing ?-(1,3)-glycosidic bonds as acceptor substrate. An agtA knockout of A. niger showed an increased susceptibility towards the cell wall-disrupting compound calcofluor white, indicating a cell wall integrity defect in this strain. Homologues of AgtA and AgtB are present in other fungal species with ?-glucans in their cell walls, but not in yeast species lacking cell wall ?-glucan. Possible roles for these enzymes in the synthesis and/or maintenance of the fungal cell wall are discussed.
van der Kaaij, R. M.; Yuan, X.-L.; Franken, A.; Ram, A. F. J.; Punt, P. J.; van der Maarel, M. J. E. C.; Dijkhuizen, L.
The filamentous fungus Aspergillusniger is widely exploited for industrial production of enzymes and organic acids. An integrated genomics approach was developed to determine cellular responses of A. niger to protein production in well-controlled fermentations. Different protein extraction methods in combination with automated sample processing and protein identification allowed quantitative analysis of 898 proteins. Three different enzyme overproducing strains were compared to their isogenic fungal host strains. Clear differences in response to the amount and nature of the overproduced enzymes were observed. The corresponding genes of the differentially expressed proteins were studied using transcriptomics. Genes that were up-regulated both at the proteome and transcriptome level were selected as leads for generic strain improvement. Up-regulated proteins included proteins involved in carbon and nitrogen metabolism as well as (oxidative) stress response, and proteins involved in protein folding and endoplasmic reticulum-associated degradation (ERAD). Reduction of protein degradation through the removal of the ERAD factor doaA combined with overexpression of the oligosaccharyl transferase sttC in A. niger overproducing beta-glucuronidase (GUS) strains indeed resulted in a small increase in GUS expression. PMID:18824119
Jacobs, Denise I; Olsthoorn, Maurien M A; Maillet, Isabelle; Akeroyd, Michiel; Breestraat, Stefaan; Donkers, Serge; van der Hoeven, Rob A M; van den Hondel, Cees A M J J; Kooistra, Rolf; Lapointe, Thomas; Menke, Hildegard; Meulenberg, Rogier; Misset, Marijke; Müller, Wally H; van Peij, Noël N M E; Ram, Arthur; Rodriguez, Sabrina; Roelofs, Marc S; Roubos, Johannes A; van Tilborg, Marcel W E M; Verkleij, Arie J; Pel, Herman J; Stam, Hein; Sagt, Cees M J
Sound mature kernels, broken mature kernels, immature kernels, and unshelled Early Runner peanuts were heat-treated in controlled\\u000a environment cabinets and inoculated with spores ofAspergillusflavus. Treatments were incubated at 97–99% relative humidity at different temperatures ranging from 5 to 55C and also at 30C with\\u000a relative humidities ranging from 55 to 99%. Samples were removed after 7 and 21 days
Two strains of Aspergillusflavus, non-toxigenic NRRL 6550 and toxigenic NRRL 5940, were studied over a period of 44 days, in order to detect the presence of virus-like particles (VLPs) by means of electron microscopy (EM) and nucleic acids electrophoresis. Only the toxigenic strain contained VLPs, presenting three-segmented dsRNA. An increase in VLPs number was observed during the exponential phase
Valéria N. Silva; Edison Luiz Durigon; Maria de Fátima Costa Pires; Alexandre Lourenço; Maria Jacinta de Faria; Benedito Corręa
Background Many filamentous fungal genomes contain complex groups of multicopper oxidase (MCO) coding genes that makes them a good source for new laccases with potential biotechnological interest. A bioinformatics analysis of the Aspergillusniger ATCC 1015 genome resulted in the identification of thirteen MCO genes. Ten of them were cloned and homologously overexpressed. Results A bioinformatic analysis of the A. niger ATCC 1015 genome revealed the presence of 13 MCO genes belonging to three different subfamilies on the basis of their phylogenetic relationships: ascomycete laccases, fungal pigment MCOs and fungal ferroxidases. According to in silico amino acid sequence analysis, the putative genes encoding for functional extracellular laccases (mcoA, mcoB, mcoC, mcoD, mcoE, mcoF, mcoG, mcoI, mcoJ and mcoM) were placed under the control of the glaA promoter and overexpressed in A. niger N593. Enzyme activity plate assays with several common laccase substrates showed that all genes are actually expressed and code for active MCOs. Interestingly, expressed enzymes show different substrate specificities. In addition, optimization of fungal pigment MCOs extracellular production was investigated. The performance of the widely used glucoamylase signal sequence (ssGlaA) in McoA secretion was studied. Results obtained suggest that ssGlaA do not yield higher levels of secreted McoA when compared to its native secretion signal. Also, McoB synthesis was investigated using different nitrogen sources in minimal medium liquid cultures. Higher yields of extracellular McoB were achieved with (NH4)2 tartrate. Conclusions Aspergillusniger is a good source of new laccases. The different substrate specificity observed in plate assays makes them interesting to be purified and biochemically compared. The homologous signal sequence of McoA has been shown to be a good choice for its extracellular overexpression. From the nitrogen sources tested (NH4)2 tartrate has been found to be the most appropriate for McoB production in A. niger.
Background Aspergillusniger was selected as a host for producing itaconic acid due to its versatile and tolerant character in various growth environments, and its extremely high capacity of accumulating the precursor of itaconic acid: citric acid. Expressing the CAD gene from Aspergillus terreus opened the metabolic pathway towards itaconic acid in A. niger. In order to increase the production level, we continued by modifying its genome and optimizing cultivation media. Results Based on the results of previous transcriptomics studies and research from other groups, two genes : gpdA encoding the glyceraldehyde ?3-dehydrogenase (GPD) and hbd1 encoding a flavohemoglobin domain (HBD) were overexpressed in A. niger. Besides, new media were designed based on a reference medium for A. terreus. To analyze large numbers of cultures, we developed an approach for screening both fungal transformants and various media in 96-well micro-titer plates. The hbd1 transformants (HBD 2.2/2.5) did not improve itaconic acid titer while the gpdA transformant (GPD 4.3) decreased the itaconic acid production. Using 20 different media, copper was discovered to have a positive influence on itaconic acid production. Effects observed in the micro-titer plate screening were confirmed in controlled batch fermentation. Conclusions The performance of gpdA and hbd1 transformants was found not to be beneficial for itaconic acid production using the tested cultivation conditions. Medium optimization showed that, copper was positively correlated with improved itaconic acid production. Interestingly, the optimal conditions for itaconic acid clearly differ from conditions optimal for citric- and oxalic acid production.
Biological control of preharvest aflatoxin contamination by atoxigenic stains of Aspergillusflavus has been demonstrated in several crops. The assumption is that some form of competition suppresses the fungus's ability to infect or produce aflatoxin when challenged. Intraspecific aflatoxin inhibition was demonstrated by others. This work investigates the mechanistic basis of that phenomenon. A toxigenic and atoxigenic isolate of A. flavus which exhibited intraspecific aflatoxin inhibition when grown together in suspended disc culture were not inhibited when grown in a filter insert-plate well system separated by a .4 or 3 µm membrane. Toxigenic and atoxigenic conidial mixtures (50?50) placed on both sides of these filters restored inhibition. There was ?50% inhibition when a 12 µm pore size filter was used. Conidial and mycelial diameters were in the 3.5–7.0 µm range and could pass through the 12 µm filter. Larger pore sizes in the initially separated system restored aflatoxin inhibition. This suggests isolates must come into physical contact with one another. This negates a role for nutrient competition or for soluble diffusible signals or antibiotics in aflatoxin inhibition. The toxigenic isolate was maximally sensitive to inhibition during the first 24 hrs of growth while the atoxigenic isolate was always inhibition competent. The atoxigenic isolate when grown with a green fluorescent protein (GFP) toxigenic isolate failed to inhibit aflatoxin indicating that there is specificity in the touch inhibiton. Several atoxigenic isolates were found which inhibited the GFP isolate. These results suggest that an unknown signaling pathway is initiated in the toxigenic isolate by physical interaction with an appropriate atoxigenic isolate in the first 24 hrs which prevents or down-regulates normal expression of aflatoxin after 3–5 days growth. We suspect thigmo-downregulation of aflatoxin synthesis is the mechanistic basis of intraspecific aflatoxin inhibition and the major contributor to biological control of aflatoxin contamination.
This article reports the production of high levels of l-asparaginase from a new isolate of Aspergillusniger in solid state fermentation (SSF) using agrowastes from three leguminous crops (bran of Cajanus cajan, Phaseolus mungo, and Glycine max). When used as the sole source for growth in SSF, bran of G. max showed maximum enzyme production followed by that of P.
Welwitschia mirabilis Hook. fil. is a unique and rare dioecious desert gymnosperm endemic to the Namib Desert. The female plants bear 90–100 megasporophylls, of which 50–60% may be fertile, but up to 80% of those fertile seeds may be infected by Aspergillusniger var. phoenicis. This contamination results in seed and seedling death, potentially negatively affecting recruitment of plants into
In the present investigation the fungi, Aspergillusniger and Nigrospora sp. were employed for decolorization of Synozol red HF-6BN. Decolorization study showed that Aspergillusniger and Nigrospora sp. were able to decolorize 88% and 96% Synozol red 6BN, respectively, in 24 days. It was also studied that 86% and 90% Synozol red containing of dye effluent was decolorized by Aspergillusniger and Nigrospora sp. after 28 days of incubation at room temperature. A fungal-based protein with relative molecular mass of 70 kDa was partially purified and examined for enzymatic characteristics. The enzyme exhibited highest activity at temperature ranging from 40-50°C and at pH=6.0. The enzyme activity was enhanced in the presence of metal cations. High performance liquid chromatography analysis confirmed that these fungal strains are capable to degrade Synozol red dye into metabolites. No zones of inhibition on agar plates and growth of Vigna radiata in the presence of dye extracted sample, indicated that the fungal degraded dye metabolites are nontoxic to beneficial micro-flora and plant growth. Aspergillusniger and Nigrospora sp. have promising potential in color removal from textile wastewater-containing azo dyes.
Antifungal activities of rubberwood treated with vapour of peppermint oil against Aspergillusniger identified from rubberwood surfaces was investigated. The vapour of peppermint oil at 60°C was employed to determine the minimal inhibitory concentration (MIC using the concentration of substances between 100 and 900 µl ml-1). Peppermint oil exhibited high fungal activities with the MIC of 300µl ml-1 against the
BACKGROUND: Fumonisins are economically important mycotoxins which until recently were considered to originate from only a few Fusarium species. However recently a putative fumonisin gene cluster was discovered in two different Aspergillusniger strains followed by detection of an actual fumonisin B2 (FB2) production in four strains of this biotechnologically important workhorse. RESULTS: In the present study, a screening of
Jesper M Mogensen; Kristian F Nielsen; Robert A Samson; Jens C Frisvad; Ulf Thrane
Data from batch fermentations of citric acid producing Aspergillusniger cultures in shake flasks, loop and stirred tank bioreactors, were used to construct diffusion models for the transport of glucose. It was found that the mediated diffusion model does not reflect the relationship between the observed uptake rate and glucose concentration, nor for the lack of sensitivity to citrate. This
Background Fumonisins are economically important mycotoxins which until recently were considered to originate from only a few Fusarium species. However recently a putative fumonisin gene cluster was discovered in two different Aspergillusniger strains followed by detection of an actual fumonisin B2 (FB2) production in four strains of this biotechnologically important workhorse. Results In the present study, a screening of 5 A. niger strains and 25 assumed fumonisin producing Fusarium strains from 6 species, showed that all 5 A. niger strains produced FB2 and 23 of 25 Fusarium produced fumonisin B1 and other isoforms (fumonisin B2 and B3). Five A. niger and five Fusarium spp. were incubated at six different temperatures from 15-42°C on Czapek Yeast Agar +5% salt or Potato Dextrose Agar. A. niger had the highest production of FB2 at 25-30°C whereas Fusarium spp. had the maximal production of FB1 and FB2 at 20-25°C. Addition of 2.5-5% NaCl, or 10-20% sucrose increased the FB2 production of A. niger, whereas addition of glycerol reduced FB2 production. All three water activity lowering solutes reduced the fumonisin production of the Fusarium species. Conclusion The present study shows that the regulation of fumonisin production is very different in A. niger and Fusarium, and that food and feeds preserved by addition of sugar or salts may be good substrates for fumonisin B2 production by A. niger.
Aspergillusniger forms aerial hyphae and conidiophores after a period of vegetative growth. The hyphae within the mycelium of A. niger are divided by septa. The central pore in these septa allows for cytoplasmic streaming. Here, we studied inter- and intra-compartmental streaming of the reporter protein GFP in A. niger. Expression of the gene encoding nuclear targeted GFP from the gpdA or glaA promoter resulted in strong fluorescence of nuclei within the vegetative hyphae and weak fluorescence in nuclei within the aerial structures. These data and nuclear run on experiments showed that gpdA and glaA are higher expressed in the vegetative mycelium when compared to aerial hyphae, conidiophores and conidia. Notably, gpdA or glaA driven expression of the gene encoding cytosolic GFP resulted in strongly fluorescent vegetative hyphae and aerial structures. Apparently, GFP streams from vegetative hyphae into aerial structures. This was confirmed by monitoring fluorescence of photo-activatable GFP (PA-GFP). In contrast, PA-GFP did not stream from aerial structures to vegetative hyphae. Streaming of PA-GFP within vegetative hyphae or within aerial structures of A. niger occurred at a rate of 10-15 ?m s(-1). Taken together, these results not only show that GFP streams from the vegetative mycelium to aerial structures but it also indicates that its encoding RNA is not streaming. Absence of RNA streaming would explain why distinct RNA profiles were found in aerial structures and the vegetative mycelium by nuclear run on analysis and micro-array analysis. PMID:23450745
Bleichrodt, R; Vinck, A; Krijgsheld, P; van Leeuwen, M R; Dijksterhuis, J; Wösten, H A B
Aspergillusniger forms aerial hyphae and conidiophores after a period of vegetative growth. The hyphae within the mycelium of A. niger are divided by septa. The central pore in these septa allows for cytoplasmic streaming. Here, we studied inter- and intra-compartmental streaming of the reporter protein GFP in A. niger. Expression of the gene encoding nuclear targeted GFP from the gpdA or glaA promoter resulted in strong fluorescence of nuclei within the vegetative hyphae and weak fluorescence in nuclei within the aerial structures. These data and nuclear run on experiments showed that gpdA and glaA are higher expressed in the vegetative mycelium when compared to aerial hyphae, conidiophores and conidia. Notably, gpdA or glaA driven expression of the gene encoding cytosolic GFP resulted in strongly fluorescent vegetative hyphae and aerial structures. Apparently, GFP streams from vegetative hyphae into aerial structures. This was confirmed by monitoring fluorescence of photo-activatable GFP (PA-GFP). In contrast, PA-GFP did not stream from aerial structures to vegetative hyphae. Streaming of PA-GFP within vegetative hyphae or within aerial structures of A. niger occurred at a rate of 10–15 ?m s-1. Taken together, these results not only show that GFP streams from the vegetative mycelium to aerial structures but it also indicates that its encoding RNA is not streaming. Absence of RNA streaming would explain why distinct RNA profiles were found in aerial structures and the vegetative mycelium by nuclear run on analysis and micro-array analysis.
Filamentous fungi in the Aspergillus section Nigri (the black aspergilli) represent some of the most widespread food and feed contaminants known but they are also some of the most important workhorses used by the biotechnological industry. The Nigri section consists of six commonly found species (excluding A. aculeatus and its close relatives) from which currently 145 different secondary metabolites have been isolated and/or detected. From a human and animal safety point of view, the mycotoxins ochratoxin A (from A. carbonarius and less frequently A. niger) and fumonisin B(2) (from A. niger) are currently the most problematic compounds. Especially in foods and feeds such as coffee, nuts, dried fruits, and grape-based products where fumonisin-producing fusaria are not a problem, fumonisins pose a risk. Moreover, compounds such as malformins, naptho-gamma-pyrones, and bicoumarins (kotanins) call for monitoring in food, feed, and biotechnology products as well as for a better toxicological evaluation, since they are often produced in large amounts by the black aspergilli. For chemical differentiation/identification of the less toxic species the diketopiperazine asperazine can be used as a positive marker since it is consistently produced by A. tubingensis (177 of 177 strains tested) and A. acidus (47 of 47 strains tested) but never by A. niger (140 strains tested). Naptho-gamma-pyrones are the compounds produced in the highest quantities and are produced by all six common species in the group (A. niger 134 of 140; A. tubingensis 169 of 177; A. acidus 44 of 47; A. carbonarius 40 of 40, A. brasiliensis 18 of 18; and A. ibericus three of three). PMID:19756540
Nielsen, Kristian Fog; Mogensen, Jesper Mřlgaard; Johansen, Maria; Larsen, Thomas O; Frisvad, Jens Christian
The wastes materials from the sweet orange (Citrus sinensis) were used as substrate for the production of cellulase. The rind, the pericarp or albedo and the pulp were hydrolyzed by cellulolytic enzymes of Trichoderma longibrachiatum, Aspergillusniger and Saccharomyces cerevisiae after they were treated with alkali and steam. The amount of glucose released from the substrates following the secretion of cellulase by the three microorganisms was measured. The orange wastes released amounts of glucose ranging from 0.76-0.96 mg mL(-1) by Trichoderma longibrachiatum, 0.90-1.08 mg mL(-1) by A. niger and 0.60-0.76 mg mL(-1) by S. cerevisiae after five days of fermentation. The conditions of the fermentation were then varied to determine their effect on cellulase production. Fermentation parameters varied were time, pH, substrate concentration, temperature and inoculum size. After this, conditions that produced highest amounts of glucose were combined in an optimization experiment. Glucose production under optimized conditions were 0.94 mg mL(-1) by T. longibrachiatum, 0.83 mg mL(-1) by A. niger and 0.67 mg mL(-1) by S. cerevisae. The activity of the test organisms' cellulase against CMC on the orange wastes was also determined with T. longibrachiatum producing 3.86 mg mL(-1), A. niger 2.94 mg mL(-1) and S. cerevisiae 2.30 mg mL(-1) glucose amounts all from orange pulp. PMID:19137846
Background The filamentous fungus Aspergillusniger is a widely used strain in a broad range of industrial processes from food to pharmaceutical industry. One of the most intriguing and often uncontrollable characteristics of this filamentous organism is its complex morphology, ranging from dense spherical pellets to viscous mycelia depending on culture conditions. Optimal productivity correlates strongly with a specific morphological form, thus making high demands on process control. Results In about 50 2L stirred tank cultivations the influence of osmolality on A. niger morphology and productivity was investigated. The specific productivity of fructofuranosidase producing strain A. niger SKAn 1015 could be increased notably from 0.5 to 9 U mg-1 h-1 around eighteen fold, by increasing the culture broth osmolality by addition of sodium chloride. The specific productivity of glucoamylase producing strain A. niger AB1.13, could be elevated using the same procedure. An optimal producing osmolality was shown to exist well over the standard osmolality at about 3.2 osmol kg-1 depending on the strain. Fungal morphology of all cultivations was examined by microscope and characterized by digital image analysis. Particle shape parameters were combined to a dimensionless Morphology number, which enabled a comprehensive characterization of fungal morphology correlating closely with productivity. A novel method for determination of germination time in submerged cultivations by laser diffraction, introduced in this study, revealed a decelerated germination process with increasing osmolality. Conclusions Through the introduction of the versatile Morphology number, this study provides the means for a desirable characterization of fungal morphology and demonstrates its relation to productivity. Furthermore, osmolality as a fairly new parameter in process engineering is introduced and found to affect fungal morphology and productivity. Osmolality might provide an auspicious and reliable approach to increase the productivity in industrial processes. Because of the predictable behavior fungal morphology showed in dependence of osmolality, a customization of morphology for process needs seems feasible.
In the present study, the molecular and basic biochemical characterization of endopolygalacturonase E, the fourth Aspergillusniger N400 endopolygalacturonase, is reported. The entire endopolygalacturonase E gene consists of 1293 bp interrupted by three short introns (50, 50, and 59 bp, respectively) as concluded from the cDNA sequence. The deduced amino acid sequence comprises 378 residues that include 39 N-terminal amino acids of the prepropeptide. The calculated Mr and pI of the mature protein are 35,584 and 3.6, respectively. Compared with other endopolygalacturonases from A. niger N400, the mature protein endopolygalacturonase E has the highest sequence identity with endopolygalacturonase C (77.6%) followed by endopolygalacturonase I (57.6%) and endopolygalacturonase II (54.3%). For overproduction of endopolygalacturonase E, an A. niger multicopy strain was used that was transformed with a promoter gene fusion construct that directs expression from the glycolytic A. niger pyruvate kinase promoter. The enzyme was purified and characterized as an endopolygalacturonase based on product analysis after polygalacturonate hydrolysis and on bond cleavage frequencies of oligogalacturonates of different degree of polymerisation (n = 2-7). The pH optimum was 3.8. The Km and Vmax for polygalacturonate hydrolysis were 2.5 +/- 0.4 mg x ml(-1) and 1.3 +/- 0.2 microkat x mg(-1), respectively. A subsite map was calculated by the combination of the methods of Suganuma et al. [Suganuma, T., Matsuno, R., Ohnishi, M. & Hiromi, K. (1978) J. Biochem. (Tokyo) 84, 293-316] and Nitta et al. [Nitta, Y., Mizushima, M., Hiromi, K. & Ono, S. (1971) J. Biochem. (Tokyo) 69, 567-576]. This indicated that the enzyme was composed of at least five subsites. PMID:9492270
OBJECTIVE: Phytase is a phosphatase derived from Aspergillusniger that enhances phosphate bioavailability in the gut, and therefore has been increasingly used as an animal feed additive since the early 1990s. The aim of this study was to assess whether work related respiratory symptoms among workers in a so called premix factory producing animal feed additives, could be due to type I (mediated by immunoglobulin E (IgE) allergic sensitisation to phytase. METHODS: Preparations of specific IgE against phytase as used in the factory were assessed by enzyme immunoassay (EIA) in serum samples of 11 exposed workers who regularly handled the enzyme, in 11 office and laboratory workers of the same plant (non-exposed internal controls), and in 19 laboratory animal workers as external controls. The factory workers also completed a questionnaire on common and work related respiratory symptoms. RESULTS: Depending on the cut off level in the EIA for IgE, and the preparation used as coated allergen, antiphytase sensitisation was found in one to four of the 19 external controls, in one to five of the 11 internal controls, and in four to 10 of the 11 exposed workers. Strongest IgE reactions were found in four exposed workers who reported work related respiratory symptoms, particularly wheezing, and in one internal control who possibly had become sensitised because the structure of the factory building did not preclude airborne exposure in the offices and corridors of the plant. Experiments with inhibition EIA for IgE showed that (a) phytase of another commercial source was only partially cross reactive with phytase as used in the premix factory, and (b) phytase used as an animal feed additive did not cross react with common mould extracts, except for extracts from the species of origin, Aspergillusniger. The amount of IgE binding phytase in Aspergillusniger was estimated to be between 0.1% and 1% of the extractable mould proteins. CONCLUSIONS: Phytase is a potentially important new occupational allergen causing specific IgE immune responses among exposed workers. Such IgE sensitisation could probably be the cause of work related asthmatic and other respiratory symptoms if no effective measures are taken to prevent airborne occupational exposure at sites where phytase is handled, particularly during addition of enzyme preparations to animal feed.
Doekes, G.; Kamminga, N.; Helwegen, L.; Heederik, D.
In the process of the fermentation of steroid C11?-hydroxylgenation strain Aspergillusflavus AF-ANo208, a red pigment is derived, which will affect the isolation and purification of the target product. Low energy ion beam implantation is a new tool for breeding excellent mutant strains. In this study, the ion beam implantation experiments were performed by infusing two different ions: argon ion (Ar+) and nitrogen ion (N+). The results showed that the optimal ion implantation was N+ with an optimum dose of 2.08 × 1015 ions/cm2, with which the mutant strain AF-ANm16 that produced no red pigment was obtained. The strain had high genetic stability and kept the strong capacity of C11?-hydroxylgenation, which could be utilized in industrial fermentation. The differences between the original strain and the mutant strain at a molecular level were analyzed by randomly amplified polymorphic DNA (RAPD). The results indicated that the frequency of variation was 7.00%, which would establish the basis of application investigation into the breeding of pigment mutant strains by low energy ion implantation.
Aspergillusflavus is second to A. fumigatus as a cause of invasive aspergillosis, but no standard method exists for molecular typing of strains from human sources. A repetitive DNA sequence cloned from A. flavus and subcloned into a pUC19 vector, pAF28, was used to type 18 isolates from diverse clinical, environmental, and geographic sources. The restriction fragment length polymorphisms generated with EcoRI- or PstI-digested genomic DNA and probed with digoxigenin-labeled pAF28 revealed complete concordance between patterns. Eighteen distinct fingerprints were observed. The probe was used to investigate two cases of cutaneous A. flavus infection in low-birth-weight infants in a neonatal intensive care unit (NICU). Both infants were transported by the same ambulance and crew to the NICU on the same day. A. flavus strains of the same genotype were isolated from both infants, from a roll of tape used to fasten their umbilical catheters, from a canvas bag used to store the tape in the ambulance, and from the tape tray in the ambulance isolette. These cases highlight the need to consider exposures in critically ill neonates that might occur during their transport to the NICU and for stringent infection control practices. The hybridization profiles of strains from a second cluster of invasive A. flavus infections in two pediatric hematology-oncology patients revealed a genotype common to strains from a definite case patient and a health care worker. A probable case patient was infected with a strain with a genotype different from that of the strain from the definite case patient but highly related to that of an environmental isolate. The high degree of discrimination and reproducibility obtained with the pAF28 probe underscores its utility for typing clinical and environmental isolates of A. flavus.
James, Michael J.; Lasker, Brent A.; McNeil, Michael M.; Shelton, Mark; Warnock, David W.; Reiss, Errol
Aspergillusflavus is second to A. fumigatus as a cause of invasive aspergillosis, but no standard method exists for molecular typing of strains from human sources. A repetitive DNA sequence cloned from A. flavus and subcloned into a pUC19 vector, pAF28, was used to type 18 isolates from diverse clinical, environmental, and geographic sources. The restriction fragment length polymorphisms generated with EcoRI- or PstI-digested genomic DNA and probed with digoxigenin-labeled pAF28 revealed complete concordance between patterns. Eighteen distinct fingerprints were observed. The probe was used to investigate two cases of cutaneous A. flavus infection in low-birth-weight infants in a neonatal intensive care unit (NICU). Both infants were transported by the same ambulance and crew to the NICU on the same day. A. flavus strains of the same genotype were isolated from both infants, from a roll of tape used to fasten their umbilical catheters, from a canvas bag used to store the tape in the ambulance, and from the tape tray in the ambulance isolette. These cases highlight the need to consider exposures in critically ill neonates that might occur during their transport to the NICU and for stringent infection control practices. The hybridization profiles of strains from a second cluster of invasive A. flavus infections in two pediatric hematology-oncology patients revealed a genotype common to strains from a definite case patient and a health care worker. A probable case patient was infected with a strain with a genotype different from that of the strain from the definite case patient but highly related to that of an environmental isolate. The high degree of discrimination and reproducibility obtained with the pAF28 probe underscores its utility for typing clinical and environmental isolates of A. flavus. PMID:11015372
James, M J; Lasker, B A; McNeil, M M; Shelton, M; Warnock, D W; Reiss, E
Wild-type Aspergillusniger NRRL-3 was transformed with multiple copies of the glucose oxidase structural gene (god). The gene was placed under the control of the gpdA promoter of A. nidulans. For more efficient secretion the alpha-amylase signal peptide from A. oryzae was inserted in front of god. Compared to the wild type, the recombinant strain NRRL-3 (GOD3-18) produced up to four times more extracellular glucose oxidase under identical culture conditions. Addition of yeast extract (2 gl-1) to a mineral salts medium containing only glucose as carbon source increased volumetric and specific extracellular glucose oxidase activities by 130% and 50% respectively. With the same medium composition and inoculum size, volumetric and specific extracellular glucose oxidase activities increased more than ten times in bioreactor cultivations compared to shake-flask cultures. PMID:8590664
An elicitor of plant disease resistance, pectinase, was produced by solid state fermentation with Aspergillusniger. Sugar beet pulp was used as carbon source and the wastewater from monosodium glutamate production was used as nitrogen and water source. The composition of the fermentation medium was: 11 ml concentrated wastewater (containing NH3-N 38.2 mg/ml), sugar beet pulp 10 g, Na2HPO4.12H2O 0.2 g, KH2PO4 0.04 g in a 500 ml Erlenmeyer flask. The fermentation temperature was 30 degrees C and the relative humidity of the air was 75-90%. The maximum production of pectinase was reached after 96 h cultivation. The crude pectinase extracted from the fermented materials could elicit disease resistance in cucumber and tomato seedlings. PMID:15207294
Bioactivity-guided fractionation of the cytotoxic extract of Aspergillusniger, an endophytic fungus from the Chinese liverwort Heteroscyphus tener (Steph.) Schiffn., afforded five new naphtho-?-pyrones, rubrofusarin-6-O-?-D-ribofuranoside (1), (R)-10-(3-succinimidyl)-TMC-256A1 (2), asperpyrone E (3), isoaurasperone A (4), and isoaurasperone F (5), as well as four known ones, dianhydroaurasperone C (6), aurasperone D (7), asperpyrone D (8), and asperpyrone A (9), together with a cytotoxic cyclic pentapeptide, malformin A1 (10). Their structures were determined by extensive spectroscopic analysis. The absolute configurations of dimeric naphtho-?-pyrones 3-9 were also determined by analysis of their respective CD spectra. PMID:23847065
In this study, anidulafungin (AFG) showed high in vitro activity against 10 isolates of Aspergillusniger by broth microdilution and disk diffusion methods. The efficacy of AFG at 1, 5 and 10 mg/kg was tested against six of the isolates in a murine model of disseminated infection. AFG was able to reduce mortality, showing survival rates of 70-100%, 60-100% and 30-60% in mice treated with AFG at 10, 5 and 1 mg/kg, respectively. AFG also showed a dose-response efficacy in reducing tissue burden in kidneys and spleen. A parallel experiment demonstrated that administration of AFG did not reduce serum concentrations of galactomannan in mice. Histopathological studies confirmed the efficacy of AFG. PMID:21824751
Calvo, Enrique; Pastor, F Javier; Mayayo, Emilio; Guarro, Josep
Citrus peels are rich in polymethoxylated flavones (PMFs) and are potential sources of natural preservatives. Six PMFs extracts, isolated and purified from the peels of three mandarins (Citrus reticulata) and three sweet oranges (Citrus sinensis), were identified and quantitated. Their inhibitory effects on Aspergillusniger were evaluated using a microbroth dilution assay. The Red tangerine variety exhibited the greatest antifungal activity (MIC = 0.2 mg/mL), while Jincheng showed the lowest activity (MIC = 1.8 mg/mL). An analysis of principal components was applied to the results in order to elucidate the structure-activity relationships of the citrus PMFs. The structure-activity relationship analysis revealed that, for good inhibitory effect, the 5-OH, 3-OCH?, and 8-OCH? functionalities were essential, while the presence of 3-OH and 3'-OCH? greatly reduced inhibition. The findings of this study provide important information for the exploitation and utilization of citrus PMFs as natural biopreservatives. PMID:22500738
The ability of 88 fungi, which had been obtained as high-potency strains for acid proteinase production, to produce a new type of acid carboxypeptidase (having on optimal pH of about 3 for hydrolysis of benzyloxycarbonyl-glutamyltyrosine) in surface koji culture was determined. Among the aspergilli, substantial amounts of this new acid carboxypeptidase were produced by Aspergillus saitoi, A. usamii, A. awamori, A. inuii, and A. niger. Maximum yields of acid carboxypeptidase per gram of substrate were obtained by submerged culture in a medium containing 0.9% defatted soybean and 0.6% wheat bran. However, the maximum enzyme concentration per milliliter was obtained with a medium containing 3% defatted soybean and 2% wheat bran. The terminal pH could be controlled by varying the concentrations of soybean oil meal and wheat bran. The maximum enzyme production was reached after 4 days or more at 30 C. PMID:4796163
Ichishima, E; Yamane, A; Nitta, T; Kinoshita, M; Nikkuni, S
A major fraction of monoterpenes and norisoprenoids in young wines is conjugated to sugars representing a significant reservoir of aromatic precursors. To promote their release, ?-glucosidase, ?-arabinosidase, and ?-rhamnosidase from a commercial Aspergillusniger preparation, were immobilized onto acrylic beads. 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. In addition, the obtained derivative showed increased stability in simile wine conditions. After the treatment of Muscat wine with the biocatalyst for 20days, free monoterpenes increased significantly (from 1119 to 2132?g/L, p<0.01) with respect to the control wine. Geraniol was increased 3,4-fold over its flavor thresholds, and accordingly its impact on sensorial properties was very relevant: nine of ten judges considered treated wine more intense in fruit and floral notes. PMID:24054229
The main concern of this study is to develop a feasible and economical technique to microbially recover metals from oxide low-grade ores. Owing to the significant quantities of metals that are embodied in low-grade ores and mining residues, these are potential viable sources of metals. In addition, they potentially endanger the environment, as the metals they contain may be released to the environment in hazardous form. Hence, mining industries are seeking an efficient, economic technique to handle these ores. Pyrometallurgical and hydrometallurgical techniques are either very expensive, energy intensive or have a negative impact on the environment. For these reasons, biohydrometallurgical techniques are coming into perspective. In this study, by employing Aspergillusniger, the feasibility of recovery of metals from a mining residue is shown. A. niger exhibits good potential in generating a variety of organic acids effective for metal solubilization. Organic acid effectiveness was enhanced when sulfuric acid was added to the medium. Different agricultural wastes such as potato peels were tested. In addition, different auxiliary processes were evaluated in order to either elevate the efficiency or reduce costs. Finally, maximum solubilization of 68%, 46% and 34% were achieved for copper, zinc and nickel, respectively. Also iron co-dissolution was minimized as only 7% removal occurred. PMID:15177728
Mulligan, Catherine N; Kamali, Mahtab; Gibbs, Bernard F
Aspergillusniger GH1 previously isolated and identified by our group as a wild tannase producer was grown under solid-state (SSC) and submerged culture (SmC) conditions to select the enzyme production system. For tannase purification, extracellular tannase was produced under SSC using polyurethane foam as the inert support. Tannase was purified to apparent homogeneity by ultrafiltration, anion-exchange chromatography, and gel filtration that led to a purified enzyme with a specific activity of 238.14 IU/mg protein with a final yield of 0.3% and a purification fold of 46. Three bands were found on the SDS-PAG with molecular masses of 50, 75, and 100 kDa. PI of 3.5 and 7.1% Nglycosylation were noted. Temperature and pH optima were 60 degrees and 6.0 [methyl 3,4,5-trihydroxybenzoate (MTB) as substrate], respectively. Tannase was found with a KM value of 0.41 x 10-4 M and the value of Vmax was 11.03 micromoL/min at 60 degrees for MTB. Effects of several metal salts, solvents, surfactants, and typical enzyme inhibitors on tannase activity were evaluated to establish the novelty of the enzyme. Finally, the tannase from A. niger GH1 was significantly inhibited by PMSF (phenylmethylsulfonyl fluoride), and therefore, it is possible to consider the presence of a serine or cysteine residue in the catalytic site. PMID:19809257
Mata-Gomez, Marco; Rodriguez, Luis V; Ramos, Erika L; Renovato, Jacqueline; Cruz-Hernandez, Mario A; Rodriguez, Raul; Contreras, Juan; Aguilar, Cristobal N
Statistically based experimental design was employed for the optimization of fermentation conditions for maximum production of enzyme tannase from Aspergillusniger. Central composite rotatable design (CCRD) falling under response surface methodology (RSM) was used. Based on the results of 'one-at-a-time' approach in submerged fermentation, the most influencing factors for tannase production from A. niger were concentrations of tannic acid and sodium nitrate, agitation rate and incubation period. Hence, to achieve the maximum yield of tannase, interaction of these factors was studied at optimum production pH of 5.0 by RSM. The optimum values of parameters obtained through RSM were 5% tannic acid, 0.8% sodium nitrate, 5.0 pH, 5 × 10(7) spores/50mL inoculum density, 150 rpm agitation and incubation period of 48 h which resulted in production of 19.7 UmL(-1) of the enzyme. This activity was almost double as compared to the amount obtained by 'one-at-a-time' approach (9.8 UmL(-1)). PMID:23100655
In various biotechnological processes, filamentous fungi, e.g. Aspergillusniger, are widely applied for the production of high value-added products due to their secretion efficiency. There is, however, a tangled relationship between the morphology of these microorganisms, the transport phenomena and the related productivity. The morphological characteristics vary between freely dispersed mycelia and distinct pellets of aggregated biomass. Hence, advantages and disadvantages for mycel or pellet cultivation have to be balanced out carefully. Due to this inadequate understanding of morphogenesis of filamentous microorganisms, fungal morphology, along with reproducibility of inocula of the same quality, is often a bottleneck of productivity in industrial production. To obtain an optimisation of the production process it is of great importance to gain a better understanding of the molecular and cell biology of these microorganisms as well as the approaches in biochemical engineering and particle technique, in particular to characterise the interactions between the growth conditions, cell morphology, spore-hyphae-interactions and product formation. Advances in particle and image analysis techniques as well as micromechanical devices and their applications to fungal cultivations have made available quantitative morphological data on filamentous cells. This chapter provides the ambitious aspects of this line of action, focussing on the control and characterisation of the morphology, the transport gradients and the approaches to understand the metabolism of filamentous fungi. Based on these data, bottlenecks in the morphogenesis of A. niger within the complex production pathways from gene to product should be identified and this may improve the production yield.
The efficacy of lipase from Aspergillusniger MTCC 2594 as an additive in laundry detergent formulations was assessed using response surface methodology (RSM). A five-level four-factorial central composite design was chosen to explain the washing protocol with four critical factors, viz. detergent concentration, lipase concentration, buffer pH and washing temperature. The model suggested that all the factors chosen had a significant impact on oil removal and the optimal conditions for the removal of olive oil from cotton fabric were 1.0% detergent, 75 U of lipase, buffer pH of 9.5 and washing temperature of 25 degrees C. Under optimal conditions, the removal of olive oil from cotton fabric was 33 and 17.1% at 25 and 49 degrees C, respectively, in the presence of lipase over treatment with detergent alone. Hence, lipase from A. niger could be effectively used as an additive in detergent formulation for the removal of triglyceride soil both in cold and warm wash conditions. PMID:16491364
Saisubramanian, N; Edwinoliver, N G; Nandakumar, N; Kamini, N R; Puvanakrishnan, R
There is a wide range of biotechnological applications for amylases, including the textile, pharmaceutical, food and laundry industries. Hydrolytic enzymes are 100% biodegradable and enzymatic detergents can achieve effective cleaning with lukewarm water. Microorganisms and culture media were tested for amylase production and the best producer was Aspergillusniger L119 (3.9 U ml(-1) +/- 0.2) in submerged culture and its amylase demonstrated excellent activity at 50-55 degrees C and pH 4.0, remaining stable at 53 degrees C for up to 200 h. In order to establish the potential uses of this enzyme in detergents, different formulations were tested using the A. niger amylase extract. Enzyme activity was compared with three commercial formulations. The detergents are used in hospitals to clean surgical and endoscopy equipment. The presence of amylase in the formulation is because of its action within hospital drainage system, whether or not it has any function in cleaning the equipment. PMID:16112858
Identification of missing genes or proteins participating in the metabolic pathways as enzymes are of great interest. One such class of pathway is involved in the eugenol to vanillin bioconversion. Our goal is to develop an integral approach for identifying the topology of a reference or known pathway in other organism. We successfully identify the missing enzymes and then reconstruct the vanillin biosynthetic pathway in Aspergillusniger. The procedure combines enzyme sequence similarity searched through BLAST homology search and orthologs detection through COG & KEGG databases. Conservation of protein domains and motifs was searched through CDD, PFAM & PROSITE databases. Predictions regarding how proteins act in pathway were validated experimentally and also compared with reported data. The bioconversion of vanillin was screened on UV-TLC plates and later confirmed through GC and GC-MS techniques. We applied a procedure for identifying missing enzymes on the basis of conserved functional motifs and later reconstruct the metabolic pathway in target organism. Using the vanillin biosynthetic pathway of Pseudomonas fluorescens as a case study, we indicate how this approach can be used to reconstruct the reference pathway in A. niger and later results were experimentally validated through chromatography and spectroscopy techniques.
Srivastava, Suchita; Luqman, Suaib; Khan, Feroz; Chanotiya, Chandan S; Darokar, Mahendra P
Infection of the maize (Zea mays L.) with aflatoxigenic fungus Aspergillusflavus and consequent contamination with carcinogenic aflatoxin is a persistent and serious agricultural problem causing disease and significant crop losses worldwide. The rachis (cob) is an important structure of maize ear that delivers essential nutrients to the developing kernels and A. flavus spreads through the rachis to infect kernels within the ear. Therefore, rachis plays an important role in fungal proliferation and subsequent kernel contamination. We used proteomic approaches and investigated the rachis tissue from aflatoxin accumulation resistant (Mp313E and Mp420) and susceptible (B73 and SC212m) maize inbred lines. First, we compared rachis proteins from resistant and susceptible inbred lines, which revealed that the young resistant rachis contains higher levels of abiotic stress-related proteins and proteins from phenylpropanoid metabolism, whereas susceptible young rachis contains pathogenesis-related proteins, which are generally inducible upon biotic stress. Second, we identified A. flavus-responsive proteins in rachis of both resistant and susceptible genotypes after 10- and 35-day infection. Differential expression of many stress/defense proteins during rachis juvenility, maturation and after A. flavus challenge demonstrates that resistant rachis relies on constitutive defenses, while susceptible rachis is more dependent on inducible defenses. PMID:21182199
Pechanova, Olga; Pechan, Tibor; Williams, W Paul; Luthe, Dawn S
Eosinophilic pneumonia was confirmed by bronchoalveolar lavage fluid examination and transbronchial lung biopsy. Aspergillusniger was cultured from the patient's pharyngeal swab and bronchoalveolar lavage fluid. Inhalation bronchoprovocation test with A. niger antigen was positive. Although the patient's condition improved promptly with 10 mg/day prednisolone administration, dry cough recurred approximately 2 months after completion of this therapy. Severe coughing disappeared on oral cleansing with 300 mg/day amphotericin B, and he recovered completely on 100 mg/day amphotericin B administration. Oral cleansing with amphotericin B may be efficacious in preventing relapses of eosinophilic pneumonia caused by allergic reaction to fungal antigen. PMID:19191146
The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillusflavus and aflatoxin contamination levels within the kernels. Aflatoxin contamination in corn has been a long-standing problem plaguing the grain industry with potentially devastating consequences to corn growers. In this study, aflatoxin-contaminated corn kernels were produced through artificial inoculation of corn ears in the field with toxigenic A. flavus spores. The kernel fluorescence emission data were taken with a fluorescence hyperspectral imaging system when corn kernels were excited with ultraviolet light. Raw fluorescence image data were preprocessed and regions of interest in each image were created for all kernels. The regions of interest were used to extract spectral signatures and statistical information. The aflatoxin contamination level of single corn kernels was then chemically measured using affinity column chromatography. A fluorescence peak shift phenomenon was noted among different groups of kernels with different aflatoxin contamination levels. The fluorescence peak shift was found to move more toward the longer wavelength in the blue region for the highly contaminated kernels and toward the shorter wavelengths for the clean kernels. Highly contaminated kernels were also found to have a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also noted that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green regions. The correlation coefficients of determination, r(2), was 0.72 for the multiple linear regression model. The multivariate analysis of variance found that the fluorescence means of four aflatoxin groups, <1, 1-20, 20-100, and >or=100 ng g(-1) (parts per billion), were significantly different from each other at the 0.01 level of alpha. Classification accuracy under a two-class schema ranged from 0.84 to 0.91 when a threshold of either 20 or 100 ng g(-1) was used. Overall, the results indicate that fluorescence hyperspectral imaging may be applicable in estimating aflatoxin content in individual corn kernels. PMID:20221935
The effects of infection of seed yam by Aspergillusniger on shoot emergence and vine development were investigated in three yam species. Shoot emergence was particularly poor in D. esculenta; this was attributed to a greater susceptibility to A. niger due to the relatively smaller size of the tuber, less compact inner tissue and thinner periderm in the species. Reductions
The author conducted experiments with 7 groups of 3 piglets and one pregnant sow each. Prolonged feeding to the piglets of corn strongly infected with Aspergillusniger, A. fumigatus, A. flavus, A. candidus, A. glaucus, or A. clavatus in an amount compris...
In separate treatments, a spore suspension ofA. flavus (control), an aqueous leaf extract of the subtropical neem tree plus a spore suspension ofA. flavus, or an aqueous neem leaf extract followed by anA. flavus spore suspension were injected 48 hr later onto the surfaces of locks of developing cotton bolls (30-day post anthesis).\\u000a Thirteen days after the treatments, the seeds
Niger is two-thirds Sahara desert and the rest savannah with an area irrigated by the Niger River valley. The 6.2 million people are therefore either nomadic herdsmen or subsistence farmers, coping with a hot, dry climate. There are 5 or more ethnic groups, 2 main languages other than the official French, and most people are Muslim. The growth rate is 3.1%; children make up 45% of the population; infant mortality is 145/1000; life expectancy is 44.5 years. The constitutional government has been suspended by a military regime. A multi-layered structure called "development society" has been instituted. Per capita income is about $265. Niger has uranium, coal, iron, tin and phosphates, and farm products include peanuts, millet, sorghum, beans, cotton, rice and cowpeas. Niger received assistance from France, US, West Germany, Canada, Saudi Arabia, as well as international organizations and military assistance from several countries. PMID:12177951
The proteins VeA, VelB and LaeA of Aspergillus nidulans form a heterotrimeric complex (the velvet complex) in the dark to coordinate sexual development and production of some secondary metabolites. VeA and VelB of A. nidulans and Aspergillus fumigatus also are repressors of conidiation, but VeA of Aspergillusflavus in studied strains acts positively on conidiation. In the present study, we show via yeast-two hybrid assays that interactions among A. flavus VeA, VelB, and LaeA are conserved as in the A. nidulans velvet complex. We found that FluG, which is required for conidiophore formation in A. nidulans but whose deletion in A. flavus delays onset of conidiation, was probably an interacting partner of VelB. Deletion of velB in A. flavus CA14 severely impaired conidiation in the dark although to a lesser extent than deletion of veA. In both mutants fluG deletion resulted in further decreased conidiation even in the light. Deletion of fluG in the ?laeA strain, however, did not affect conidiation. All mutant types were unable to produce aflatoxin and sclerotia. Cross-complementation of the ?velB strain with gpdA::veA restored conidiation but not aflatoxin production although aflR, the aflatoxin pathway regulatory gene, was expressed at a normal level. Cross-complementation of the ?veA strain with gpdA::velB failed to restore conidiation and aflatoxin production. The ?velB strain complemented with or a wild type transformed by gpdA::velB had elevated sclerotial production as the ?fluG strain. Concerted interactions of A. flavus VeA and VelB with LaeA are critical for conidiation and aflatoxin biosynthesis. VelB may have a dual role and likely coordinates with FluG to modulate sclerotial production. PMID:23994319
Chang, Perng-Kuang; Scharfenstein, Leslie L; Li, Ping; Ehrlich, Kenneth C
Maize is one of the more important agricultural crops in the world and, under certain conditions, prone to attack from pathogenic fungi. One of these, Aspergillusflavus, produces toxic and carcinogenic metabolites, called aflatoxins, as byproducts of its infection of maize kernels. The alpha-amylase of A. flavus is known to promote aflatoxin production in the endosperm of these infected kernels, and a 36-kDa protein from the Lablab purpureus, denoted AILP, has been shown to inhibit alpha-amylase production and the growth of A. flavus. Here, we report the isolation of six full-length labAI genes encoding AILP and a detailed analysis of the activities of the encoded proteins. Each of the six labAI genes encoded sequences of 274 amino acids, with the deduced amino acid sequences showing approximately 95-99% identity. The sequences are similar to those of lectin members of a legume lectin-arcelin-alpha-amylase inhibitor family reported to function in plant resistance to insect pests. The labAI genes did not show any of the structures characteristic of conserved structures identified in alpha-amylase inhibitors to date. The recombinant proteins of labAI-1 and labAI-2 agglutinated human red blood cells and inhibited A. flavus alpha-amylase in a manner similar to that shown by AILP. These data indicate that labAI genes are a new class of lectin members in legume seeds and that their proteins have both lectin and alpha-amylase inhibitor activity. These results are a valuable contribution to our knowledge of plant-pathogen interactions and will be applicable for developing protocols aimed at controlling A. flavus infection. PMID:17149640
Kim, Young-Hwa; Woloshuk, Charles P; Cho, Eun Hee; Bae, Jung Myung; Song, Young-Sun; Huh, Gyung Hye