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1

Amylase synthesis in Aspergillus flavus and Aspergillus niger grown on cassava peel  

Microsoft Academic Search

Summary Aspergillus flavus andAspergillus niger produce extracellular amylase into the culture medium when grown on basal medium containing 2% (w\\/v) soluble starch or cassava peel as the sole carbon source. On soluble tarch the highest amylase activities were 1.6 and 5.2 mg of starch hydrolyzed\\/min per mg protein forA. flavus andA. niger, respectively. When grown on cassava peel, the highest

Alhassan Sani; Francis A. Awe; Joseph A. Akinyanju

1992-01-01

2

Aspergillus flavus.  

PubMed

Aspergillus flavus 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

Amaike, Saori; Keller, Nancy P

2011-01-01

3

Terpenoid composition and antifungal activity of three commercially important essential oils against Aspergillus flavus and Aspergillus niger.  

PubMed

Hydro-distilled essential oils extracted from three commercially important aromatic plants were analysed by capillary gas chromatography-flame ionization detector and gas chromatography/quadrupole mass spectrometry and subjected to antifungal activity. Fifteen compounds, which accounted for 97.8% of Acorus calamus root oil composition have been identified. Besides the major constituent (Z)-asarone (81.1-92.4%), (Z)-methyl isoeugenol (1.8-2.1%), (Z)-isoelemicin (1.2-1.3%), (E)-asarone (1.0-2.6%), (E)-methyl isoeugenol (0.2-0.4%), (Z)-?-ocimene (0.2-0.4%), elemicin (0.2-0.3%), linalool (0.1-0.9%) and kessane (t-0.2%) were identified. Monoterpenes constituted the main fraction of Origanum vulgare essential oil attaining 90.5% of the total oil composition. p-Cymene (10.3%) was the major component of the monoterpene hydrocarbon fraction while thymol (53.2%) and carvacrol (3.9%) were the most abundant oxygenated monoterpenes among the 33 identified constituents. Cinnamomum tamala leaf oil contained (E)-cinnamaldehyde as the principal component. Quantitative variations in (Z)-cinnamaldehyde (5.8-7.1%), linalool (6.4-8.5%) and (E)-cinnamyl acetate (4.7-5.2%) were significant. The antifungal activity of the hydro-distilled essential oils of A. calamus, O. vulgare and C. tamala were evaluated against Aspergillus flavus and Aspergillus niger. Disc diffusion method was used for the determination of the inhibitory effect. O. vulgare essential oil exhibited the highest activity. Moreover, all three essential oils inhibit the growth of A. flavus and A. niger. PMID:21707253

Bisht, Deepa; Pal, Anirban; Chanotiya, C S; Mishra, Dhirendra; Pandey, K N

2011-12-01

4

Optimization of the production of thermostable endo-beta-1,4 mannanases from a newly isolated Aspergillus niger gr and Aspergillus flavus gr.  

PubMed

The aim of this work was to establish optimal conditions for the maximum production of endo-beta-1,4 mannanases using cheaper sources. Eight thermotolerant fungal strains were isolated from garden soil and compost samples collected in and around the Gulbarga University campus, India. Two strains were selected based on their ability to produce considerable endo-beta-1,4 mannanases activity while growing in liquid medium at 37 degrees C with locust bean gum (LBG) as the only carbon source. They were identified as Aspergillus niger gr and Aspergillus flavus gr. The experiment to evaluate the effect of different carbon sources, nitrogen sources, temperatures and initial pH of the medium on maximal enzyme production was studied. Enzyme productivity was influenced by the type of polysaccharide used as the carbon source. Copra meal defatted with n-hexane showed to be a better substrate than LBG and guar gum for endo-beta-1,4 mannanases production by A. niger gr (40.011 U/ml), but for A. flavus gr (33.532 U/ml), the difference was not significant. Endo-beta-1,4 mannanases produced from A. niger gr and A. flavus gr have high optimum temperature (65 and 60 degrees C) and good thermostability in the absence of any stabilizers (maintaining 50% of residual activity for 8 and 6 h, respectively, at 60 degrees C) and are stable over in a wide pH range. These new strains offer an attractive alternative source of enzymes for the food and feed processing industries. PMID:18597050

Kote, Naganagouda V; Patil, Aravind Goud G; Mulimani, V H

2009-02-01

5

76 FR 16297 - Aspergillus flavus  

Federal Register 2010, 2011, 2012, 2013

...pesticide, Aspergillus flavus AF36, in or on corn food and feed commodities, when applied...residues of Aspergillus flavus AF36 in or on corn food and feed commodities. This notice...May 23, 2007) (FRL-8129-4) and on corn (72 FR 72965, Dec. 26, 2007)...

2011-03-23

6

Colonization of rye green manure and peanut fruit debris by Aspergillus falvus and Aspergillus niger group in field soils.  

PubMed Central

Aspergillus flavus and Aspergillus niger group colonization of deep-plowed, decomposing rye green manure cover crops in peanut field soils was studied in four fields during 1972 and 1973; colonization of decomposing peanut fruits was studied in 1972 in two fields. A. flavus colonization of rye and peanut fruits was greater in soils of heavy texture, and an A. flavus population as high as 165 propagules per g of soil was observed in soil adjacent to rye, whereas A. flavus populations in soils not associated with rye were 18 propagules per g of soil or lower. Highest A. flavus populations in soil adjacent to decomposing peanut fruits were usually comparable to populations associated with rye. Little decomposing rye or peanut fruit colonization was generally observed by the A. flavus competitor, A. niger group. A. flavus may maintain or increase its inoculum potential by colonization of these and other moribund plant tissues.

Griffin, G J; Garren, K H

1976-01-01

7

Aspergillus nomius , a new aflatoxin-producing species related to Aspergillus flavus and Aspergillus tamarii  

Microsoft Academic Search

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.

C. P. Kurtzman; B. W. Horn; C. W. Hesseltine

1987-01-01

8

Cyclopiazonic acid biosynthesis of Aspergillus flavus and Aspergillus oryzae.  

PubMed

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

Chang, Perng-Kuang; Ehrlich, Kenneth C; Fujii, Isao

2009-12-01

9

The Phylogenetics of Mycotoxin and Sclerotium Production in Aspergillus flavus and Aspergillus oryzae  

Microsoft Academic Search

Geiser, D. M., Dorner, J. W., Horn, B. W., and Taylor, J. W. 2000. The phylogenetics of mycotoxin and scle- rotium production in Aspergillus flavus and Aspergillus oryzae. Fungal Genetics and Biology 31, 169 -179. Aspergillus flavus is a common filamentous fungus that produces aflatoxins and presents a major threat to agriculture and human health. Previous phylogenetic studies of A.

David M. Geiser; Joe W. Dorner; Bruce W. Horn; John W. Taylor

2001-01-01

10

Aspergillus flavus endaortitis following aortic valvotomy  

PubMed Central

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 Aspergillus flavus, 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

Malcolm, A. D.; Bakerspigel, A.; Enriquez, A. A.

1971-01-01

11

Nitrile biotransformation by Aspergillus niger  

Microsoft Academic Search

A nitrile-converting enzyme activity was induced in Aspergillus niger K10 by 3-cyanopyridine. The whole cell biocatalyst was active at pH 3–11 and hydrolyzed the cyano group into acid and\\/or amide functions in benzonitrile as well as in its meta- and para-substituted derivatives, cyanopyridines, 2-phenylacetonitrile and thiophen-2-acetonitrile. Amides constituted a significant part of the total biotransformation products of 2- and 4-cyanopyridine,

Radka Šnajdrová; Veronika Kristová-Mylerová; Dominique Crestia; Konstantina Nikolaou; Marek Kuzma; Marielle Lemaire; Estelle Gallienne; Jean Bolte; Karel Bezouška; Vladim??r K?en; Ludmila Mart??nková

2004-01-01

12

What does genetic diversity of Aspergillus flavus tell us about Aspergillus oryzae?  

PubMed

Aspergillus flavus 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

Chang, Perng-Kuang; Ehrlich, Kenneth C

2010-04-15

13

Heavy metal biosorption sites in Aspergillus niger  

Microsoft Academic Search

Aspergillus niger 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

Anoop Kapoor; T. Viraraghavan

1997-01-01

14

Ageratum conyzoides essential oil as aflatoxin suppressor of Aspergillus flavus  

Microsoft Academic Search

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oil of Ageratum conyzoides, on the mycelial growth and aflatoxin B1 production by Aspergillus flavus were studied. Cultures were incubated in yeast extract-sucrose (YES) broth for days at 25°C at the following different concentrations of the essential

Juliana H. C. Nogueira; Edlayne Gonçalez; Silvia R. Galleti; Roseane Facanali; Márcia O. M. Marques; Joana D. Felício

2010-01-01

15

The Phylogenetics of Mycotoxin and Sclerotium Production in Aspergillus flavus and Aspergillus oryzae  

Microsoft Academic Search

Aspergillus flavus is a common filamentous fungus that produces aflatoxins and presents a major threat to agriculture and human health. Previous phylogenetic studies of A. flavus have shown that it consists of two subgroups, called groups I and II, and morphological studies indicated that it consists of two morphological groups based on sclerotium size, called “S” and “L.” The industrially

David M Geiser; Joe W Dorner; Bruce W Horn; John W Taylor

2000-01-01

16

Potential of Aspergillus flavus genomics for applications in biotechnology.  

PubMed

Aspergillus flavus 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

2009-03-01

17

Development and evaluation of a real-time quantitative PCR assay for Aspergillus flavus  

Microsoft Academic Search

Aspergillus flavus is a ubiquitous mold and the most common mold contaminating foodstuffs. Many strains of A. flavus produce aflatoxins. In addition it is an allergen and an opportunistic pathogen of animals and plants. A. flavus often is underestimated in traditional culture analyses due to the expertise required and the cost associated with speciating members of the genus Aspergillus. The

Patricia Cruz; Mark P. Buttner

2008-01-01

18

Lipids in Aspergillus flavus-maize interaction.  

PubMed

In some filamentous fungi, the pathways related to the oxidative stress and oxylipins production are involved both in the process of host-recognition and in the pathogenic phase. In fact, recent studies have shown that the production of oxylipins in filamentous fungi, yeasts and chromists is also related to the development of the organism itself and to mechanisms of communication with the host at the cellular level. The oxylipins, also produced by the host during defense reactions, are able to induce sporulation and to regulate the biosynthesis of mycotoxins in several pathogenic fungi. In A. flavus, the oxylipins play a crucial role as signals for regulating the biosynthesis of aflatoxins, the conidiogenesis and the formation of sclerotia. To investigate the involvement of an oxylipins based cross-talk into Z. mays and A. flavus interaction, we analyzed the oxylipins profile of the wild type strain and of three mutants of A. flavus that are deleted at the Aflox1 gene level also during maize kernel invasion. A lipidomic approach has been addressed through the use of LC-ToF-MS, followed by a statistical analysis of the principal components (PCA). The results showed the existence of a difference between the oxylipins profile generated by the WT and the mutants onto challenged maize. In relation to this, aflatoxin synthesis which is largely hampered in vitro, is intriguingly restored. These results highlight the important role of maize oxylipin in driving secondary metabolism in A. flavus. PMID:24578700

Scarpari, Marzia; Punelli, Marta; Scala, Valeria; Zaccaria, Marco; Nobili, Chiara; Ludovici, Matteo; Camera, Emanuela; Fabbri, Anna A; Reverberi, Massimo; Fanelli, Corrado

2014-01-01

19

Formation of aflatoxins by some Egyptian Aspergillus flavus strains.  

PubMed

In all the fifteen investigated Aspergillus flavus and A. parasiticus strains the maximum quantities of aflatoxins, produced on rice powder-corn steep (RC) medium, ranged from 1.17 to 23.29 times as much as those produced on yeast extract-sucrose (YES) medium. The shake cultures lowered aflatoxin formation. The maximum yields of aflatoxins did not coincide with maximum fungal growth. In most A. flavus strains investigated, the total aflatoxin content of the mycelia highly exceeded that of the culture filtrates. PMID:6792813

Mabrouk, S S; El-Shayeb, N M

1981-01-01

20

Aflatoxin production by Aspergillus flavus in Brazil nuts  

Microsoft Academic Search

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

2005-01-01

21

Genotypic and phenotypic versatility of Aspergillus flavus during maize exploitation.  

PubMed

Aspergillus flavus 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

2013-01-01

22

Genotypic and Phenotypic Versatility of Aspergillus flavus during Maize Exploitation  

PubMed Central

Aspergillus flavus 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).

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.

2013-01-01

23

Aspergillus Flavus Keratitis after Deep Anterior Lamellar Keratoplasty  

PubMed Central

Purpose To report the clinical, microbiologic, confocal scan and histopathologic features of Aspergillus flavus 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 Aspergillus flavus. Early diagnosis and appropriate management resulted in complete recovery from this potentially devastating infection. Conclusion Aspergillus Flavus 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.

Jafarinasab, Mohammad-Reza; Feizi, Sepehr; Yazdizadeh, Forouzan; Rezaei Kanavi, Mozhgan; Moein, Hamid-Reza

2012-01-01

24

New dimeric naphthopyrones from Aspergillus niger.  

PubMed

Three new dimeric naphthopyrones, asperpyrones A (1), B (2), and C (3), together with two known compounds, fonsecinone A (4) and aurasperone A (5), have been isolated from okara that was fermented with Aspergillus niger JV-33-48. Compounds 1, 4, and 5 showed inhibitory activity on Taq DNA polymerase. PMID:12542363

Akiyama, Kohki; Teraguchi, Seigo; Hamasaki, Yukiko; Mori, Mika; Tatsumi, Kunihiko; Ohnishi, Kenji; Hayashi, Hideo

2003-01-01

25

Transcriptomic profiling of Aspergillus flavus in response to 5-azacytidine.  

PubMed

Aspergillus flavus is a common saprophyte and opportunistic pathogen producing aflatoxin (AF) and many other secondary metabolites. 5-Azacytidine (5-AC), a derivative of the nucleoside cytidine, is widely used for studies in epigenetics and cancer biology as an inactivator of DNA methyltransferase and is also used for studying secondary metabolism in fungi. Our previous studies showed that 5-AC affects development and inhibits AF production in A. flavus, and that A. flavus lacks DNA methylation. In this study, an RNA-Seq approach was applied to explore the mechanism of 5-AC's effect on A. flavus. We identified 240 significantly differentially expressed (Q-value<0.05) genes after 5-AC treatment, including two backbone genes respectively in secondary metabolite clusters #27 and #35. These two clusters are involved in development or survival of sclerotia. GO functional enrichment analysis showed that these significantly differentially expressed genes were mainly involved in catalytic activity and proteolytic functions. The expressed transcripts of most genes in the AF biosynthetic gene cluster in A. flavus showed no significant changes after treatment with 5-AC and were expressed at low levels, and the transcription regulator genes aflR and aflS in this cluster did not show differential expression relative to the sample without 5-AC treatment. We found that the veA gene, which encodes protein bridges VelB and LaeA, decreased profoundly the expressed transcripts, and brlA, which encodes an early regulator of development, increased its transcripts in A. flavus after 5-AC treatment. Our data support a model whereby 5-AC affects development through increasing the expression of brlA by depressing the expression of veA and AF production through suppressing veA expression and dysregulating carboxypeptidase activity, which then prevents the aflatoxisomes (vesicles) from performing their normal function in AF formation. Furthermore, the suppressed veA expression weakens or even interrupts the connection between VelB and LaeA, leading to dysregulation of the expression pattern of genes involved in development and secondary metabolism in A. flavus. The RNA-seq data presented in this work were also served to improve the annotation of the A. flavus genome. This work provides a comprehensive view of the transcriptome of A. flavus responsive to 5-AC and supports the conclusion that fungal development and secondary metabolism are co-regulated. PMID:23644151

Lin, Jian-Qing; Zhao, Xi-Xi; Zhi, Qing-Qing; Zhao, Ming; He, Zhu-Mei

2013-07-01

26

Comparison of four media for the isolation of Aspergillus flavus group fungi  

Microsoft Academic Search

Four agar media used to isolate aflatoxin producing fungi were compared for utility in isolating fungi in theAspergillus flavus group from agricultural soils collected in 15 fields and four states in the southern United States. The four media wereAspergillus flavus andparasiticus Agar (AFPA, 14), the rose bengal agar described by Bell and Crawford (BCRB; 3), a modified rose bengal agar

Peter J. Cotty

1994-01-01

27

Effect of gamma radiation on Aspergillus flavus and Aspergillus ochraceus ultrastructure and mycotoxin production  

NASA Astrophysics Data System (ADS)

The aim of this work was to study the effect of gamma radiation (2 kGy) on Aspergillus flavus and Aspergillus ochraceus ultrastructure. Moreover, the influence on aflatoxin B 1 and ochratoxin A production was also observed. Irradiated A. flavus strain showed a dull orangish colony while control strain showed the typical green color. Minor differences were observed on stipes, metulae and conidia size between control and irradiated A. flavus and A. ochraceus strains. Irradiated fungi showed ultrastructural changes on cell wall, plasmalema and cytoplasm levels. The levels of mycotoxins produced by irradiated strains were two times greater than those produced by control strains. Successive transferences of irradiated strains on malt extract agar allowed the fungus to recuperate morphological characteristics. Although minor changes in the fungal morphology were observed, ultrastructural changes at cell wall level and the increase of mycotoxin production ability were observed. Inappropriate storage of irradiated food and feed would allow the development of potentially more toxicogenic fungal propagules.

Ribeiro, J.; Cavaglieri, L.; Vital, H.; Cristofolini, A.; Merkis, C.; Astoreca, A.; Orlando, J.; Carú, M.; Dalcero, A.; Rosa, C. A. R.

2011-05-01

28

How Peroxisomes Affect Aflatoxin Biosynthesis in Aspergillus Flavus  

PubMed Central

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 Aspergillus flavus, 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.

Reverberi, Massimo; Punelli, Marta; Smith, Carrie A.; Zjalic, Slaven; Scarpari, Marzia; Scala, Valeria; Cardinali, Giorgia; Aspite, Nicaela; Pinzari, Flavia; Payne, Gary A.; Fabbri, Anna A.; Fanelli, Corrado

2012-01-01

29

How peroxisomes affect aflatoxin biosynthesis in Aspergillus flavus.  

PubMed

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 Aspergillus flavus, 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. PMID:23094106

Reverberi, Massimo; Punelli, Marta; Smith, Carrie A; Zjalic, Slaven; Scarpari, Marzia; Scala, Valeria; Cardinali, Giorgia; Aspite, Nicaela; Pinzari, Flavia; Payne, Gary A; Fabbri, Anna A; Fanelli, Corrado

2012-01-01

30

Cladal relatedness among Aspergillus oryzae isolates and Aspergillus flavus S and L morphotype isolates.  

PubMed

Aspergillus flavus is the main etiological agent for aflatoxin contamination of crops. Its close relative, A. oryzae, does not produce aflatoxins and has been widely used to produce fermented foods. We compared the phylogeny of A. oryzae isolates and L- and S-type sclerotial isolates of A. flavus using single nucleotide polymorphisms in the omtA gene in the aflatoxin biosynthesis gene cluster and deletions in and distal to the norB-cypA intergenic region as phylogenetic signals. Aflatoxin-producing ability and sclerotial size also were weighted in the analysis. Like A. flavus, the A. oryzae isolates form a polyphyletic assemblage. A. oryzae isolates in one clade strikingly resemble an A. flavus subgroup of atoxigenic L-type isolates. All toxigenic S-type isolates closely resemble another subgroup of atoxigenic L-type isolates. Because atoxigenic S-type isolates are extremely rare, we hypothesize that loss of aflatoxin production in S-type isolates may occur concomitantly with a change to L-type sclerotia. All toxigenic L-type isolates, unlike A. oryzae, have a 1.0 kb deletion in the norB-cypA region. Although A. oryzae isolates, like S-type, have a 1.5 kb deletion in the norB-cypA region, none were cladally related to S-type A. flavus isolates. Our results show that A. flavus populations are genetically diverse. A. oryzae isolates may descend from certain atoxigenic L-type A. flavus isolates. PMID:16430983

Chang, Perng-Kuang; Ehrlich, Kenneth C; Hua, Sui-Sheng T

2006-04-25

31

Orbital tuberculosis with coexisting fungal (Aspergillus flavus) infection  

PubMed Central

Background: A coexisting invasive fungal and tubercular involvement of the skull base is a rare event. Co-infection has been reported with involvement of paranasal sinuses and middle ear cleft. Case Description: We herein report a case of an elderly male diabetic patient who presented with gradually progressive visual loss, which on imaging showed an orbital lesion. Surgical decompression and microbiological evaluation showed growth of Mycobacterium tuberculosis and Aspergillus flavus. Conclusion: Rare combinations of such infections do exist and should be treated aggressively to achieve good outcomes in a losing battle with fastidious organisms in the backdrop of compromised immunity.

Reddy, Sunkara Srikanth; Penmmaiah, Devi Chendira; Rajesh, Alugolu; Patil, Madhusudan

2014-01-01

32

Enrichment of Auxotrophic Mutants of Aspergillus flavus by Tritium Suicide  

PubMed Central

A method based on tritium suicide was developed to enrich auxotrophic mutants of Aspergillus flavus. N-methyl-N?-nitro-N-nitrosoguanidine (NG) was chosen as a mutagen, since a wide variety of mutations were induced by the action of 0.1% NG on A. flavus conidia suspended in phosphate buffer (pH 7.0). The decimal reduction time under these conditions was about 30 min, and the surviving population contained 4 to 6% auxotrophs after 1 hr of mutagenesis. This proportion was then increased by tritium suicide of wild-type cells. At a concentration of 1.3 ?m, 3H-leucine was incorporated better than 3H-proline or 3H-thymidine into the germinating conidia. With about 20 hr of incubation and a short treatment in a high-speed mixer to disentangle mycelia and conidia, a 5- to 20-fold decrease in the number of survivors resulted from the incorporated 3H-leucine (5 c/mmole) after 1 week of storage at 5 C. At a 10-fold lower concentration, the uptake of radioactivity and the subsequent suicide rate were much lower. With 3H-leucine, the proportion of auxotrophs in the surviving population rose from 5 to about 20% during 2 weeks of storage at 5 C. Mutants requiring various intermediates for protein or nucleic acid synthesis or requiring vitamins were isolated. Finally, it was noted that A. flavus shows a much higher resistance to tritium suicide than does Escherichia coli.

Donkersloot, J. A.; Mateles, R. I.

1968-01-01

33

Survey of Vietnamese peanuts, corn and soil for the presence of Aspergillus flavus and Aspergillus parasiticus.  

PubMed

Aspergillus flavus and Aspergillus parasiticus cause perennial infection of agriculturally important crops in tropical and subtropical areas. Invasion of crops by these fungi may result in contamination of food and feed by potent carcinogenic aflatoxins. Consumption of aflatoxin contaminated foods is a recognised risk factor for human hepatocellular carcinoma (HCC) and may contribute to the high incidence of HCC in Southeast Asia. This study conducted a survey of Vietnamese crops (peanuts and corn) and soil for the presence of aflatoxigenic fungi and used microsatellite markers to investigate the genetic diversity of Vietnamese Aspergillus strains. From a total of 85 samples comprising peanut (25), corn (45) and soil (15), 106 strains were isolated. Identification of strains by colony morphology and aflatoxin production found all Vietnamese strains to be A. flavus with no A. parasiticus isolated. A. flavus was present in 36.0% of peanut samples, 31.1% of corn samples, 27.3% of farmed soil samples and was not found in virgin soil samples. Twenty-five per cent of the strains produced aflatoxins. Microsatellite analysis revealed a high level of genetic diversity in the Vietnamese A. flavus population. Clustering, based on microsatellite genotype, was unrelated to aflatoxin production, geographic origin or substrate origin. PMID:19693687

Tran-Dinh, N; Kennedy, I; Bui, T; Carter, D

2009-11-01

34

Aflatoxin Biosynthesis and Sclerotial Development in Aspergillus flavus and Aspergillus parasiticus  

Microsoft Academic Search

\\u000a Aflatoxins are a family of fungal secondary metabolites. They are produced by species in the genus Aspergillus. The commonly recognized producers of aflatoxins include A. flavus, A. parasiticus, A. nomius, A. tamarii, A. pseudotamarii, A. bombycis, and A. ochraceoroseus (Cary et al. 2005). Aflatoxin contamination of agricultural commodities can arise from field conditions conducive to fungal\\u000a growth before harvest as

Perng-Kuang Chang

35

Fingernail Onychomycosis Due to Aspergillus niger  

PubMed Central

Onychomycosis is usually caused by dermatophytes, but some species of nondermatophytic molds and yeasts are also associated with nail invasion. Aspergillus niger is a nondermatophytic mold which exists as an opportunistic filamentous fungus in all environments. Here, we report a case of onychomycosis caused by A. niger in a 66-year-old female. The patient presented with a black discoloration and a milky white base and onycholysis on the proximal portion of the right thumb nail. Direct microscopic examination of scrapings after potassium hydroxide (KOH) preparation revealed dichotomous septate hyphae. Repeated cultures on Sabouraud's dextrose agar (SDA) without cycloheximide produced the same black velvety colonies. No colony growth occurred on SDA with cycloheximide slants. Biseriate phialides covering the entire vesicle with radiate conidial heads were observed on the slide culture. The DNA sequence of the internal transcribed spacer region of the clinical sample was a 100% match to that of A. niger strain ATCC 16888 (GenBank accession number AY373852). A. niger was confirmed by KOH mount, colony identification, light microscopic morphology, and DNA sequence analysis. The patient was treated orally with 250 mg terbinafine daily and topical amorolfine 5% nail lacquer for 3 months. As a result, the patient was completely cured clinically and mycologically.

Kim, Dong Min; Ha, Gyoung Yim; Sohng, Seung Hyun

2012-01-01

36

Bisulfite Sequencing Reveals That Aspergillus flavus Holds a Hollow in DNA Methylation  

Microsoft Academic Search

Aspergillus flavus 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

Si-Yang Liu; Jian-Qing Lin; Hong-Long Wu; Cheng-Cheng Wang; Shu-Jia Huang; Yan-Feng Luo; Ji-Hua Sun; Jian-Xiang Zhou; Shu-Jing Yan; Jian-Guo He; Jun Wang; Zhu-Mei He

2012-01-01

37

Co?production of aflatoxins and cyclopiazonic acid in isolates of Aspergillus flavus  

Microsoft Academic Search

The distribution of total aflatoxin (AFT) and cyclopiazonic acid (CPA) between conidia and mycelial matrix was studied in five isolates of Aspergillus flavus Link cultured on maize grain for 20 days at 30°C. Total aflatoxin and CPA production differed between the isolates with Aspergillus flavus F2R4FP 1–5 producing the most AFT (conidia—0.245 ?g\\/g; mycelial matrix—83 ?g\\/g) and CPA (conidia—0.091 ?g\\/g;

N. Gqaleni; J. E. Smith; J. Lacey

1996-01-01

38

Aspergillus niger contains the cryptic phylogenetic species A. awamori.  

PubMed

Aspergillus section Nigri is an important group of species for food and medical mycology, and biotechnology. The Aspergillus niger 'aggregate' represents its most complicated taxonomic subgroup containing eight morphologically indistinguishable taxa: A. niger, Aspergillus tubingensis, Aspergillus acidus, Aspergillus brasiliensis, Aspergillus costaricaensis, Aspergillus lacticoffeatus, Aspergillus piperis, and Aspergillus vadensis. Aspergillus awamori, first described by Nakazawa, has been compared taxonomically with other black aspergilli and recently it has been treated as a synonym of A. niger. Phylogenetic analyses of sequences generated from portions of three genes coding for the proteins ?-tubulin (benA), calmodulin (CaM), and the translation elongation factor-1 alpha (TEF-1?) of a population of A. niger strains isolated from grapes in Europe revealed the presence of a cryptic phylogenetic species within this population, A. awamori. Morphological, physiological, ecological and chemical data overlap occurred between A. niger and the cryptic A. awamori, however the splitting of these two species was also supported by AFLP analysis of the full genome. Isolates in both phylospecies can produce the mycotoxins ochratoxin A and fumonisin B?, and they also share the production of pyranonigrin A, tensidol B, funalenone, malformins, and naphtho-?-pyrones. In addition, sequence analysis of four putative A. awamori strains from Japan, used in the koji industrial fermentation, revealed that none of these strains belong to the A. awamori phylospecies. PMID:22036292

Perrone, Giancarlo; Stea, Gaetano; Epifani, Filomena; Varga, János; Frisvad, Jens C; Samson, Robert A

2011-11-01

39

Field experiments on colony foundation by Lasius niger (L.) and L. flavus (F.) (Hym., Formicidae)  

Microsoft Academic Search

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.

A. J. Pontin

1960-01-01

40

Restriction enzyme analysis of mitochondrial DNA of the Aspergillus flavus group: A. flavus, A. parasiticus, and A. nomius.  

PubMed Central

Mitochondrial DNA restriction fragment length polymorphisms were identified that clearly distinguish Aspergillus flavus, 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

Moody, S F; Tyler, B M

1990-01-01

41

Specificity of Immunofluorescent Staining for Study of Aspergillus flavus in Soil  

PubMed Central

Fluorescein-labeled antiserum prepared with Aspergillus flavus strain CS was tested for specificity by staining fungi grown in soil in the vicinity of buried slides. All 14 strains of A. flavus fluoresced as intensely or nearly as intensely as the antigen control. Among 21 isolates of species of Aspergillus other than A. flavus, 17 reacted with moderate to low fluorescence at intensities readily distinguishable from that of A. flavus. The fluorescence of the remaining four cultures, and particularly A. sydowi, was indistinguishable from that of A. flavus. Fungi other than aspergilli were generally nonreactive. Interfering cross-reactions were encountered for one strain of Spicaria and one strain of Stemphylium; three isolates could not be evaluated because of interfering autofluorescence. An additional 22 isolates were either wholly negative or had a low order of fluorescence. Agglutination tests between each of the fungi and A. flavus CS serum revealed close agreement between agglutination titer and fluorescent-staining reaction. Unknown fungi freshly isolated from soil were checked for reaction to the A. flavus labeled antiserum; only one isolate gave a pronounced staining reaction, and that one proved to be a strain of A. flavus. In a simplified ecological model, the fluorescent-antibody technique was used to follow the development of A. flavus in mixed culture in soil with five other soil fungi. Images Fig. 1

Schmidt, E. L.; Bankole, R. O.

1965-01-01

42

Aspergillus flavus genomics as a tool for studying the mechanism of aflatoxin formation.  

PubMed

Aspergillus flavus 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

2008-09-01

43

Identification of the Predominant Volatile Compounds Produced by Aspergillus flavus  

PubMed Central

A culture of Aspergillus flavus grown on moistened wheat meal was homogenized with a blendor, and the resulting slurry was vacuum-distilled at 5 mm of Hg and 35 C. The aqueous distillate was collected in traps cooled to -10 to -80 C. The culture volatiles were extracted from the distillate with CH2Cl2, and, after removal of the bulk of the solvent, the concentrated volatiles were examined by packed-column gas chromatography. Nineteen peaks were observed, and coupled gas chromatography-mass spectrometry was employed to identify the larger components. The compounds identified were: 3-methyl-butanol, 3-octanone, 3-octanol, 1-octen-3-ol, 1-octanol, and cis-2-octen-1-ol. The two octenols were the predominant compounds, and sufficient sample was trapped from the gas chromatograph for infrared analyses; this confirmed the mass spectral identifications and permitted the assignment of the cis designation to 2-octen-1-ol. Both oct-1-en-3-ol and cis-2-octen-1-ol are thought to be responsible for the characteristic musty-fungal odor of certain fungi; the latter compound may be a useful chemical index of fungal growth.

Kaminski, E.; Libbey, L. M.; Stawicki, S.; Wasowicz, E.

1972-01-01

44

Fumonisin and Ochratoxin Production in Industrial Aspergillus niger Strains  

Microsoft Academic Search

Aspergillus niger is perhaps the most important fungus used in biotechnology, and is also one of the most commonly encountered fungi contaminating foods and feedstuffs, and occurring in soil and indoor environments. Many of its industrial applications have been given GRAS status (generally regarded as safe). However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins:

Jens C. Frisvad; Thomas O. Larsen; Ulf Thrane; Martin Meijer; Janos Varga; Robert A. Samson; Kristian F. Nielsen

2011-01-01

45

Simultaneous Quantitation of Aspergillus flavus\\/A. parasiticus and Aflatoxins in Peanuts  

Microsoft Academic Search

A method was developed for simultaneous quantitation of Aspergillus flavus\\/A. parasiticus and aflatoxins in peanuts. Peanut samples were ground with an equal weight of water in a vertical cutter mixer to produce a slurry. Separate subsamples were taken for dilution-plating to de- termine total colony forming units (CFU)\\/g of A. flavus\\/A. parasiticus and for liquid chromato- graphic analysis to determine

JOE W. DORNER

2002-01-01

46

Differences in fungicidal efficiency against Aspergillus flavus for neutralized and acidic electrolyzed oxidizing waters  

Microsoft Academic Search

Neutralized electrolyzed oxidizing water (NEW) and acidic electrolyzed oxidizing water (AcEW) are electrolyzed oxidizing waters (EOW) that have significantly different fungicidal efficiencies against Aspergillus flavus (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

Ke Xiong; Hai-jie Liu; Rong Liu; Li-te Li

2010-01-01

47

Genetic variability of aflatoxin B 1 producing Aspergillus flavus strains isolated from discolored rice grains  

Microsoft Academic Search

Twenty-two aflatoxin B1 (AFB1) producing Aspergillus flavus 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

2009-01-01

48

Spatial and Temporal Patterns of Aspergillus flavus Strain Composition and Propagule Density in Yuma County, Arizona, Soils  

Microsoft Academic Search

Orum, T. V., Bigelow, D. M., Nelson, M. R., Howell, D. R., and Cotty, P. J. 1997. Spatial and temporal patterns of Aspergillus flavus strain composition and propagule density in Yuma County, Arizona, soils. Plant Dis. 81:911-916. Aspergillus flavus 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

1997-01-01

49

Requirement of LaeA for secondary metabolism and sclerotial production in Aspergillus flavus.  

PubMed

The nuclear regulator LaeA has been shown to govern production of multiple secondary metabolites in Aspergillus nidulans and Aspergillus fumigatus. Herein we examine the role of this protein in Aspergillus flavus. Similarly as in other Aspergilli, LaeA had a major effect on A. flavus secondary metabolism where DeltalaeA and over-expression laeA (OE::laeA) strains yielded opposite phenotypes resulting in decreased (increased) secondary metabolite production. The two mutant strains also exhibited striking morphological phenotypes in the loss (increase) of sclerotial production in comparison to wildtype. Growth on seed was marked by decreased (increased) conidial and aflatoxin production of the respective mutants; this was accompanied by decreased lipase activity in DeltalaeA, an enzymatic process correlated with seed maceration. Transcriptional examination of the mutants showed LaeA negatively regulates expression of its recently identified nuclear partner VeA, another global regulator of A. flavus secondary metabolites and sclerotia. PMID:18667168

Kale, Shubha P; Milde, Lane; Trapp, Marisa K; Frisvad, Jens C; Keller, Nancy P; Bok, Jin Woo

2008-10-01

50

Invertase production of common storage moulds in food and feed grains as a possibility for rapid detection of aspergillus flavus group and Aspergillus fumigatus  

Microsoft Academic Search

Invertase production of grain storage moulds was studied. Aspergillus spp. and Penicillium spp. were grown in a sucrose based liquid medium, at 37°C. The A. flavus group (A. flavus, A. parasiticus, A. nomius, A. oryzae) and A. fumigatus showed a fast growth and intense invertase activity, while other Aspergillus spp. and Penicillium spp. grew slower and produced less invertase. The

T. Mátrai; Susan Mayer; Susan Kókai; Irene Salamon

2000-01-01

51

21 CFR 173.120 - Carbohydrase and cellulase derived from Aspergillus niger.  

Code of Federal Regulations, 2013 CFR

...PERMITTED IN FOOD FOR HUMAN CONSUMPTION Enzyme Preparations and Microorganisms § 173...Aspergillus niger. Carbohydrase and cellulase enzyme preparation derived from Aspergillus niger... from the carbohydrase and cellulase enzyme product. (d) The additive is...

2013-04-01

52

Use of Native 'Aspergillus flavus' Strains to Prevent Aflatoxin Contamination.  

National Technical Information Service (NTIS)

Certain strains of A. flavus produce little or no aflatoxin and yet are highly aggressive. These strains are effective agents for the prevention of aflatoxin contamination in commodities. It has been found that aflatoxin production by A. flavus is not req...

P. J. Cotty

1989-01-01

53

Galactosaminogalactan from cell walls of Aspergillus niger.  

PubMed Central

A new heteropolysaccharide has been isolated by alkaline extraction of hyphal walls of Aspergillus niger NRRL 326 grown in surface culture. Its composition by weight, as determined by paper and gas chromatography and colorimetric analyses, is 70% galactose, 20% galactosamine, 6% glucose, and 1% acetyl. Two independent experiments have been used to ascertain copolymer structure: permeation chromatography in 6 M guanidinium hydrochloride, with controlled-pore glass columns of two fractionation ranges, and nitrous acid deaminative cleavage of galactosaminogalactan followed by reduction of fragments with [3H]borohydride and gel filtration chromatography. One of the tritiated fragments is tentatively identified as the disaccharide derivative galactopyranosyl 2,5-anhydrotalitol, on the basis of chromatographic properties and by kinetics of its acid hydrolysis. Smith degradation, methylation, deamination, and optical rotation studies indicate that the galactosaminogalactan consists of a linear array of hexopyranosyl units joined almost exclusively by alpha-(1 leads to 4) linkages. Hexosaminyl moieties are distributed randomly along the chains, which have an average degree of polymerization of about 100. The possible significance of this macromolecule in hyphal structure is considered.

Bardalaye, P C; Nordin, J H

1976-01-01

54

Solubilization of Morocco phosphorite by Aspergillus niger.  

PubMed

Phosphorus containing fertilizers have an important role in agriculture. Conventionally phosphate fertilizers are obtained by rock phosphate (RP) dissolution using mineral acids. Biotechnological methods can be a promising alternative in RP processing. The influence of Aspergillus niger strain, the composition of a nutritive medium, Morocco phosphorite (MP) concentration in the liquid medium, the time of bioconversion and the preliminary mechanical activation (PMA) of MP on the phosphorite microbial solubilization has been presented. The phosphorus concentration (as P2O5), citric acid production, glucose concentration and pH in the cultural medium were monitored. The phosphate concentration was expressed as water soluble - alpha1 (in the native cultural liquid), citrate soluble - alpha2 (after treating the biomass and remaining mineral mass with citric acid) and biomass available phosphorus - alpha3. Phosphate dissolution was not strongly correlated both with the citric acid production and the incubation period. When the fungi were grown without water soluble phosphorus compounds the MP solubilization had higher values. A maximum of 94.80% total P2O5 extraction was achieved. The PMA activity does not facilitate MP dissolution during the bioconversion. PMID:18468889

Bojinova, D; Velkova, R; Ivanova, R

2008-10-01

55

Aspergillus Niger Genomics: Past, Present and into the Future  

SciTech Connect

Aspergillus niger 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.

Baker, Scott E.

2006-09-01

56

The relationship of Aspergillus flavus and Aspergillus parasiticus with reference to production of aflatoxins and cyclopiazonic acid  

Microsoft Academic Search

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.

Joe W. Dorner; Richard J. Cole; Urban L. Diener

1984-01-01

57

Influence of woodsmoke on aflatoxin production by Aspergillus flavus  

Microsoft Academic Search

Woodsmoke delayed aflatoxius B1 and G1 release and significantly exerted inhibitory effects on the toxins production by a toxigenic Asperigillus flavus. The fungistatic efficiency of the woodsmoke increased with reduced moisture content in fish.

Nduka Uraih; Lucy Ogbadu

1982-01-01

58

Use of mycological, nested PCR, and real-time PCR methods on BAL fluids for detection of Aspergillus fumigatus and A. flavus in solid organ transplant recipients.  

PubMed

Invasive aspergillosis continues to be a significant cause of morbidity and mortality in solid organ transplant (SOT) recipients. A reliable and early diagnostic method is needed to improve survival. In this study, four methods direct microscopy, culture, nested PCR on internal transcribed spacer region, and TaqMan real-time PCR targeted ?-tubulin gene were examined for the detection of Aspergillus fumigatus and A. flavus in sixty-four bronchoalveolar lavage (BAL) fluids that were obtained from SOT recipients. Direct examination with 20 % KOH (potassium hydroxide) and culture on mycological media were also performed. Of the 64 samples, seven (10.9 %) were positive in direct examination (five with septate hyphae and two with aseptate hyphae), and 15 (23 %) had positive culture including five A. flavus, four A. niger, two Penicillium spp., two Rhizopus spp., one Fusarium spp. and one mixed A. flavus/A. niger. Twenty five (39 %) samples had positive nested PCR with A. flavus and 6 (9.4 %) with A. fumigatus-specific primers. Only eight (12.5 %) had positive real-time PCR for A. flavus and nine (14 %) for A. fumigatus. The incidence of aspergillosis in these patients included proven invasive pulmonary aspergillosis (IPA) in two (3 %), probable IPA in 14 (22 %), possible IPA in 38 (59 %), and not IPA in 10 (16 %). A. flavus was the most common cause of pulmonary aspergillosis (PA) in the study. The results suggest that because nested PCR is too sensitive it may increase the number of false-positive results and is not recommended for BAL samples for diagnosis of PA. Although further studies with significant number of proved positive/negative standard BAL samples are necessary for better evaluation, the novel multiplex real-time PCR developed in the study could be promising as a valid diagnostic method for IPA. PMID:24045934

Zarrinfar, Hossein; Mirhendi, Hossein; Makimura, Koichi; Satoh, Kazuo; Khodadadi, Hossein; Paknejad, Omolbanin

2013-12-01

59

Storability of onion bulbs contaminated by Aspergillus niger mold  

Microsoft Academic Search

In the course of pre- and postharvest epidemiological studies on bulbs contamination byAspergillus niger, two Sudanese onion cultivars were tested: ‘Saggai Red’ and ‘El-Hilo White’.A. niger spores, whether seedborne, soilborne or airborne, were avirulent to the healthy growing onion plants. The fungus heavily\\u000a contaminated the dead onion tissues, mainly the dead leaves followed by the dry scales, the dead roots

S. A. F. El-Nagerabi; A. H. M. Ahmed

2003-01-01

60

Removal of heavy metals using the fungus Aspergillus niger  

Microsoft Academic Search

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 Aspergillus niger to remove lead, cadmium, copper and nickel ions was evaluated. A. niger biomass pretreated by boiling in 0.1N NaOH solution for 15 min

Anoop Kapoor; T Viraraghavan; D. Roy Cullimore

1999-01-01

61

Single cell transcriptomics of neighboring hyphae of Aspergillus niger  

PubMed Central

Single cell profiling was performed to assess differences in RNA accumulation in neighboring hyphae of the fungus Aspergillus niger. 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.

2011-01-01

62

Mannitol is required for stress tolerance in Aspergillus niger conidiospores  

Microsoft Academic Search

D-Mannitol is the predominant carbon compound in conidiospores of the filamentous fungus Aspergillus niger 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

2003-01-01

63

Use of PCR for Detecting Aspergillus flavus in Maize Treated by Gamma Radiation Process  

Microsoft Academic Search

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 Aspergillus flavus 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

2008-01-01

64

Substrate depletion during formation of aflatoxin and kojic acid on corn inoculated with Aspergillus flavus  

Microsoft Academic Search

Depletion of sugar and starch carbon sources and concomitant formation of secondary fungal metabolites, aflatoxin and kojic acid, were examined in growing corn inoculated with Aspergillus flavus. Kernels from control and inoculated ears were removed and analyzed after 16, 24, 48, 96 and 168 hrs.

L. S. Lee; F. W. Parrish; T. J. Jacks

1986-01-01

65

Time of Aspergillus flavus infection and aflatoxin formation in ripening of figs  

Microsoft Academic Search

Figs in an orchard were inoculated with an aflatoxigenicAspergillus flavus 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

Hamid Boudra; Joseph Le Bars; Pierette Le Bars; Jacques Dupuy

1994-01-01

66

40 CFR 180.1206 - Aspergillus flavus AF36; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2013 CFR

...Aspergillus flavus AF36 in or on pistachio when applied as an antifungal agent and used in accordance with good agricultural practices...grain; and corn, pop, stover, when applied/used as an antifungal agent. [68 FR 41541, July 14, 2003, as amended...

2013-07-01

67

Control of Aspergillus flavus with essential oil and methanol extract of Satureja hortensis  

Microsoft Academic Search

The essential oil and methanol extract of Satureja hortensis were tested for antifungal activity against Aspergillus flavus in vitro on Petri plates and liquid culture, and under storage conditions. The oil showed strong antifungal activity based on the inhibition zone and minimal inhibitory concentration values against the pathogen on Petri plates assays. The very low concentrations of them also reduced

Neslihan Dikbas; Recep Kotan; Fatih Dadasoglu; Fikrettin Sahin

2008-01-01

68

Aflatoxin-producing Strains of Aspergillus flavus Isolated from Feeds in Norway  

Microsoft Academic Search

The aflatoxigenic ability of 300 strains of Aspergillus flavus (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

Henrik Stenwig

1988-01-01

69

Phytochemical Inhibition of Aflatoxigenicity in Aspergillus flavus by Constituents of Walnut ( Juglans regia )  

Microsoft Academic Search

Tulare walnut, a cultivar highly resistant to aflatoxin formation, was investigated for endogenous phytochemical constituents capable of inhibiting aflatoxigenesis in Aspergillus flavus. The activity, located entirely in the pellicle (seed coat), was extractable to various degrees with polar solvents, although some activity remained unextractable, indicating that the bioactivity resided in a complex of hydrolyzable tannins. These tannins can be hydrolyzed

Noreen Mahoney; Russell J. Molyneux

2004-01-01

70

Aspergillus flavus Infection and Aflatoxin Production in Corn: Influence of Trace Elements  

PubMed Central

Distribution of trace element levels in corn germ fractions from kernels naturally infected with Aspergillus flavus 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.

Lillehoj, E. B.; Garcia, W. J.; Lambrow, M.

1974-01-01

71

Production of citric acid with immobilized Aspergillus niger  

Microsoft Academic Search

The spores of Aspergillus niger were entrapped in calcium-alginate beads and precultivated in growth media with various amounts of nitrogen. During the following citric acid production in shaking cultures an optimum of acid formation and yield was observed after the precultivation with 100–200 mg\\/l NH4NO3. The productivity of the immobilized Aspergillus was found to be 1.5 times higher than in

H. Eikmeier; H. J. Rehm

1984-01-01

72

Expression profiling of pectinolytic genes from Aspergillus niger  

Microsoft Academic Search

The expression of 26 pectinolytic genes from Aspergillus niger was studied in a wild type strain and a CreA derepressed strain, under 16 different growth conditions, to obtain an expression profile for each gene. These expression profiles were then submitted to cluster analysis to identify subsets of genes with similar expression profiles. With the exception of the feruloyl esterase encoding

Ronald P. de Vries; Jenny Jansen; Guillermo Aguilar; Lucie Pa?enicová; Vivi Joosten; Florian Wülfert; Jacques A. E. Benen; Jaap Visser

2002-01-01

73

Novel metabolites in phenanthrene and pyrene transformation by Aspergillus niger.  

PubMed Central

Aspergillus niger, isolated from hydrocarbon-contaminated soil, was examined for its potential to degrade phenanthrene and pyrene. Two novel metabolites, 1-methoxyphenanthrene and 1-methoxypyrene, were identified by conventional chemical techniques. Minor metabolites identified were 1- and 2-phenanthrol and 1-pyrenol. No 14CO2 evolution was observed in either [14C]phenanthrene or [14C]pyrene cultures.

Sack, U; Heinze, T M; Deck, J; Cerniglia, C E; Cazau, M C; Fritsche, W

1997-01-01

74

Pectinases of Aspergillus niger: A Molecular and Biochemical Characterisation  

Microsoft Academic Search

The major topics of this thesis are the microfilamentous fungus Aspergillus niger and the pectinases a group of extracellular enzymes. Many 'products' of this species hold the GRAS (Generally Regarded As Safe) status and thus pectinases find a broad range of applications in food, feed and beverage industries.Pectinases are enzymes which degrade pectin, a heteropolysaccharide found in the middle lamella

L. Parenicová

2000-01-01

75

Bioleaching of spent fluid catalytic cracking catalyst using Aspergillus niger  

Microsoft Academic Search

The use of the fungus Aspergillus niger for the bioleaching of heavy metals from spent catalyst was investigated, with fluid catalytic cracking (FCC) catalyst as a model. Bioleaching was examined in batch cultures with the spent catalysts at various pulp densities (1–12%). Chemical leaching was also performed using mineral acids (sulphuric and nitric acids) and organic acids (citric, oxalic and

Khin Moh Moh Aung; Yen-Peng Ting

2005-01-01

76

Solubilization of rock phosphate by immobilized Aspergillus niger  

Microsoft Academic Search

Aspergillus niger, an acid-producing filamentous fungus, was immobilized on polyurethane foam. Various amounts of foam cubes and spore suspension were tested in order to obtain an efficient immobilization process. The best combination selected for further experiments was 0.2 g polyurethane foam and 3 ml spore suspension. Immobilized cells were reused, with higher levels of acid formation being maintained for longer

Nikolay Vassilev; Maria Vassileva; Rosario Azcon

1997-01-01

77

Citric acid production by Aspergillus niger immobilized on polyurethane foam  

Microsoft Academic Search

Citric acid was produced using Aspergillus niger 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

Yong Hee Lee; Chang Woo Lee; Ho Nam Chang

1989-01-01

78

Distribution and characteristics of aflatoxin-producing Aspergillus flavus in the soil in Kanagawa Prefecture, Central Japan  

Microsoft Academic Search

In Kanagawa Prefecture, located in central Japan, aflatoxin-producingAspergillus flavus 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,

Takanori Takahashi

1993-01-01

79

Effect of Citrus reticulata and Cymbopogon citratus Essential Oils on Aspergillus flavus Growth and Aflatoxin Production on Asparagus racemosus  

Microsoft Academic Search

Essential oils extracted from Citrus reticulata and Cymbopogon citratus were tested in vitro against the toxigenic strain of Aspergillus flavus, isolated from the tuberous roots of Asparagus racemosus, used in preparation of herbal drugs. The essential oils completely inhibited the growth of A. flavus at 750 ppm and also exhibited a broad fungitoxic spectrum against nine additional fungi isolated from the

Priyanka Singh; Ravindra Shukla; Ashok Kumar; Bhanu Prakash; Shubhra Singh; Nawal Kishore Dubey

2010-01-01

80

Utility of Aspergillus niger citrate synthase promoter for heterologous expression.  

PubMed

Citrate synthase is a central player in the acidogenic metabolism of Aspergillus niger. The 5' upstream sequence (0.9kb DNA) of citrate synthase gene (citA) from A. niger NCIM 565 was analyzed and its promoter function demonstrated through the heterologous expression of two proteins. The cloned citrate synthase promoter (PcitA) sequence was able to express bar coding sequence thereby conferring phosphinothricin resistance. This sequence was further analyzed by systematic deletions to define an effective but compact functional promoter. The PcitA driven egfp expression showed that PcitA was active in all differentiation cell-stages of A. niger. EGFP expression was highest on non-repressible carbon sources like acetate and glycerol. Mycelial EGFP levels increased during acidogenic growth suggesting that PcitA is functional throughout this cultivation. A. niger PcitA is the first Krebs cycle gene promoter used to express heterologous proteins in filamentous fungi. PMID:21723343

Dave, Kashyap; Punekar, Narayan S

2011-09-10

81

Requirement of LaeA for Secondary Metabolism and Sclerotial Production in Aspergillus flavus  

PubMed Central

The nuclear regulator LaeA has been shown to govern production of multiple secondary metabolites in A. nidulans and A. fumigatus. Herein we examine the role of this protein in Aspergillus flavus. Similarly as in other Aspergilli, LaeA had a major effect on A. flavus secondary metabolism where ?laeA and over-expression laeA (OE::laeA) strains yielded opposite phenotypes resulting in decreased (increased) secondary metabolite production. The two mutant strains also exhibited striking morphological phenotypes in the loss (increase) of sclerotial production in comparison to wildtype. Growth on seed was marked by decreased (increased) conidial and aflatoxin production of the respective mutants; this was accompanied by decreased lipase activity in ?laeA, an enzymatic process correlated with seed maceration. Transcriptional examination of the mutants showed LaeA negatively regulates expression of its recently identified nuclear partner VeA, another global regulator of A. flavus secondary metabolites and sclerotia.

Kale, Shubha P.; Milde, Lane; Trapp, Marisa K.; Frisvad, Jens C.; Keller, Nancy P.; Bok, Jin Woo

2009-01-01

82

Kojic acid production by Aspergillus flavus using gelatinized and hydrolyzed sago starch as carbon sources  

Microsoft Academic Search

Direct conversion of gelatinized sago starch into kojic acid byAspergillus flavus strain having amylolytic enzymes was carried out at two different scales of submerged batch fermentation in a 250-mL shake\\u000a flask and in a 50-L stirred-tank fermentor. For comparison, fermentations were also carried out using glucose and glucose\\u000a hydrolyzate from enzymic hydrolysis of sago starch as carbon sources. During kojic

M. Rosfarizan; A. B. Ariff; M. A. Hassan; M. I. A. Karim

1998-01-01

83

Aeration and yeast extract requirements for kojic acid production by Aspergillus flavus link  

Microsoft Academic Search

Growth and kojic acid production by Aspergillus flavus Link 44-1 were studied at different levels of dissolved oxygen tension (DOT) using a 2-l stirred tank fermenter. In all experiments, agitation was fixed at 600 rpm and DOT was controlled at different levels by varying airflow rates. Single-phase DOT control at three different levels (30, 50, and 80% saturation) did not

A. B. Ariff; M. S. Salleh; B. Ghani; M. A. Hassan; G. Rusul; M. I. A. Karim

1996-01-01

84

Use of UV photography to identify aflatoxin-producing strains of Aspergillus flavus and A. parasiticus  

Microsoft Academic Search

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 ofAspergillus flavus 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%

Zdenka Cvetni?; Stjepan Pepeljnjak

1995-01-01

85

Toxigenic Aspergillus flavus and aflatoxins in Sri Lankan medicinal plant material.  

PubMed

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. Aspergillus flavus, 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

Abeywickrama, K; Bean, G A

1991-03-01

86

Production of extremophilic bacterial cellulase enzymes in aspergillus niger.  

SciTech Connect

Enzymes can be used to catalyze a myriad of chemical reactions and are a cornerstone in the biotechnology industry. Enzymes have a wide range of uses, ranging from medicine with the production of pharmaceuticals to energy were they are applied to biofuel production. However, it is difficult to produce large quantities of enzymes, especially if they are non-native to the production host. Fortunately, filamentous fungi, such as Aspergillus niger, are broadly used in industry and show great potential for use a heterologous enzyme production hosts. Here, we present work outlining an effort to engineer A. niger to produce thermophilic bacterial cellulases relevant to lignocellulosic biofuel production.

Gladden, John Michael

2013-09-01

87

The Mechanism of Antifungal Action of Essential Oil from Dill (Anethum graveolens L.) on Aspergillus flavus  

PubMed Central

The essential oil extracted from the seeds of dill (Anethum graveolens L.) was demonstrated in this study as a potential source of an eco-friendly antifungal agent. To elucidate the mechanism of the antifungal action further, the effect of the essential oil on the plasma membrane and mitochondria of Aspergillus flavus was investigated. The lesion in the plasma membrane was detected through flow cytometry and further verified through the inhibition of ergosterol synthesis. The essential oil caused morphological changes in the cells of A. flavus and a reduction in the ergosterol quantity. Moreover, mitochondrial membrane potential (MMP), acidification of external medium, and mitochondrial ATPase and dehydrogenase activities were detected. The reactive oxygen species (ROS) accumulation was also examined through fluorometric assay. Exposure to dill oil resulted in an elevation of MMP, and in the suppression of the glucose-induced decrease in external pH at 4 µl/ml. Decreased ATPase and dehydrogenase activities in A. flavus cells were also observed in a dose-dependent manner. The above dysfunctions of the mitochondria caused ROS accumulation in A. flavus. A reduction in cell viability was prevented through the addition of L-cysteine, which indicates that ROS is an important mediator of the antifungal action of dill oil. In summary, the antifungal activity of dill oil results from its ability to disrupt the permeability barrier of the plasma membrane and from the mitochondrial dysfunction-induced ROS accumulation in A. flavus.

Tian, Jun; Ban, Xiaoquan; Zeng, Hong; He, Jingsheng; Chen, Yuxin; Wang, Youwei

2012-01-01

88

Localization, morphology and transcriptional profile of Aspergillus flavus during seed colonization.  

PubMed

Aspergillus flavus is an opportunistic fungal pathogen that infects maize kernels pre-harvest, creating major human health concerns and causing substantial agricultural losses. Improved control strategies are needed, yet progress is hampered by the limited understanding of the mechanisms of infection. A series of studies were designed to investigate the localization, morphology and transcriptional profile of A.?flavus during internal seed colonization. Results from these studies indicate that A.?flavus is capable of infecting all tissues of the immature kernel by 96?h after infection. Mycelia were observed in and around the point of inoculation in the endosperm and were found growing down to the germ. At the endosperm-germ interface, hyphae appeared to differentiate and form a biofilm-like structure that surrounded the germ. The exact nature of this structure remains unclear, but is discussed. A custom-designed A.?flavus?Affymetrix GeneChip® microarray was used to monitor genome-wide transcription during pathogenicity. A total of 5061 genes were designated as being differentially expressed. Genes encoding secreted enzymes, transcription factors and secondary metabolite gene clusters were up-regulated and considered to be potential effector molecules responsible for disease in the kernel. Information gained from this study will aid in the development of strategies aimed at preventing or slowing down A.?flavus colonization of the maize kernel. PMID:23834374

Dolezal, Andrea L; Obrian, Gregory R; Nielsen, Dahlia M; Woloshuk, Charles P; Boston, Rebecca S; Payne, Gary A

2013-12-01

89

The mechanism of antifungal action of essential oil from dill (Anethum graveolens L.) on Aspergillus flavus.  

PubMed

The essential oil extracted from the seeds of dill (Anethum graveolens L.) was demonstrated in this study as a potential source of an eco-friendly antifungal agent. To elucidate the mechanism of the antifungal action further, the effect of the essential oil on the plasma membrane and mitochondria of Aspergillus flavus was investigated. The lesion in the plasma membrane was detected through flow cytometry and further verified through the inhibition of ergosterol synthesis. The essential oil caused morphological changes in the cells of A. flavus and a reduction in the ergosterol quantity. Moreover, mitochondrial membrane potential (MMP), acidification of external medium, and mitochondrial ATPase and dehydrogenase activities were detected. The reactive oxygen species (ROS) accumulation was also examined through fluorometric assay. Exposure to dill oil resulted in an elevation of MMP, and in the suppression of the glucose-induced decrease in external pH at 4 µl/ml. Decreased ATPase and dehydrogenase activities in A. flavus cells were also observed in a dose-dependent manner. The above dysfunctions of the mitochondria caused ROS accumulation in A. flavus. A reduction in cell viability was prevented through the addition of L-cysteine, which indicates that ROS is an important mediator of the antifungal action of dill oil. In summary, the antifungal activity of dill oil results from its ability to disrupt the permeability barrier of the plasma membrane and from the mitochondrial dysfunction-induced ROS accumulation in A. flavus. PMID:22272289

Tian, Jun; Ban, Xiaoquan; Zeng, Hong; He, Jingsheng; Chen, Yuxin; Wang, Youwei

2012-01-01

90

Differences in fungicidal efficiency against Aspergillus flavus for neutralized and acidic electrolyzed oxidizing waters.  

PubMed

Neutralized electrolyzed oxidizing water (NEW) and acidic electrolyzed oxidizing water (AcEW) are electrolyzed oxidizing waters (EOW) that have significantly different fungicidal efficiencies against Aspergillus flavus (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 research. This study hypothesized that this difference did not originate from the structure of water but based on the OH radical (OH). It was proved by the UV spectroscopy, (17)O-NMR spectroscopy and electron spin resonance analysis. NEW contains more OH compared with AcEW in the same available chlorine concentration level. The OH that exists in NEW and AcEW was found to have an important fungicidal factor that destroys the cellular structures of the A. flavus conidia. It also damages the cellular normal function of A. flavus conidia that brought about K+ and Mg2+ leakages. The levels of OH that exist in NEW and AcEW could be the important reason that leads to significant fungicidal efficiencies against A. flavus. PMID:19926156

Xiong, Ke; Liu, Hai-Jie; Liu, Rong; Li, Li-Te

2010-01-31

91

Development and refinement of a high-efficiency gene-targeting system for Aspergillus flavus.  

PubMed

An efficient gene-targeting system based on impairment of the nonhomologous end-joining pathway and the orotidine monophosphate decarboxylase gene (pyrG) in Aspergillus flavus 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

Chang, Perng-Kuang; Scharfenstein, Leslie L; Wei, Qijian; Bhatnagar, Deepak

2010-06-01

92

Catalytic Properties of Lipase Extracts from Aspergillus niger  

Microsoft Academic Search

Summary Screening of lipolytic strains using Rhodamine-B\\/olive oil plate technique allowed the selection of Aspergillus niger MYA 135. Lipase production in submerged culture containing 2 % olive oil was enhanced by more than 50 % compared to basal cultural conditions. Op- timal catalytic conditions for olive oil-induced lipase were pH=6.5 and 30-35 °C. These values were shifted to the acid

Licia M. Pera; Cintia M. Romero; Mario D. Baigori; Guillermo R. Castro

2006-01-01

93

Sodium gluconate production by Aspergillus niger with intermittent broth replacement  

Microsoft Academic Search

Intermittent broth replacement was carried out to enhance the productivity and purity of sodium gluconate usingAspergillus niger by reducing the concentration of unmetabolized glucose. As inoculum size increased, length of lag phase was shortened and\\u000a high initial production rate of sodium gluconate was achieved. However, too high inoculum concentration lowered productivity\\u000a during the later stage of fermentation and increased residual

Sang-Yoon Lee; Bu-Su Park; Jin-Hyup Kim; Byung-Gee Kim; Dong-Il Kim

1999-01-01

94

Genetic analysis of benzoate metabolism in Aspergillus niger  

Microsoft Academic Search

The benzoate metabolism of Aspergillus niger was studied as part of a design to clone the benzoate-4-hydroxylase gene of this fungus on the basis of complementation. Filtration enrichment techniques yielded mutants defective for different steps of benzoate degradation: bph (benzoate-4-hydroxylase), phh (4-hydroxybenzoate-3-hydroxylase) and prc (protocatechuate ring cleavage) mutants. In this way the degradation pathway for benzoate, involving the formation of

J. G. Boschloo; A. Paffen; T. Koot; W. J. J. van den Tweel; R. F. M. van Gorcom; J. H. G. Cordewener; C. J. Bos

1990-01-01

95

Six novel constitutive promoters for metabolic engineering of Aspergillus niger.  

PubMed

Genetic tools for the fine-tuning of gene expression levels are a prerequisite for rational strain optimization through metabolic engineering. While Aspergillus niger 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

Blumhoff, Marzena; Steiger, Matthias G; Marx, Hans; Mattanovich, Diethard; Sauer, Michael

2013-01-01

96

Activity of essential oil and its major compound, 1,8-cineole, from Eucalyptus globulus Labill., against the storage fungi Aspergillus flavus Link and Aspergillus parasiticus Speare  

Microsoft Academic Search

The essential oil from leaves of Eucalyptus globulus obtained by hydrodistillation, as well as its major compound 1,8-cineole, identified by gas chromatography coupled with a mass selective detector, were evaluated for their effectiveness against the storage fungi Aspergillus flavus and Aspergillus parasiticus. The evaluation was performed by compound dissolution in yeast extract sucrose (YES) medium and exposure to headspace volatiles.

Georgia Rocha Vilela; Gustavo Steffen de Almeida; Marisa Aparecida Bismara Regitano D'Arce; Maria Heloisa Duarte Moraes; José Otávio Brito; Maria Fátima das G. F. da Silva; Sebastiăo Cruz Silva; Sônia Maria de Stefano Piedade; Maria Antonia Calori-Domingues; Eduardo Micotti da Gloria

2009-01-01

97

Molecular characterization of Aspergillus flavus and aflatoxin contamination of wheat grains from Saudi Arabia.  

PubMed

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 Aspergillus flavus 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

2013-01-01

98

Comparative Chemistry of Aspergillus oryzae (RIB40) and A. flavus (NRRL 3357)  

PubMed Central

Aspergillus oryzae and A. flavus are important species in industrial biotechnology and food safety and have been some of the first aspergilli to be fully genome sequenced. Bioinformatic analysis has revealed 99.5% gene homology between the two species pointing towards a large coherence in the secondary metabolite production. In this study we report on the first comparison of secondary metabolite production between the full genome sequenced strains of A. oryzae (RIB40) and A. flavus (NRRL 3357). Surprisingly, the overall chemical profiles of the two strains were mostly very different across 15 growth conditions. Contrary to previous studies we found the aflatrem precursor 13-desoxypaxilline to be a major metabolite from A. oryzae under certain growth conditions. For the first time, we additionally report A. oryzae to produce parasiticolide A and two new analogues hereof, along with four new alkaloids related to the A. flavus metabolites ditryptophenalines and miyakamides. Generally the secondary metabolite capability of A. oryzae presents several novel end products likely to result from the domestication process from A. flavus.

Rank, Christian; Klejnstrup, Marie Louise; Petersen, Lene Maj; Kildgaard, Sara; Frisvad, Jens Christian; Gotfredsen, Charlotte Held; Larsen, Thomas Ostenfeld

2012-01-01

99

C15H24 Volatile Compounds Unique to Aflatoxigenic Strains of Aspergillus flavus  

PubMed Central

Headspace volatiles from eight strains of Aspergillus flavus (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.

Zeringue, H. J.; Bhatnagar, D.; Cleveland, T. E.

1993-01-01

100

Phenolic compounds in peanut seeds: Enhanced elicitation by chitosan and effects on growth and aflatoxin B1 production by Aspergillus flavus  

Microsoft Academic Search

Effects of chitosan and Aspergillus flavus 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

1995-01-01

101

Phenolic compounds in peanut seeds: Enhanced elicitation by chitosan and effects on growth and aflatoxin b1 production by aspergillus flavus  

Microsoft Academic Search

Effects of chitosan and Aspergillus flavus 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

1994-01-01

102

Co-occurrence of aflatoxin B 1 and cyclopiazonic acid in sour lime ( Citrus aurantifolia Swingle ) during post-harvest pathogenesis by Aspergillus flavus  

Microsoft Academic Search

During hot and humid seasons, extensive rot of sour lime was observed to be caused by Aspergillus flavus. In view of this, investigations were undertaken to obtain data on the production of various toxins by A. flavus during post harvest pathogenesis of sour lime. Sixty percent of the pathogenic A. flavus isolates were detected to be aflatoxin B1 producers in

Rozy Bamba; Geeta Sumbali

2005-01-01

103

Fumonisin and Ochratoxin Production in Industrial Aspergillus niger Strains  

PubMed Central

Aspergillus niger is perhaps the most important fungus used in biotechnology, and is also one of the most commonly encountered fungi contaminating foods and feedstuffs, and occurring in soil and indoor environments. Many of its industrial applications have been given GRAS status (generally regarded as safe). However, A. niger has the potential to produce two groups of potentially carcinogenic mycotoxins: fumonisins and ochratoxins. In this study all available industrial and many non-industrial strains of A. niger (180 strains) as well as 228 strains from 17 related black Aspergillus species were examined for mycotoxin production. None of the related 17 species of black Aspergilli produced fumonisins. Fumonisins (B2, B4, and B6) were detected in 81% of A. niger, and ochratoxin A in 17%, while 10% of the strains produced both mycotoxins. Among the industrial strains the same ratios were 83%, 33% and 26% respectively. Some of the most frequently used strains in industry NRRL 337, 3112 and 3122 produced both toxins and several strains used for citric acid production were among the best producers of fumonisins in pure agar culture. Most strains used for other biotechnological processes also produced fumonisins. Strains optimized through random mutagenesis usually maintained their mycotoxin production capability. Toxigenic strains were also able to produce the toxins on media suggested for citric acid production with most of the toxins found in the biomass, thereby questioning the use of the remaining biomass as animal feed. In conclusion it is recommended to use strains of A. niger with inactive or inactivated gene clusters for fumonisins and ochratoxins, or to choose isolates for biotechnological uses in related non-toxigenic species such as A. tubingensis, A. brasiliensis, A vadensis or A. acidus, which neither produce fumonisins nor ochratoxins.

Frisvad, Jens C.; Larsen, Thomas O.; Thrane, Ulf; Meijer, Martin; Varga, Janos; Samson, Robert A.; Nielsen, Kristian F.

2011-01-01

104

A Lectin from Spatholobus parviflorus Inhibits Aspergillus flavus ?-Amylase: Enzyme Kinetics and Thermodynamic Studies.  

PubMed

Aspergillus flavus is a commonly found fungal pathogen which produces structurally related and highly toxic secondary metabolites, aflatoxins. It has been proposed that ?-amylase inhibitors may limit the ability of the fungus to produce aflatoxins. Hence, this enzyme is a potent target for the development of antifungal agents. In this study, it was found that Spatholobus parviflorus seed lectin (SPL) can inhibit the growth of A. flavus with a MIC value of 1.5 mg/mL. The enzyme kinetics, molecular modeling and isothermal titration calorimetric studies suggest that SPL can inhibit ?-amylase with Ki value of 0.0042 mm. Hence, it is suggested that the antifungal activity of SPL might be partly due to its ability to inhibit the enzyme ?-amylase. PMID:24460654

Tintu, Ignatius; Abhilash, Joseph; Dileep, Kalarickal V; Augustine, Anu; Haridas, Madathilkovilakath; Sadasivan, Chittalakkottu

2014-07-01

105

A rapid identification method for aflatoxin-producing strains of Aspergillus flavus and A. parasiticus by ammonia vapor  

Microsoft Academic Search

The colony reverse of aflatoxin (AF)-producing strains ofAspergillus flavus 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

Michihiko Saito; Sachiko Machida

1999-01-01

106

Influence of manganese on morphology and cell wall composition of Aspergillus niger during citric acid fermentation  

Microsoft Academic Search

Morphology and cell wall composition of Aspergillus niger were studied under conditions of manganese sufficient or deficient cultivation in an otherwise citric acid producing medium. Omission of Mn2+ (less than 10-7 M) from the nutrient medium of Aspergillus niger results in abnormal morphological development which is characterized by increased spore swelling, and squat, bulbeous hyphae. Fractionation and analysis of manganese

Monika Kisser; C. P. Kubicek; M. Röhr

1980-01-01

107

Recombinant bacterial hemoglobin alters metabolism of Aspergillus niger.  

PubMed

The filamentous fungus Aspergillus niger 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

Hofmann, Gerald; Diano, Audrey; Nielsen, Jens

2009-01-01

108

Potential of essential oils for protection of grains contaminated by aflatoxin produced by Aspergillus flavus.  

PubMed

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oils of Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) on the mycelial growth and aflatoxin B1 production by Aspergillus flavus have been studied previously in culture medium. The aim of this study was to evaluate aflatoxin B1 production by Aspergillus flavus in real food systems (corn and soybean) treated with Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) essential oils. Samples with 60 g of the grains were treated with different volumes of essential oils, 200, 100, 50, and 10 ?L for oregano and 50, 30, 15, and 10 ?L for mentrasto. Fungal growth was evaluated by disk diffusion method. Aflatoxin B1 production was evaluated inoculating suspensions of A. flavus containing 1.3 × 10(5) spores/mL in 60 g of grains (corn and soybeans) after adjusting the water activity at 0.94. Aflatoxin was quantified by photodensitometry. Fungal growth and aflatoxin production were inhibited by essential oils, but the mentrasto oil was more effective in soybeans than that of oregano. On the other hand, in corn samples, the oregano essential oil was more effective than that of mentrasto. Chemical compositions of the essential oils were also investigated. The GC/MS oils analysis showed that the main component of mentrasto essential oil is precocene I and of the main component of oregano essential oil is 4-terpineol. The results indicate that both essential oils can become an alternative for the control of aflatoxins in corn and soybeans. PMID:24926289

Esper, Renata H; Gonçalez, Edlayne; Marques, Marcia O M; Felicio, Roberto C; Felicio, Joana D

2014-01-01

109

Potential of essential oils for protection of grains contaminated by aflatoxin produced by Aspergillus flavus  

PubMed Central

Aflatoxin B1 (AFB1) is a highly toxic and carcinogenic metabolite produced by Aspergillus species on food and agricultural commodities. Inhibitory effects of essential oils of Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) on the mycelial growth and aflatoxin B1 production by Aspergillus flavus have been studied previously in culture medium. The aim of this study was to evaluate aflatoxin B1 production by Aspergillus flavus in real food systems (corn and soybean) treated with Ageratum conyzoides (mentrasto) and Origanum vulgare (oregano) essential oils. Samples with 60 g of the grains were treated with different volumes of essential oils, 200, 100, 50, and 10 ?L for oregano and 50, 30, 15, and 10 ?L for mentrasto. Fungal growth was evaluated by disk diffusion method. Aflatoxin B1 production was evaluated inoculating suspensions of A. flavus containing 1.3 × 105 spores/mL in 60 g of grains (corn and soybeans) after adjusting the water activity at 0.94. Aflatoxin was quantified by photodensitometry. Fungal growth and aflatoxin production were inhibited by essential oils, but the mentrasto oil was more effective in soybeans than that of oregano. On the other hand, in corn samples, the oregano essential oil was more effective than that of mentrasto. Chemical compositions of the essential oils were also investigated. The GC/MS oils analysis showed that the main component of mentrasto essential oil is precocene I and of the main component of oregano essential oil is 4-terpineol. The results indicate that both essential oils can become an alternative for the control of aflatoxins in corn and soybeans.

Esper, Renata H.; Goncalez, Edlayne; Marques, Marcia O. M.; Felicio, Roberto C.; Felicio, Joana D.

2014-01-01

110

Influence of growth conditions on the production of xylanolytic enzymes by Aspergillus flavus.  

PubMed

Investigations were carried out to optimize the culture conditions for the production of xylanase and beta-xylosidase by Aspergillus flavus, a filamentous fungus isolated from soil. The production of enzymes was tolerant to a wide range of initial culture pH values. Maximum xylanase (190 U/ml) and beta-xylosidase (35 U/ml) production was obtained when the strain was grown on mineral medium supplemented with 3% (w/v) corn cob powder as the carbon source. The enzymes had optimal activities at pH values between 5.5 and 6.0 and exhibited high activity and stability under alkaline conditions. PMID:10427736

de Souza, C G; Girardo, N S; Costa, M A; Peralta, R M

1999-01-01

111

Fungicidal properties of the essential oil of Hesperozygis marifolia on Aspergillus flavus link.  

PubMed

The chemical composition of the essential oil from Hesperozygis marifolia was analyzed by gas chromatography-mass spectrometry (GC-MS), and fourteen compounds were identified. (R)-pulegone (40.75%), isomenthone (30.34%) and menthone (4.46%) were found to be the main components of the oil. The essential oil at a concentration of 2.0 mg/mL and (R)-pulegone at concentration of 0.8 mg/mL completely inhibited the growth of Aspergillus flavus Link. The fungicidal effects of this essential oil warrant further research into its potential for commercial use. PMID:21407150

González-Chávez, Marco Martín; Cárdenas-Ortega, Norma Cecilia; Méndez-Ramos, Cristina Andrea; Pérez-Gutiérrez, Salud

2011-01-01

112

Bioremediation of CCA-C treated wood by Aspergillus niger fermentation  

Microsoft Academic Search

This study evaluated the potential of the fungus Aspergillus niger to remove copper, chromium, and arsenic from waste wood treated with chromated copper arsenate (CCA) wood preservative. The removal of heavy metals by A. niger was carried out in two stages. In the first stage, A. niger was cultivated in carbohydrates media in order to produce large quantities of oxalic

S. N. Kartal; T. Kakitani; Y. Imamura

2004-01-01

113

Aspergillus niger time to growth in dried tomatoes.  

PubMed

Individual and combined effects of aw and incorporation of selected concentrations of Mexican oregano essential oil on the time to growth (TTG) of Aspergillus niger 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

2013-06-01

114

A novel selectable marker based on Aspergillus niger arginase expression.  

PubMed

Selectable markers are valuable tools in transforming asexual fungi like Aspergillus niger. An arginase (agaA) expression vector and a suitable arginase-disrupted host would define a novel nutritional marker/selection for transformation. The development of such a marker was successfully achieved in two steps. The single genomic copy of A. niger arginase gene was disrupted by homologous integration of the bar marker. The agaA disruptant was subsequently complemented by transforming it with agaA expression vectors. Both citA and trpC promoters were able to drive the expression of arginase cDNA. Such agaA+ transformants displayed arginase expression pattern distinct from that of the parent strain. The results are also consistent with a single catabolic route for arginine in this fungus. A simple yet novel arginine-based selection for filamentous fungal transformation is thus described. PMID:22579391

Dave, Kashyap; Ahuja, Manmeet; Jayashri, T N; Sirola, Rekha Bisht; Punekar, Narayan S

2012-06-10

115

Targeted Lipid Analysis of Haemolytic Mycelial Extracts of Aspergillus niger.  

PubMed

Ethanolic extracts of mycelia from Aspergillus niger (strain N402) grown in liquid media were observed to have haemolytic activity on bovine erythrocytes. This haemolytic activity decreased significantly during the time of growth (1-3 days). Moreover, when A. niger was grown on carbon-deprived medium, the efficiency of this haemolytic activity in the ethanolic extracts was much lower than when grown in carbon-enriched medium, and became almost undetectable after 3 days of growth in carbon-deprived medium. The lipid composition of these ethanolic extracts was analysed by liquid chromatography-electrospray ionisation tandem mass spectrometry. This haemolytic activity can be mainly linked to the relative levels of the molar ratios of the unsaturated fatty acids and lysophosphatidylcholines. PMID:24983857

Novak, Maruša; Sep?i?, Kristina; Kraševec, Nada; Križaj, Igor; Ma?ek, Peter; Anderluh, Gregor; Guella, Graziano; Mancini, Ines

2014-01-01

116

Loss of msnA, a putative stress regulatory gene, in Aspergillus parasiticus and Aspergillus flavus increased production of conidia, aflatoxins and kojic acid.  

PubMed

Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillus flavus 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

2011-01-01

117

Loss of msnA, a Putative Stress Regulatory Gene, in Aspergillus parasiticus and Aspergillus flavus Increased Production of Conidia, Aflatoxins and Kojic Acid  

PubMed Central

Production of the harmful carcinogenic aflatoxins by Aspergillus parasiticus and Aspergillus flavus 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.

Chang, Perng-Kuang; Scharfenstein, Leslie L.; Luo, Meng; Mahoney, Noreen; Molyneux, Russell J.; Yu, Jiujiang; Brown, Robert L.; Campbell, Bruce C.

2011-01-01

118

Isolation and characterization of alpha-glucosidase from Aspergillus niger.  

PubMed

alpha-Glucosidase is an enzyme widely used in biochemical analytical methods. Aspergillus niger was selected as a potential source for its production. Conditions for glucosidase production were optimized and the enzyme was isolated from the culture supernatant by dialysis and anion-exchange chromatography. The activity of the enzyme was determined by maltose hydrolysis to glucose, which was determined using a glucose-specific electrode or by high-performance liquid chromatography. The isolated enzyme was further characterized by sodium dodecyl sulphate-polyacrylamide gel electrophoresis, substrate specificity and fast protein liquid chromatography. The Michaelis constant, optimal temperature and stability of the enzyme preparation were determined. PMID:1639895

Brízová, K; Králová, B; Demnerová, K; Vins, I

1992-02-28

119

Funalenone, a novel collagenase inhibitor produced by Aspergillus niger.  

PubMed

Funalenone, a phenalene compound that inhibits type I collagenase (MMP-1), was isolated from mycelium of Aspergillus niger FO-5904 by solvent extaction, ODS column chromatography, Sephadex LH-20 column chromatography and reversed phase HPLC. Funalenone inhibited 50% of type I collagenase activity at a concentration of 170 microM, but inhibited 18.3% and 38.7% against 72 kDa and 92 kDa type IV collagenase, respectively, at a concentration of 400 microM. PMID:10695672

Inokoshi, J; Shiomi, K; Masuma, R; Tanaka, H; Yamada, H; Omura, S

1999-12-01

120

Characterization of Natural Antisense Transcript, Sclerotia Development and Secondary Metabolism by Strand-Specific RNA Sequencing of Aspergillus flavus  

PubMed Central

Aspergillus flavus has received much attention owing to its severe impact on agriculture and fermented products induced by aflatoxin. Sclerotia morphogenesis is an important process related to A. flavus reproduction and aflatoxin biosynthesis. In order to obtain an extensive transcriptome profile of A. flavus and provide a comprehensive understanding of these physiological processes, the isolated mRNA of A. flavus CA43 cultures was subjected to high-throughput strand-specific RNA sequencing (ssRNA-seq). Our ssRNA-seq data profiled widespread transcription across the A. flavus genome, quantified vast transcripts (73% of total genes) and annotated precise transcript structures, including untranslated regions, upstream open reading frames (ORFs), alternative splicing variants and novel transcripts. We propose natural antisense transcripts in A. flavus might regulate gene expression mainly on the post-transcriptional level. This regulation might be relevant to tune biological processes such as aflatoxin biosynthesis and sclerotia development. Gene Ontology annotation of differentially expressed genes between the mycelia and sclerotia cultures indicated sclerotia development was related closely to A. flavus reproduction. Additionally, we have established the transcriptional profile of aflatoxin biosynthesis and its regulation model. We identified potential genes linking sclerotia development and aflatoxin biosynthesis. These genes could be used as targets for controlled regulation of aflatoxigenic strains of A. flavus.

Yin, Chao; Guo, Yong; Lin, Ying; Pan, Li; Wang, Bin

2014-01-01

121

Effect of intraspecific competition by Aspergillus flavus on aflatoxin formation in suspended disc culture.  

PubMed

The ability of two non-aflatoxin producing strains of Aspergillus flavus to interfere with aflatoxin production by a toxigenic A. flavus strain was examined using a replacement series with suspended disc culture method. Individual glass fiber discs, affixed to a pin suspended from the caps of scintillation vials, were inoculated with medium containing A. flavus conidial mixtures in different proportions (aflatoxin producer:non-producer = 100:0, 80:20, 60:40, 20:80 and 0:100 by vol) at a constant total density (1 x 10(5) spores ml(-1)). Reductions in the total conidial density of these strains when grown alone, had little effect on fungal growth (mycelium dry weight) or aflatoxin production. Significant (P < 0.0001) reductions in aflatoxin B1 were recorded when non-toxigenic strains represented any proportion of the inoculum mixture. Aflatoxin yield values were less than (P < 0.0001) expected from the input ratios for toxigenic vs. non-toxigenic conidial inoculum within the replacement series. Aflatoxin yields were also reduced (P < 0.001), with a corresponding increase in fungal growth (P < 0.001), when conidia from aflatoxin producing strains were mixed in equal proportions. This suggests that the substantial inhibition of aflatoxin yield for inoculum mixtures results from the failure of spore germlings to establish a cooperative mycelial network. PMID:12884960

Wicklow, Donald T; Bobell, John R; Palmquist, Debra E

2003-05-01

122

Simple and Highly Discriminatory VNTR-Based Multiplex PCR for Tracing Sources of Aspergillus flavus Isolates  

PubMed Central

Aspergillus flavus 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.

Wang, Dong Ying; Hadj-Henni, Leila; Thierry, Simon; Arne, Pascal; Chermette, Rene; Botterel, Francoise; Hadrich, Ines; Makni, Fattouma; Ayadi, Ali; Ranque, Stephane; Huang, Wei Yi; Guillot, Jacques

2012-01-01

123

Arabinase gene expression in Aspergillus niger: indications for coordinated regulation.  

PubMed

Aspergillus niger secretes three glycosylated glycosyl hydrolases which are involved in degradation of the plant cell wall polysaccharide L-arabinan: alpha-L-arabinofuranosidases (ABF) A and B, and endo-1,5-alpha-L-arabinase (ABN) A. The nucleotide sequence of the previously cloned gene encoding ABF A (abfA) from A. niger was determined. The coding region contains seven introns. Mature ABF A comprises 603 amino acids with a molecular mass of 65.4 kDa as deduced from the nucleotide sequence. The secreted enzyme is N-glycosylated. The primary structures of the three A. niger arabinases characterized lack similarity. Regulation of arabinase expression upon induction by sugar beet pulp and by L-arabitol was studied as a function of time. This was done in wild-type A. niger as well as in transformants carrying multiple copies of either one of the ABF-encoding genes. Each arabinase gene responded differently upon a mycelial transfer to L-arabitol-containing medium. Extra copies of abfA or abfB led to a decreased expression level of ABN A, though the repression elicited by abfB is stronger and more persistent than that effected by abfA. Multiple copies of both abf genes influence expression of the other ABF similarly, but to a far less pronounced degree than they affect ABN A synthesis. Four putative promoter elements, shared by all three arabinase genes, could be involved in coordination of L-arabinan degradation by A. niger. PMID:8000538

Flipphi, M J; Visser, J; van der Veen, P; de Graaff, L H

1994-10-01

124

Genes differentially expressed by Aspergillus flavus strains after loss of aflatoxin production by serial transfers.  

PubMed

Aflatoxins are carcinogenic fungal secondary metabolites produced by Aspergillus flavus 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

2007-12-01

125

An insight into the curdione biotransformation pathway by Aspergillus niger.  

PubMed

Curdione (1), a sesquiterpene with a germacrane skeleton from rhizomes of Curcuma wenyujin, has attracted attention due to its important pharmacological properties. Herein, we investigated the chemo-biotransformation of curdione (1) systematically using Aspergillus niger AS 3.739. Regio- and stereoselective hydroxylation of curdione with filamentous fungus A. niger AS 3.739 led to seven metabolites including four new compounds 3?-hydroxycurcumalactone, 2?-hydroxycurcumalactone, (10S)-9,10-dihydroxy-curcumalactone and (10R)-9,10-dihydroxy-curcumalactone. Their structures were determined by spectroscopic techniques including two-dimensional NMR and TOF-MS (Time of Flight Mass Spectrometry). Based upon the analysis of biological and chemical conversions of curdione, a tentative metabolic pathway via chemo-bio cascade reactions is proposed in A. niger system, which provides an insight into the corresponding metabolism of curdione in animal systems. In addition, experiments with selected monooxygenase inhibitors suggest that cytochrome P450 monooxygenase played a crucial role in the hydroxylation of curdione. PMID:24456521

Chen, Yinan; Zhang, Lang; Qin, Bin; Zhang, Xin; Jia, Xian; Wang, Xiaoying; Jin, Danni; You, Song

2014-01-01

126

Effect of application of nontoxigenic strains of Aspergillus flavus and A. parasiticus on subsequent aflatoxin contamination of peanuts in storage  

Microsoft Academic Search

Experiments were conducted to determine the potential for biological control of aflatoxin contamination of peanuts during storage. Florunner peanuts were treated in field plots by applying competitive, nontoxigenic strains of Aspergillus flavus and A. parasiticus, at 76 and 67 days after planting in 1998 and 1999, respectively. After harvest, half the peanuts from both treated and control plots were sprayed

Joe W Dorner; Richard J Cole

2002-01-01

127

In vitro effect of some fungicides on growth and aflatoxins production by Aspergillus flavus isolated from Capsicum powder  

Microsoft Academic Search

The aim of this study was to determine the effect of some pre-harvest fungicides on growth and aflatoxin (AF) production of three Aspergillus flavus 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

L. Santos; S. Marín; V. Sanchis; A. J. Ramos

2011-01-01

128

Multilocus variable-number tandem-repeat analysis of clinical isolates of Aspergillus flavus from Iran reveals the first cases of Aspergillus minisclerotigenes associated with human infection  

PubMed Central

Background Aspergillus flavus is intensively studied for its role in infecting crop plants and contaminating produce with aflatoxin, but its role as a human pathogen is less well understood. In parts of the Middle East and India, A. flavus surpasses A. fumigatus as a cause of invasive aspergillosis and is a significant cause of cutaneous, sinus, nasal and nail infections. Methods A collection of 45 clinical and 10 environmental A. flavus isolates from Iran were analysed using Variable-Number Tandem-Repeat (VNTR) markers with MICROSAT and goeBURST to determine their genetic diversity and their relatedness to clinical and environmental A. flavus isolates from Australia. Phylogeny was assessed using partial ?-tubulin and calmodulin gene sequencing, and mating type was determined by PCR. Antifungal susceptibility testing was performed on selected isolates using a reference microbroth dilution method. Results There was considerable diversity in the A. flavus collection, with no segregation on goeBURST networks according to source or geographic location. Three Iranian isolates, two from sinus infections and one from a paranasal infection grouped with Aspergillus minisclerotigenes, and all produced B and G aflatoxin. Phylogenic analysis using partial ?-tubulin and calmodulin sequencing confirmed two of these as A. minisclerotigenes, while the third could not be differentiated from A. flavus and related species within Aspergillus section flavi. Based on epidemiological cut-off values, the A. minisclerotigens and A. flavus isolates tested were susceptible to commonly used antifungal drugs. Conclusions This is the first report of human infection due to A. minisclerotigenes, and it raises the possiblity that other species within Aspergillus section flavi may also cause clinical disease. Clinical isolates of A. flavus from Iran are not distinct from Australian isolates, indicating local environmental, climatic or host features, rather than fungal features, govern the high incidence of A. flavus infection in this region. The results of this study have important implications for biological control strategies that aim to reduce aflatoxin by the introduction of non-toxigenic strains, as potentially any strain of A. flavus, and closely related species like A. minisclerotigenes, might be capable of human infection.

2014-01-01

129

The inhibitory effects of Curcuma longa L. essential oil and curcumin on Aspergillus flavus link growth and morphology.  

PubMed

The essential oil from Curcuma longa L. was analysed by GC/MS. The major components of the oil were ar-turmerone (33.2%), ? -turmerone (23.5%) and ? -turmerone (22.7%). The antifungal activities of the oil were studied with regard to Aspergillus flavus growth inhibition and altered morphology, as preliminary studies indicated that the essential oil from C. longa inhibited Aspergillus flavus Link aflatoxin production. The concentration of essential oil in the culture media ranged from 0.01% to 5.0%?v/v, and the concentration of curcumin was 0.01-0.5%?v/v. The effects on sporulation, spore viability, and fungal morphology were determined. The essential oil exhibited stronger antifungal activity than curcumin on A. flavus. The essential oil reduced the fungal growth in a concentration-dependent manner. A. flavus growth rate was reduced by C. longa essential oil at 0.10%, and this inhibition effect was more efficient in concentrations above 0.50%. Germination and sporulation were 100% inhibited in 0.5% oil. Scanning electron microscopy (SEM) of A. flavus exposed to oil showed damage to hyphae membranes and conidiophores. Because the fungus is a plant pathogen and aflatoxin producer, C. longa essential oil may be used in the management of host plants. PMID:24367241

Dias Ferreira, Flávio; Mossini, Simone Aparecida Galerani; Dias Ferreira, Francine Maery; Arrotéia, Carla Cristina; da Costa, Christiane Luciana; Nakamura, Celso Vataru; Machinski, Miguel

2013-01-01

130

Clustered genes involved in cyclopiazonic acid production are next to the aflatoxin biosynthesis gene cluster in Aspergillus flavus.  

PubMed

Cyclopiazonic acid (CPA), an indole-tetramic acid mycotoxin, is produced by many species of Aspergillus and Penicillium. In addition to CPA Aspergillus flavus 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

Chang, Perng-Kuang; Horn, Bruce W; Dorner, Joe W

2009-02-01

131

Relating significance and relations of differentially expressed genes in response to Aspergillus flavus infection in maize  

PubMed Central

Aspergillus flavus is a pathogenic fungus infecting maize and producing aflatoxins that are health hazards to humans and animals. Characterizing host defense mechanism and prioritizing candidate resistance genes are important to the development of resistant maize germplasm. We investigated methods amenable for the analysis of the significance and relations among maize candidate genes based on the empirical gene expression data obtained by RT-qPCR technique from maize inbred lines. We optimized a pipeline of analysis tools chosen from various programs to provide rigorous statistical analysis and state of the art data visualization. A network-based method was also explored to construct the empirical gene expression relational structures. Maize genes at the centers in the network were considered as important candidate genes for maize DNA marker studies. The methods in this research can be used to analyze large RT-qPCR datasets and establish complex empirical gene relational structures across multiple experimental conditions.

Asters, Matthew C.; Williams, W. Paul; Perkins, Andy D.; Mylroie, J. Erik; Windham, Gary L.; Shan, Xueyan

2014-01-01

132

Relating significance and relations of differentially expressed genes in response to Aspergillus flavus infection in maize.  

PubMed

Aspergillus flavus is a pathogenic fungus infecting maize and producing aflatoxins that are health hazards to humans and animals. Characterizing host defense mechanism and prioritizing candidate resistance genes are important to the development of resistant maize germplasm. We investigated methods amenable for the analysis of the significance and relations among maize candidate genes based on the empirical gene expression data obtained by RT-qPCR technique from maize inbred lines. We optimized a pipeline of analysis tools chosen from various programs to provide rigorous statistical analysis and state of the art data visualization. A network-based method was also explored to construct the empirical gene expression relational structures. Maize genes at the centers in the network were considered as important candidate genes for maize DNA marker studies. The methods in this research can be used to analyze large RT-qPCR datasets and establish complex empirical gene relational structures across multiple experimental conditions. PMID:24770700

Asters, Matthew C; Williams, W Paul; Perkins, Andy D; Mylroie, J Erik; Windham, Gary L; Shan, Xueyan

2014-01-01

133

Control of Aspergillus flavus with essential oil and methanol extract of Satureja hortensis.  

PubMed

The essential oil and methanol extract of Satureja hortensis were tested for antifungal activity against Aspergillus flavus in vitro on Petri plates and liquid culture, and under storage conditions. The oil showed strong antifungal activity based on the inhibition zone and minimal inhibitory concentration values against the pathogen on Petri plates assays. The very low concentrations of them also reduced wet and dry mycelium weight of pathogen fungus in liquid culture. When the oils at 25, 12.5 and 6.25 microl/mL concentrations were applied to lemon fruits before seven days of pathogen inoculation on storage conditions, the decay on fruits caused by the pathogen could be prevented completely. The results in this study showed that the essential oil of S. hortensis had strong antifungal activity against pathogen fungi tested. So, the essential oil of S. hortensis could be used for management of this pathogen as a potential source of sustainable eco-friendly botanical fungicides. PMID:18455819

Dikbas, Neslihan; Kotan, Recep; Dadasoglu, Fatih; Sahin, Fikrettin

2008-05-31

134

Use of UV photography to identify aflatoxin-producing strains of Aspergillus flavus and A. parasiticus.  

PubMed

UV photography in glucose, yeast extract (GY) agar medium was tested as a simple and rapid method for the distinction of aflatoxin-positive from aflatoxin-negative strains of Aspergillus flavus and A. parasiticus. In the UV photographs aflatoxin-producing moulds were identified as grey or black colonies, whereas aflatoxin-nonproducing moulds appeared as white colonies. Of the aflatoxin-positive strains detected by the UV photographic method, 10% was confirmed by extraction of the GY agar medium and mould mycelium in chloroform, extracts which were analysed subsequently using thin-layer chromatography. Confirmation of aflatoxigenic strains was achieved by biosynthesis on liquid medium yeast extract sucrose (YES) broth. PMID:8525708

Cvetni?, Z; Pepeljnjak, S

1995-10-01

135

Nanosulfur: A Potent Fungicide Against Food Pathogen, Aspergillus niger  

SciTech Connect

Elemental sulfur (S{sup 0}), man's oldest eco-friendly fungicide for curing fungal infections in plants and animals, is registered in India as a non-systemic and contact fungicide. However due to its high volume requirement, Indian agrochemical industry and farmers could not effectively use this product till date. We hypothesize that intelligent nanoscience applications might increase the visibility of nanosulfur in Indian agriculture as a potent and eco-safe fungicide. Sulfur nanoparticles (NPs) were synthesized bottom-up via a liquid synthesis method with average particle size in the range of 50-80 nm and the shapes of the NPs were spherical. A comparative study of elemental and nano-sulfur produced has been tested against facultative fungal food pathogen, Aspergillus niger. Results showed that nanosulfur is more efficacious than its elemental form.

Choudhury, Samrat Roy; Goswami, Arunava [Agricultural and Ecological Research Unit, Biological Sciences Division, Indian Statistical Institute, 203 B. T. Road, Kolkata, West Bengal-700108 (India); Nair, Kishore K.; Kumar, Rajesh; Gopal, Madhuban; Devakumar, C. [Department of Agricultural Chemicals, Pusa Campus, New Delhi (India); Gogoi, Robin [Plant Pathology, Pusa Campus, New Delhi (India); Srivastava, Chitra; Subhramanyam, B. S. [Entomology, Indian Agricultural Research Institute, Pusa Campus, New Delhi (India)

2010-10-04

136

Tandem shock waves to enhance genetic transformation of Aspergillus niger.  

PubMed

Filamentous fungi are used in several industries and in academia to produce antibiotics, metabolites, proteins and pharmaceutical compounds. The development of valuable strains usually requires the insertion of recombinant deoxyribonucleic acid; however, the protocols to transfer DNA to fungal cells are highly inefficient. Recently, underwater shock waves were successfully used to genetically transform filamentous fungi. The purpose of this research was to demonstrate that the efficiency of transformation can be improved significantly by enhancing acoustic cavitation using tandem (dual-pulse) shock waves. Results revealed that tandem pressure pulses, generated at a delay of 300?s, increased the transformation efficiency of Aspergillus niger up to 84% in comparison with conventional (single-pulse) shock waves. This methodology may also be useful to obtain new strains required in basic research and biotechnology. PMID:24680880

Loske, Achim M; Fernández, Francisco; Magańa-Ortíz, Denis; Coconi-Linares, Nancy; Ortíz-Vázquez, Elizabeth; Gómez-Lim, Miguel A

2014-08-01

137

Antimicrobial textile treated with chitosan from Aspergillus niger mycelial waste.  

PubMed

The waste biomass of Aspergillus niger, following citric acid production, was used as a source for fungal chitosan extraction. The produced chitosan was characterized with deacetylation degree of 89.6%, a molecular weight of 25,000 dalton, 97% solubility in 1% acetic acid solution and comparable FT-IR spectra to standard shrimp chitosan. Fungal chitosan was applied as a cotton fabric finishing agent using pad-dry-cure method. The topographical structure of chitosan-treated fabrics (CTF) was much improved compared with control fabrics. CTF, after durability tests, exhibited a powerful antimicrobial activity against both E. coli and Candida albicans, the captured micrographs for E. coli cells contacted with CTF showed a complete lysis of cell walls with the prolonging contact time. The produced antimicrobial CTF could be proposed as a suitable material for many medical and hygienic applications. PMID:21596059

Tayel, Ahmed A; Moussa, Shaaban H; El-Tras, Wael F; Elguindy, Nihal M; Opwis, Klaus

2011-08-01

138

Structure of the catalytic domain of glucoamylase from Aspergillus niger.  

PubMed

Glucoamylase from Aspergillus niger is an industrially important biocatalyst that is utilized in the mass production of glucose from raw starch or soluble oligosaccharides. The G1 isoform consists of a catalytic domain and a starch-binding domain connected by a heavily glycosylated linker region. The amino-terminal catalytic domain of the G1 isoform generated by subtilisin cleavage has been crystallized at pH 8.5, which is a significantly higher pH condition than used for previously characterized glucoamylase crystals. The refined structure at 1.9 Ĺ resolution reveals the active site of the enzyme in complex with both Tris and glycerol molecules. The ligands display both unique and analogous interactions with the substrate-binding site when compared with previous structures of homologous enzymes bound to inhibitors. PMID:21301084

Lee, Jaeyong; Paetzel, Mark

2011-02-01

139

Bioleaching of spent fluid catalytic cracking catalyst using Aspergillus niger.  

PubMed

The use of the fungus Aspergillus niger for the bioleaching of heavy metals from spent catalyst was investigated, with fluid catalytic cracking (FCC) catalyst as a model. Bioleaching was examined in batch cultures with the spent catalysts at various pulp densities (1-12%). Chemical leaching was also performed using mineral acids (sulphuric and nitric acids) and organic acids (citric, oxalic and gluconic acids), as well as a mixture of organic acids at the same concentrations as that biogenically produced. It was shown that bioleaching realised higher metal extraction than chemical leaching, with A. niger mobilizing Ni (9%), Fe (23%), Al (30%), V (36%) and Sb (64%) at 1% pulp density. Extraction efficiency generally decreased with increased pulp density. Compared with abiotic controls, bioleaching gave rise to higher metal extractions than leaching using fresh medium and cell-free spent medium. pH decreased during bioleaching, but remained relatively constant in both leaching using fresh medium and cell-free spent medium, thus indicating that the fungus played a role in effecting metal extraction from the spent catalyst. PMID:15664080

Aung, Khin Moh Moh; Ting, Yen-Peng

2005-03-16

140

Starch-binding domain shuffling in Aspergillus niger glucoamylase.  

PubMed

Aspergillus niger glucoamylase (GA) consists mainly of two forms, GAI [from the N-terminus, catalytic domain + linker + starch-binding domain (SBD)] and GAII (catalytic domain + linker). These domains were shuffled to make RGAI (SBD + linker + catalytic domain), RGAIDeltaL (SBD + catalytic domain) and RGAII (linker + catalytic domain), with domains defined by function rather than by tertiary structure. In addition, Paenibacillus macerans cyclomaltodextrin glucanotransferase SBD replaced the closely related A.niger GA SBD to give GAE. Soluble starch hydrolysis rates decreased as RGAII approximately GAII approximately GAI > RGAIDeltaL approximately RGAI approximately GAE. Insoluble starch hydrolysis rates were GAI > RGAIDeltaL > RGAI > GAE approximately RGAII > GAII, while insoluble starch-binding capacities were GAI > RGAI > RGAIDeltaL > RGAII > GAII > GAE. These results indicate that: (i) moving the SBD to the N-terminus or replacing the native SBD somewhat affects soluble starch hydrolysis; (ii) SBD location significantly affects insoluble starch binding and hydrolysis; (iii) insoluble starch hydrolysis is imperfectly correlated with its binding by the SBD; and (iv) placing the P.macerans cyclomaltodextrin glucanotransferase SBD at the end of a linker, instead of closely associated with the rest of the enzyme, severely reduces its ability to bind and hydrolyze insoluble starch. PMID:12915730

Cornett, Catherine A G; Fang, Tsuei-Yun; Reilly, Peter J; Ford, Clark

2003-07-01

141

Optimized bioprocess for production of fructofuranosidase by recombinant Aspergillus niger.  

PubMed

A comprehensive approach of bioprocess design at various levels was used to optimize microbial production of extracellular fructofuranosidase, important as biocatalyst to derive fructooligosaccharides with broad application in food or pharmaceutical industry. For production, the recombinant strain Aspergillus niger SKAn1015 was used, which expresses the fructofuranosidase encoding gene suc1 under control of a strong constitutive promoter. In a first screening towards an optimized medium, glucose, nitrate, Fe(2+), and Mn(2+) were identified as beneficial for production. A minimal medium with optimized concentration of these key nutrients, obtained by central composite design experiments and quadratic modelling, provided a threefold increased fructofuranosidase activity in the culture supernatant (400 U/mL) as compared to the originally described medium. Utilizing the optimized medium, the process was then transferred from shake flask into a fed-batch-operated bioreactor. Hereby, the intended addition of talc microparticles allowed engineering the morphology of A. niger into a highly active mycelial form, which strongly boosted production. Fructofuranosidase production was highly specific as confirmed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. The secreted enzyme activity of 2,800 U/mL, corresponding to about 3 g/L of fructofuranosidase, achieved by the microparticle-enhanced fed-batch process, is tenfold higher than that of any other process reported so far, so that the presented bioprocess strategy appears as a milestone towards future industrial fructofuranosidase production. PMID:20502893

Driouch, Habib; Roth, Andreas; Dersch, Petra; Wittmann, Christoph

2010-08-01

142

Homologue expression of a ?-xylosidase from native Aspergillus niger.  

PubMed

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 3.2.1.37) 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 Aspergillus niger 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

2011-09-01

143

Physiological characterization of ATP-citrate lyase in Aspergillus niger.  

PubMed

Acetyl-CoA, an important molecule in cellular metabolism, is generated in multiple subcellular compartments and mainly used for energy production, biosynthesis of a diverse set of molecules, and protein acetylation. In eukaryotes, cytosolic acetyl-CoA is derived mainly from the conversion of citrate and CoA by ATP-citrate lyase. Here, we describe the targeted deletions of acl1 and acl2, two tandem divergently transcribed genes encoding subunits of ATP-citrate lyase in Aspergillus niger. We show that loss of acl1 or/and acl2 results in a significant decrease of acetyl-CoA and citric acid levels in these mutants, concomitant with diminished vegetative growth, decreased pigmentation, reduced asexual conidiogenesis, and delayed conidial germination. Exogenous addition of acetate repaired the defects of acl-deficient strains in growth and conidial germination but not pigmentation and conidiogenesis. We demonstrate that both Acl1 and Acl2 subunits are required to form a functional ATP-citrate lyase in A. niger. First, deletion of acl1 or/and acl2 resulted in similar defects in growth and development. Second, enzyme activity assays revealed that loss of either acl1 or acl2 gene resulted in loss of ATP-citrate lyase activity. Third, in vitro enzyme assays using bacterially expressed 6His-tagged Acl protein revealed that only the complex of Acl1 and Acl2 showed ATP-citrate lyase activity, no enzyme activities were detected with the individual protein. Fourth, EGFP-Acl1 and mCherry-Acl2 proteins were co-localized in the cytosol. Thus, acl1 and acl2 coordinately modulate the cytoplasmic acetyl-CoA levels to regulate growth, development, and citric acid synthesis in A. niger. PMID:24566752

Chen, Hong; He, Xihong; Geng, Hongran; Liu, Hao

2014-04-01

144

Ram horn peptone as a source of citric acid production by Aspergillus niger , with a process  

Microsoft Academic Search

The present study deals with the production of citric acid from a ram horn peptone (RHP) by Aspergillus niger NRRL 330. A medium from RHP and a control medium (CM) were compared for citric acid production using A. niger in a batch culture. For this purpose, first, RHP was produced. Ram horns were hydrolyzed by treatment with acids (6 N H

Esabi B. Kurbanoglu; Namudar I. Kurbanoglu

2004-01-01

145

Production of Single Cell Protein in Stickwater by Lactobacillus acidophilus and Aspergillus niger  

Microsoft Academic Search

The aim of this study was to investigate production of single cell protein (SCP) using Lactobacillus acidophilus and Aspergillus niger in stickwater from fish meal factories. Stickwater was used as substrate for L. acidophilus and A. niger and compared with standard medium as control. The maximum chemical oxygen demand reduction by L. acidophilus was achieved at 55.4 and 86.4% and

Safarbibi Kam; Abdolmohammad Abedian Kenari; Habibollah Younesi

2011-01-01

146

Apple pomace: A potential substrate for citric acid production by Aspergillus niger  

Microsoft Academic Search

Apple pomace was used as a fsubstrate for citric acid production by five strains of Aspergillus niger. A. niger NRRL 567 produced the greatest amount of citric acid from apple pomace in the presence of 4% methanol. The yield was 88% based on the amount of sugar consumed.

Y. D. Hang; E. E. Woodams

1984-01-01

147

Citric Acid Production by Aspergillus niger Using Date-Based Medium Fortified with Whey and Additives  

Microsoft Academic Search

The ability of Aspergillus niger to produce citric acid from dates was evaluated. Two strains of A. niger (ATCC 6275 and 9642) were grown in media containing different concentrations of date extract or molasses fortified with whey, methanol and tricalcium phosphate. The fermentation experiments were conducted at 25° C for 12 days and samples were withdrawn at different time intervals

G. F. Mehyar; K. S. Delaimy; S. A. Ibrahim

2005-01-01

148

Impact of a Streptomyces (AS1) strain and its metabolites on control of Aspergillus flavus and aflatoxin B1 contamination in vitro and in stored peanuts  

Microsoft Academic Search

Six actinomycetes were isolated from peanuts in Egypt. Of these, a Streptomyces strain (AS1) was found in in vitro assays to inhibit directly or via secondary metabolites both germination and growth of Aspergillus flavus. Tests of the AS1 cells for direct control of A. flavus populations or aflatoxin B1 (AFB1) production on stored peanuts was unsuccessful over 14 day storage

Y. Sultan; N. Magan

2011-01-01

149

Biotransformation of one monoterpene by sporulated surface cultures of Aspergillus niger and Penicillium sp.  

PubMed

In this study, biotransformation of menthol by sporulated surface culture of Aspergillus niger and Penicillium sp. was studied. The main bioconversion product obtained from menthol of A. niger was cis-p-menthan-7-ol and the main products obtained by surface Penicillium sp. were limonene, p-cymene and gamma-terpinene using sporulated surface culture. The pathways involved in the biotransformation of menthol by A. niger and Penicillium sp. to main products are also discussed. PMID:19521921

Esmaeili, Akbar; Sharafian, Shirin; Safaiyan, Shila; Rezazadeh, Shamsali; Rustaivan, Abdolhossein

2009-01-01

150

Comparison of expression of secondary metabolite biosynthesis cluster genes in Aspergillus flavus, A. parasiticus, and A. oryzae.  

PubMed

Fifty six secondary metabolite biosynthesis gene clusters are predicted to be in the Aspergillus flavus genome. In spite of this, the biosyntheses of only seven metabolites, including the aflatoxins, kojic acid, cyclopiazonic acid and aflatrem, have been assigned to a particular gene cluster. We used RNA-seq to compare expression of secondary metabolite genes in gene clusters for the closely related fungi A. parasiticus, A. oryzae, and A. flavus S and L sclerotial morphotypes. The data help to refine the identification of probable functional gene clusters within these species. Our results suggest that A. flavus, a prevalent contaminant of maize, cottonseed, peanuts and tree nuts, is capable of producing metabolites which, besides aflatoxin, could be an underappreciated contributor to its toxicity. PMID:24960201

Ehrlich, Kenneth C; Mack, Brian M

2014-06-01

151

Aspergillus flavus diversity on crops and in the environment can be exploited to reduce aflatoxin exposure and improve health.  

PubMed

Humans and animals are exposed to aflatoxins, toxic carcinogenic fungal metabolites, through consumption of contaminated food and feed. Aspergillus flavus, 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

2012-12-01

152

Comparison of Expression of Secondary Metabolite Biosynthesis Cluster Genes in Aspergillus flavus, A. parasiticus, and A. oryzae  

PubMed Central

Fifty six secondary metabolite biosynthesis gene clusters are predicted to be in the Aspergillus flavus genome. In spite of this, the biosyntheses of only seven metabolites, including the aflatoxins, kojic acid, cyclopiazonic acid and aflatrem, have been assigned to a particular gene cluster. We used RNA-seq to compare expression of secondary metabolite genes in gene clusters for the closely related fungi A. parasiticus, A. oryzae, and A. flavus S and L sclerotial morphotypes. The data help to refine the identification of probable functional gene clusters within these species. Our results suggest that A. flavus, a prevalent contaminant of maize, cottonseed, peanuts and tree nuts, is capable of producing metabolites which, besides aflatoxin, could be an underappreciated contributor to its toxicity.

Ehrlich, Kenneth C.; Mack, Brian M.

2014-01-01

153

Identification and cloning of a second phytase gene (phyB) from Aspergillus niger (ficuum).  

PubMed

An Aspergillus niger (ficuum) genomic DNA lambda EMBL3 library was probed with a 354-bp DNA fragment obtained by polymerase chain reaction of A. niger DNA with oligonucleotides based on partial amino acid sequence of a pH 2.5 optimum acid phosphatase. A clone containing a 1605 bp segment (phyB) encoding the 479 amino acid enzyme was isolated and found to contain four exons. Global alignment revealed 23.5% homology to Aspergillus niger phytase (PhyA); four regions of extensive homology were identified. Some of these regions may contain catalytic sites for phosphatase function. PMID:7916610

Ehrlich, K C; Montalbano, B G; Mullaney, E J; Dischinger, H C; Ullah, A H

1993-08-31

154

Genome-wide analysis of the Zn(II)?Cys? zinc cluster-encoding gene family in Aspergillus flavus.  

PubMed

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. Aspergillus flavus 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

Chang, Perng-Kuang; Ehrlich, Kenneth C

2013-05-01

155

Antifungal activity of thyme, summer savory and clove essential oils against Aspergillus flavus in liquid medium and tomato paste  

Microsoft Academic Search

Antifungal activity of essential oils of thyme, summer savory and clove were evaluated in culture medium and tomato paste. Aspergillus flavus 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

Maryam Omidbeygi; Mohsen Barzegar; Zohreh Hamidi; Hassanali Naghdibadi

2007-01-01

156

Kinetics and modelling of kojic acid production by Aspergillus flavus Link in batch fermentation and resuspended mycelial system  

Microsoft Academic Search

An unstructured model based on logistic and Luedeking-Piret equations was proposed to describe growth, substrate consumption and kojic acid production by Aspergillus flavus Link strain 44-1 in batch fermentation and also in a resuspended cell system. The model showed that kojic acid production was non-growth associated. The maximum kojic acid and cell concentrations obtained in batch fermentations using the fermenter

A. B. Ariff; M. Rosfarizan; L. S. Herng; S. Madihah; M. I. A. Karim

1997-01-01

157

Chemoprevention by essential oil of turmeric leaves ( Curcuma longa L.) on the growth of Aspergillus flavus and aflatoxin production  

Microsoft Academic Search

Turmeric is well known for a wide range of medicinal properties. Essential oil of turmeric leaves (Curcuma longa L.) were evaluated at varying concentrations of 0.01, 0.05, 0.1, 0.5, 0.75, 1.0 and 1.5% (v\\/v) in Yeast Extract Sucrose (YES) broth inoculated with spore suspension of Aspergillus flavus of 106conidia\\/ml. These were evaluated for their potential in the control of aflatoxigenic

S. Sindhu; B. Chempakam; N. K. Leela; R. Suseela Bhai

2011-01-01

158

In vitro studies on the potential for biological control of Aspergillus flavus and Fusarium moniliforme by Trichoderma species  

Microsoft Academic Search

Culture filtrates of Trichoderma viride and Trichoderma harzianum were inhibitory of Fusarium moniliforme and, to a lesser\\u000a extent, Aspergillus flavus. 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

Claudia Calistru; Michelle McLean; Patricia Berjak

1997-01-01

159

Distinct roles for VeA and LaeA in development and pathogenesis of Aspergillus flavus.  

PubMed

Aspergillus flavus, 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. PMID:19411623

Amaike, Saori; Keller, Nancy P

2009-07-01

160

Cloning and characterization of three Aspergillus niger promoters.  

PubMed

An Aspergillus niger (An) genomic library was constructed using the promoter-trap vector, pLX2A, which contains a hygromycin B (Hy) phosphotransferase-encoding gene (hph) for selection of DNA fragments with promoter activity. This library was transformed in Escherichia coli and 80,000 colonies were obtained, 94% of which contained inserts. Transformations of plasmid DNA from the library into An resulted in 53 Hy-resistant (HyR) colonies. Southern blot analysis of 21 transformants confirmed the integration of hph into the An genome. Using the sib selection procedure, three functional promoters, PX6, PX18 and PX21, were identified from this library. Both DNA strands of all three fragments were sequenced and their sequences showed no significant homology to those in the database. Comparison of the sequences of all known promoters from An suggested that C+T-rich stretches are probably important for promoter structures. The promoter activity was analysed further using beta-galactosidase (beta Gal) as a quantitative marker. The results suggest that while PX21 is a much stronger promoter than the known alpha-amylase promoter of A. oryzae, PX6 promotes only weak expression of beta Gal. PMID:7557461

Luo, X

1995-09-22

161

The composition of the cell wall of Aspergillus niger  

PubMed Central

1. The cell-wall composition of Aspergillus niger has been investigated. Analysis shows the presence of six sugars, glucose, galactose, mannose, arabinose, glucosamine and galactosamine, all in the d-configuration, except that a small amount of l-galactose may be present. Sixteen common amino acids are also present. 2. The wall consists chiefly of neutral carbohydrate (73–83%) and hexosamine (9–13%), with smaller amounts of lipid (2–7%), protein (0·5–2·5%) and phosphorus (less than 0·1%). The acetyl content (3·0–3·4%) corresponds to 1·0mole/mole of hexosamine nitrogen. 3. A fractionation of the cell-wall complex was achieved, with or without a preliminary phenol extraction, by using n-sodium hydroxide. Though this caused some degradation, 30–60% of the wall could be solubilized (depending on the preparation). Analyses on several fractions suggest that fractionation procedures bring about some separation of components although not in a clear-cut fashion. 4. Cell-wall preparations were shown to yield a fraction having [?]D approx. +240° (in n-sodium hydroxide) and consisting largely of glucose. This was separated into two subfractions, one of which had [?]D+281° (in n-sodium hydroxide) and had properties resembling the polysaccharide nigeran; the other had [?]D +231° (in n-sodium hydroxide). It is suggested that nigeran is a cell-wall component.

Johnston, I. R.

1965-01-01

162

Biochemical and Molecular Characterization of Secreted ?-Xylosidase from Aspergillus niger*  

PubMed Central

?-Linked xylose is a major component of xyloglucans in the cell walls of higher plants. An ?-xylosidase (AxlA) was purified from a commercial enzyme preparation from Aspergillus niger, and the encoding gene was identified. The protein is a member of glycosyl hydrolase family 31. It was active on p-nitrophenyl-?-d-xyloside, isoprimeverose, xyloglucan heptasaccharide (XXXG), and tamarind xyloglucan. When expressed in Pichia pastoris, AxlA had activity comparable to the native enzyme on pNP?X and IP despite apparent hyperglycosylation. The pH optimum of AxlA was between 3.0 and 4.0. AxlA together with ?-glucosidase depolymerized xyloglucan heptasaccharide. A combination of AxlA, ?-glucosidase, xyloglucanase, and ?-galactosidase in the optimal proportions of 51:5:19:25 or 59:5:11:25 could completely depolymerize tamarind XG to free Glc or Xyl, respectively. To the best of our knowledge, this is the first characterization of a secreted microbial ?-xylosidase. Secreted ?-xylosidases appear to be rare in nature, being absent from other tested commercial enzyme mixtures and from the genomes of most filamentous fungi.

Scott-Craig, John S.; Borrusch, Melissa S.; Banerjee, Goutami; Harvey, Christopher M.; Walton, Jonathan D.

2011-01-01

163

Studies on sulfhydryl groups of Aspergillus niger amine oxidase.  

PubMed

Amino acid analysis of the amine oxidase of Aspergillus niger (monoamine:O2 oxidoreductase (deaminating), EC 1.4.3.4) showed a composition similar to that of bovine plasma enzyme. One molecule of enzyme contained 25 Cys residues. It was shown that 9 to 11 residues of Cys were titrated to be SH groups. The amine oxidase reaction was markedly inhibited by metal ions (Cu2+, Hg2+, Ag+). The enzyme was inactivated with SH reagents (phenyl mercuric acetate, Cl-HgBzO-) and the extent of this inactivation was dependent on the time of incubation with SH reagents. Also, the Cl-HgBzO- -inactivated enzyme was reactivated with cysteine and this reactivation was biphasic with the time of incubation. The Cl-HgBzO--inactivated amine oxidase was compared with the native enzyme in their reactivity with phenylhydrazine and their spectral properties. The results showed that the Cl-HgBzO--inactivated enzyme had lower reactivity with phenylhydrazine than the native enzyme and had higher absorbance values than the native enzyme around 400 nm wavelengths. PMID:1174546

Suzuki, H; Ogura, Y; Yamada, H; Arima, K

1975-09-22

164

Some factors affecting tannase production by Aspergillus niger Van Tieghem  

PubMed Central

One variable at a time procedure was used to evaluate the effect of qualitative variables on the production of tannase from Aspergillus niger Van Tieghem. These variables including: fermentation technique, agitation condition, tannins source, adding carbohydrates incorporation with tannic acid, nitrogen source type and divalent cations. Submerged fermentation under intermittent shaking gave the highest total tannase activity. Maximum extracellular tannase activity (305 units/50 mL) was attained in medium containing tannic acid as tannins source and sodium nitrate as nitrogen source at 30 °C for 96 h. All added carbohydrates showed significant adverse effects on the production of tannase. All tested divalent cations significantly decreased tannase production. Moreover, split plot design was carried out to study the effect of fermentation temperature and fermentation time on tannase production. The results indicated maximum tannase production (312.7 units/50 mL) at 35 °C for 96 h. In other words, increasing fermentation temperature from 30 °C to 35 °C resulted in increasing tannase production.

Aboubakr, Hamada A.; El-Sahn, Malak A.; El-Banna, Amr A.

2013-01-01

165

Population balance modeling of the conidial aggregation of Aspergillus niger.  

PubMed

Numerous biotechnological production processes are based on the submerse cultivation of filamentous fungi. Process design, however, is often hampered by the complex growth pattern of these organisms. In the morphologic development of coagulating filamentous fungi, like Aspergillus niger, conidial aggregation is the first step of filamentous morphogenesis. For a proper description of this phenomenon it is necessary to characterize conidial populations. Kinetic studies performed with an in-line particle size analyzer suggested that two distinct aggregation steps have to be considered. The first step of conidial aggregation starts immediately after inoculation. Both the rate constants of formation and disintegration of aggregates have been determined by measuring the concentration of conidia at the beginning of the cultivation and the concentration of particles at steady state during the first hours of cultivation. In contrast to the first aggregation step, where the collision of conidia is presumed to be responsible for the process, the second aggregation step is thought to be initiated by germination of conidia. Growing hyphae provide additional surface for the attachment of non- germinated conidia, which leads to a strong decrease in particle concentration. The specific hyphal length growth rate and the ratio of particle concentration to the growing adhesion hyphal surface are decisive matters of the second aggregation step. Both aggregation steps can be described by population dynamics and simulated using the program package PARSIVAL (PARticle SIze eVALution) for the treatment of general particle population balances. PMID:17625790

Lin, P-J; Grimm, L H; Wulkow, M; Hempel, D C; Krull, R

2008-02-01

166

Indole Diterpenoids and Isocoumarin from the Fungus, Aspergillus flavus, Isolated from the Prawn, Penaeus vannamei  

PubMed Central

Two new indole-diterpenoids (1 and 2) and a new isocoumarin (3), along with the known ?-aflatrem (4), paspalinine (5), leporin B (6), ?-cyclopiazonic acid (7), iso-?-cyclopiazonic acid (8), ditryptophenaline (9), aflatoxin B1 (10), 7-O-acetylkojic acid (11) and kojic acid (12), were isolated from the fermentation broth of the marine-derived fungus, Aspergillus flavus OUCMDZ-2205. The structures of Compounds 1–12 were elucidated by spectroscopic analyses, quantum ECD calculations and the chemical method. New Compound 1 exhibited antibacterial activity against Staphylococcus aureus with a MIC value of 20.5 ?M. Both new Compounds 1 and 2 could arrest the A549 cell cycle in the S phase at a concentration of 10 ?M. Compound 1 showed PKC-beta inhibition with an IC50 value of 15.6 ?M. In addition, the absolute configurations of the known compounds, 4–6 and leporin A (6a), were also determined for the first time.

Sun, Kunlai; Li, Ye; Guo, Lei; Wang, Yi; Liu, Peipei; Zhu, Weiming

2014-01-01

167

Some 2S albumin from peanut seeds exhibits inhibitory activity against Aspergillus flavus.  

PubMed

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 Aspergillus flavus. 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

Duan, Xiao Hua; Jiang, Rui; Wen, Yun Jie; Bin, Jin Hua

2013-05-01

168

Indole Diterpenoids and Isocoumarin from the Fungus, Aspergillus flavus, Isolated from the Prawn, Penaeus vannamei.  

PubMed

Two new indole-diterpenoids (1 and 2) and a new isocoumarin (3), along with the known ?-aflatrem (4), paspalinine (5), leporin B (6), ?-cyclopiazonic acid (7), iso-?-cyclopiazonic acid (8), ditryptophenaline (9), aflatoxin B1 (10), 7-O-acetylkojic acid (11) and kojic acid (12), were isolated from the fermentation broth of the marine-derived fungus, Aspergillus flavus OUCMDZ-2205. The structures of Compounds 1-12 were elucidated by spectroscopic analyses, quantum ECD calculations and the chemical method. New Compound 1 exhibited antibacterial activity against Staphylococcus aureus with a MIC value of 20.5 ?M. Both new Compounds 1 and 2 could arrest the A549 cell cycle in the S phase at a concentration of 10 ?M. Compound 1 showed PKC-beta inhibition with an IC50 value of 15.6 ?M. In addition, the absolute configurations of the known compounds, 4-6 and leporin A (6a), were also determined for the first time. PMID:24983640

Sun, Kunlai; Li, Ye; Guo, Lei; Wang, Yi; Liu, Peipei; Zhu, Weiming

2014-01-01

169

Morphological Transitions Governed by Density Dependence and Lipoxygenase Activity in Aspergillus flavus? †  

PubMed Central

Aspergillus flavus differentiates to produce asexual dispersing spores (conidia) or overwintering survival structures called sclerotia. Results described here show that these two processes are oppositely regulated by density-dependent mechanisms and that increasing the cell density (from 101 to 107 cells/plate) results in the lowest numbers of sclerotial and the highest numbers of conidial. Extract from spent medium of low-cell-density cultures induced a high-sclerotium-number phenotype, whereas high-cell-density extract increased conidiation. Density-dependent development is also modified by changes in lipid availability. Exogenous linoleic acid increased sclerotial production at intermediate cell densities (104 and 105 cells/plate), whereas oleic and linolenic acids inhibited sclerotium formation. Deletion of Aflox encoding a lipoxygenase (LOX) greatly diminished density-dependent development of both sclerotia and conidia, resulting in an overall increase in the number of sclerotia and a decrease in the number of conidia at high cell densities (>105 cells/plate). Aflox mutants showed decreased linoleic acid LOX activity. Taken together, these results suggest that there is a quorum-sensing mechanism in which a factor(s) produced in dense cultures, perhaps a LOX-derived metabolite, activates conidium formation, while a factor(s) produced in low-density cultures stimulates sclerotium formation.

Horowitz Brown, S.; Zarnowski, R.; Sharpee, W. C.; Keller, N. P.

2008-01-01

170

Nutritional changes in powdered red pepper upon in vitro infection of Aspergillus flavus  

PubMed Central

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 Aspergillus flavus 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.

Tripathi, Smita; Mishra, H.N.

2009-01-01

171

A two-step bioconversion process for vanillin production from ferulic acid combining Aspergillus niger and Pycnoporus cinnabarinus  

Microsoft Academic Search

A two-step bioconversion process of ferulic acid to vanillin was elaborated combining two filamentous fungi, Aspergillus niger 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

Laurence Lesage-Meessen; Michel Delattre; Mireille Haon; Jean-François Thibault; Benoit Colonna Ceccaldi; Pascal Brunerie; Marcel Asther

1996-01-01

172

The effect of bread making steps on the degradation of aflatoxins produced as a result of single inoculation with Aspergillus flavus and combined inoculation with Aspergillus flavus and Aspergillus ochraceus.  

PubMed

This study aimed to determine the effect of bread making steps on the stability of aflatoxin. Sakha 8 wheat and Gemaiza 5 wheat cultivars, were used in the present study. They were inoculated with a dense spore suspension of toxigenic fungal species of Aspergillus flavus and a non toxigenic species of Aspergillus ochraceus singly and combined. Aflatoxin concentration was determined in the whole wheat grain, after milling, after fermentation, and after bread-baking process. Results showed that the highest reduction percentage for the total aflatoxins (81, G1 and G2), was in Sakha 8 (32.96%) (single treatment), Gemaiza 5 (19.54%) (single treatment ), Gemaiza 5 (18.65%) (combined treatment), and finally in Sakha 8 (16.49%) (combined treatment). There was no significant difference (p < 0.05) in aflatoxins content between Sakha 8 and Gemaiza 5 treated singly and in a combined way before and after milling process. In the mean time, the percentage of AFB1, AFG1 and AFG2 were reduced by 31.98%, 44.53% and 35.35%, respectively, while the total aflatoxins concentration were reduced by 41.17% after baking. Results also showed the presence of a significant difference at p < 0.05 among the whole grain, after milling and after baking concerning AFG1, AFG2 and the total aflatoxins content. No significant difference was found in case of AFB1. PMID:17219901

El-Tawila, Mahmoud M; Ibrahim, Nabeh A; Gomaa, Naglaa F; Omar, Rasha M

2003-01-01

173

Beyond aflatoxin: four distinct expression patterns and functional roles associated with Aspergillus flavus secondary metabolism gene clusters.  

PubMed

Species of Aspergillus produce a diverse array of secondary metabolites, and recent genomic analysis has predicted that these species have the capacity to synthesize many more compounds. It has been possible to infer the presence of 55 gene clusters associated with secondary metabolism in Aspergillus flavus; however, only three metabolic pathways-aflatoxin, cyclopiazonic acid (CPA) and aflatrem-have been assigned to these clusters. To gain an insight into the regulation of and to infer the ecological significance of the 55 secondary metabolite gene clusters predicted in A. flavus, we examined their expression over 28 diverse conditions. Variables included culture medium and temperature, fungal development, colonization of developing maize seeds and misexpression of laeA, a global regulator of secondary metabolism. Hierarchical clustering analysis of expression profiles allowed us to categorize the gene clusters into four distinct clades. Gene clusters for the production of aflatoxins, CPA and seven other unknown compound(s) were identified as belonging to one clade. To further explore the relationships found by gene expression analysis, aflatoxin and CPA production were quantified under five different cell culture environments known to be conducive or nonconducive for aflatoxin biosynthesis and during the colonization of developing maize seeds. Results from these studies showed that secondary metabolism gene clusters have distinctive gene expression profiles. Aflatoxin and CPA were found to have unique regulation, but are sufficiently similar that they would be expected to co-occur in substrates colonized with A. flavus. PMID:20447271

Georgianna, D Ryan; Fedorova, Natalie D; Burroughs, James L; Dolezal, Andrea L; Bok, Jin Woo; Horowitz-Brown, Sigal; Woloshuk, Charles P; Yu, Jiujiang; Keller, Nancy P; Payne, Gary A

2010-03-01

174

New metal-binding ethyldiamino- and dicarboxy-products from Aspergillus niger industrial wastes  

Microsoft Academic Search

The metal-binding ability of Aspergillus niger mycelial waste was improved by chemical modification. The latter was performed by introducing additional carboxy groups using oxidation methods or the introduction of the ethyldiamino group first by chlorination of A. niger using mesyl chloride and subsequent reaction of the product with ethylene diamine. Metal binding abilities of the products for Cd2+, Co2+, Ni2+ and

Markus Krämer; Hans-Ulrich Meisch

1999-01-01

175

Optimization of Aspergillus niger Fermentation for the Production of Glucose Oxidase  

Microsoft Academic Search

A number of nutritional factors influencing glucose oxidase (EC 1.1.3.4) production by Aspergillus niger 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

2009-01-01

176

Solubilization of hardly soluble iron and aluminum phosphates by the fungus Aspergillus niger in the soil  

Microsoft Academic Search

Some Brazilian soils present high contents of hardly soluble iron and aluminum phosphates and a high capacity for fixation\\u000a of soluble phosphates. This study evaluated the ability of the fungus Aspergillus niger F111 isolated from soil to solubilize Fe and Al phosphates. Iron, aluminum or calcium phosphate were added to soil samples and\\u000a inoculated with the A. niger F111. Sugar-cane

C. B. Barroso; E. Nahas

177

Production of vanillin from waste residue of rice bran oil by Aspergillus niger and Pycnoporus cinnabarinus  

Microsoft Academic Search

A new technology of transforming ferulic acid, which was from waste residue of rice bran oil, into vanillin was developed by a combination of fungal strains Aspergillus niger CGMCC0774 and Pycnoporus cinnabarinus CGMCC1115. Various concentrations of ferulic acid were compared, and the highest yield reached 2.2gl?1 of vanillic acid by A. niger CGMCC0774 in a 25l fermenter when concentration of

Lirong Zheng; Pu. Zheng; Zhihao Sun; Yanbing Bai; Jun Wang; Xinfu Guo

2007-01-01

178

Invasive Aspergillus niger complex infections in a Belgian tertiary care hospital.  

PubMed

The incidence of invasive infections caused by the Aspergillus niger species complex was 0.043 cases/10 000 patient-days in a Belgian university hospital (2005-2011). Molecular typing was performed on six available A. niger complex isolates involved in invasive disease from 2010 to 2011, revealing A. tubingensis, which has higher triazole minimal inhibitory concentrations, in five out of six cases. PMID:24102876

Vermeulen, E; Maertens, J; Meersseman, P; Saegeman, V; Dupont, L; Lagrou, K

2014-05-01

179

Biosorption of phenol from an aqueous solution by Aspergillus niger biomass  

Microsoft Academic Search

Phenols in trace quantities are usually present in the treated effluent of many wastewater-treatment plants. Phenol contamination of drinking water even at 1 ?g\\/l concentration can cause significant taste and odor problems. This study investigates the use of non-viable pretreated cells of Aspergillus niger to remove phenol from an aqueous solution. Five types of non-viable pretreated A. niger biomass powders

J. R Rao; T Viraraghavan

2002-01-01

180

Production and characterization of extracellular protease of mutant Aspergillus niger AB 100 grown on fish scale  

Microsoft Academic Search

Fish scale, the chief waste material of fish processing industries was processed and tested for production of extracellular\\u000a protease by mutant Aspergillus niger AB100. Protease production by A. niger AB100 was greatly enhanced in presence of processed fish scale powder. Where as among the three complex nutrients tested, soya\\u000a bean meal shows maximum stimulatory effect over protease production (2,776 ?mol\\/ml\\/min) when

Barnali Ray Basu; Ajit K. Banik; Manas Das

2008-01-01

181

Calcium oxalate crystal deposition in a patient with Aspergilloma due to Aspergillus niger  

PubMed Central

Discrimination between aspergilloma and chronic necrotizing pulmonary aspergillosis (CNPA) based on radiological findings can difficult. We describe a patient with aspergilloma and organizing pneumonia that was possibly caused by Aspergillus niger infection and radiologically mimicked CNPA. A postmortem histological analysis showed diffuse alveolar damage that had originated in peri-cavitary lung parenchyma. Calcium oxalate or Aspergillus niger was located inside, but not outside the cavity in the right upper lobe. Calcium oxalate or other unknown hyphal bioactive components might provoke severe lung inflammation not only adjacent to the cavity, but also on the contralateral side.

Oda, Miku; Wakayama, Megumi; Shibuya, Kazutoshi; Ogawa, Yukari; Inui, Toshiya; Yokoyama, Emi; Inoue, Manami; Shimoyamada, Hiroaki; Fujiwara, Masachika; Ota, Tomohiro; Takizawa, Hajime; Goto, Hajime

2013-01-01

182

Efficient expression and secretion of Aspergillus niger RH5344 polygalacturonase in Saccharomyces cerevisiae  

Microsoft Academic Search

An Aspergillus niger endopolygalacturonase (EC 3.2.1.15) cDNA was expressed in the yeast Saccharomyces cerevisiae. Secretion of the protein into the growth medium was efficiently directed by the fungal leader sequence, and processing occurred at the same site as in Aspergillus. The expression level was significantly enhanced by using a “short” version of the yeast ADHI promoter. An additional increase in

C. Lang; A. C. Looman

1995-01-01

183

Purification and characterization of a nitrilase from Aspergillus niger K10  

Microsoft Academic Search

Aspergillus niger K10 cultivated on 2-cyanopyridine produced high levels of an intracellular nitrilase, which was partially purified (18.6-fold) with a 24% yield. The N-terminal amino acid sequence of the enzyme was highly homologous with that of a putative nitrilase from Aspergillus fumigatus Af293. The enzyme was copurified with two proteins, the N-terminal amino acid sequences of which revealed high homology

Ond?ej Kaplan; Vojt?ch Vejvoda; Ond?ej Plíhal; Petr Pompach; Daniel Kavan; Pavla Bojarová; Karel Bezouška; Martina Macková; Maria Cantarella; Vladimír Jirk?; Vladimír K?en; Ludmila Martínková

2006-01-01

184

Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger  

PubMed Central

Background Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction [1]. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation [2-4]. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger. Results The current study shows experimentally that A. niger produces the oxylipins 8,11-dihydroxy octadecadienoic acid (8,11-diHOD), 5,8-dihydroxy octadecadienoic acid (5,8-diHOD), lactonized 5,8-diHOD, 8-hydroxy octadecadienoic acid (8-HOD), 10-hydroxy octadecadienoic acid (10-HOD), small amounts of 8-hydroxy octadecamonoenoic acid (8-HOM), 9-hydroxy octadecadienoic acid (9-HOD) and 13-hydroxy octadecadienoic acid (13-HOD). Importantly, this study shows that the A. niger genome contains three putative dioxygenase genes, ppoA, ppoC and ppoD. Expression analysis confirmed that all three genes are indeed expressed under the conditions tested. Conclusion A. niger produces the same oxylipins and has similar dioxygenase genes as A. nidulans. Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development.

2009-01-01

185

Co-occurrence of aflatoxin B(1) and cyclopiazonic acid in sour lime (Citrus aurantifolia Swingle) during post-harvest pathogenesis by Aspergillus flavus.  

PubMed

During hot and humid seasons, extensive rot of sour lime was observed to be caused by Aspergillus flavus. In view of this, investigations were undertaken to obtain data on the production of various toxins by A. flavus during post harvest pathogenesis of sour lime. Sixty percent of the pathogenic A. flavus isolates were detected to be aflatoxin B(1) producers in sour lime tissue. It was also noted that thirty three percent of aflatoxigenic A. flavus isolates had the potential to coproduce cyclopiazonic acid (CPA). Such aflatoxigenic isolates produced quantitatively more CPA (ranging from 250.0 to 2501.3 microg/kg) than aflatoxin B(1) (ranging from 141.3 to 811.7 microg/kg) in the affected sour lime. This study demonstrates for the first time that sour lime are a favourable substrate for aflatoxin B(1) and cyclopiazonic acid production by A. flavus isolates. This is of great concern to the health of consumers. PMID:15883727

Bamba, Rozy; Sumbali, Geeta

2005-04-01

186

The role of Aspergillus flavus veA in the production of extracellular proteins during growth on starch substrates.  

PubMed

The aflatoxin-producer and opportunistic plant pathogenic, filamentous fungus Aspergillus flavus is responsible for the contamination of corn and other important agricultural commodities. In order to obtain nutrients from the host A. flavus produces a variety of extracellular hydrolytic enzymes. Interestingly, A. flavus amylase and protease activity are dependent on the global regulator veA, a gene known to regulate morphogenesis and secondary metabolism in numerous fungi. Analysis of starch degradation by fungal enzymes secreted into broths of starch- or corn kernel-based media showed a notable accumulation of glucose in samples of the A. flavus control strain while the deletion veA sample accumulated high levels of maltose and maltotriose and only a small amount of glucose. Furthermore, SDS-PAGE and proteomics analysis of culture broths from starch- or corn kernel-based media demonstrated differential production of a number of proteins that included a reduction in the amount of a glucoamylase protein in the veA mutant compared to the control strain, while an alpha-amylase was produced in greater quantities in the veA mutant. Quantitative real-time PCR and western blot analyses using anti-glucoamylase or alpha-amylase antisera supported the proteomics results. Additionally, an overall reduction in protease activity was observed in the veA mutant including production of the alkaline protease, oryzin, compared to the control strain. These findings contribute to our knowledge of mechanisms controlling production of hydrolases and other extracellular proteins during growth of A. flavus on natural starch-based substrates. PMID:24584515

Duran, Rocio M; Gregersen, Scott; Smith, Timothy D; Bhetariya, Preetida J; Cary, Jeffrey W; Harris-Coward, Pamela Y; Mattison, Christopher P; Grimm, Casey; Calvo, Ana M

2014-06-01

187

Biosorption of Remazol Black B dye (Azo dye) by the growing Aspergillus flavus.  

PubMed

In the present study, an attempt was made for the removal of Remazol Black B dye (azo dye) by using Aspergillus Flavus during its growth. Biosorption of the azo dye by growing fungi was investigated in batch reactors as a function of initial concentration of dye (25-1000 mg/L), inoculum concentration (5-20%), and pH (2.5-6.5). The total biomass concentration decreased from 6.3 g/L to 1.44 g/L by increasing the dye concentration from 0 to 1000 mg/L. The dye uptake increased from 4.37 to 233 mg/g of dried biomass by increasing initial concentration of dye from 25 to 1000 mg/L. The nearly complete removal of dye was found at initial concentration upto 250 mg/L and at pH 4.5 which was used as working pH value for removal of dye in all the batch studies. The removal of Chemical Oxygen Demand (COD) was found to be 90% at 100 mg/L initial concentration of dye. The experiments were also performed with wastewater from textile industry with an aim to examine the potential of fungal biomass for the removal of dyes from wastewater under actual field conditions. The maximum dye removal was obtained at 30° C temperature (87%) in presence of 1 % glucose concentration (89%) and 10 % inoculum concentration (91%) after 96 hours from textile wastewater. The surface of the biosorbent before and after the sorption of the dye was examined by FTIR and SEM analysis. PMID:20635293

Ranjusha, V P; Pundir, Reena; Kumar, Kapil; Dastidar, M G; Sreekrishnan, T R

2010-08-01

188

Purification and characterization of a novel heparin degrading enzyme from Aspergillus flavus (MTCC-8654).  

PubMed

A heparinase-producing fungus was isolated, and the strain was taxonomically characterized as Aspergillus flavus by morphophysiological and 26S rRNA gene homology studies. The culture produced intracellular heparinase enzyme, which was purified 40.5-fold by DEAE-Sephadex A-50, CM-Sephadex C-50, and Sephadex G-100 column chromatography. Specific activity of the purified enzyme was found to be 44.6 IU/microg protein and the molecular weight of native as well as reduced heparinase was 24 kDa, showing a monomeric unit structure. Peptide mass spectrum showed poor homogeneity with the database in the peptide bank. The enzyme activity was maximum at 30 degrees C in the presence of 300 mM NaCl at pH 7.0. In the presence of Co2+, Mn2+ ions, and reducing agents (beta-mercaptoethanol, dithiothreitol), enzyme activity was enhanced and inhibited by iodoacetic acid. These observations suggested that free sulfohydryl groups of cysteine residues were necessary for catalytic activity of the enzyme. The enzyme was also inhibited by histidine modifier, DEPC, which suggests that along with cysteine, histidine may be present at its active site. The enzyme showed a high affinity for heparin as a substrate with K (m) and V (max) as 2.2 x 10(-5 )M and 30.8 mM min(-1), respectively. The affinity of the enzyme for different glycosaminoglycans studied varied, with high substrate specificity toward heparin and heparin-derived polysaccharides. Depolymerization of heparin and fractionation of the oligosaccharides yielded heparin disaccharides as main product. PMID:19214796

Banga, Jaspreet; Tripathi, C K M

2010-02-01

189

Cloning and expression of a second Aspergillus niger pectin lyase gene ( pel A): Indications of a pectin lyase gene family in A. niger  

Microsoft Academic Search

Using the previously cloned Aspergillus niger N756 pectin lyase D gene as a probe, the corresponding pelD gene has been isolated from a genomic library of the loboratory strain A. niger N400. This gene encodes PLD, previously described as PLI, which is one of the two major pectin lyases isolated from the commeriial pectinase preparation Ultrazym®. Heterologous hybridization of the

J. A. M. Harmsen; M. A. Kusters-van Someren; J. Visser

1990-01-01

190

Value of Aspergillus niger fermentation product as a dietary ingredient for broiler chickens  

Microsoft Academic Search

The experiment reported was a study on Aspergillus niger inoculation into the waste liquor from glutamate manufacturing and used as a dietary protein source for broilers. The program involved a toxicological and nutritional evaluation of the product using a short-term toxicity and a nutritional feeding trial in broilers. Both trials involved a total of 800 broilers from the commercial Arbor

Peter W. S Chiou; S. W Chiu; C. R Chen

2001-01-01

191

Optimization of glucose oxidase production by Aspergillus niger in a benchtop bioreactor using response surface methodology  

Microsoft Academic Search

Response surface methodology (RSM) was applied to optimize the speed of agitation and the rate of aeration for the maximum production of glucose oxidase (GOD) by Aspergillus niger. A 22 central composite design using RSM was employed in this investigation. A quadratic model for GOD production was obtained. Aeration had more negative effect on GOD production than agitation. Significant negative

Jian-Zhong Liu; Li-Ping Weng; Qian-Ling Zhang; Hong Xu; Liang-Nian Ji

2003-01-01

192

NIGERLYSINTM, HEMOLYSIN PRODUCED BY ASPERGILLUS NIGER, CAUSES LETHALITY OF PRIMARY RAT CORTICAL NEURONAL CELLS IN VITRO  

EPA Science Inventory

Aspergillus niger produced a proteinaceous hemolysin, nigerlysinTM when incubated on sheep's blood agar at both 23° C and 37°C. Nigerlysin was purified from tryptic soy broth culture filtrate. Purified nigerlysin has a molecular weight of approximately 72 kDa, with an...

193

Sorption of Heavy Metals by the Soil Fungi 'Aspergillus niger' and Mucor rouxii.  

National Technical Information Service (NTIS)

Sorption of the nitrate salts of cadmium(II), copper(II), lanthanum(III) and silver(I) by two fungi, Aspergillus niger and Mucor rouxii, was evaluated using Freundlich adsorption isotherms and energy dispersive X-ray electron microscopy. The linearized Fr...

M. D. Mullen D. C. Wolf T. J. Beveridge G. W. Bailey

1992-01-01

194

Systemic analysis of the response of Aspergillus niger to ambient pH  

Microsoft Academic Search

ABSTRACT: BACKGROUND: The filamentous fungus Aspergillus niger 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

Mikael R Andersen; Linda Lehmann; Jens Nielsen

2009-01-01

195

Effect of fermentation conditions on the production of citric acid from cheese whey by Aspergillus niger  

Microsoft Academic Search

The effect of pH value, methanol, and salt concentration on the production of citric acid from cheese whey by two strains of Aspergillus niger i.e. CAIM 111 and CAIM 167, was investigated. Lactose concentration, utilized lactose, citric acid concentration, conversion coefficient of lactose to citric acid, and mycelial dry weight were measured during the fermentation process. The maximum citric acid

Y. A. El-Samragy; M. A. Khorshid; M. I. Foda; A. E. Shehata

1996-01-01

196

SORPTION OF HEAVY METALS BY THE SOIL FUNGI ASPERGILLUS NIGER AND MUCOR ROUXII  

EPA Science Inventory

Sorption of the nitrate salts of cadmium(II), copper (II), lanthanum(III) and silver (I) by two fungi, Aspergillus niger and Mucor rouxii, was evaluated using Fruendlich adsorption isotherms and energy dispersive X-ray electron microscopy. The linearized Freundlich isotherm descr...

197

The effect of the sugar source on citric acid production by Aspergillus niger  

Microsoft Academic Search

Under otherwise identical fermentation conditions, the sugar source has been shown to have a marked effect on citric acid production by Aspergillus niger. 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

M. Hossain; J. D. Brooks; I. S. Maddox

1984-01-01

198

Solid-state fermentation for the synthesis of citric acid by Aspergillus niger  

Microsoft Academic Search

Solid-state fermentation was carried out to evaluate three different agro-industrial wastes, sugar cane bagasse, coffee husk and cassava bagasse for their efficiency in production of citric acid by a culture of Aspergillus niger. Cassava bagasse best supported the mould's growth, giving the highest yield of citric acid among the tested substrates. Results showed the fungal strain had good adaptation to

Luciana P. S Vandenberghe; Carlos R Soccol; Ashok Pandey; J.-M Lebeault

2000-01-01

199

Pseudoepidemic of Aspergillus niger Infections Traced to Specimen Contamination in the Microbiology Laboratory  

PubMed Central

We report a pseudo-outbreak of Aspergillus niger that followed building construction in our clinical microbiology laboratory. Because outbreaks of invasive aspergillosis have been linked to hospital construction, strategies to minimize dust in patient care areas are common practice. We illustrate that the impact of false-positive cultures on patient care should compel laboratories to prevent specimen contamination during construction.

Laurel, Valerie L.; Meier, Patricia A.; Astorga, Alicia; Dolan, Donna; Brockett, Royce; Rinaldi, Michael G.

1999-01-01

200

Aspergillus niger DLFCC-90 Rhamnoside Hydrolase, a New Type of Flavonoid Glycoside Hydrolase  

PubMed Central

A novel rutin-?-l-rhamnosidase hydrolyzing ?-l-rhamnoside of rutin, naringin, and hesperidin was purified and characterized from Aspergillus niger DLFCC-90, and the gene encoding this enzyme, which is highly homologous to the ?-amylase gene, was cloned and expressed in Pichia pastoris GS115. The novel enzyme was classified in glycoside-hydrolase (GH) family 13.

Liu, Tingqiang; Zhang, Chunzhi; Lu, Mingchun; Piao, Yongzhe; Ohba, Masashi; Tang, Minqian; Yuan, Xiaodong; Wei, Shenghua; Wang, Kan; Ma, Anzhou; Feng, Xue; Qin, Siqing; Mukai, Chisato; Tsuji, Akira

2012-01-01

201

Bioleaching of zinc and nickel from silicates using Aspergillus niger cultures  

Microsoft Academic Search

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

2000-01-01

202

Disseminated Aspergillosis due to Aspergillus niger in Immunocompetent Patient: A Case Report  

PubMed Central

Invasive aspergillosis is a major cause of morbidity and mortality in immunocompromised patients. Many cases of pulmonary, cutaneous, cerebral, and paranasal sinus aspergillosis in immunocompetent patient were defined in literature but disseminated aspergillosis is very rare. Here we present an immunocompetent case with extrapulmonary disseminated aspergillosis due to Aspergillus niger, totally recovered after effective antifungal treatment with voriconazole.

Ergene, Ulku; Akcali, Zeynep; Ozbalci, Demircan; Nese, Nalan; Senol, Sebnem

2013-01-01

203

Treatment of two postoperative endophthalmitis cases due to Aspergillus flavus and Scopulariopsis spp. with local and systemic antifungal therapy  

PubMed Central

Background Endophthalmitis is the inflammatory response to invasion of the eye with bacteria or fungi. The incidence of endophthalmitis after cataract surgery varies between 0.072–0.13 percent. Treatment of endophthalmitis with fungal etiology is difficult. Case Presentation Case 1: A 71-year old male diabetic patient developed postoperative endophthalmitis due to Aspergillus flavus. The patient was treated with topical amphotericin B ophthalmic solution, intravenous (IV) liposomal amphotericin-B and caspofungin following vitrectomy. Case 2: A 72-year old male cachectic patient developed postoperative endophthalmitis due to Scopulariopsis spp. The patient was treated with topical and IV voriconazole and caspofungin. Conclusion Aspergillus spp. are responsible of postoperative fungal endophthalmitis. Endophthalmitis caused by Scopulariopsis spp. is a very rare condition. The two cases were successfully treated with local and systemic antifungal therapy.

Aydin, Sayime; Ertugrul, Bulent; Gultekin, Berna; Uyar, Guliz; Kir, Erkin

2007-01-01

204

Purification and Characterization of a Keratinase from a Feather-Degrading Fungus, Aspergillus flavus Strain K-03.  

PubMed

A keratinolytic enzyme secreted by Aspergillus flavus K-03 cultured in feather meal basal medium (FMBM) containing 2% (w/v) chicken feather was purified and characterized. Keratinolytic enzyme secretion was the maximal at day 16 of the incubation period at pH 8 and 28?. No relationship was detected between enzyme yield and increase of fungal biomass. The fraction obtained at 80% ammonium sulfate saturation showed 2.39-fold purification and was further purified by gel filtration in Sephadex G-100 followed by ion exchange chromatography on DEAE-Sephadex A-50, yielding an active protein peak showing 11.53-fold purification. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and zymograms indicated that the purified keratinase is a monomeric enzyme with 31 kDa molecular weight. The extracellular keratinase of A. flavus was active in a board range of pH (7~10) and temperature (30?~70?) profiles with the optimal for keratinase activity at pH 8 and 45?. The keratinase activity was totally inhibited by protease inhibitors such as phenylmethylsulfonyl fluoride (PMSF), iodoacetic acid, and ethylenediaminetetraacetate (EDTA) while no reduction of activity by the addition of dithiothreitol (DTT) was observed. N-terminal amino acid sequences were up to 80% homologous with the fungal subtilisins produced by Fusarium culmorum. Therefore, on the basis of these characteristics, the keratinase of A. flavus K-03 is determined to be subtilisins-like. PMID:24015101

Kim, Jeong-Dong

2007-12-01

205

Purification and Characterization of a Keratinase from a Feather-Degrading Fungus, Aspergillus flavus Strain K-03  

PubMed Central

A keratinolytic enzyme secreted by Aspergillus flavus K-03 cultured in feather meal basal medium (FMBM) containing 2% (w/v) chicken feather was purified and characterized. Keratinolytic enzyme secretion was the maximal at day 16 of the incubation period at pH 8 and 28?. No relationship was detected between enzyme yield and increase of fungal biomass. The fraction obtained at 80% ammonium sulfate saturation showed 2.39-fold purification and was further purified by gel filtration in Sephadex G-100 followed by ion exchange chromatography on DEAE-Sephadex A-50, yielding an active protein peak showing 11.53-fold purification. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and zymograms indicated that the purified keratinase is a monomeric enzyme with 31 kDa molecular weight. The extracellular keratinase of A. flavus was active in a board range of pH (7~10) and temperature (30?~70?) profiles with the optimal for keratinase activity at pH 8 and 45?. The keratinase activity was totally inhibited by protease inhibitors such as phenylmethylsulfonyl fluoride (PMSF), iodoacetic acid, and ethylenediaminetetraacetate (EDTA) while no reduction of activity by the addition of dithiothreitol (DTT) was observed. N-terminal amino acid sequences were up to 80% homologous with the fungal subtilisins produced by Fusarium culmorum. Therefore, on the basis of these characteristics, the keratinase of A. flavus K-03 is determined to be subtilisins-like.

2007-01-01

206

Effects of Cymbopogon citratus L. essential oil on the growth, morphogenesis and aflatoxin production of Aspergillus flavus ML2-strain.  

PubMed

The mycelial growth of Aspergillus flavus 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

2007-02-01

207

Beyond aflatoxin: four distinct expression patterns and functional roles associated with Aspergillus flavus secondary metabolism gene clusters  

PubMed Central

SUMMARY Species of Aspergillus produce a diverse array of secondary metabolites, and recent genomic analysis predicts that these species have the capacity to synthesize many more compounds. It has been possible to infer the presence of 55 gene clusters associated with secondary metabolism in A. flavus, however, only three metabolic pathways - aflatoxin, cyclopiazonic acid (CPA), and aflatrem - have been assigned to these clusters. To gain insight into the regulation of, and infer ecological significance for the 55 secondary metabolite gene clusters predicted in A. flavus, we examined their expression over 28 diverse conditions. Variables included culture media and temperature, fungal development, colonization of developing maize seeds, and misexpression of laeA, a global regulator of secondary metabolism. Hierarchical clustering analysis of expression profiles allowed us to categorize the gene clusters into four distinct clades. Gene clusters for the production of aflatoxins, CPA, and seven other unknown compound(s) were identified as belonging to one clade. To further explore the relationships found by gene expression analysis, aflatoxin and CPA production were quantified under five different cell culture environments known to be conducive or non-conducive for aflatoxin biosynthesis and during colonization of developing maize seeds. Results from these studies showed that secondary metabolism gene clusters have distinctive gene expression profiles. Aflatoxin and CPA were found to have unique regulation but are similar enough that they would be expected to co-occur in substrates colonized with A. flavus.

Georgianna, D. Ryan; Fedorova, Natalie D.; Burroughs, James L.; Dolezal, Andrea L.; Bok, J.; Horowitz-Brown, S.; Woloshuk, Charles P.; Yu, Jiujiang; Keller, Nancy P.; Payne, Gary A.

2014-01-01

208

Incidence of fumonisin B(2) production by Aspergillus niger in Portuguese wine regions.  

PubMed

Fumonisin B(2) (FB(2)) was recently found to be produced by Aspergillus niger . When grape-derived products were subsequently analyzed, FB(2) contamination was found in raisins, must, and wine. This study evaluated 681 strains of black aspergilli species isolated from Portuguese wine grapes for FB(2) production when grown on Czapek yeast agar. FB(2) was not detected in Aspergillus carbonarius (n = 75) or Aspergillus ibericus (n = 9) strains, but it was detected in 176 (29%) of the strains belonging to A. niger aggregate (n = 597). The amount of FB(2) produced by these strains ranged from 0.003 to 6.0 mg/kg with a mean of 0.66 mg/kg. The Alentejo region had the lowest percentage (10%) of fumonisinogenic strains, whereas the Douro region had the highest percentage of fumonisinogenic strains (38%). Only 10 strains were found to produce FB(2) and ochratoxin A simultaneously. PMID:21668017

Abrunhosa, Luis; Calado, Thalita; Venancio, Armando

2011-07-13

209

Phytase Production by Aspergillus niger CFR 335 and Aspergillus ficuum SGA 01 through Submerged and Solid-State Fermentation  

PubMed Central

Fermentation is one of the industrially important processes for the development of microbial metabolites that has immense applications in various fields. This has prompted to employ fermentation as a major technique in the production of phytase from microbial source. In this study, a comparison was made between submerged (SmF) and solid-state fermentations (SSF) for the production of phytase from Aspergillus niger CFR 335 and Aspergillus ficuum SGA 01. It was found that both the fungi were capable of producing maximum phytase on 5th day of incubation in both submerged and solid-state fermentation media. Aspergillus niger CFR 335 and A. ficuum produced a maximum of 60.6?U/gds and 38?U/gds of the enzyme, respectively, in wheat bran solid substrate medium. Enhancement in the enzyme level (76 and 50.7?U/gds) was found when grown in a combined solid substrate medium comprising wheat bran, rice bran, and groundnut cake in the ratio of 2?:?1?:?1. A maximum of 9.6 and 8.2?U/mL of enzyme activity was observed in SmF by A. niger CFR 335 and A.ficuum, respectively, when grown in potato dextrose broth.

Shivanna, Gunashree B.; Venkateswaran, Govindarajulu

2014-01-01

210

Phytase Production by Aspergillus niger CFR 335 and Aspergillus ficuum SGA 01 through Submerged and Solid-State Fermentation.  

PubMed

Fermentation is one of the industrially important processes for the development of microbial metabolites that has immense applications in various fields. This has prompted to employ fermentation as a major technique in the production of phytase from microbial source. In this study, a comparison was made between submerged (SmF) and solid-state fermentations (SSF) for the production of phytase from Aspergillus niger CFR 335 and Aspergillus ficuum SGA 01. It was found that both the fungi were capable of producing maximum phytase on 5th day of incubation in both submerged and solid-state fermentation media. Aspergillus niger CFR 335 and A. ficuum produced a maximum of 60.6?U/gds and 38?U/gds of the enzyme, respectively, in wheat bran solid substrate medium. Enhancement in the enzyme level (76 and 50.7?U/gds) was found when grown in a combined solid substrate medium comprising wheat bran, rice bran, and groundnut cake in the ratio of 2?:?1?:?1. A maximum of 9.6 and 8.2?U/mL of enzyme activity was observed in SmF by A. niger CFR 335 and A.ficuum, respectively, when grown in potato dextrose broth. PMID:24688383

Shivanna, Gunashree B; Venkateswaran, Govindarajulu

2014-01-01

211

Overexpression of Aspergillus tubingensis faeA in protease-deficient Aspergillus niger enables ferulic acid production from plant material.  

PubMed

The production of ferulic acid esterase involved in the release of ferulic acid side groups from xylan was investigated in strains of Aspergillus tubingensis, Aspergillus carneus, Aspergillus niger and Rhizopus oryzae. The highest activity on triticale bran as sole carbon source was observed with the A. tubingensis T8.4 strain, which produced a type A ferulic acid esterase active against methyl p-coumarate, methyl ferulate and methyl sinapate. The activity of the A. tubingensis ferulic acid esterase (AtFAEA) was inhibited twofold by glucose and induced twofold in the presence of maize bran. An initial accumulation of endoglucanase was followed by the production of endoxylanase, suggesting a combined action with ferulic acid esterase on maize bran. A genomic copy of the A. tubingensis faeA gene was cloned and expressed in A. niger D15#26 under the control of the A. niger gpd promoter. The recombinant strain has reduced protease activity and does not acidify the media, therefore promoting high-level expression of recombinant enzymes. It produced 13.5 U/ml FAEA after 5 days on autoclaved maize bran as sole carbon source, which was threefold higher than for the A. tubingensis donor strain. The recombinant AtFAEA was able to extract 50 % of the available ferulic acid from non-pretreated maize bran, making this enzyme suitable for the biological production of ferulic acid from lignocellulosic plant material. PMID:24664515

Zwane, Eunice N; Rose, Shaunita H; van Zyl, Willem H; Rumbold, Karl; Viljoen-Bloom, Marinda

2014-06-01

212

Effects of Clitoria ternatea leaf extract on growth and morphogenesis of Aspergillus niger.  

PubMed

Clitoria ternatea is known for its antimicrobial activity but the antifungal effects of leaf extract on growth and morphogenesis of Aspergillus niger have not been observed. The extract showed a favorable antifungal activity against A. niger with a minimum inhibition concentration 0.8 mg/mL and minimum fungicidal concentration 1.6 mg/mL, respectively. The leaf extract exhibited considerable antifungal activity against filamentous fungi in a dose-dependent manner with 0.4 mg/mL IC50 value on hyphal growth of A. niger. The main changes observed under scanning electron microscopy after C. ternatea extract treatment were loss of cytoplasm in fungal hyphae and the hyphal wall and its diameter became markedly thinner, distorted, and resulted in cell wall disruption. In addition, conidiophore alterations were also observed when A. niger was treated with C. ternatea leaf extract. PMID:19575837

Kamilla, L; Mansor, S M; Ramanathan, S; Sasidharan, S

2009-08-01

213

Properties of Aspergillus niger citrate synthase and effects of citA overexpression on citric acid production 1 1 The EMBL accession number for the Aspergillus niger citA sequence reported in this paper is AJ243204  

Microsoft Academic Search

Using a combination of dye adsorption and affinity elution we purified Aspergillus niger citrate synthase to homogeneity using a single column and characterised the enzyme. An A. niger citrate synthase cDNA was isolated by immunological screening and used to clone the corresponding citA gene. The deduced amino acid sequence showed high similarity to other fungal citrate synthases. After processing upon

George J. G Ruijter; Henk Panneman; Ding-Bang Xu; Jaap Visser

2000-01-01

214

Regional Differences in Production of Aflatoxin B 1 and Cyclopiazonic Acid by Soil Isolates of Aspergillus flavus along a Transect within the United States  

Microsoft Academic Search

Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in

B. W. HORN; J. W. DORNER

1999-01-01

215

Constitutive expression of fluorescent protein by Aspergillus var. niger and Aspergillus carbonarius to monitor fungal colonization in maize plants.  

PubMed

Aspergillus niger and Aspergillus carbonarius are two species in the Aspergillus section Nigri (black-spored aspergilli) frequently associated with peanut (Arachis hypogea), maize (Zea mays), and other plants as pathogens. These infections are symptomless and as such are major concerns since some black aspergilli produce important mycotoxins, ochratoxins A, and the fumonisins. To facilitate the study of the black aspergilli-maize interactions with maize during the early stages of infections, we developed a method that used the enhanced yellow fluorescent protein (eYFP) and the monomeric red fluorescent protein (mRFP1) to transform A. niger and A. carbonarius, respectively. The results were constitutive expressions of the fluorescent genes that were stable in the cytoplasms of hyphae and conidia under natural environmental conditions. The hyphal in planta distribution in 21-day-old seedlings of maize were similar wild type and transformants of A. niger and A. carbonarius. The in planta studies indicated that both wild type and transformants internally colonized leaf, stem and root tissues of maize seedlings, without any visible disease symptoms. Yellow and red fluorescent strains were capable of invading epidermal cells of maize roots intercellularly within the first 3 days after inoculation, but intracellular hyphal growth was more evident after 7 days of inoculation. We also tested the capacity of fluorescent transformants to produce ochratoxin A and the results with A. carbonarius showed that this transgenic strain produced similar concentrations of this secondary metabolite. This is the first report on the in planta expression of fluorescent proteins that should be useful to study the internal plant colonization patterns of two ochratoxigenic species in the Aspergillus section Nigri. PMID:23899775

Palencia, Edwin Rene; Glenn, Anthony Elbie; Hinton, Dorothy Mae; Bacon, Charles Wilson

2013-09-01

216

Citric acid production by Aspergillus niger immobilized on cellulose microfibrils: influence of morphology and fermenter conditions on productivity  

Microsoft Academic Search

Continuous and batch production of citric acid from sucrose has been investigated using Aspergillus niger NCIM 588. Mycelia of A. niger grown on cellulose microfibril forms a uniform and thin mycelial proliferation under controlled conditions of cultivation rich in oxygen. In the fed batch mode using a recycle reactor, the DO of the system was maintained at 20 mg l?1

N. V Sankpal; A. P Joshi; B. D Kulkarni

2001-01-01

217

Characterization of the Aspergillus niger prtT, a unique regulator of extracellular protease encoding genes.  

PubMed

Expression of several Aspergillus niger genes encoding major secreted, but not vacuolar, protease genes including the major acid protease gene pepA, was shown to be affected in the previously isolated A. niger protease mutant, AB1.13 [Mattern, I.E., van Noort, J.M., van den Berg, P., Archer, D.A., Roberts, I.N., Hondel, C.A.M.J.J., 1992. Isolation and characterization of mutants of Aspergillus niger deficient in extracellular proteases. Molecular & General Genetics 2, 332-336]. Complementation cloning of the putative protease-regulatory gene affected in this mutant was accomplished using a functional selection approach based on the use of the A. nidulans amdS selection marker driven by the A. niger pepA promoter. As expected the PpepA::amdS selection marker is not expressed in the mutant. Introduction of a self-replicating cosmid library into the mutant strain carrying the PpepA::amdS marker allowed selection of AmdS+ transformants functionally complementing the proposed regulatory mutation. Analysis of complementing cosmid clones revealed that the complementing sequences contained a gene encoding a member of the fungal-specific Zn2Cys6-binuclear cluster protein family. Sequence comparison of the encoded protein, PrtT, showed that it has homologues among different Aspergillus species. The A. oryzae homologue was shown to govern expression of the major alkaline protease AlpA and neutral protease Np1 in this species. In contrast to several other pathway specific regulators, such as AmyR and XlnR, no PrtT orthologues could be found in any other non-Aspergillus (or related) species and surprisingly, also not in Aspergillus nidulans. Interestingly, in all Aspergillus species carrying a prtT orthologue the gene is tightly clustered to a completely syntenous region carrying an amylolytic gene cluster including another Zn2Cys6-binuclear cluster protein, AmyR. Northern analysis of the A. niger prtT gene showed (constitutive) expression from two upstream promoters about 700 bp apart. The presence of several short upstream open reading frames downstream of both the distal and the proximal transcription start point of the prtT gene suggests regulation at the post-translational level. Also regulation at the level of differential splicing is suggested by the fact that several Aspergillus EST databases carry a considerable fraction of clones in which in frame intron sequences are retained. PMID:18930158

Punt, Peter J; Schuren, Frank H J; Lehmbeck, Jan; Christensen, Tove; Hjort, Carsten; van den Hondel, Cees A M J J

2008-12-01

218

Effect of fermentation conditions on the production of citric acid from cheese whey by Aspergillus niger.  

PubMed

The effect of pH value, methanol, and salt concentration on the production of citric acid from cheese whey by two strains of Aspergillus niger, i.e. CAIM 111 and CAIM 167, was investigated. Lactose concentration, utilized lactose, citric acid concentration, conversion coefficient of lactose to citric acid, and mycelial dry weight were measured during the fermentation process. The maximum citric acid concentration (1.06 and 0.82 g/l), and conversion coefficient (5.58 and 7.45%) were obtained at pH 3.5 after 9 days of fermentation for A. niger CAIM 111 and A. niger CAIM 167, respectively. The presence of 4% (v/v) methanol in the fermentation medium increased the amount of citric acid produced by A. niger CAIM 111 and A. niger CAIM 167 by 23% and 18%, respectively. Both strains showed a high ability to utilize lactose for the production of citric acid when grown in the presence of 10% (w/v) salt. The conversion coefficient of lactose to citric acid was 28.24% for A. niger CAIM 111 and 25.60% for A. niger CAIM 167 when the fermentation medium had a 10% (w/v) level of salt. The cumulative effect of fermentation medium pH (3.5), methanol concentration (4%, v/v) and salt concentration (10%, w/v) during the fermentation process of whey did not enhance the production of citric acid by A. niger CAIM 111, while it did increase the production of citric acid by A. niger CAIM 167 by about 4-fold. PMID:8796442

el-Samragy, Y A; Khorshid, M A; Foda, M I; Shehata, A E

1996-04-01

219

Production of Fumonisin B2 and B4 by Aspergillus niger on grapes and raisins.  

PubMed

The recent discovery of fumonisin production in Aspergillus niger, 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

2010-01-27

220

Autophagy promotes survival in aging submerged cultures of the filamentous fungus Aspergillus niger.  

PubMed

Autophagy is a well-conserved catabolic process constitutively active in eukaryotes that is involved in maintaining cellular homeostasis by the targeting of cytoplasmic content and organelles to vacuoles. Autophagy is strongly induced by the limitation of nutrients including carbon, nitrogen, and oxygen and is clearly associated with cell death. It has been demonstrated that the accumulation of empty hyphal compartments and cryptic growth in carbon-starved submerged cultures of the filamentous fungus Aspergillus niger is accompanied by a joint transcriptional induction of autophagy genes. This study examines the role of autophagy by deleting the atg1, atg8, and atg17 orthologs in A. niger and phenotypically analyzing the deletion mutants in surface and submerged cultures. The results indicate that atg1 and atg8 are essential for efficient autophagy, whereas deletion of atg17 has little to no effect on autophagy in A. niger. Depending on the kind of oxidative stress confronted with, autophagy deficiency renders A. niger either more resistant (menadione) or more sensitive (H2O2) to oxidative stress. Fluorescence microscopy showed that mitochondrial turnover upon carbon depletion in submerged cultures is severely blocked in autophagy-impaired A. niger mutants. Furthermore, automated image analysis demonstrated that autophagy promotes survival in maintained carbon-starved cultures of A. niger. Taken together, the results suggest that besides its function in nutrient recycling, autophagy plays important roles in physiological adaptation by organelle turnover and protection against cell death upon carbon depletion in submerged cultures. PMID:23700238

Nitsche, Benjamin M; Burggraaf-van Welzen, Anne-Marie; Lamers, Gerda; Meyer, Vera; Ram, Arthur F J

2013-09-01

221

The promoter of the glucoamylase-encoding gene of Aspergillus niger functions in Ustilago maydis.  

PubMed

Promoter sequences from the Aspergillus niger glucoamylase-encoding gene (glaA) were linked to the bacterial hygromycin (Hy) phosphotransferase-encoding gene (hph) and this chimeric marker was used to select Hy-resistant (HyR) Ustilago maydis transformants. This is an example of an Ascomycete promoter functioning in a Basidiomycete. HyR transformants varied with respect to copy number of integrated vector, mitotic stability, and tolerance to Hy. Only 216 bp of glaA promoter sequence is required for expression in U. maydis but this promoter is not induced by starch as it is in Aspergillus spp. The transcriptional start points are the same in U. maydis and A. niger. PMID:2112106

Smith, T L; Gaskell, J; Berka, R M; Yang, M; Henner, D J; Cullen, D

1990-04-16

222

Thermal Characterization of Purified Glucose Oxidase from A Newly Isolated Aspergillus Niger UAF-1  

PubMed Central

An intracellular glucose oxidase was isolated from the mycelium extract of a locally isolated strain of Aspergillus niger UAF-1. The enzyme was purified to a yield of 28.43% and specific activity of 135 U mg?1 through ammonium sulfate precipitation, anion exchange and gel filtration chromatography. The enzyme showed high affinity for D-glucose with a Km value of 2.56 mM. The enzyme exhibited optimum catalytic activity at pH 5.5. Temperature optimum for glucose oxidase, catalyzed D-glucose oxidation was 40°C. The enzyme showed a high thermostability having a half-life 30 min, enthalpy of denaturation 99.66 kJ mol?1 and free energy of denaturation 103.63 kJ mol?1. These characteristics suggest the use of glucose oxidase from Aspergillus niger UAF-1 as an analytical reagent and in the design of biosensors for clinical, biochemical and diagnostic assays.

Anjum Zia, Muhammad; Khalil-ur-Rahman; K. Saeed, Muhammad; Andaleeb, Fozia; I. Rajoka, Muhammad; A. Sheikh, Munir; A. Khan, Iftikhar; I. Khan, Azeem

2007-01-01

223

Deletion of the Aspergillus flavus Orthologue of A. nidulans fluG Reduces Conidiation and Promotes Production of Sclerotia but Does Not Abolish Aflatoxin Biosynthesis  

PubMed Central

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 Aspergillus flavus 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.

2012-01-01

224

Transcriptomic profiles of Aspergillus flavus CA42, a strain that produces small sclerotia, by decanal treatment and after recovery.  

PubMed

Aspergillus flavus is a ubiquitous saprophyte and is capable of producing many secondary metabolites including the carcinogenic aflatoxins. The A. flavus population that produces small sclerotia (S strain) has been implicated as the culprit for persistent aflatoxin contamination in field crops. We investigated how the plant volatile decanal, a C10 fatty aldehyde, affected the growth and development of the S strain A. flavus. Decanal treatment yielded fluffy variants lacking sclerotia and conidia and exhibiting a dosage-dependent radial colony growth. We used RNA-Seq analysis to examine transcriptomic changes caused by decanal and after removal of decanal. Mature sclerotia contained only 80% of the total transcripts detected in all samples in comparison to 94% for the decanal treated culture. Gene ontology (GO) analysis showed that decanal treatment increased expression of genes involved in oxidoreductase activity, cellular carbohydrate metabolism, alcohol metabolism and aflatoxin biosynthesis. The treatment affected cellular components associated with cell wall, and gene expression of glucanases, ?-amylases, pectinesterase and peptidase required for its biosynthesis was increased. After decanal was removed, the culture resumed sclerotial production. Moreover, its GO terms significantly overlapped with those of the untreated culture; five of the enriched molecular functions, oxidoreductase activity, monooxygenase activity, electron carrier activity, heme binding, and iron binding were found in the untreated culture. The GO term of cellular component enriched was mainly integral protein constituents of the membrane. The results suggested that decanal halted development at the vegetative state rendering the fungus unable to produce conidia and sclerotia. The induced fluffy phenotype could be related to lower transcript abundance of flbB, flbD, and flbE but not to veA expression. Increased abundance of the laeA transcript in the treated culture correlated with early transcriptional activation of aflatoxin and kojic acid biosynthesis gene clusters. Expression profiles revealed subtle differences in timing of activation of the respective 55 secondary metabolite gene clusters. PMID:24780887

Chang, Perng-Kuang; Scharfenstein, Leslie L; Mack, Brian; Yu, Jiujiang; Ehrlich, Kenneth C

2014-07-01

225

Production of glucose oxidase using Aspergillus niger and corn steep liquor  

Microsoft Academic Search

Glucose oxidase production was optimized using an isolated strain of Aspergillus niger and an economical nutrient source, corn steep liquor (CSL). The culture produced 580±30 units\\/ml of the enzyme using 70 g\\/l sucrose as the carbon source. Using CSL as the sole nutrient source enzyme synthesis was increased to 640±36 units\\/ml. None of the nitrogen sources (nitrates of calcium, sodium,

R. P. Kona; N. Qureshi; J. S. Pai

2001-01-01

226

Medium optimization by orthogonal array designs for urease production by Aspergillus niger PTCC5011  

Microsoft Academic Search

This paper describes medium optimization for urease production by Aspergillus niger PTCC5011 by one-factor-at-a-time and orthogonal array design methods. The one-factor-at-a-time method was used to study the effects of carbon and nitrogen sources on urease production. Among various carbon and nitrogen sources used, sucrose and yeast extract were the most suitable for urease production, respectively. Subsequently, the concentration of sucrose,

M. R. Bakhtiari; M. G. Faezi; M. Fallahpour; A. Noohi; N. Moazami; Z. Amidi

2006-01-01

227

Tensidols, new potentiators of antifungal miconazole activity, produced by Aspergillus niger FKI-2342.  

PubMed

Two new furopyrrols, designated tensidols A and B, were isolated from the culture broth of Aspergillus niger FKI-2342 by solvent extraction, silica gel column chromatography and HPLC. Their structures were elucidated and shown to have the common skeleton of 6-benzyl-6H-furo[2,3-b]pyrrole. Tensidols A and B potentiated miconazole activity against Candida albicans. Tensidols also showed moderate antimicrobial activity only against Pyricularia oryzae. PMID:17080684

Fukuda, Takashi; Hasegawa, Yoko; Hagimori, Keiichi; Yamaguchi, Yuichi; Masuma, Rokuro; Tomoda, Hiroshi; Omura, Satoshi

2006-08-01

228

Enzymatic detergent formulation containing amylase from Aspergillus niger: A comparative study with commercial detergent formulations  

Microsoft Academic Search

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 Aspergillus niger 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

2006-01-01

229

Accelerated Death Kinetics of Aspergillus niger Spores under High-Pressure Carbonation  

Microsoft Academic Search

The death kinetics of Aspergillus niger spores under high-pressure carbonation were investigated with respect to the concentration of dissolved CO2 (dCO2) and treatment temperature. All of the inactivation followed first-order death kinetics. The D value (decimal reduction time, or the time required for a 1-log-cycle reduction in the microbial population) in the saline carbonated at 10 MPa was 0.16 min

M. Shimoda; H. Kago; N. Kojima; M. Miyake; Y. Osajima; I. Hayakawa

2002-01-01

230

Mixed culture solid substrate fermentation of Trichoderma reesei with Aspergillus niger on sugar cane bagasse  

Microsoft Academic Search

Trichoderma reesei LM-UC4, the parent strain, and its hypercellulolytic mutant LM-UC4E1 were co-cultured with Aspergillus niger ATCC 10864 in solid substrate fermentation on alkali-treated sugar cane for cellulolytic enzyme production. Bagasse was supplemented with either soymeal or with ammonium sulfate and urea, and fermented at 80% moisture content and 30°C. Mixed culturing produced better results with the inorganic supplement. The

Marcel Gutierrez-Correa; Leticia Portal; Patricia Moreno; Robert P. Tengerdy

1999-01-01

231

The role of the tricarboxylic acid cycle in citric acid accumulation by Aspergillus niger  

Microsoft Academic Search

Determinations of the momentary levels of various intermediates related to the activity of the tricarboxylic acid cycle have been made during citric acid production in high-accumulating (manganese deficient) and lowaccumulating (manganese supplemented) mycelia of Aspergillus niger. During the growth period the levels of almost all TCA cycle acids, with the exception of 2-oxo-acids, were unusually high; during the induction phase

C. P. Kubicek; M. Röhr

1978-01-01

232

Lipase production from Aspergillus niger by solid-state fermentation using gingelly oil cake  

Microsoft Academic Search

Cultural conditions for the production of lipase by Aspergillus niger 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

N. R. Kamini; J. G. S. Mala; R. Puvanakrishnan

1998-01-01

233

Functional expression of amine oxidase from Aspergillus niger (AO-I) in Saccharomyces cerevisiae  

Microsoft Academic Search

The aim of this work was to prepare recombinant amine oxidase from Aspergillus niger after overexpressing in yeast. The yeast expression vector pDR197 that includes a constitutive PMA1 promoter was used for\\u000a the expression in Saccharomyces cerevisiae. Recombinant amine oxidase was extracted from the growth medium of the yeast, purified to homogeneity and identified by activity\\u000a assay and MALDI-TOF peptide

Kate?ina Kola?íková; Petr Galuszka; Iva Sedlá?ová; Marek Šebela; Ivo Frébort

2009-01-01

234

Partial purification and characterization of a polyphenol esterase from Aspergillus niger  

Microsoft Academic Search

Crude pectinase extract (FI), obtained from Aspergillus niger, was partially purified by ammonium sulphate precipitation at saturation of 0–20% (FIIa), 20–80% (FIIb) and 80–100% (FIIc). While all precipitated fractions exhibited pectin methyl esterase (PME), ?-1,3-glucanase, polyphenol esterase (PPE), polygalacturonase (PG) and ?-galactosidase activities, fraction FIIa contained the majority of PME and ?-1,3-glucanase activities. However, fraction FIIc contained the highest PPE,

W. Madani; S. Kermasha; M. Goetghebeur; M. Tse

1997-01-01

235

Expression of an Aspergillus niger Phytase Gene (phyA )i n Saccharomyces cerevisiae  

Microsoft Academic Search

Phytase improves the bioavailability of phytate phosphorus in plant foods to humans and animals and reduces phosphorus pollution of animal waste. Our objectives were to express an Aspergillus niger phytase gene (phyA )i nSaccharomyces cerevisiae and to determine the effects of glycosylation on the phytase's activity and thermostability. A 1.4-kb DNA fragment containing the coding region of the phyA gene

YANMING HAN; DAVID B. WILSON; XIN GEN LEI

1999-01-01

236

Rock phosphate solubilization by Aspergillus niger grown on sugar-beet waste medium  

Microsoft Academic Search

Solubilization of rock phosphate by Aspergillus niger was studied in solid-state fermentation on sugar-beet waste. This combination was selected after testing three agroindustrial waste materials, namely rice hulls, sugar-beet waste and alperujo. Sugar-beet waste was the best substrate for fungal growth with 69% mineralization, followed by rice hulls and alperujo. The fungus was successfully cultivated on sugar-beet waste supplemented with

N. Vassilev; M. T. Baca; M. Vassileva; I. Franco; R. Azcon

1995-01-01

237

Production of high activity thermostable phytase from thermotolerant Aspergillus niger in solid state fermentation  

Microsoft Academic Search

  The thermotolerant fungus, Aspergillus niger 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

T N Mandviwala; J M Khire

2000-01-01

238

Citric and gluconic acid production from fig by Aspergillus niger using solid-state fermentation  

Microsoft Academic Search

  The production of citric and gluconic acids from fig by Aspergillus niger ATCC 10577 in solid-state fermentation was investigated. The maximal citric and gluconic acids concentration (64 and 490\\u000a g\\/kg dry figs, respectively), citric acid yield (8%), and gluconic acid yield (63%) were obtained at a moisture level of 75%,\\u000a initial pH 7.0, temperature 30°C, and fermentation time in 15

T Roukas

2000-01-01

239

Nutritional Status of Cassava Peels and Root Sieviate Biodegraded With Aspergillus niger  

Microsoft Academic Search

2 Abstract: The ability of Aspergillus niger to improve the nutritional status of Cassava Root Sieviate (CRS) and peels was assessed for ten days through biodegradation. The biodegradation within this time had several effects on the proximate content of the substrates. The protein content of CRS recorded for 0, 5 and 10 days were 2.09, 5.21 and 7.34% while these

F. A. Aderemi; F. C. Nworgu

240

Effect of pH on ochratoxin A production by Aspergillus niger aggregate species  

Microsoft Academic Search

The effect of pH (2–10) on growth and ochratoxin A (OTA) production by 12 Aspergillus niger 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

2006-01-01

241

Effect of water activity on ochratoxin A production by Aspergillus niger aggregate species  

Microsoft Academic Search

The effect of water activity (aw) (0.82–0.99) on growth and ochratoxin A (OTA) production by twelve Aspergillus niger 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

2006-01-01

242

Purification and Characterization of a Lipase from Aspergillus niger F044  

Microsoft Academic Search

A lipase from Aspergillus niger F044 was purified to homogeneity using ammonium sulfate precipitation, dialysis, DEAE-Sepharose Fast Flow anion exchange chromatography, and Sephadex G-75 gel filtration chromatography. This purification protocol resulted in a 73.71-fold purification of lipase with 33.99 % final yield, and the relative molecular weight of the lipase were determined to be approximately 35-40 kD using SDS-PAGE. The

Zheng-Yu SHU; Jiang-Ke YANG; Yun-Jun YAN

2007-01-01

243

Spore cell wall components of Aspergillus niger elicit downy mildew disease resistance in pearl millet  

Microsoft Academic Search

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 ofAspergillus niger 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

2006-01-01

244

Enzymatic Enhancement of Citric Acid Production by Aspergillus niger From Corn Cobs  

Microsoft Academic Search

Rapidase Pomaliq (Gist-Brocades), a commercial apple juice processing enzyme preparation, was used to enhance the production of citric acid from corn cobs by Aspergillus niger (NRRL, 2001). Combined treatments of corn cobs with dilute NaOH and the commercial enzyme significantly increased the yield of citric acid. Under favorable conditions (pretreated with 0.1 N NaOH, followed by 72 h of fermentation

Y. D. Hang; E. E. Woodams

2001-01-01

245

Corn Husks: A Potential Substrate for Production of Citric Acid by Aspergillus niger  

Microsoft Academic Search

Corn husks could serve as a potential substrate for the production of citric acid by Aspergillus niger NRRL 2001. Combined treatments of corn husks with dilute NaOH and Rapidase Pomaliq (a commercial apple juice processing enzyme preparation) significantly enhanced the yield of citric acid. Under favourable conditions (pretreated with 0.5 mol\\/L NaOH, followed by 120 h of fermentation at 30°C

Y. D Hang; E. E Woodams

2000-01-01

246

Immobilization of Aspergillus niger NRC 107 xylanase and ?-xylosidase, and properties of the immobilized enzymes  

Microsoft Academic Search

Aspergillus niger NRC 107 xylanase and ?-xylosidase were immobilized on various carriers by different methods of immobilization, including\\u000a physical adsorption, covalant binding, ionic binding, and entrapment. The immobilized enzymes were prepared by physical adsorption\\u000a on tannin-chitosan, ionic binding onto Dowex-50W, covalent binding on chitosan beads through glutaraldehyde, and entrapment\\u000a in polyacrylamide had the highest activities. In most cases, the optimum

Mohamed A. Abdel-Naby

1993-01-01

247

Production of cellulase and xylanase in a bubble gum column using immobilized Aspergillus niger KKS  

SciTech Connect

Aspergillus niger KKS, isolated from a farmland near Suwon, was immobilized on Celite and polyurethane foams. Enzyme activities produced by the immobilized cell system in a bubble column were higher than that of shake-flask culture. The enzyme productivities were twice as high. {Beta}-Glucosidase, {Beta}-xylosidase, and xylanase activities obtained in a bubble column were significant when the ground rice straw was used as a substrate. 9 refs., 2 figs., 3 tabs.

Kang, Seong-Woo; Kim, Seung-Woo [Univ. of Suwon (Korea, Republic of); Lee, Jin-Suk [Korea Institute of Energy Research, Daejeon (Korea, Republic of)

1995-05-01

248

Citric acid production by a novel Aspergillus niger isolate: I. Mutagenesis and cost reduction studies  

Microsoft Academic Search

Ultraviolet-irradiation (UV), ethyl methane sulfonate (EMS) and acridine orange (AO) were used to induce citric acid overproduction mutations in Aspergillus niger UMIP 2564. Among 15, eight of the mutant derivatives, were improved with respect to citric acid production from sucrose in batch cultures. Maximum product yield (60.25%) was recorded by W5, a stable UV mutant, with approximately 3.2-fold increase when

Walid A. Lotfy; Khaled M. Ghanem; Ehab R. El-Helow

2007-01-01

249

Optimization of enantioselective resolution of racemic ibuprofen by native lipase from Aspergillus niger  

Microsoft Academic Search

Resolution of (R,S)-ibuprofen (2-(4-isobutylphenyl)propionic acid) enantiomers by esterification reaction with 1-propanol in different organic solvents was studied using native Aspergillus niger lipase. The main variables controlling the process (enzyme concentration and 1-propanol:ibuprofen molar ratio) have been optimized using response surface methodology based on a five-level, two-variable central composite rotatable design, in which the selected objective function was enantioselectivity. This enzyme

Patrícia de O. Carvalho; Fabiano J. Contesini; Renato Bizaco; Silvana Ap. Calafatti; Gabriela A. Macedo

2006-01-01

250

Bioleaching of spent refinery processing catalyst using Aspergillus niger with high-yield oxalic acid  

Microsoft Academic Search

A spent refinery processing catalyst was physically and chemically characterized, and subjected to one-step and two-step bioleaching processes using Aspergillus niger. During bioleaching of the spent catalysts of various particle sizes (“as received”, 100–150?m, <37?m, and xŻ=2.97 (average) ?m) and pulp densities, the biomass dry weight and pH were determined. The corresponding leach liquor was analysed for excreted organic acids

Deenan Santhiya; Yen-Peng Ting

2005-01-01

251

Production of fructose from inulin using mixed inulinases from Aspergillus niger and Candida guilliermondii  

Microsoft Academic Search

Two new effective microbial producers of inulinases were isolated from Jerusalem artichoke tubers grown in Thailand and identified\\u000a as Aspergillus niger TISTR 3570 and Candida\\u000a guilliermondii TISTR 5844. The inulinases produced by both these microorganisms were appropriate for hydrolysing inulin to fructose as the\\u000a principal product. An initial inulin concentration of ?100 g l?1 and the enzyme concentration of 0.2 U g?1 of

Sarote Sirisansaneeyakul; Nisakorn Worawuthiyanan; Wirat Vanichsriratana; Penjit Srinophakun; Yusuf Chisti

2007-01-01

252

Production of gluconic acid by Aspergillus niger immobilized on polyurethane foam  

Microsoft Academic Search

Production of gluconic acid by cells of Aspergillus niger immobilized on polyurethane foam was studied in repeated-batch shake-flask and bubble-column fermentations. For passive immobilization, various amounts of polyurethane foam and spore suspension were tested in order to obtain a suitable combination for optimal concentration of immobilized biomass. Immobilized cells were sucessfully reused with higher levels of product formation being maintained

Nikolay B. Vassilev; Maria Ch. Vassileva; Dimitrinka I. Spassova

1993-01-01

253

Effect of Citrus reticulata and Cymbopogon citratus essential oils on Aspergillus flavus growth and aflatoxin production on Asparagus racemosus.  

PubMed

Essential oils extracted from Citrus reticulata and Cymbopogon citratus were tested in vitro against the toxigenic strain of Aspergillus flavus, isolated from the tuberous roots of Asparagus racemosus, used in preparation of herbal drugs. The essential oils completely inhibited the growth of A. flavus at 750 ppm and also exhibited a broad fungitoxic spectrum against nine additional fungi isolated from the roots. Citrus reticulata and Cymbopogon citratus essential oils completely inhibited aflatoxin B(1) production at 750 and 500 ppm, respectively. During in vivo investigation, the incidence of fungi and aflatoxin B(1) production decreased considerably in essential oil-treated root samples. The findings thus indicate possible exploitation of the essential oils as effective inhibitor of aflatoxin B(1) production and as post-harvest fungitoxicant of traditionally used plant origin for the control of storage fungi. These essential oils may be recommended as plant-based antifungals as well as aflatoxin B(1) suppressors in post-harvest processing of herbal samples. PMID:20401550

Singh, Priyanka; Shukla, Ravindra; Kumar, Ashok; Prakash, Bhanu; Singh, Shubhra; Dubey, Nawal Kishore

2010-09-01

254

Antifungal activity evaluation of Mexican oregano (Lippia berlandieri Schauer) essential oil on the growth of Aspergillus flavus by gaseous contact.  

PubMed

The antifungal activity of Mexican oregano (Lippia berlandieri Schauer) essential oil by gaseous contact on the growth of Aspergillus flavus at selected essential oil concentrations (14.7, 29.4, 58.8, or 117.6 ?l of essential oil per liter of air) and temperatures (25, 30, or 35°C) was evaluated in potato dextrose agar formulated at water activity of 0.98 and pH 4.0. Mold growth curves were adequately fitted (0.984 < R(2) < 0.999) by the modified Gompertz model. The effect of the independent variables (concentration of essential oil and temperature) on the estimated model parameters (reciprocal of growth rate [1/?(m)] and lag time [?]) were evaluated through polynomial equations. Both ?(m) and ? were significantly (P < 0.05) affected by the independent variables; ?(m) decreased and ? increased as essential oil concentration increased and temperature decreased, which suggests that Mexican oregano essential oil retards or inhibits mold germination stage. Further, minimum fungistatic and fungicide essential oil concentrations at 30 and 35°C were determined. Mexican oregano essential oil applied in gas phase exerts important antifungal activity on the growth of A. flavus, suggesting its potential to inhibit other food spoilage molds. PMID:22186064

Gómez-Sánchez, Aída; Palou, Enrique; López-Malo, Aurelio

2011-12-01

255

The inhibitory effect of Bacillus megaterium on aflatoxin and cyclopiazonic acid biosynthetic pathway gene expression in Aspergillus flavus.  

PubMed

Aspergillus flavus is one of the major moulds that colonize peanut in the field and during storage. The impact to human and animal health, and to the economy in agriculture and commerce, is significant since this mold produces the most potent known natural toxins, aflatoxins, which are carcinogenic, mutagenic, immunosuppressive, and teratogenic. A strain of marine Bacillus megaterium isolated from the Yellow Sea of East China was evaluated for its effect in inhibiting aflatoxin formation in A. flavus through down-regulating aflatoxin pathway gene expression as demonstrated by gene chip analysis. Aflatoxin accumulation in potato dextrose broth liquid medium and liquid minimal medium was almost totally (more than 98 %) inhibited by co-cultivation with B. megaterium. Growth was also reduced. Using expression studies, we identified the fungal genes down-regulated by co-cultivation with B. megaterium across the entire fungal genome and specifically within the aflatoxin pathway gene cluster (aflF, aflT, aflS, aflJ, aflL, aflX). Modulating the expression of these genes could be used for controlling aflatoxin contamination in crops such as corn, cotton, and peanut. Importantly, the expression of the regulatory gene aflS was significantly down-regulated during co-cultivation. We present a model showing a hypothesis of the regulatory mechanism of aflatoxin production suppression by AflS and AflR through B. megaterium co-cultivation. PMID:24652062

Kong, Qing; Chi, Chen; Yu, Jiujiang; Shan, Shihua; Li, Qiyu; Li, Qianting; Guan, Bin; Nierman, William C; Bennett, Joan W

2014-06-01

256

Chemoprevention by essential oil of turmeric leaves (Curcuma longa L.) on the growth of Aspergillus flavus and aflatoxin production.  

PubMed

Turmeric is well known for a wide range of medicinal properties. Essential oil of turmeric leaves (Curcuma longa L.) were evaluated at varying concentrations of 0.01, 0.05, 0.1, 0.5, 0.75, 1.0 and 1.5% (v/v) in Yeast Extract Sucrose (YES) broth inoculated with spore suspension of Aspergillus flavus of 10(6)conidia/ml. These were evaluated for their potential in the control of aflatoxigenic fungus A. flavus and aflatoxin production. Turmeric leaf oil exhibited 95.3% and 100% inhibition of toxin production respectively at 1.0% and 1.5%. The extent of inhibition of fungal growth and aflatoxin production was dependent on the concentration of essential oil used. The oil exhibited significant inhibition of fungal growth as well as aflatoxins B(1) and G(1) production. The LD(50) and LD(90) were also determined. GC-MS analysis of the oil showed ?-phellandrene, p-cymene and terpinolene as the major components in turmeric leaf oil. The possibility of using these phytochemical components as bio-preservatives for storage of spices is discussed. PMID:21354246

Sindhu, S; Chempakam, B; Leela, N K; Suseela Bhai, R

2011-05-01

257

Proteomic analysis reveals an aflatoxin-triggered immune response in cotyledons of Arachis hypogaea infected with Aspergillus flavus.  

PubMed

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 Aspergillus flavus. 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

2012-05-01

258

Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger.  

PubMed Central

Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of Pi and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added 14CO2 was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this was oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle.

Kubicek, C P; Schreferl-Kunar, G; Wohrer, W; Rohr, M

1988-01-01

259

Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger.  

PubMed

Oxalate accumulation of up to 8 g/liter was induced in Aspergillus niger by shifting the pH from 6 to 8. This required the presence of Pi and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added 14CO2 was not incorporated into oxalate, but was incorporated into acetate and malate, thus indicating the biosynthesis of oxalate by hydrolytic cleavage of oxaloacetate. Inhibition of mitochondrial citrate metabolism by fluorocitrate did not significantly decrease the oxalate yield. The putative enzyme that was responsible for this was oxaloacetate hydrolase (EC 3.7.1.1), which was induced de novo during the pH shift. Subcellular fractionation of oxalic acid-forming mycelia of A. niger showed that this enzyme is located in the cytoplasm of A. niger. The results are consistent with a cytoplasmic pathway of oxalate formation which does not involve the tricarboxylic acid cycle. PMID:3132096

Kubicek, C P; Schreferl-Kunar, G; Wöhrer, W; Röhr, M

1988-03-01

260

Functional expression of amine oxidase from Aspergillus niger (AO-I) in Saccharomyces cerevisiae.  

PubMed

The aim of this work was to prepare recombinant amine oxidase from Aspergillus niger after overexpressing in yeast. The yeast expression vector pDR197 that includes a constitutive PMA1 promoter was used for the expression in Saccharomyces cerevisiae. Recombinant amine oxidase was extracted from the growth medium of the yeast, purified to homogeneity and identified by activity assay and MALDI-TOF peptide mass fingerprinting. Similarity search in the newly published A. niger genome identified six genes coding for copper amine oxidase, two of them corresponding to the previously described enzymes AO-I a methylamine oxidase and three other genes coding for FAD amine oxidases. Thus, A. niger possesses an enormous metabolic gear to grow on amine compounds and thus support its saprophytic lifestyle. PMID:17899443

Kolaríková, Katerina; Galuszka, Petr; Sedlárová, Iva; Sebela, Marek; Frébort, Ivo

2009-01-01

261

Kinetic modeling for the biosorption of copper by pretreated Aspergillus niger biomass.  

PubMed

In this present work, a kinetic model for biosorption of copper was developed considering the possibility of different forms of functional groups being present on the surface of the biomass prepared from Aspergillus niger. Results showed that metal uptake by A. niger was a mass transfer driven process, requiring only 30min to achieve 70% adsorption efficiency. Copper sorption by A. niger was influenced by the biomass dose, initial metal ion concentration, and pH of the solution. The Langmuir and Freundlich adsorption isotherms were used to describe the behavior of the system at different pH. The retention capacity of the biomass was determined at pH 6.0 to be equal to 23.62mg/g of biomass. The pretreatment with formalin improved the uptake of metal ion. PMID:16996263

Mukhopadhyay, Mausumi; Noronha, S B; Suraishkumar, G K

2007-07-01

262

Direct fermentation of potato starch to ethanol by cocultures of Aspergillus niger and Saccharomyces cerevisiae.  

PubMed Central

Direct fermentation of unhydrolyzed potato starch to ethanol by monocultures of an amylolytic fungus, Aspergillus niger, 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.

Abouzied, M M; Reddy, C A

1986-01-01

263

Effect of pH on ochratoxin A production by Aspergillus niger aggregate species.  

PubMed

The effect of pH (2-10) on growth and ochratoxin A (OTA) production by 12 Aspergillus niger 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 better culture medium than CYA for OTA production. In this medium, OTA was produced from pH 2 or 3 to 10 depending on the strain. The results show the ability of A. niger aggregate strains not only to grow, but also to produce OTA over a wide pH range. The results will lead to a better understanding of the role of A. niger aggregate strains in the OTA contamination of several food commodities. PMID:16766460

Esteban, A; Abarca, M L; Bragulat, M R; Cabańes, F J

2006-06-01

264

Biocatalytic potential of laccase-like multicopper oxidases from Aspergillus niger  

PubMed Central

Background Laccase-like multicopper oxidases have been reported in several Aspergillus species but they remain uncharacterized. The biocatalytic potential of the Aspergillus niger 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 Aspergillus niger 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.

2012-01-01

265

Enantioselective behavior of lipases from Aspergillus niger immobilized in different supports.  

PubMed

Considering the extraordinary microbial diversity and importance of fungi as enzyme producers, the search for new biocatalysts with special characteristics and possible applications in biocatalysis is of great interest. Here, we report the performance in the resolution of racemic ibuprofen of a native enantioselective lipase from Aspergillus niger, free and immobilized in five types of support (Accurel EP-100, Amberlite MB-1, Celite, Montmorillonite K10 and Silica gel). Amberlite MB-1 was found to be the best support, with a conversion of 38.2%, enantiomeric excess of 50.7% and enantiomeric ratio (E value) of 19 in 72 h of reaction. After a thorough optimization of several parameters, the E value of the immobilized Aspergillus niger lipase was increased (E = 23) in a shorter reaction period (48 h) at 35 degrees C. Moreover, the immobilized Aspergillus niger lipase maintained an esterification activity of at least 80% after 8 months of storage at 4 degrees C and could be reused at least six times. PMID:19390883

da Silva, Vania Castriani Fernandes; Contesini, Fabiano Jares; de Oliveira Carvalho, Patrícia

2009-07-01

266

Effect of increasing inoculum sizes of Aspergillus hyphae on MICs and MFCs of antifungal agents by broth microdilution method  

Microsoft Academic Search

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, Aspergillus flavus, Aspergillus niger 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

2003-01-01

267

Gluconate formation and polyol metabolism in Aspergillus niger  

Microsoft Academic Search

The capacity of A.niger to accumulate metabolites is remarkable. Under all conditions polyols accumulate in the cell and when mycelium in later developmental stages is considered, depending on the carbon source, aeration and external pH, polyols and\\/or organic acids can be formed in a very efficient way. The aim of this thesis was to obtain a better understanding of the

C. F. B. Witteveen

1993-01-01

268

Control of aflatoxin production of Aspergillus flavus and Aspergillus parasiticus using RNA silencing technology by targeting aflD (nor-1) gene.  

PubMed

Aspergillus ?avus and Aspergillus parasiticus are important pathogens of cotton, corn, peanuts and other oil-seed crops, producing toxins both in the field and during storage. We have designed three siRNA sequences (Nor-Ia, Nor-Ib, Nor-Ic) to target the mRNA sequence of the aflD gene to examine the potential for using RNA silencing technology to control aflatoxin production. Thus, the effect of siRNAs targeting of two key genes in the aflatoxin biosynthetic pathway, aflD (structural) and aflR (regulatory gene) and on aflatoxin B(1 )(AFB(1)), and aflatoxin G(1) (AFG(1)) production was examined. The study showed that Nor-Ib gave a significant decrease in aflD mRNA, aflR mRNA abundance, and AFB(1) production (98, 97 and 97% when compared to the controls) in A. flavus NRRL3357, respectively. Reduction in aflD and aflR mRNA abundance and AFB(1 )production increased with concentration of siRNA tested. There was a significant inhibition in aflD and AFB(1) production by A. flavus EGP9 and AFG(1 )production by A. parasiticus NRRL 13005. However, there was no significant decrease in AFG(1) production by A. parasiticus SSWT 2999. Changes in AFB(1) production in relation to mRNA levels of aflD showed a good correlation (R = 0.88; P = 0.00001); changes in aflR mRNA level in relation to mRNA level of aflD also showed good correlation (R = 0.82; P = 0.0001). The correlations between changes in aflR and aflD gene expression suggests a strong relationship between these structural and regulatory genes, and that aflD could be used as a target gene to develop efficient means for aflatoxin control using RNA silencing technology. PMID:22069731

Abdel-Hadi, Ahmed M; Caley, Daniel P; Carter, David R F; Magan, Naresh

2011-06-01

269

Control of Aflatoxin Production of Aspergillus flavus and Aspergillus parasiticus Using RNA Silencing Technology by Targeting aflD (nor-1) Gene  

PubMed Central

Aspergillus ?avus and Aspergillus parasiticus are important pathogens of cotton, corn, peanuts and other oil-seed crops, producing toxins both in the field and during storage. We have designed three siRNA sequences (Nor-Ia, Nor-Ib, Nor-Ic) to target the mRNA sequence of the aflD gene to examine the potential for using RNA silencing technology to control aflatoxin production. Thus, the effect of siRNAs targeting of two key genes in the aflatoxin biosynthetic pathway, aflD (structural) and aflR (regulatory gene) and on aflatoxin B1 (AFB1), and aflatoxin G1 (AFG1) production was examined. The study showed that Nor-Ib gave a significant decrease in aflD mRNA, aflR mRNA abundance, and AFB1 production (98, 97 and 97% when compared to the controls) in A. flavus NRRL3357, respectively. Reduction in aflD and aflR mRNA abundance and AFB1 production increased with concentration of siRNA tested. There was a significant inhibition in aflD and AFB1 production by A. flavus EGP9 and AFG1 production by A. parasiticus NRRL 13005. However, there was no significant decrease in AFG1 production by A. parasiticus SSWT 2999. Changes in AFB1 production in relation to mRNA levels of aflD showed a good correlation (R = 0.88; P = 0.00001); changes in aflR mRNA level in relation to mRNA level of aflD also showed good correlation (R = 0.82; P = 0.0001). The correlations between changes in aflR and aflD gene expression suggests a strong relationship between these structural and regulatory genes, and that aflD could be used as a target gene to develop efficient means for aflatoxin control using RNA silencing technology.

Abdel-Hadi, Ahmed M.; Caley, Daniel P.; Carter, David R. F.; Magan, Naresh

2011-01-01

270

Spatial and Developmental Differentiation of Mannitol Dehydrogenase and Mannitol-1-Phosphate Dehydrogenase in Aspergillus niger?†  

PubMed Central

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 Aspergillus niger. 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.

2010-01-01

271

Pectinolytic activity of revertants of auxotrophic strains of Aspergillus niger.  

PubMed

From conidia of 4 different auxotrophic A. niger strains 400 spontaneous revertants (100 from each strain) were obtained, and in one case additionally 100 revertants induced by mutagens (UV+NTG). The revertants showed a considerable differentiation with regard to the total pectinolytic activity. Its highest increase occurred in revertants originating from auxotrophs greatly predisposed to synthesize pectinases. In the case of revertants induced by mutagenes an increase in the frequency of their formation was observed, as well as an increased participation of revertants with higher pectinolytic activity compared to both their initial auxotrophic and prototrophic strain. PMID:2442973

Fiedurek, J; Ilczuk, Z

1987-01-01

272

Growth and hydrolase profiles can be used as characteristics to distinguish Aspergillus niger and other black aspergilli  

PubMed Central

Wild type Aspergillus niger isolates from different biotopes from all over the world were compared to each other and to the type strains of other black Aspergillus species with respect to growth and extracellular enzyme profiles. The origin of the A. niger isolate did not result in differences in growth profile with respect to monomeric or polymeric carbon sources. Differences were observed in the growth rate of the A. niger isolates, but these were observed on all carbon sources and not specific for a particular carbon source. In contrast, carbon source specific differences were observed between the different species. Aspergillus brasiliensis is the only species able to grow on D-galactose, and A. aculeatus had significantly better growth on Locus Bean gum than the other species. Only small differences were found in the extracellular enzyme profile of the A. niger isolates during growth on wheat bran, while large differences were observed in the profiles of the different black aspergilli. In addition, differences were observed in temperature profiles between the black Aspergillus species, but not between the A. niger isolates, demonstrating no isolate-specific adaptations to the environment. These data indicate that the local environment does not result in stable adaptations of A. niger with respect to growth profile or enzyme production, but that the potential is maintained irrespective of the environmental parameters. It also demonstrates that growth, extracellular protein and temperature profiles can be used for species identification within the group of black aspergilli.

Meijer, M.; Houbraken, J.A.M.P.; Dalhuijsen, S.; Samson, R.A.; de Vries, R.P.

2011-01-01

273

Degradation of chlorimuron-ethyl by Aspergillus niger isolated from agricultural soil.  

PubMed

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, Aspergillus niger survived in minimal broth containing chlorimuron at 2 mg mL(-1) . Aspergillus niger 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

2012-12-01

274

Lethal effects of Aspergillus niger against mosquitoes vector of filaria, malaria, and dengue: a liquid mycoadulticide.  

PubMed

Aspergillus niger 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 LC(50), LC(90), and LC(99) 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/cm(2), after exposure of seven hours. We have calculated significant LT(90) 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. PMID:22629156

Singh, Gavendra; Prakash, Soam

2012-01-01

275

Extracellular lipase of Aspergillus niger NRRL3; production, partial purification and properties.  

PubMed

Four strains of Aspergillus niger were screened for lipase production. Each was cultivated on four different media differing in their contents of mineral components and sources of carbon and nitrogen. Aspergillus niger NRRL3 produced maximal activity (325U/ml) when grown in 3% peptone, 0.05% MgSO(4).7H(2)O, 0.05% KCl, 0.2% K(2)HPO(4) and 1% olive oil:glucose (0.5:0.5). A. niger NRRL3 lipase was partially purified by ammonium sulphate precipitation. The majority of lipase activity (48%) was located in fraction IV precipitated at 50-60% of saturation with a 18-fold enzyme purification. The optimal pH of the partial purified lipase preparation for the hydrolysis of emulsified olive oil was 7.2 and the optimum temperature was 60°C. At 70°C, the enzyme retained more than 90% of its activity. Enzyme activity was inhibited by Hg(2+) and K(+), whereas Ca(2+) and Mn(2+) greatly stimulated its activity. Additionally, the formed lipase was stored for one month without any loss in the activity. PMID:23100754

Adham, Nehad Z; Ahmed, E M

2009-03-01

276

Gene cloning and enzymatic characterization of an endoprotease Endo-Pro-Aspergillus niger.  

PubMed

A novel endoprotease Endo-Pro-Aspergillus niger (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-Aspergillus niger. 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

Kang, Chao; Yu, Xiao-Wei; Xu, Yan

2013-08-01

277

D-Galactose uptake is nonfunctional in the conidiospores of Aspergillus niger.  

PubMed

The majority of black Aspergilli (Aspergillus section Nigri), including Aspergillus niger, as well as many other Ascomycetes fail to germinate on d-galactose as a sole carbon source. Here, we provide evidence that the ability of A. niger to transport D-galactose is growth stage dependent, being absent in the conidiospores but present in the mycelia. Despite earlier claims, we could identify galactokinase activity in growing cells and all genes of the Leloir pathway (responsible for channelling D-galactose into the EMP pathway) are well induced on D-galactose (and also on lactose, D-xylose and L-arabinose) in the mycelial stage. Expression of all Leloir pathway genes was also detectable in conidiospores, although galE (encoding a galactokinase) and galD (encoding a galactose-1-phosphate uridylyl transferase) were expressed poorly. These results suggest that the D-galactose-negative phenotype of A. niger conidiospores may be due to the lack of inducer uptake. PMID:22324294

Fekete, Erzsébet; de Vries, Ronald P; Seiboth, Bernhard; vanKuyk, Patricia A; Sándor, Erzsébet; Fekete, Eva; Metz, Benjamin; Kubicek, Christian P; Karaffa, Levente

2012-04-01

278

In-vitro Inhibition of Biofilm Formation in Candida albicans and Candida tropicalis by Heat Stable Compounds in Culture Filtrate of Aspergillus flavus  

PubMed Central

Background: Invasive candidiasis, caused mostly by Candida albicans and C. tropicalis is one of the most common causes of bloodstream infection with a substantial attributable mortality. This disease is associated with formation of structured, multilayered microbial communities known as biofilms over indwelling devices. Treatment is rendered difficult owing to factors like poor drug penetration through biofilms and high cost of the available antifungal drugs. Hence there is imminent need of developing low-cost natural compounds inhibiting Candidal biofilm formation in vitro. Organohalgen compounds derived from crude culture filtrate of Aspergillus flavus have been documented to impair in vitro Candidal survival. Aim: We aimed to detect the effect of preheated and unheated crude culture filtrate of Aspergillus flavus on biofilm formation of Candida albicans and C. tropicalis in vitro. Setting and Designs: Ours was a laboratory-based observational study with clinical isolates of the microorganisms selected randomly. Material and Methods: In this study, we showed for the first time by microtitre plate method that heat stable compounds which were present in preheated and unheated culture filtrates of Aspergillus flavus inhibited biofilm formation of Candida albicans and C. tropicalis and also lipase activities of these pathogens, and filtrate was non-toxic on human cell line as checked microscopically. Statistical Analysis used: Z-test of significance was used to calculate significant difference between Candidal biofilm formation in normal liquid medium and culture filtrate, respectively. Results and Conclusion: Heat stable compounds present in culture filtrate of Aspergillus flavus inhibit biofilm formation of Candida albicans and C. tropicalis and also in-vitro lipase activity of these pathogens and could pave the way for development of low-cost alternatives to treat invasive candidiasis.

Bhattacharyya, Sayan; Gupta, Prashant; Banerjee, Gopa; Jain, Amita; Singh, Mastan

2013-01-01

279

Formation of Sclerotia and Production of Indoloterpenes by Aspergillus niger and Other Species in Section Nigri.  

PubMed

Several species in Aspergillus section Nigri have been reported to produce sclerotia on well-known growth media, such as Czapek yeast autolysate (CYA) agar, with sclerotia considered to be an important prerequisite for sexual development. However Aspergillus niger sensu stricto has not been reported to produce sclerotia, and is thought to be a purely asexual organism. Here we report, for the first time, the production of sclerotia by certain strains of Aspergillus niger when grown on CYA agar with raisins, or on other fruits or on rice. Up to 11 apolar indoloterpenes of the aflavinine type were detected by liquid chromatography and diode array and mass spectrometric detection where sclerotia were formed, including 10,23-dihydro-24,25-dehydroaflavinine. Sclerotium induction can thus be a way of inducing the production of new secondary metabolites from previously silent gene clusters. Cultivation of other species of the black aspergilli showed that raisins induced sclerotium formation by A. brasiliensis, A. floridensis A. ibericus, A. luchuensis, A. neoniger, A. trinidadensis and A. saccharolyticus for the first time. PMID:24736731

Frisvad, Jens C; Petersen, Lene M; Lyhne, E Kirstine; Larsen, Thomas O

2014-01-01

280

Formation of Sclerotia and Production of Indoloterpenes by Aspergillus niger and Other Species in Section Nigri  

PubMed Central

Several species in Aspergillus section Nigri have been reported to produce sclerotia on well-known growth media, such as Czapek yeast autolysate (CYA) agar, with sclerotia considered to be an important prerequisite for sexual development. However Aspergillus niger sensu stricto has not been reported to produce sclerotia, and is thought to be a purely asexual organism. Here we report, for the first time, the production of sclerotia by certain strains of Aspergillus niger when grown on CYA agar with raisins, or on other fruits or on rice. Up to 11 apolar indoloterpenes of the aflavinine type were detected by liquid chromatography and diode array and mass spectrometric detection where sclerotia were formed, including 10,23-dihydro-24,25-dehydroaflavinine. Sclerotium induction can thus be a way of inducing the production of new secondary metabolites from previously silent gene clusters. Cultivation of other species of the black aspergilli showed that raisins induced sclerotium formation by A. brasiliensis, A. floridensis A. ibericus, A. luchuensis, A. neoniger, A. trinidadensis and A. saccharolyticus for the first time.

Frisvad, Jens C.; Petersen, Lene M.; Lyhne, E. Kirstine; Larsen, Thomas O.

2014-01-01

281

Inactivation of Aspergillus niger in mango nectar by high-pressure homogenization combined with heat shock.  

PubMed

This research evaluated the inactivation of a heat-resistant Aspergillus niger conidia in mango nectar by high-pressure homogenization (HPH) combined with heat shock. A. niger were inoculated in mango nectar (10(6) conidia mL(-1)) and subjected to HPH (300 to 100 MPa) and heat shock (80 degrees C for 5 to 20 min) before or after HPH. Processes were evaluated according to number of decimal reductions reached by each isolated or combined process. Scanning electron microscopy was performed to observe conidia wall after pressure treatment. Pressures below 150 MPa did not inactivate A. niger while pressures of 200 and 300 MPa resulted in 2 and more than 6 log reductions, respectively. D(80 degrees C) of A. niger was determined as 5.03 min. A heat shock of 80 degrees C/15 min, reaching 3 decimal conidia reductions, was applied before or after a 200 MPa pressure treatment to improve the decimal reduction to 5 log cycles. Results indicated that HPH inactivated A. niger in mango nectar at 300 MPa (>6.24 log cycles) and that, with pressure (200 MPa) combined with post heat shock, it was possible to obtain the same decimal reduction, showing a synergistic effect. On the other hand, pre heat shock associated with HPH resulted in an additive effect. The observation of A. niger conidia treated by HPH at 100 and 200 MPa by scanning electron microscopy indicated that HPH promoted intense cell wall damage, which can sensitize the conidia to post heat shock and possibly explain the synergistic effect observed. Practical Application: The results obtained in this paper are relevant to elucidate the mechanism of conidia inactivation in order to develop the application of HPH as an alternative pasteurization process for the fruit nectar industry. PMID:20492122

Tribst, Alline A L; Franchi, Mark A; Cristianini, Marcelo; de Massaguer, Pilar R

2009-01-01

282

Removal of silver nanoparticles using live and heat shock Aspergillus niger cultures.  

PubMed

Silver nanoparticles (SNPs) are extensively used in many industrial and medical applications; however, the impact of their release in the environment is still considered an understudied field. In the present work, SNPs present in aqueous lab waste water (average size of 30 nm) were used to determine their impact on microflora if released in soil rhizosphere and sewage waste water. The results showed that 24 h incubation with different SNP concentrations resulted in a 2.6-fold decrease for soil rhizosphere microflora and 7.45-fold decrease for sewage waste water microflora, both at 24 ppm. Live and heat shock (50 and 70 °C) Aspergillus niger cultures were used to remove SNP waste, the results show 76.6, 81.74 and 90.8 % SNP removal, respectively after 3 h incubation. There was an increase in the log total bacterial count again after SNP removal by A. niger in the following order: live A. niger < 50 °C heat shock A. niger < 70 °C heat shock A. niger. The pH value decreased from 5.8 to 3.8 in the same order suggesting the production of an acid in the culture media. Scanning electron microscopy images showed agglomeration and/or complexation of SNP particles, in a micron size, in between the fungal mycelia, hence settling on and in between the mycelial network. The results suggest that silver was reduced again and agglomerated and/or chelated together in its oxidized form by an acid in A. niger media. More studies are recommended to determine the acid and the heat shock proteins to confirm the exact mode of action. PMID:24415500

Gomaa, Ola M

2014-06-01

283

Generation, annotation, and analysis of an extensive Aspergillus niger EST collection  

PubMed Central

Background Aspergillus niger, 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.

Semova, Natalia; Storms, Reginald; John, Tricia; Gaudet, Pascale; Ulycznyj, Peter; Min, Xiang Jia; Sun, Jian; Butler, Greg; Tsang, Adrian

2006-01-01

284

Characterization of a Foldase, Protein Disulfide Isomerase A, in the Protein Secretory Pathway of Aspergillus niger  

PubMed Central

Protein disulfide isomerase (PDI) is important in assisting the folding and maturation of secretory proteins in eukaryotes. A gene, pdiA, encoding PDIA was previously isolated from Aspergillus niger, and we report its functional characterization here. Functional analysis of PDIA showed that it catalyzes the refolding of denatured and reduced RNase A. pdiA also complemented PDI function in a Saccharomyces cerevisiae ?pdi1 mutant in a yeast-based killer toxin assay. Levels of pdiA mRNA and PDIA protein were raised by the accumulation of unfolded proteins in the endoplasmic reticulum. This response of pdiA mRNA levels was slower and lower in magnitude than that of A. niger bipA, suggesting that the induction of pdiA is not part of the primary stress response. An increased level of pdiA transcripts was also observed in two A. niger strains overproducing a heterologous protein, hen egg white lysozyme (HEWL). Although overexpression of PDI has been successful in increasing yields of some heterologous proteins in S. cerevisiae, overexpression of PDIA did not increase secreted yields of HEWL in A. niger, suggesting that PDIA itself is not limiting for secretion of this protein. Downregulation of pdiA by antisense mRNA reduced the levels of microsomal PDIA activity by up to 50%, lowered the level of PDIA as judged by Western blots, and lowered the secreted levels of glucoamylase by 60 to 70%.

Ngiam, Celina; Jeenes, David J.; Punt, Peter J.; Van Den Hondel, Cees A. M. J. J.; Archer, David B.

2000-01-01

285

Cloning of the Aspergillus niger gene encoding alpha-L-arabinofuranosidase A.  

PubMed

Using L-arabitol as an inducer, simple induction conditions were established that resulted in high-level expression of alpha-L-arabinofuranosidase A by an Aspergillus niger D-xylulose kinase mutant strain. These conditions were adapted to construct a cDNA expression library from which an alpha-L-arabinofuranosidase A cDNA clone was isolated using specific antiserum. The corresponding gene encoding alpha-L-arabinofuranosidase A (abfA) was isolated from a genomic library and cloned into a high copy plasmid vector. By co-transformation of uridine auxotrophic mutants lacking orotidine-5-phosphate decarboxylase activity, the afbA gene was introduced both in A. niger and A. nidulans, using the A. niger pyrA gene as selection marker. The identity of the abfA gene was confirmed by overexpression of the gene product by A. niger and A. nidulans transformants, upon growth using sugar beet pulp as the carbon source. PMID:7764056

Flipphi, M J; Visser, J; van der Veen, P; de Graaff, L H

1993-06-01

286

Improved mannan-degrading enzymes' production by Aspergillus niger through medium optimization.  

PubMed

The effect of different carbon and nitrogen sources on the production of mannan-degrading enzymes, focussing on ?-mannanase, by Aspergillus niger was investigated using shake flask culture. The ?-mannanase activity obtained during growth of A. niger on guar gum (GG, 1495 nkat mL(-1)) was much higher than those observed on other carbon substrates, locust bean gum (1148 nkat mL(-1)), ?-cellulose (10.7 nkat mL(-1)), glucose (8.8 nkat mL(-1)) and carboxymethylcellulose (4.6 nkat mL(-1)). For fermentation using GG as a carbon source, bacteriological peptone gave the highest ?-mannanase activity (1744 nkat mL(-1)) followed by peptone from meat (1168 nkat mL(-1)), yeast extract (817 nkat mL(-1)), ammonium sulphate (241 nkat mL(-1)), ammonium nitrate (113 nkat mL(-1)) and ammonium chloride (99 nkat mL(-1)) when used as a nitrogen source. The composition of bacteriological peptone and initial pH of the medium were further optimized using response surface methodology (RSM). Medium consisted of 21.3 g L(-1) GG and 57 g L(-1) peptone with initial culture pH of 5.5 was optimum for ?-mannanase production (2063 nkat mL(-1)) by A. niger. The ?-mannanase production obtained in this study using A. niger was significantly higher than those reported in the literature. PMID:20970530

Mohamad, Siti Norita; Ramanan, Ramakrishnan Nagasundara; Mohamad, Rosfarizan; Ariff, Arbakariya B

2011-02-28

287

Biological leaching of heavy metals from a contaminated soil by Aspergillus niger.  

PubMed

Bioleaching of heavy metals from a contaminated soil in an industrial area using metabolites, mainly weak organic acids, produced by a fungus Aspergillus niger was investigated. Batch experiments were performed to compare the leaching efficiencies of one-step and two-step processes and to determine the transformation of heavy metal chemical forms during the bioleaching process. After the one or two-step processes, the metal removals were compared using analysis of variance (ANOVA) and least-significance difference (LSD). A. niger exhibits a good potential in generating a variety of organic acids effective for metal solubilisation. Results showed that after the one-step process, maximum removals of 56%, 100%, 30% and 19% were achieved for copper, cadmium, lead and zinc, respectively. After the two-step process, highest removals of 97.5% Cu, 88.2% Cd, 26% Pb, and 14.5% Zn were obtained. Results of sequential extraction showed that organic acids produced by A. niger were effective in removing the exchangeable, carbonate, and Fe/Mn oxide fractions of Cu, Cd, Pb and Zn; and after both processes the metals remaining in the soil were mainly bound in stable fractions. Such a treatment procedure indicated that leaching of heavy metals from contaminated soil using A. niger has the potential for use in remediation of contaminated soils. PMID:19232463

Ren, Wan-Xia; Li, Pei-Jun; Geng, Yong; Li, Xiao-Jun

2009-08-15

288

Production of Proteolytic Enzymes by a Keratin-Degrading Aspergillus niger  

PubMed Central

A fungal isolate with capability to grow in keratinous substrate as only source of carbon and nitrogen was identified as Aspergillus niger using the sequencing of the ITS region of the rDNA. This strain produced a slightly acid keratinase and an acid protease during cultivation in feather meal. The peak of keratinolytic activity occurred in 48?h and the maximum proteolytic activity in 96?h. These enzymes were partly characterized as serine protease and aspartic protease, respectively. The effects of feather meal concentration and initial pH on enzyme production were evaluated using a central composite design combined with response surface methodology. The optimal conditions were determined as pH 5.0 for protease and 7.8 for keratinase and 20?g/L of feather meal, showing that both models were predictive. Production of keratinases by A. niger is a less-exploited field that might represent a novel and promising biotechnological application for this microorganism.

Lopes, Fernanda Cortez; Silva, Lucas Andre Dedavid e; Tichota, Deise Michele; Daroit, Daniel Joner; Velho, Renata Voltolini; Pereira, Jamile Queiroz; Correa, Ana Paula Folmer; Brandelli, Adriano

2011-01-01

289

Inhibition of Aspergillus niger Phosphate Solubilization by Fluoride Released from Rock Phosphate  

PubMed Central

The simultaneous release of various chemical elements with inhibitory potential for phosphate solubilization from rock phosphate (RP) was studied in this work. Al, B, Ba, Ca, F, Fe, Mn, Mo, Na, Ni, Pb, Rb, Si, Sr, V, Zn, and Zr were released concomitantly with P during the solubilization of Araxá RP (Brazil), but only F showed inhibitory effects on the process at the concentrations detected in the growth medium. Besides P solubilization, fluoride decreased fungal growth, citric acid production, and medium acidification by Aspergillus niger. At the maximum concentration found during Araxá RP solubilization (22.9 mg F? per liter), fluoride decreased P solubilization by 55%. These findings show that fluoride negatively affects RP solubilization by A. niger through its inhibitory action on the fungal metabolism. Given that fluoride is a common component of RPs, the data presented here suggest that most of the microbial RP solubilization systems studied so far were probably operated under suboptimal conditions.

Mendes, Gilberto de Oliveira; Vassilev, Nikolay Bojkov; Bonduki, Victor Hugo Araujo; da Silva, Ivo Ribeiro; Ribeiro, Jose Ivo

2013-01-01

290

Air pressure pulsation solid state fermentation of feruloyl esterase by Aspergillus niger.  

PubMed

Air pressure pulsation solid state fermentation (APP-SSF) was applied to produce feruloyl esterase (FAE) by Aspergillus niger. With the optimization of some variables by orthogonal design, the optimal condition obtained was 0.2 MPa (gauge pressure) of high pressure intensity, 30 min of low pressure duration and 20s of high pressure duration. Based on the optimized condition, the APP-SSF achieved the reasonable enzyme yield of 881 mU/g at 48 h, which was 58% more than that by static solid state fermentation (static SSF) at 72 h. By comparison of two fermentation methods in temperature, O(2) and CO(2) concentration, and respiration intensity, it was concluded that APP-SSF enhanced heat and mass transfer of fermentation system and strengthened the metabolism of microorganisms. The APP-SSF had a greatly positive effect on FAE production by A. niger, by enhancing mass and heat transfer and activating growth and metabolism. PMID:18929480

Zeng, W; Chen, H Z

2009-02-01

291

Heterologous expression of manganese peroxidase in Aspergillus niger and its effect on phenanthrene removal from soil.  

PubMed

A strain of Aspergillus niger, previously isolated from sugarcane bagasse because of its capacity to degrade phenanthrene in soil by solid culture, was used to express a manganese peroxidase gene (mnp1) from Phanerochaete chrysosporium, aiming at increasing its polycyclic aromatic hydrocarbons degradation capacity. Transformants were selected based on their resistance to hygromycin B and the discoloration induced on Poly R-478 dye by the peroxidase activity. The recombinant A. niger SBC2-T3 strain developed MnP activity and was able to remove 95% of the initial phenanthrene (400 ppm) from a microcosm soil system after 17 days, whereas the wild strain removed 72% under the same conditions. Transformation success was confirmed by PCR amplification using gene-specific primers, and a single fragment (1,348 bp long, as expected) of the recombinant mnp1 was amplified in the DNA from transformants, which was absent from the parental strain. PMID:22286039

Cortés-Espinosa, Diana V; Absalón, Ángel E; Sanchez, Noé; Loera, Octavio; Rodríguez-Vázquez, Refugio; Fernández, Francisco J

2011-01-01

292

Lipase Production in Solid-State Fermentation Monitoring Biomass Growth of Aspergillus niger Using Digital Image Processing  

Microsoft Academic Search

The aim of this study was to monitor the biomass growth of Aspergillus niger in solid-state fermentation (SSF) for lipase production using digital image processing technique. The strain A. niger 11T53A14 was cultivated in SSF using wheat bran as support, which was enriched with 0.91% (m\\/v) of ammonium sulfate. The addition of several vegetable oils (castor, soybean, olive, corn, and

Júlio C. V. Dutra; Selma da C. Terzi; Juliana Vaz Bevilaqua; Mônica C. T. Damaso; Sônia Couri; Marta A. P. Langone; Lilian F. Senna

2008-01-01

293

Proteomic analysis of rutin-induced secreted proteins from Aspergillus flavus  

Microsoft Academic Search

Few studies have been conducted to identify the extracellular proteins and enzymes secreted by filamentous fungi, particularly with respect to dispensable metabolic pathways. Proteomic analysis has proven to be the most powerful method for identification of proteins in complex mixtures and is suitable for the study of the alteration of protein expression under different environmental conditions. The filamentous fungus Aspergillus

Martha L Medina; Urban A Kiernan; Wilson A Francisco

2004-01-01

294

Methanol production is enhanced by expression of an Aspergillus niger pectin methylesterase in tobacco cells.  

PubMed

Tobacco suspension culture cell (Nicotiana tabacum, BY2) was transformed with an Aspergillus niger pectin methylesterase (PME; EC 3.1.1.11) cDNA under the control of cauliflower mosaic virus (CaMV) 35S promoter. The transformant indicated a significant rise of PME and the level of methanol in the transformant increased by 28.7% compared to the vector control transformant. This is the first report of methanol overproduction in plant cells by means of genetic engineering. PMID:14636709

Hasunuma, Tomohisa; Fukusaki, Ei-ichiro; Kobayashi, Akio

2003-12-01

295

Production of verbenol, a high valued food flavourant from a fusant strain of Aspergillus niger.  

PubMed

A hyperperformer for the production of verbenol was produced from the fusion of two improved strains of Aspergillus niger. A 2-deoxy glucose de-repressed mutant [high sporulation (50%), viability (80%) showing a conversion of 15.6% of initial alpha-pinene to verbenol in 6 h under the conditions used] was fused with another strain enriched with alpha-pinene (26.4% of alpha pinene converted to verbenol) to obtain a final verbenol conversion yield of 48.6% of initial alpha pinene. PMID:12759788

Vidya, C M; Agrawal, R

2003-09-01

296

Exopectinases produced by Aspergillus niger in solid-state and submerged fermentation: a comparative study  

Microsoft Academic Search

  Exopectinase production by Aspergillus niger was compared in submerged fermentation (SmF) and solid-state fermentation (SSF). SSF was carried out using polyurethane foam\\u000a (PUF) as the solid support. The purpose was to study the effect of sucrose addition (0 or 40 g\\/l) and water activity level\\u000a (A\\u000a w=0.99 or 0.96) on the level of enzyme activity induced by 15 g\\/l of

G Díaz-Godínez; J Soriano-Santos; C Augur; G Viniegra-González

2001-01-01

297

[Isolation and characterization of mutants of Aspergillus niger deficient in extracellular proteases].  

PubMed

Several mutants of Aspergillus niger 3.795, deficient in extracellular protease expression, have been isolated and characterized biochemically after in vitro UV-mutagenesis of conidiospores and selected by halo-screening on the gelatin/casein plate and skim milk plate. Extracellular proteolytic activities of 3.795-1-23 and 3.795-1-30 are 5.4% and 8.4% of the parental strain and these strains may be used as the host for efficient expression of foreign proteins. PMID:12548962

Hong, B; Zhang, Y; Li, Y

2000-08-01

298

Induced reactive oxygen species improve enzyme production from Aspergillus niger cultivation.  

PubMed

Intracellular reactive oxygen species (iROS) induction by HOCl was used as a novel strategy to improve enzyme productivities in Aspergillus niger growing in a bioreactor. With induced iROS, the specific intracellular activities of alpha-amylase, protease, catalase, and glucose oxidase were increased by about 170%, 250%, 320%, and 260%, respectively. The optimum specific iROS level for achieving maximum cell concentration and enzyme production was about 15 mmol g cell-1. The type of iROS inducing the enzyme production was identified to be a derivative of the superoxide radical. PMID:12882014

Sahoo, Susmita; Rao, K Krishnamurthy; Suraishkumar, G K

2003-05-01

299

The non-metabolizable glucose analog D-glucal inhibits aflatoxin biosynthesis and promotes kojic acid production in Aspergillus flavus  

PubMed Central

Background Aflatoxins (AFs) are potent carcinogenic compounds produced by several Aspergillus species, which pose serious threats to human health. As sugar is a preferred carbohydrate source for AF production, we examined the possibility of using sugar analogs to inhibit AF biosynthesis. Results We showed that although D-glucal cannot be utilized by A. flavus as the sole carbohydrate source, it inhibited AF biosynthesis and promoted kojic acid production without affecting mycelial growth when applied to a glucose-containing medium. The inhibition occurred before the production of the first stable intermediate, norsolorinic acid, suggesting a complete inhibition of the AF biosynthetic pathway. Further studies showed that exogenous D-glucal in culture led to reduced accumulation of tricarboxylic acid (TCA) cycle intermediates and reduced glucose consumption, indicating that glycolysis is inhibited. Expression analyses revealed that D-glucal suppressed the expression of AF biosynthetic genes but promoted the expression of kojic acid biosynthetic genes. Conclusions D-glucal as a non-metabolizable glucose analog inhibits the AF biosynthesis pathway by suppressing the expression of AF biosynthetic genes. The inhibition may occur either directly through interfering with glycolysis, or indirectly through reduced oxidative stresses from kojic acid biosynthesis.

2014-01-01

300

Use of response surface methodology to study the effect of media composition on aflatoxin production by Aspergillus flavus.  

PubMed

Aflatoxins are one of the most important secondary metabolites. These extrolites are produced by a number of Aspergillus fungi. In this study, we demonstrate the effect of media components and enhanced aflatoxin yield shown by A. flavus using response surface methodology in response to different nutrients. Different components of a chemically defined media that influence the aflatoxin production were monitored using Plackett-Burman experimental design and further optimized by Box-Behnken factorial design of response surface methodology in liquid culture. Interactions were studied with five variables, namely sorbitol, fructose, ammonium sulfate, KH(2)PO(4), and MgSO(4).7H(2)O. Maximum aflatoxin production was envisaged in medium containing 4.94 g/l sorbitol, 5.56 g/l fructose, 0.62 g/l ammonium sulfate, 1.33 g/l KH(2)PO(4), and 0.65 g/l MgSO(4)·7H(2)O using response surface plots and the point prediction tool of the DESIGN EXPERT 8.1.0 (Stat-Ease, USA) software. However, a production of 5.25 ?g/ml aflatoxin production was obtained, which was in agreement with the prediction observed in verification experiment. The other component (MgSO(4).7H(2)O) was found to be an insignificant variable. PMID:23334723

Ahmad, Mahboob; Ahmad, Malik M; Hamid, Rifat; Abdin, M Z; Javed, Saleem

2013-02-01

301

Identification of Genes Associated with Morphology in Aspergillus Niger by Using Suppression Subtractive Hybridization  

SciTech Connect

The morphology of citric acid production strains of Aspergillus niger is sensitive to a variety of factors including the concentration of manganese (Mn2+). Upon increasing the Mn2+ concentration in A. niger (ATCC 11414) cultures to 14 ppb or higher, the morphology switches from pelleted to filamentous, accompanied by a rapid decline in citric acid production. Molecular mechanisms through which Mn2+ exerts effects on morphology and citric acid production in A. niger have not been well defined, but our use of suppression subtractive hybridization has identified 22 genes responsive to Mn2+. Fifteen genes were differentially expressed when A. niger was grown in media containing 1000 ppb Mn2+ (filamentous form) and seven genes in 10 ppb Mn2+ (pelleted form). Of the fifteen filamentous-associated genes, seven are novel and eight share 47-100% identity to genes from other organisms. Five of the pellet-associated genes are novel, and the other two genes encode a pepsin-type protease and polyubiquitin. All ten genes with deduced functions are either involved in amino acid metabolism/protein catabolism or cell regulatory processes. Northern-blot analysis showed that the transcripts of all 22 genes were rapidly enhanced or suppressed by Mn2+. Steady-state mRNA levels of six selected filamentous associated genes remained high during five days of culture in a filamentous state and low under pelleted growth conditions. The opposite behavior was observed for four selected pellet-associated genes. The full-length cDNA of the filamentous-associated clone, Brsa-25 was isolated. Antisense expression of Brsa-25 permitted pelleted growth and increased citrate production at higher concentrations of Mn2+ than could be tolerated by the parent strain. The results suggest the involvement of the newly isolated genes in regulation of A. niger morphology.

Dai, Ziyu; Mao, Xingxue; Magnuson, Jon K.; Lasure, Linda L.

2004-04-01

302

Gene overexpression and biochemical characterization of the biotechnologically relevant chlorogenic acid hydrolase from Aspergillus niger.  

PubMed

The full-length gene that encodes the chlorogenic acid hydrolase from Aspergillus niger 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 x 10(6) 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. PMID:17630312

Benoit, Isabelle; Asther, Michčle; Bourne, Yves; Navarro, David; Canaan, Stéphane; Lesage-Meessen, Laurence; Herweijer, Marga; Coutinho, Pedro M; Asther, Marcel; Record, Eric

2007-09-01

303

Dual transcriptional profiling of a bacterial/fungal confrontation: Collimonas fungivorans versus Aspergillus niger  

PubMed Central

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 Aspergillus niger, 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

2011-01-01

304

Effect of oxygen transfer rate on the composition of the pectolytic enzyme complex of Aspergillus niger  

SciTech Connect

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 Aspergillus niger 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 Aspergillus niger 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.

Zetelaki-Horvath, K.; Vas, K.

1981-01-01

305

beta-Galactosidase from Aspergillus niger in adult lactose malabsorption: a double-blind crossover study.  

PubMed

An assessment was made of the efficacy of a beta-galactosidase, obtained from Aspergillus niger and added to intact milk, in decreasing lactose malabsorption and intolerance. Sixteen adult patients with malabsorption and intolerance to this sugar were studied in a double-blind crossover study vs. placebo. A 5-hour hydrogen breath test was used to assess malabsorption of lactose contained in 400 ml milk. When compared with placebo, the addition of exogenous lactase to intact milk caused a statistically significant reduction in the maximum breath H2 concentration (P less than 0.01) and in the cumulative H2 excretion (P less than 0.005). In the same way, the cumulative index for gastrointestinal intolerance was significantly lower (P less than 0.005) after the ingestion of lactase-added milk. This study demonstrates that enzyme replacement therapy, with beta-galactosidases obtained from Aspergillus niger, is effective in decreasing lactose malabsorption and its consequent intolerance in adult subjects with lactase deficiency. PMID:1543816

Corazza, G R; Benati, G; Sorge, M; Strocchi, A; Calza, G; Gasbarrini, G

1992-02-01

306

Effect of aw and CO2 level on Aspergillus flavus growth and aflatoxin production in high moisture maize post-harvest.  

PubMed

The potential for using modified atmospheres of 25-75% CO2 (balanced with N2) and water activity (aw, 0.95, 0.92) to control Aspergillus flavus development and aflatoxin B1 production has been evaluated (a) on synthetic medium and (b) on maize grain during storage for up to 21 days at 25 degrees C. On agar medium up to 75% CO2 at both 0.95 and 0.92 aw significant inhibition of growth was obtained (P<0.05). In stored grain inoculated with spores of A. flavus there was significantly higher populations of the species at 0.95 aw than 0.92 aw. Up to 75% CO2 resulted in an inhibition of the populations of A. flavus isolated from the grain. Contrasting aflatoxin B1 production was obtained on agar and in stored maize grain. On agar, greatest amounts were produced at 0.92 aw, while more was produced at 0.95 aw on maize grain. Overall, the efficacy of controlled atmospheres x aw showed that treatment with 25% CO2 could be sufficient to efficiently reduce A. flavus development but at least 50% CO2 was required to obtain a significant reduction of aflatoxin synthesis. PMID:18162193

Giorni, Paola; Battilani, Paola; Pietri, Amedeo; Magan, Naresh

2008-02-29

307

Heterologous expression of Trametes versicolor laccase in Pichia pastoris and Aspergillus niger.  

PubMed

Convenient expression systems for efficient heterologous production of different laccases are needed for their characterization and application. The laccase cDNAs lcc1 and lcc2 from Trametes versicolor were expressed in Pichia pastoris and Aspergillus niger under control of their respective glyceraldehyde-3-phosphate dehydrogenase promoters and with the native secretion signal directing catalytically active laccase to the medium. P. pastoris batch cultures in shake-flasks gave higher volumetric activity (1.3 U/L) and a better activity to biomass ratio with glucose than with glycerol or maltose as carbon source. Preliminary experiments with fed-batch cultures of P. pastoris in bioreactors yielded higher activity (2.8 U/L) than the shake-flask experiments, although the levels remained moderate and useful primarily for screening purposes. With A. niger, high levels of laccase (2700 U/L) were produced using a minimal medium containing sucrose and yeast extract. Recombinant laccase from A. niger harboring the lcc2 cDNA was purified to homogeneity and it was found to be a 70-kDa homogeneous enzyme with biochemical and catalytic properties similar to those of native T. versicolor laccase A. PMID:16915640

Bohlin, Christina; Jönsson, Leif J; Roth, Robyn; van Zyl, Willem H

2006-01-01

308

[Cloning and sequence analysis of the phytase phyA gene of Aspergillus niger N25].  

PubMed

The phyA encoding phytase of Aspergillus niger N25 was amplified by the polymerase chain reaction (PCR) with primers designed according to the sequences of the phyA in GenBank. The amplified fragment was cloned and sequenced. The results show that: the coding region is 1506 bp in size, includes a 102 bp intron, and encodes a peptide of 476 amino acid residues, in which there is a signal peptide with 19 amino acids and a mature peptide of 448 amino acids. Comparison of this sequence with the phyA of the natural A. niger NRRL3135 (GenBank Accession: M94550), the most highly secreting-phytase strain, shows that the nucleotide homology is as high as 96.746%, and the amino acid homology comes up to 97.64%. The phyA of A. niger N25 strain in this paper is appropriate to be used to construct the phytase gene-engineering bacteria. PMID:12561778

Wang, H; Wu, Q; Liu, S; Xie, J; Ma, M

2001-06-01

309

Glucoamylase starch-binding domain of Aspergillus niger B1: molecular cloning and functional characterization.  

PubMed Central

Carbohydrate-binding modules (CBMs) are protein domains located within a carbohydrate-active enzyme, with a discrete fold that can be separated from the catalytic domain. Starch-binding domains (SBDs) are CBMs that are usually found at the C-terminus in many amylolytic enzymes. The SBD from Aspergillus niger B1 (CMI CC 324262) was cloned and expressed in Escherichia coli as an independent domain and the recombinant protein was purified on starch. The A. niger B1 SBD was found to be similar to SBD from A. kawachii, A. niger var. awamori and A. shirusami (95-96% identity) and was classified as a member of the CBM family 20. Characterization of SBD binding to starch indicated that it is essentially irreversible and that its affinity to cationic or anionic starch, as well as to potato or corn starch, does not differ significantly. These observations indicate that the fundamental binding area on these starches is essentially the same. Natural and chemically modified starches are among the most useful biopolymers employed in the industry. Our study demonstrates that SBD binds effectively to both anionic and cationic starch.

Paldi, Tzur; Levy, Ilan; Shoseyov, Oded

2003-01-01

310

An optimized method for Aspergillus niger spore production on natural carrier substrates.  

PubMed

Aspergillus niger spores have wide ranging applications in the fermentation industry as well as in wastewater treatment. We present an optimized method for production of A. niger spores on natural substrates such as rice, split pea, and millet. The specific productivity (number of spores per gram of dry substrate) was 31-fold greater and volumetric productivity was 750-fold greater compared to agar slopes. The important process variables were incubation temperature, moisture content, and inoculum quantity. We find that the optimal condition for total spore count is different from the viable spore count for millet. The optimum lies in a narrow region defined by the process parameters. Of the three substrates tested split pea gave the highest specific spore productivity of 3.1 x 10(10) spores per gram of dry substrate. This is the first report of systematic study on the effect of process parameters on spore viability. The method of A. niger spore production on natural substrate appears advantageous as compared to the currently practiced method in terms of scale-up, cost, and ease of operation. PMID:14656142

Bapat, Prashant M; Kundu, Sucharita; Wangikar, Pramod P

2003-01-01

311

Mechanisms of interaction of chromium with Aspergillus niger var tubingensis strain Ed8.  

PubMed

Experiments were conducted to determine the mechanisms of interaction with chromium of Aspergillus niger var tubingensis strain Ed8 in batch culture and in bioreactor experiments. Results obtained in this work showed that the interaction of A. niger var tubingensis Ed8 with Cr(VI) is based mainly in a reduction process and also, secondly, in a sorption process. Using electron microscopy techniques the ultrathin sections obtained from the mycelium biomass produced by the fungus in batch cultures showed the ability to incorporate Cr intracellulary, into low electron-dense inclusions, but not extracellularly. On the other hand, cultures without Cr(VI) of A. niger var tubingensis Ed8, grown in a bubble column bioreactor, reduced Cr(VI) immediately after repeated addition of this oxyanion; after six loads, 460 mg Cr(VI) was reduced to Cr(III) in 60 h, corresponding to a reduction rate of 2.62 mg Cr(VI)g(-1) dry biomass h(-1). PMID:24607453

Coreńo-Alonso, A; Solé, A; Diestra, E; Esteve, I; Gutiérrez-Corona, J F; Reyna López, G E; Fernández, F J; Tomasini, A

2014-04-01

312

Effect of water activity on ochratoxin A production by Aspergillus niger aggregate species.  

PubMed

The effect of water activity (a(w)) (0.82-0.99) on growth and ochratoxin A (OTA) production by twelve Aspergillus niger 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 rDNA Restriction Fragment Length Polymorphism (RFLP) pattern. They were characterized by Random Amplification of Polymorphic DNA (RAPD) and ITS-5.8 S rDNA and 28 S rDNA (D1/D2) sequencing. Regardless of the a(w) value tested, YES was a better culture medium than CYA for OTA production. The a(w) range for OTA production was narrower than that for growth. OTA was produced from 0.90, 0.92, 0.94 or 0.96 to 0.99 a(w) depending on the strain and the culture medium. The molecular study differentiated strains into two groups which corresponded to the RFLP types N and T although it did not distinguish them by their source of isolation or OTA producing abilities. Our results show that A. niger aggregate strains are able to grow and produce OTA over a wide a(w) range. These results will lead to a better understanding of the contribution of A. niger aggregate in OTA contamination of food and feed. PMID:16443301

Esteban, A; Abarca, M L; Bragulat, M R; Cabańes, F J

2006-04-25

313

Regulation of the alpha-glucuronidase-encoding gene ( aguA) from Aspergillus niger.  

PubMed

The alpha-glucuronidase gene aguA from Aspergillus niger was cloned and characterised. Analysis of the promoter region of aguA revealed the presence of four putative binding sites for the major carbon catabolite repressor protein CREA and one putative binding site for the transcriptional activator XLNR. In addition, a sequence motif was detected which differed only in the last nucleotide from the XLNR consensus site. A construct in which part of the aguA coding region was deleted still resulted in production of a stable mRNA upon transformation of A. niger. The putative XLNR binding sites and two of the putative CREA binding sites were mutated individually in this construct and the effects on expression were examined in A. niger transformants. Northern analysis of the transformants revealed that the consensus XLNR site is not actually functional in the aguA promoter, whereas the sequence that diverges from the consensus at a single position is functional. This indicates that XLNR is also able to bind to the sequence GGCTAG, and the XLNR binding site consensus should therefore be changed to GGCTAR. Both CREA sites are functional, indicating that CREA has a strong influence on aguA expression. A detailed expression analysis of aguA in four genetic backgrounds revealed a second regulatory system involved in activation of aguA gene expression. This system responds to the presence of glucuronic and galacturonic acids, and is not dependent on XLNR. PMID:12242504

de Vries, R P; van de Vondervoort, P J I; Hendriks, L; van de Belt, M; Visser, J

2002-09-01

314

Effects of a defective ERAD pathway on growth and heterologous protein production in Aspergillus niger  

PubMed Central

Endoplasmic reticulum associated degradation (ERAD) is a conserved mechanism to remove misfolded proteins from the ER by targeting them to the proteasome for degradation. To assess the role of ERAD in filamentous fungi, we have examined the consequences of disrupting putative ERAD components in the filamentous fungus Aspergillus niger. Deletion of derA, doaA, hrdC, mifA, or mnsA in A. niger yields viable strains, and with the exception of doaA, no significant growth phenotype is observed when compared to the parental strain. The gene deletion mutants were also made in A. niger strains containing single- or multicopies of a glucoamylase–glucuronidase (GlaGus) gene fusion. The induction of the unfolded protein response (UPR) target genes (bipA and pdiA) was dependent on the copy number of the heterologous gene and the ERAD gene deleted. The highest induction of UPR target genes was observed in ERAD mutants containing multiple copies of the GlaGus gene. Western blot analysis revealed that deletion of the derA gene in the multicopy GlaGus overexpressing strain resulted in a 6-fold increase in the intracellular amount of GlaGus protein detected. Our results suggest that impairing some components of the ERAD pathway in combination with high expression levels of the heterologous protein results in higher intracellular protein levels, indicating a delay in protein degradation.

Carvalho, Neuza D. S. P.; Arentshorst, Mark; Kooistra, Rolf; Stam, Hein; Sagt, Cees M.; van den Hondel, Cees A. M. J. J.

2010-01-01

315

Comparative analysis of calcium gluconate and sodium gluconate techniques for the production of gluconic acid by Aspergillus niger  

Microsoft Academic Search

Sodium gluconate and calcium gluconate methods are important techniques available for gluconic acid fermentation. The comparative analysis of these fermentations has been addressed using Aspergillus niger. The techniques are equally influenced by the spores age in slant growth, inoculum level in germination and production media, different levels of Fe, Cu, Zn and Mn. Sodium gluconate method is promising with respect

D. Subba Rao; T. Panda

1993-01-01

316

Influence of sucrose concentration and phosphate limitation on citric acid production by immobilized cells of Aspergillus niger  

Microsoft Academic Search

Immobilized cells of Aspergillus niger needed a lower initial sucrose concentration than free cells in order to obtain maximal yields of citric acid production. High sucrose concentrations led to reduced yields and increased polyol formation (glycerol, erythritol, arabitol). Continuous fermentation with media containing low sugar concentrations prevented the formation of polyols. The change from nitrogen-limited to phosphate-limited precultivation of immobilized

S. Honecker; B. Bisping; Zhu Yang; H.-J. Rehm

1989-01-01

317

The influence of type and concentration of the carbon source on production of citric acid by Aspergillus niger  

Microsoft Academic Search

The influence of various carbon sources and their concentration on the production of citrate by Aspergillus niger has been investigated. The sugars maltose, sucrose, glucose, mannose and fructose (in the given order) were carbon sources giving high yields of citric acid. Optimal yields were observed at sugar concentrations of 10% (w\\/v), with the exception of glucose (7.5%). No citric acid

Ding-Bang Xu; Cynthia P. Madrid; Max Rfihr; Christian P. Kubicek

1989-01-01

318

Regulation of citric acid production by oxygen: Effect of dissolved oxygen tension on adenylate levels and respiration in Aspergillus niger  

Microsoft Academic Search

The mechanism of the control of citric acid accumulation by oxygen was investigated by means of pilot plant fermentation using Aspergillus niger. The critical dissolved oxygen tension (DOT) for oxygen uptake of this fungus was about 18–21 and 23–26 mbar for trophophase and idiophase, respectively. Minimal DOT for citric acid production was about 25 mbar. Citric acid production increased steadily

C. P. Kubicek; O. Zehentgruber; Housam El-Kalak; M. Röhr

1980-01-01

319

Bioconversion of waste office paper to gluconic acid in a turbine blade reactor by the filamentous fungus Aspergillus niger  

Microsoft Academic Search

Gluconic acid production was investigated using an enzymatic hydrolysate of waste office automation paper in a culture of Aspergillus niger. In repeated batch cultures using flasks, saccharified solution medium (SM) did not show any inhibitory effects on gluconic acid production compared to glucose medium (GM). The average gluconic acid yields were 92% (SM) and 80% (GM). In repeated batch cultures

Yuko Ikeda; Enock Y. Park; Naoyuki Okuda

2006-01-01

320

Production of bio-ethanol from corncobs using Aspergillus niger and Saccharomyces cerevisae in simultaneous saccharification and fermentation  

Microsoft Academic Search

Maize is the most abundant cereal grown in Ghana and is accompanied by enormous amount of agrowastes of which corncobs form 30%. This agrowaste which is currently under utilized was used to produce bio-ethanol. Aspergillus niger isolated from soil sampled from Ejura farms was used to hydrolyze the corncobs into simple sugars. Filtrate obtained from corncobs broth fermented by A.

H. D. Zakpaa; E. E. Mak-Mensah; F. S. Johnson

2009-01-01

321

Inhibition of aflatoxin production in Aspergillus flavus infected cotton bolls after treatment with neem ( Azadirachta indica ) leaf extracts  

Microsoft Academic Search

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

Hampden J. Zeringue; Deepak Bhatnagar

1990-01-01

322

Cytosolic streaming in vegetative mycelium and aerial structures of Aspergillus niger  

PubMed Central

Aspergillus niger 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.

Bleichrodt, R.; Vinck, A.; Krijgsheld, P.; van Leeuwen, M.R.; Dijksterhuis, J.; Wosten, H.A.B.

2013-01-01

323

Differential Expression of Three ?-Galactosidase Genes and a Single ?-Galactosidase Gene from Aspergillus niger  

PubMed Central

A gene encoding a third ?-galactosidase (AglB) from Aspergillus niger has been cloned and sequenced. The gene consists of an open reading frame of 1,750 bp containing six introns. The gene encodes a protein of 443 amino acids which contains a eukaryotic signal sequence of 16 amino acids and seven putative N-glycosylation sites. The mature protein has a calculated molecular mass of 48,835 Da and a predicted pI of 4.6. An alignment of the AglB amino acid sequence with those of other ?-galactosidases revealed that it belongs to a subfamily of ?-galactosidases that also includes A. niger AglA. A. niger AglC belongs to a different subfamily that consists mainly of prokaryotic ?-galactosidases. The expression of aglA, aglB, aglC, and lacA, the latter of which encodes an A. niger ?-galactosidase, has been studied by using a number of monomeric, oligomeric, and polymeric compounds as growth substrates. Expression of aglA is only detected on galactose and galactose-containing oligomers and polymers. The aglB gene is expressed on all of the carbon sources tested, including glucose. Elevated expression was observed on xylan, which could be assigned to regulation via XlnR, the xylanolytic transcriptional activator. Expression of aglC was only observed on glucose, fructose, and combinations of glucose with xylose and galactose. High expression of lacA was detected on arabinose, xylose, xylan, and pectin. Similar to aglB, the expression on xylose and xylan can be assigned to regulation via XlnR. All four genes have distinct expression patterns which seem to mirror the natural substrates of the encoded proteins.

de Vries, Ronald P.; van den Broeck, Hetty C.; Dekkers, Ester; Manzanares, Paloma; de Graaff, Leo H.; Visser, Jaap

1999-01-01

324

Morphology engineering - Osmolality and its effect on Aspergillus niger morphology and productivity  

PubMed Central

Background The filamentous fungus Aspergillus niger 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.

2011-01-01

325

High incidence of Aspergillus flavus and aflatoxins in stored groundnut in Ghana and the use of a microbial assay to assess the inhibitory effects of plant extracts on aflatoxin synthesis.  

PubMed

Groundnut samples from 21 selected markets in the 10 regions of Ghana yielded high levels of the aflatoxigenic fungus Aspergillus flavus on half-strength potato dextrose agar. The fungus was associated with 31.7 and 12.8%, respectively, of all damaged and undamaged kernels assayed. Only 0.24% of total kernels assayed yielded A. parasiticus. Other fungi detected from total kernels assayed were A. niger (34%), A. candidus (1.45%), A. tamarii (3.93%), A. ochraceous (5.26%), Fusarium spp. (1.7%) Penicillium spp. (5.19%), a Mucor sp. (2.3%), a Trichoderma sp. (0.2%), Rhizopus stolonifer (12%) and certain unidentifiable fungi (11.72%). Total aflatoxin levels ranging from 5.7 to 22, 168 ppb were identified with damaged kernel samples. The mycotoxin was not detected in 50% of undamaged kernel samples tested and very low levels mostly ranging from 0.1 to 12.2 ppb were associated with the undamaged samples that tested positive for aflatoxins. In a novel in vitro microbial assay to determine the effectiveness of certain plant extracts against aflatoxin synthesis, extracts from Xylopia aethiopica, Monodera myristica, Cinnamomum verum and Piper nigrum permitted fungal growth in 1.5% potato-dextrose broth while completely suppressing NOR formation. These extracts, however, could not suppress NOR formation in a yeast extract sucrose medium. PMID:8981776

Awuah, R T; Kpodo, K A

1996-01-01

326

Aspergillus flavus VelB acts distinctly from VeA in conidiation and may coordinate with FluG to modulate sclerotial production.  

PubMed

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 Aspergillus flavus 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

2013-01-01

327

Oxalic acid production by citric acid-producing Aspergillus niger overexpressing the oxaloacetate hydrolase gene oahA.  

PubMed

The filamentous fungus Aspergillus niger is used worldwide in the industrial production of citric acid. However, under specific cultivation conditions, citric acid-producing strains of A. niger accumulate oxalic acid as a by-product. Oxalic acid is used as a chelator, detergent, or tanning agent. Here, we sought to develop oxalic acid hyperproducers using A. niger as a host. To generate oxalic acid hyperproducers by metabolic engineering, transformants overexpressing the oahA gene, encoding oxaloacetate hydrolase (OAH; EC 3.7.1.1), were constructed in citric acid-producing A. niger WU-2223L as a host. The oxalic acid production capacity of this strain was examined by cultivation of EOAH-1 under conditions appropriate for oxalic acid production with 30 g/l glucose as a carbon source. Under all the cultivation conditions tested, the amount of oxalic acid produced by EOAH-1, a representative oahA-overexpressing transformant, exceeded that produced by A. niger WU-2223L. A. niger WU-2223L and EOAH-1 produced 15.6 and 28.9 g/l oxalic acid, respectively, during the 12-day cultivation period. The yield of oxalic acid for EOAH-1 was 64.2 % of the maximum theoretical yield. Our method for oxalic acid production gave the highest yield of any study reported to date. Therefore, we succeeded in generating oxalic acid hyperproducers by overexpressing a single gene, i.e., oahA, in citric acid-producing A. niger as a host. PMID:24615146

Kobayashi, Keiichi; Hattori, Takasumi; Honda, Yuki; Kirimura, Kohtaro

2014-05-01

328

Production of a new type of acid carboxypeptidase of molds of the Aspergillus niger group.  

PubMed

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

1973-09-01

329

Amylolysis of raw corn by Aspergillus niger for simultaneous ethanol fermentation  

SciTech Connect

The novelty of this approach was hydrolysis of the raw starch in ground corn to fermentable sugars that are simultaneously fermented to ethanol by yeast in a nonsterile environment. Thus, the conventional cooking step can be eliminated for energy conservation. A koji of Aspergillus niger grown on whole corn for 3 days was the crude enzyme source. A ratio of 0.2 g dry koji/g total solids was found sufficient. Optimum pH was 4.2. Ethanol concentration was 7.7% (w/w) in the aqueous phase with 92% raw starch conversion. Agitation increased rate. Sacharification was the rate-limiting step. The initial ethanol concentration preventing fermentation was estimated to be 8.3% by weight. (Refs. 96).

Han, I.Y.; Steinberg, M.P.

1987-01-01

330

Structure-activity relationship of citrus polymethoxylated flavones and their inhibitory effects on Aspergillus niger.  

PubMed

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 Aspergillus niger 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

Liu, Li; Xu, Xiaoyun; Cheng, Dan; Yao, Xiaolin; Pan, Siyi

2012-05-01

331

Development of an unmarked gene deletion system for the filamentous fungi Aspergillus niger and Talaromyces versatilis.  

PubMed

In this article, we present a method to delete genes in filamentous fungi that allows recycling of the selection marker and is efficient in a nonhomologous end-joining (NHEJ)-proficient strain. We exemplify the approach by deletion of the gene encoding the transcriptional regulator XlnR in the fungus Aspergillus niger. To show the efficiency and advantages of the method, we deleted 8 other genes and constructed a double mutant in this species. Moreover, we showed that the same principle also functions in a different genus of filamentous fungus (Talaromyces versatilis, basionym Penicillium funiculosum). This technique will increase the versatility of the toolboxes for genome manipulation of model and industrially relevant fungi. PMID:24682295

Delmas, Stéphane; Llanos, Agustina; Parrou, Jean-Luc; Kokolski, Matthew; Pullan, Steven T; Shunburne, Lee; Archer, David B

2014-06-01

332

Screening, mutagenesis and protoplast fusion of Aspergillus niger for the enhancement of extracellular glucose oxidase production.  

PubMed

Various strains of Aspergillus niger were screened for extracellular glucose oxidase (GOD) activity. The most effective producer, strain FS-3 (15.9 U mL(-1)), was mutagenized using UV-irradiation or ethyl methane sulfonate. Of the 400 mutants obtained, 32 were found to be resistant to 2-deoxy D: -glucose, and 17 of these exhibited higher GOD activities (from 114.5 to 332.1%) than the original FS-3 strain. Following determination of antifungal resistance of the highest producing mutants, four mutants were selected and used in protoplast fusions in three different intraspecific crosses. All fusants showed higher activities (from 285.5 to 394.2%) than the original strain. Moreover, of the 30 fusants isolated, 19 showed higher GOD activity than their corresponding higher-producing parent strain. PMID:15952011

Khattab, A A; Bazaraa, W A

2005-07-01

333

Biosorption of C.I. Direct Blue 199 from aqueous solution by nonviable Aspergillus niger.  

PubMed

The capacity and mechanism with which nonviable Aspergillus niger removed the textile dye, C.I. Direct Blue 199, from aqueous solution was investigated using different parameters, such as initial dye concentration, pH and temperature. In batch experiments, the biosorption capacity increased with decrease in pH, and the maximum dye uptake capacity of the biosorbent was 29.96 mg g(-1) at 400 mg L(-1) dye concentration and 45 degrees C. The Langmuir and Freundlich models were able to describe the biosorption equilibrium of C.I. Direct Blue 199 onto the fungal biomass. Biosorption followed a pseudo-second order kinetic model with high correlation coefficients (r(2)>0.99). Thermodynamic studies revealed that the biosorption process was successful, spontaneous and endothermic in nature. PMID:19879044

Xiong, Xiao-Jing; Meng, Xue-Jiao; Zheng, Tian-Ling

2010-03-15

334

Novel oligomannose-type sugar chains derived from glucose oxidase of Aspergillus niger.  

PubMed

The primary structure of the N-linked sugar chains of glucose oxidase from Aspergillus niger was investigated. These sugar chains were released from the polypeptide backbone by hydrazinolysis, and the reducing ends of the sugar chains were pyridylaminated. HPLC of the pyridylamino sugar chains with an amide-silica column showed at least seven sugar chain peaks. Chemical and exoglycosidase digestion and 400 lMHz H-NMR studies of the sugar chains of lower molecular weight showed that these were novel oligomannose-type sugar chains, (Man)5-7 (GlcNAc)2, with the structure: +/- Man alpha 1----3Man alpha 1----3(Man alpha 1----6)Man alpha 1----6(+/- Man alpha 1----3Man alpha 1---3)Man )Man beta 1----4GlcNAc beta 1----4GlcNAc. PMID:1772443

Takegawa, K; Kondo, A; Iwamoto, H; Fujiwara, K; Hosokawa, Y; Kato, I; Hiromi, K; Iwahara, S

1991-09-01

335

[Effect of detergents on the hydroxylation of indolyl-3-acetic acid by an Aspergillus niger culture].  

PubMed

A possibility to increase the hydroxylating activity of Aspergillus niger IBFM F-212 under the action of detergents was studied during transformation of indolyl-3-acetic acid (IAA). The following non-ionogenic surface-active compounds were mainly used: Tweens, Spans, polyethyleneglycol (PEG-400). The effect of the detergents was studied at the stages of growth, transformation and preincubation. At the stage of growth, the best effect was produced by Tween-80. At the stages of transformation and preincubation, the hydroxylating activity increased 1.5 times under the action of a number of Spans and PEG-400. No total positive effect of the detergents on the enzyme activity was found at the stages of growth and transformation. The results suggest that the cellular permeability changes under the action of detergents and the hydroxylating activity of the culture increases as the result. PMID:7412617

Baklashova, T G; Koshcheenko, K A

1980-01-01

336

Temperature-stress tolerance of the fungal strain Aspergillus niger 26: physiological and ultrastructural changes.  

PubMed

The study focuses on the morphological and physiological cell responses to oxidative stress induced by high temperature treatment in the industrially relevant fungus Aspergillus niger 26. Temperatures above 30 °C lead to growth suppression and changes in morphological characteristics: decrease in the size of hyphal elements and increase in "active length" by switching from slightly branched long filaments to a multitude of branched forms containing active cytoplasm. Transmission electron microscopy of fungal cultures heated at 40 °C demonstrated abnormal wavy septation with reduced amount of chitin (as shown by WGA-gold labelling), intrahyphal hyphae development, disintegration of mitochondria and extensive autolysis. Temperature-dependent decrease in the total intracellular protein content and a sharp increase (six to tenfold) in oxidatively damaged proteins were also demonstrated. Elevated temperatures caused a two and threefold increase in catalase and superoxide dismutase activities, respectively. PMID:24366816

Abrashev, Radoslav; Stoitsova, Stoyanka; Krumova, Ekaterina; Pashova, Svetlana; Paunova-Krasteva, Tsvetelina; Vassilev, Spassen; Dolashka-Angelova, Pavlina; Angelova, Maria

2014-05-01

337

Refinement of the crystal structures of biomimetic weddellites produced by microscopic fungus Aspergillus niger  

NASA Astrophysics Data System (ADS)

The single-crystal structures of four biomimetic weddellites CaC2O4 · (2 + x)H2O with different contents of zeolitic water ( x = 0.10-0.24 formula units) produced by the microscopic fungus Aspergillus niger were refined from X-ray diffraction data ( R = 0.029-0.038). The effect of zeolitic water content on the structural stability of weddellite was analyzed. The parameter a was shown to increase with increasing x due to the increase in the distance between water molecules along this direction. The water content and structural parameters of the synthesized weddellites are similar to those of weddellites from biofilms and kidney stones.

Rusakov, A. V.; Frank-Kamenetskaya, O. V.; Gurzhiy, V. V.; Zelenskaya, M. S.; Izatulina, A. R.; Sazanova, K. V.

2014-05-01

338

Inhibitory effects of sulfur nanoparticles on membrane lipids of Aspergillus niger: a novel route of fungistasis.  

PubMed

Orthorhombic (spherical; ~10 nm) and monoclinic (cylindrical; ~50 nm) sulfur nanoparticles (SNPs) were synthesized and examined for their effects on the total lipid content and desaturase enzymes of Aspergillus niger. Synthesized SNPs were characterized for size with transmission electron microscopy, elemental composition with energy dispersive X-ray spectroscopy and allotropic nature with X-ray diffraction pattern. Both the SNPs considerably reduced total lipid content of the treated fungal isolates with significant down regulation of the expression of various desaturase enzymes (linoleoyl-CoA desaturase, stearoyl-CoA 9-desaturase and phosphatidylcholine desaturase). Unusual high accumulation of saturated fatty acids with depleted lipid layer can be inferred as one of the major reasons of SNPs mediated fungistasis. PMID:22538469

Roy Choudhury, Samrat; Ghosh, Mahua; Goswami, Arunava

2012-07-01

339

Cloning and characterization of oah, the gene encoding oxaloacetate hydrolase in Aspergillus niger.  

PubMed

The enzyme oxaloacetate hydrolase (EC 3.7.1.1), which is involved in oxalate formation, was purified from Aspergillus niger. The native enzyme has a molecular mass of 360-440 kDa, and the denatured enzyme has a molecular mass of 39 kDa, as determined by gel electrophoresis. Enzyme activity is maximal at pH 7.0 and 45 degrees C. The fraction containing the enzyme activity contained at least five proteins. The N-terminal amino acid sequences of four of these proteins were determined. The amino acid sequences were aligned with EST sequences from A. niger, and an EST sequence that showed 100% identity to all four sequences was identified. Using this EST sequence the gene encoding oxaloacetate hydrolase (oah) was cloned by inverse PCR. It consists of an ORF of 1227 bp with two introns of 92 and 112 bp, respectively. The gene encodes a protein of 341 amino acids with a molecular mass of 37 kDa. Under the growth conditions tested, the highest oah expression was found for growth on acetate as carbon source. The gene was expressed only at pH values higher than 4.0. PMID:10778746

Pedersen, H; Hjort, C; Nielsen, J

2000-03-01

340

Production of Proteolytic Enzymes by a Keratin-Degrading Aspergillus niger.  

PubMed

A fungal isolate with capability to grow in keratinous substrate as only source of carbon and nitrogen was identified as Aspergillus niger using the sequencing of the ITS region of the rDNA. This strain produced a slightly acid keratinase and an acid protease during cultivation in feather meal. The peak of keratinolytic activity occurred in 48?h and the maximum proteolytic activity in 96?h. These enzymes were partly characterized as serine protease and aspartic protease, respectively. The effects of feather meal concentration and initial pH on enzyme production were evaluated using a central composite design combined with response surface methodology. The optimal conditions were determined as pH 5.0 for protease and 7.8 for keratinase and 20?g/L of feather meal, showing that both models were predictive. Production of keratinases by A. niger is a less-exploited field that might represent a novel and promising biotechnological application for this microorganism. PMID:22007293

Lopes, Fernanda Cortez; Silva, Lucas André Dedavid E; Tichota, Deise Michele; Daroit, Daniel Joner; Velho, Renata Voltolini; Pereira, Jamile Queiroz; Corręa, Ana Paula Folmer; Brandelli, Adriano

2011-01-01

341

Metabolic pathway reconstruction of eugenol to vanillin bioconversion in Aspergillus niger  

PubMed Central

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 Aspergillus niger. 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

2010-01-01

342

GC--MS analysis reveals production of 2--Phenylethanol from Aspergillus niger endophytic in rose.  

PubMed

Endophytes include all organisms that during a variable period of their life, colonize the living internal tissues of their hosts without causing detectable symptoms. Several fungal endophytes have been isolated from a variety of plant species which have proved themselves as a rich source of secondary metabolites. The reported natural products from endophytes include antibiotics, immunosuppresants, anticancer compounds, antioxidant agents, etc. For the first time Rosa damacaena (rose) has been explored for its endophytes. The rose oil industry is the major identified deligence for its application in perfumery, flavouring, ointments, and pharmaceuticals including various herbal products. During the present investigation fungal endophytes were isolated from Rosa damacaena. A total of fifty four isolates were isolated out of which sixteen isolates were screened for the production of secondary metabolites. GCMS analysis reveals the production of 2-phenylethanol by one of the isolates JUBT 3M which was identified as Aspergillus niger. This is the first report of production of 2-phenylethanol from endophytic A. niger. 2-phenylethanol is an important constituent of rose oil constituting about 4.06% of rose oil. Presence of 2-phenylethanol indicates that the endophyte of rose may duplicate the biosynthesis of phenyl propanoids by rose plant. Besides this, the other commercial applications of phenylethanol include its use in antiseptics, disinfectants, anti-microbials and preservative in pharmaceuticals. PMID:20082377

Wani, Masood Ahmed; Sanjana, Kaul; Kumar, Dhar Manoj; Lal, Dhar Kanahya

2010-02-01

343

Esterification of ferulic acid with polyols using a ferulic acid esterase from Aspergillus niger.  

PubMed

Commercially available enzyme preparations were screened for enzymes that have a high ability to catalyze direct ester-synthesis of ferulic acid with glycerol. Only a preparation, Pectinase PL "Amano" produced by Aspergillus niger, feruloylated glycerol under the experimental conditions. The enzyme responsible for the esterification was purified and characterized. This enzyme, called FAE-PL, was found to be quite similar to an A. niger ferulic acid esterase (FAE-III) in terms of molecular mass, pH and temperature optima, substrate specificity on synthetic substrates, and the N-terminal amino acid sequence. FAE-PL highly catalyzed direct esterification of ferulic acid and sinapinic acid with glycerol. FAE-PL could feruloylate monomeric sugars including arabinose, fructose, galactose, glucose, and xylose. We determined the suitable conditions for direct esterification of ferulic acid with glycerol to be as follows: 1% ferulic acid in the presence of 85% glycerol and 5% dimethyl sulfoxide at pH 4.0 and 50 degrees C. Under these conditions, 81% of ferulic acid could be converted to 1-glyceryl ferulate, which was identified by (1)H-NMR. The ability of 1-glyceryl ferulate to scavenge 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was higher than that of the anti-oxidant butyl hydroxytoluene. PMID:16714088

Tsuchiyama, Moriyasu; Sakamoto, Tatsuji; Fujita, Tomoyuki; Murata, Shuichi; Kawasaki, Haruhiko

2006-07-01

344

Cloning, characterization and overexpression of the phytase-encoding gene (phyA) of Aspergillus niger.  

PubMed

Phytase catalyzes the hydrolysis of phytate (myo-inositol hexakisphosphate) to myo-inositol and inorganic phosphate. A gene (phyA) of Aspergillus niger NRRL3135 coding for extracellular, glycosylated phytase was isolated using degenerate oligodeoxyribonucleotides deduced from phytase amino acid (aa) sequences. Nucleotide (nt) sequence analysis of the cloned region revealed the presence of an open reading frame coding for 467 aa and interrupted once by an intron of 102 bp in the 5' part of the gene. The start codon is followed by a sequence coding for a putative signal peptide. Expression of phyA is controlled at the level of mRNA accumulation in response to inorganic phosphate levels. After cell growth in low-phosphate medium, a transcript of about 1.8 kb was visualized. Transcription of phyA initiates at at least seven start points within a region located 45-25 nt upstream from the start codon. In transformants of A. niger, expression of multiple copies of phyA resulted in up to more than tenfold higher phytase levels than in the wild-type strain. PMID:8387447

van Hartingsveldt, W; van Zeijl, C M; Harteveld, G M; Gouka, R J; Suykerbuyk, M E; Luiten, R G; van Paridon, P A; Selten, G C; Veenstra, A E; van Gorcom, R F

1993-05-15

345

Construction of a flocculent Saccharomyces cerevisiae strain secreting high levels of Aspergillus niger beta-galactosidase.  

PubMed

A flocculent Saccharomyces cerevisiae strain secreting Aspergillus niger beta-galactosidase activity was constructed by transforming S. cerevisiae NCYC869-A3 strain with plasmid pVK1.1 harboring the A. niger beta-galactosidase gene, lacA, under the control of the ADH1 promoter and terminator. Compared to other recombinant S. cerevisiae strains, this recombinant yeast has higher levels of extracellular beta-galactosidase activity. In shake-flask cultures, the beta-galactosidase activity detected in the supernatant was 20 times higher than that obtained with previously constructed strains (Domingues et al. 2000a). In bioreactor culture, with cheese-whey permeate as substrate, a yield of 878.0 nkat/gsubstrate was obtained. The recombinant strain is an attractive alternative to other fungal beta-galactosidase production systems as the enzyme is produced in a rather pure form. Moreover, the use of flocculating yeast cells allows for enzyme production with high productivity in continuous fermentation systems with facilitated downstream processing. PMID:11956748

Domingues, L; Teixeira, J A; Penttilä, M; Lima, N

2002-04-01

346

Aspergillus niger RhaR, a regulator involved in L-rhamnose release and catabolism.  

PubMed

The genome of the filamentous fungus Aspergillus niger is rich in genes encoding pectinases, a broad class of enzymes that have been extensively studied due to their use in industrial applications. The sequencing of the A. niger genome provided more knowledge concerning the individual pectinolytic genes, but little is known about the regulatory genes involved in pectin degradation. Understanding regulation of the pectinolytic genes provides a tool to optimize the production of pectinases in this industrially important fungus. This study describes the identification and characterization of one of the activators of pectinase-encoding genes, RhaR. Inactivation of the gene encoding this regulator resulted in down-regulation of genes involved in the release of L-rhamnose from the pectin substructure rhamnogalacturonan I, as well as catabolism of this monosaccharide. The rhaR disruptant was unable to grow on L-rhamnose, but only a small reduction in growth on pectin was observed. This is likely caused by the presence of a second, so far unknown regulator that responds to the presence of D-galacturonic acid. PMID:24682478

Gruben, Birgit S; Zhou, Miaomiao; Wiebenga, Ad; Ballering, Joost; Overkamp, Karin M; Punt, Peter J; de Vries, Ronald P

2014-06-01

347

Molecular and biochemical characterization of a novel intracellular invertase from Aspergillus niger with transfructosylating activity.  

PubMed

A novel subfamily of putative intracellular invertase enzymes (glycoside hydrolase family 32) has previously been identified in fungal genomes. Here, we report phylogenetic, molecular, and biochemical characteristics of SucB, one of two novel intracellular invertases identified in Aspergillus niger. The sucB gene was expressed in Escherichia coli and an invertase-negative strain of Saccharomyces cerevisiae. Enzyme purified from E. coli lysate displayed a molecular mass of 75 kDa, judging from sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis. Its optimum pH and temperature for sucrose hydrolysis were determined to be 5.0 and 37 to 40 degrees C, respectively. In addition to sucrose, the enzyme hydrolyzed 1-kestose, nystose, and raffinose but not inulin and levan. SucB produced 1-kestose and nystose from sucrose and 1-kestose, respectively. With nystose as a substrate, products up to a degree of polymerization of 4 were observed. SucB displayed typical Michaelis-Menten kinetics with substrate inhibition on sucrose (apparent K(m), K(i), and V(max) of 2.0 +/- 0.2 mM, 268.1 +/- 18.1 mM, and 6.6 +/- 0.2 mumol min(-1) mg(-1) of protein [total activity], respectively). At sucrose concentrations up to 400 mM, transfructosylation (FTF) activity contributed approximately 20 to 30% to total activity. At higher sucrose concentrations, FTF activity increased to up to 50% of total activity. Disruption of sucB in A. niger resulted in an earlier onset of sporulation on solid medium containing various carbon sources, whereas no alteration of growth in liquid culture medium was observed. SucB thus does not play an essential role in inulin or sucrose catabolism in A. niger but may be needed for the intracellular conversion of sucrose to fructose, glucose, and small oligosaccharides. PMID:17293485

Goosen, Coenie; Yuan, Xiao-Lian; van Munster, Jolanda M; Ram, Arthur F J; van der Maarel, Marc J E C; Dijkhuizen, Lubbert

2007-04-01

348

The major volatile compound 2-phenylethanol from the biocontrol yeast, Pichia anomala, inhibits growth and expression of aflatoxin biosynthetic genes of Aspergillus flavus.  

PubMed

Aspergillus flavus is a ubiquitous saprophyte that is able to produce the most potent natural carcinogenic compound known as aflatoxin B1 (AFB1). This toxin frequently contaminates crops including corn, cotton, peanuts, and tree nuts causing substantial economic loss worldwide. Consequently, more than 100 countries have strict regulations limiting AFB1 in foodstuffs and feedstuffs. Plants and microbes are able to produce volatile compounds that act as a defense mechanism against other organisms. Pichia anomala strain WRL-076 is a biocontrol yeast currently being tested to reduce AF contamination of tree nuts in California. We used the SPME-GC/MS analysis and identified the major volatile compound produced by this strain to be 2-phenylethanol (2-PE). It inhibited spore germination and AF production of A. flavus. Inhibition of AF formation by 2-PE was correlated with significant down regulation of clustering AF biosynthesis genes as evidenced by several to greater than 10,000-fold decrease in gene expression. In a time-course analysis we found that 2-PE also altered the expression patterns of chromatin modifying genes, MYST1, MYST2, MYST3, gcn5, hdaA and rpdA. The biocontrol capacity of P. anomala can be attributed to the production of 2-PE, which affects spore germination, growth, toxin production, and gene expression in A. flavus. PMID:24504634

Hua, Sui Sheng T; Beck, John J; Sarreal, Siov Bouy L; Gee, Wai

2014-05-01

349

Disruption of the serine proteinase gene (sep) in Aspergillus flavus leads to a compensatory increase in the expression of a metalloproteinase gene (mep20).  

PubMed Central

The serine proteinase gene (sep) in Aspergillus flavus was disrupted by homologous recombination with a hygromycin resistance gene as the marker. The gene-disrupted mutant GR-2 contained a single-copy insertion of the marker gene and did not express the sep gene. Serine proteinase activity, 36-kDa protein labeled by 3H-diisopropylfluorophosphate, and immunologically detectable proteinase were not detected in the culture fluid of GR-2. Despite the absence of the serine proteinase, the total elastinolytic activity levels in the mutant and the wild-type A.flavus were comparable. Immunoblots revealed that the mutant secreted greater amounts of an elastinolytic metalloproteinase gene (mep20) product than did the wild type. Furthermore, mep20 mRNA levels, measured by RNase protection assay, in the mutant were higher than those in the wild type. Inhibition of the serine proteinase by Streptomyces subtilisin inhibitor (SSI) in the culture medium of wild-type A.flavus also resulted in an elevation of mep20 gene products. Although no serine proteinase activity could be detected, the level of elastinolytic activity of the SSI-treated culture was comparable to that of the control. Immunoblots revealed that the addition of SSI caused an elevation in the levels of metalloproteinase and its mRNA. These results suggest that the expression of the genes encoding serine and metalloproteinases are controlled by a common regulatory system and the fungus has a mechanism to sense the status of extracellular proteolytic activities.

Ramesh, M V; Kolattukudy, P E

1996-01-01

350

[Paramagnetic properties of the conidial pigments of Aspergillus niger and Penicillium notatum fungi isolated from the mesosphere].  

PubMed

The conidia of Aspergillus niger and Penicillium notatum detected in the upper atmospheric layers of the Earth (58--77 km) were found to contain stable paramagnetic centres (PMC) at concentrations of 0.2 X 10(18) and 1.6 X 10(18) per gram of dry biomass, respectively. Aspergillin, the black pigment of Asp. niger, was shown to have (0.1--0.6) X 10(18) PMC per gram of dry substance (depending on the fraction). Stable paramagnetism of the conidial pigments with respect to their active protecting action in vivo is discussed on the basis of these data. PMID:213700

Liakh, S P; Lysenko, S V

1978-01-01

351

Proteome analysis of Aspergillus niger: Lactate added in starch-containing medium can increase production of the mycotoxin fumonisin B2 by modifying acetylCoA metabolism  

Microsoft Academic Search

BACKGROUND: Aspergillus niger is a filamentous fungus found in the environment, on foods and feeds and is used as host for production of organic acids, enzymes and proteins. The mycotoxin fumonisin B2 was recently found to be produced by A. niger and hence very little is known about production and regulation of this metabolite. Proteome analysis was used with the

Louise M Sřrensen; Rene Lametsch; Mikael R Andersen; Per V Nielsen; Jens C Frisvad

2009-01-01

352

Purification and characterization of a nitrilase from Aspergillus niger K10.  

PubMed

Aspergillus niger K10 cultivated on 2-cyanopyridine produced high levels of an intracellular nitrilase, which was partially purified (18.6-fold) with a 24% yield. The N-terminal amino acid sequence of the enzyme was highly homologous with that of a putative nitrilase from Aspergillus fumigatus Af293. The enzyme was copurified with two proteins, the N-terminal amino acid sequences of which revealed high homology with those of hsp60 and an ubiquitin-conjugating enzyme. The nitrilase exhibited maximum activity (91.6 U mg(-1)) at 45 degrees C and pH 8.0. Its preferred substrates, in the descending order, were 4-cyanopyridine, benzonitrile, 1,4-dicyanobenzene, thiophen-2-acetonitrile, 3-chlorobenzonitrile, 3-cyanopyridine, and 4-chlorobenzonitrile. Formation of amides as by-products was most intensive, in the descending order, for 2-cyanopyridine, 4-chlorobenzonitrile, 4-cyanopyridine, and 1,4-dicyanobenzene. The enzyme stability was markedly improved in the presence of D: -sorbitol or xylitol (20% w/v each). p-Hydroxymercuribenzoate and heavy metal ions were the most powerful inhibitors of the enzyme. PMID:17061133

Kaplan, Ondrej; Vejvoda, Vojtech; Plíhal, Ondrej; Pompach, Petr; Kavan, Daniel; Bojarová, Pavla; Bezouska, Karel; Macková, Martina; Cantarella, Maria; Jirk?, Vladimír; Kren, Vladimír; Martínková, Ludmila

2006-12-01

353

Heterologous Expression of Aspergillus Niger --beta--D-Xylosidase (XInD): Characterization on Lignocellulosic Substrates  

SciTech Connect

The gene encoding a glycosyl hydrolase family 3 xylan 1,4-beta-xylosidase, xlnD, was successfully cloned from Aspergillus niger strain ATCC 10864. The recombinant product was expressed in Aspergillus awamori, purified by column chromatography, and verified by matrix-assisted laser desorption ionization, tandem time of flight (MALDI-TOF/TOF) mass spectroscopy of tryptic digests. The T{sub max} was determined using differential scanning microcalorimetry (DSC) to be 78.2 C; the K{sub m} and k{sub cat} were found to be 255 {micro}M and 13.7 s{sup -1}, respectively, using {rho}NP-{Beta}-d-xylopyranoside as substrate. End-product inhibition by d-xylose was also verified and shown to be competitive; the K{sub i} for this inhibition was estimated to be 3.3 mM. XlnD was shown to efficiently hydrolyze small xylo-oligomers to monomeric xylose, making it a critical hydrolytic activity in cases where xylose is to be recovered from biomass conversion processes. In addition, the presence of the XlnD was shown to synergistically enhance the ability of an endoxylanase, XynA from Thermomyces lanuginosus, to convert xylan present in selected pretreated lignocellulosic substrates. Furthermore, the addition of the XynA/XlnD complex was effective in enhancing the ability of a simplified cellulase complex to convert glucan present in the substrates.

Selig, M. J.; Knoshaug, E. P.; Decker, S. R.; Baker, J. O.; Himmel, M. E.; Adney, W. S.

2008-01-01

354

Identification of genetic defects in the atoxigenic biocontrol strain Aspergillus flavus K49 reveals the presence of a competitive recombinant group in field populations.  

PubMed

Contamination of corn, cotton, peanuts and tree nuts by aflatoxins is a severe economic burden for growers. A current biocontrol strategy is to use non-aflatoxigenic Aspergillus flavus strains to competitively exclude field toxigenic Aspergillus species. A. flavus K49 does not produce aflatoxins and cyclopiazonic acid (CPA) and is currently being tested in corn-growing fields in Mississippi. We found that its lack of production of aflatoxins and CPA resulted from single nucleotide mutations in the polyketide synthase gene and hybrid polyketide-nonribosomal peptide synthase gene, respectively. Furthermore, based on single nucleotide polymorphisms of the aflatoxin biosynthesis omtA gene and the CPA biosynthesis dmaT gene, we conclude that K49, AF36 and previously characterized TX9-8 form a biocontrol group. These isolates appear to be derived from recombinants of typical large and small sclerotial morphotype strains. This finding provides an easy way to select future biocontrol strains from the reservoir of non-aflatoxigenic populations in agricultural fields. PMID:22285533

Chang, Perng-Kuang; Abbas, Hamed K; Weaver, Mark A; Ehrlich, Kenneth C; Scharfenstein, Leslie L; Cotty, Peter J

2012-03-15

355

The proportion of non-aflatoxigenic strains of the Aspergillus flavus/oryzae complex from meju by analyses of the aflatoxin biosynthetic genes.  

PubMed

Strains of the Aspergillus flavus/oryzae complex are frequently isolated from meju, a fermented soybean product, that is used as the starting material for ganjang (soy sauce) and doenjang (soybean paste) production. In this study, we examined the aflatoxin producing capacity of A. flavus/oryzae strains isolated from meju. 192 strains of A. flavus/oryzae were isolated from more than 100 meju samples collected from diverse regions of Korea from 2008 to 2011, and the norB-cypA, omtA, and aflR genes in the aflatoxin biosynthesis gene cluster were analyzed. We found that 178 strains (92.7%) belonged to non-aflatoxigenic group (Type I of norB-cypA, IB-L-B-, IC-AO, or IA-L-B- of omtA, and AO type of aflR), and 14 strains (7.3%) belonged to aflatoxin-producible group (Type II of norB-cypA, IC-L-B+/B- or IC-L-B+ of omtA, and AF type of aflR). Only 7 strains (3.6%) in the aflatoxin-producible group produced aflatoxins on Czapek yeast-extract medium. The aflatoxin-producing capability of A. flavus/oryzae strains from other sources in Korea were also investigated, and 92.9% (52/56) strains from air, 93.9% (31/33) strains from rice straw, 91.7% (11/12) strains from soybean, 81.3% (13/16) strains from corn, 82% (41/50) strains from peanut, and 73.2% (41/56) strains from arable soil were included in the non-aflatoxigenic group. The proportion of non-aflatoxigenicity of meju strains was similar to that of strains from soybean, air and rice straw, all of which have an effect on the fermentation of meju. The data suggest that meju does not have a preference for non-aflatoxigenic or aflatoxin-producible strains of A. flavus/oryzae from the environment of meju. The non-aflatoxigenic meju strains are proposed to be named A. oryzae, while the meju strains that can produce aflatoxins should be referred to A. flavus in this study. PMID:24385353

Hong, Seung-Beom; Lee, Mina; Kim, Dae-Ho; Chung, Soo-Hyun; Shin, Hyeon-Dong; Samson, Robert A

2013-12-01

356

Functional characterization of a veA-dependent polyketide synthase gene in Aspergillus flavus necessary for the synthesis of asparasone, a sclerotium-specific pigment.  

PubMed

The filamentous fungus, Aspergillus flavus, produces the toxic and carcinogenic, polyketide synthase (PKS)-derived family of secondary metabolites termed aflatoxins. While analysis of the A. flavus genome has identified many other PKSs capable of producing secondary metabolites, to date, only a few other metabolites have been identified. In the process of studying how the developmental regulator, VeA, affects A. flavus secondary metabolism we discovered that mutation of veA caused a dramatic down-regulation of transcription of a polyketide synthase gene belonging to cluster 27 and the loss of the ability of the fungi to produce sclerotia. Inactivation of the cluster 27 pks (pks27) resulted in formation of greyish-yellow sclerotia rather than the dark brown sclerotia normally produced by A. flavus while conidial pigmentation was unaffected. One metabolite produced by Pks27 was identified by thin layer chromatography and mass spectral analysis as the known anthraquinone, asparasone A. Sclerotia produced by pks27 mutants were significantly less resistant to insect predation than were the sclerotia produced by the wild-type and more susceptible to the deleterious effects of ultraviolet light and heat. Normal sclerotia were previously thought to be resistant to damage because of a process of melanization similar to that known for pigmentation of conidia. Our results show that the dark brown pigments in sclerotia derive from anthraquinones produced by Pks27 rather than from the typical tetrahydronapthalene melanin production pathway. To our knowledge this is the first report on the genes involved in the biosynthesis of pigments important for sclerotial survival. PMID:24412484

Cary, Jeffrey W; Harris-Coward, Pamela Y; Ehrlich, Kenneth C; Di Mavungu, José Diana; Malysheva, Svetlana V; De Saeger, Sarah; Dowd, Patrick F; Shantappa, Sourabha; Martens, Stacey L; Calvo, Ana M

2014-03-01

357

Secretory expression and purification of Aspergillus niger glucose oxidase in Saccharomyces cerevisiae mutant deficient in PMR1 gene  

Microsoft Academic Search

The gene encoding glucose oxidase (GOD) from Aspergillus niger was expressed as a secretory product in the yeast Saccharomyces cerevisiae. Six consecutive histidine residues were fused to the C-terminus of GOD to facilitate purification. The recombinant GOD-His6 secreted by S. cerevisiae migrated as a broad diffuse band on SDS–PAGE, with an apparent molecular weight higher than that in natural A.

Ji-Hyun Ko; Moon Sun Hahm; Hyun Ah Kang; Soo Wan Nam; Bong Hyun Chung

2002-01-01

358

Enhanced production of extracellular ribonuclease from Aspergillus niger by optimization of culture conditions using response surface methodology  

Microsoft Academic Search

Response surface methodology were used to study the cumulative effect of the culture conditions and to enhance the production of extracellular ribonuclease in shake flask fermentation by Aspergillus niger. These conditions considered include initial pH, inoculum size, total carbon, ratio of glucose to corn powder, NH4NO3 and K2SO4. The relative importance of these conditions on ribonuclease production was investigated by

Ya-Hong Xiong; Jian-Zhong Liu; Hai-Yan Song; Liang-Nian Ji

2004-01-01

359

Yam bean starch: a novel substrate for citric acid production by the protease-negative mutant strain of Aspergillus niger  

Microsoft Academic Search

Selection of protease-negative mutant strains of Aspergillus niger in semi-solid culture was carried out in order to enhance citric acid production from yam bean. The protease-negative mutants were obtained by UV-irradiation of the parental strain Yang no. 2. Using a halo-selection medium, a number of mutants with decreased extracellular protease activity were selected. Citric acid productivity by the selected mutant

Somsak Sarangbin; Yuwadee Watanapokasin

1999-01-01

360

Optimization for xylanase and cellulase production from Aspergillus niger ATTC 6275 in palm oil mill wastes and its application  

Microsoft Academic Search

Optimization of enzyme production from Aspergillus niger ATCC 6275 under both submerged and solid-substrate cultivation was investigated. Results from submerged cultivation using palm oil mill effluent revealed that pretreatment of ground palm cake did not improve enzyme production. Addition of 0.60g NH4NO3\\/l generated maximum activity of xylanase and cellulase (CMCase). The optimum aeration rate was 1.2 v\\/v min. Under solid-substrate

P. Prasertsan; A. H-Kittikul; A. Kunghae; J. Maneesri; S. Oi

1997-01-01

361

Production of tannase by Aspergillus niger HA37 growing on tannic acid and Olive Mill Waste Waters  

Microsoft Academic Search

Production of tannase (tannin acyl hydrolase, EC 3.1.1.20) by Aspergillus nigerHA37 on a synthetic culture medium containing tannic acid at different concentrations has been studied. Maximal enzymatic activity increased according to the initial concentration of tannic acid; respectively 0.6, 0.9 and 1.5 enzyme activity units (EU) ml?1 medium in the presence of 0.2%, 0.5% and 1% of tannic acid. Tannase

H. Aissam; F. Errachidi; M. J. Penninckx; M. Merzouki; M. Benlemlih

2005-01-01

362

Environment friendly crosslinked chitosan as a matrix for selective adsorption and purification of lipase of Aspergillus niger.  

PubMed

Chitosan and its derivatives have been used as affinity matrices for purification of lipase from Aspergillus niger NCIM 1207. Trimellitic anhydride (TMA)-crosslinked deacetylated chitin adsorbed lipase selectively, yielding approximately 5-fold purification of the crude lipase with 70% yield. Further 9-fold purification occurred on eluting through Sephacryl-100. These results suggest that chitosan derivatives can be used as inexpensive biopolymer matrices for the purification of lipases for industrial applications. PMID:18789352

Trimukhe, K D; Mahadik, N D; Gokhale, D V; Varma, A J

2008-12-01

363

Water activity, solute and temperature modify growth and spore production of wild type and genetically engineered Aspergillus niger strains  

Microsoft Academic Search

The effect of interactions of water activity (aw) (0.99–0.90), temperature (20, 30 and 35°C) and modifying aw solute (glycerol, NaCl) on growth and sporulation of a wild-type strain of Aspergillus niger (W) and two genetically engineered lysozyme-producing strains (L11, B1) was examined for the first time. Maximum growth rates were achieved for both strains (L11 and B1) under moderate aW

Roberto Parra; David Aldred; David B. Archer; Naresh Magan

2004-01-01

364

Enhanced production of verbenol, a highly valued food flavourant, by an intergeneric fusant strain of Aspergillus niger and Penicillium digitatum.  

PubMed

An intergeneric hybrid, obtained from Aspergillus niger and Penicillium digitatum, biotransformed (-)-cis-alpha-pinene (5 mg/25 ml) into (-)-cis-verbenol (60%; 1.08 mg/g of biomass) in 6 h compared with 0.18 mg/g of biomass for verbenol (10-15%; 0.18-0.27 mg/g of biomass) in the initial parent cultures. PMID:12630902

Rao, Smitha C V; Rao, Rati; Agrawal, Renu

2003-04-01

365

Nucleotide sequence of the Aspergillus niger trpC gene: structural relationship with analogous genes of other organisms  

Microsoft Academic Search

The nucleotide sequence of the Aspergillus niger tryptophan C (trpC) gene was determined. Northern hybridization and S1-mapping experiments showed the presence of a 2.6 kb trpC poly(A)+ RNA with two very short (5 and 6 nucleotides) noncoding 5'-regions. Comparison of the predicted amino acid sequence with that of trp gene proteins of pro- and eukaryotic organisms revealed three functional domains

Ton Kos; Anneke Kuijvenhoven; Hanny G. M. Hessing; Peter H. Pouwels; Cees A. M. J. J. Hondel

1988-01-01

366

Coffee husk: an inexpensive substrate for production of citric acid by Aspergillus niger in a solid-state fermentation system  

Microsoft Academic Search

Aspergillus niger CFTRI 30 produced 1.3 g citric acid\\/10 g dry coffee husk in 72 h solid-state fermentation when the substrate was moistened with 0.075 M NaOH solution. Production was increased by 17% by adding a mixture of iron, copper and zinc to the medium but enrichment of the moist solid medium with (NH4)2SO4, sucrose or any of four enzymes

V. S. Shankaranand; B. K. Lonsane

1994-01-01

367

Derepressed 2-deoxyglucose-resistant mutants of Aspergillus niger with altered hexokinase and acid phosphatase activity in hyperproduction of ?-fructofuranosidase  

Microsoft Academic Search

Aspergillus niger NRRL330 produces extracellular ?-fructofuranosidase (Ffase), and its production is subject to repression by hexoses in the\\u000a medium. After ultraviolet mutagenization and selection, seven derepressed mutants resistant to 2-deoxyglucose (2-DG) were\\u000a isolated on Czapek’s minimal medium containing glycerol. One of the mutants, designated DGRA-1, produced higher levels of\\u000a Ffase. A considerable difference occurred in the mutants with reference to

B. Ashokkumar; S. R. Senthilkumar; P. Gunasekaran

2004-01-01

368

Optimization of Citric Acid Production from a New Strain and Mutant of Aspergillus niger Using Solid State Fermentation  

Microsoft Academic Search

A new strain of Aspergillus niger isolated from soil and its mutant were used for citric acid production from carob under solid-state fermentation conditions. The parental strain produced 30 g\\/kg citric acid, while the mutant G4, selected after four rounds of gamma ray irradiation, produced 60 g\\/kg. Maximum citric acid production was obtained after 7 days of incubation, as the

Faiez Alani; Murray Moo-Young; William Anderson; Zakaria Bataine

2007-01-01

369

Optimization of nutrient concentration for citric acid production by solid-state culture of Aspergillus niger on polyurethane foams  

Microsoft Academic Search

Citric acid production from mussel processing effluents by Aspergillus niger in solid-state culture was studied using polyurethane foam particles soaked with the culture medium. Conditions were used that allowed comparison of the results with those obtained before in submerged culture and the attribution of the differences to the characteristics of solid-state culture.A screening of several strains gave different results than

J. Pintado; A. Torrado; M. P. González; M. A. Murado

1998-01-01

370

Production of antifungal chitinase by Aspergillus niger LOCK 62 and its potential role in the biological control.  

PubMed

Aspergillus niger LOCK 62 produces an antifungal chitinase. Different sources of chitin in the medium were used to test the production of the chitinase. Chitinase production was most effective when colloidal chitin and shrimp shell were used as substrates. The optimum incubation period for chitinase production by Aspergillus niger LOCK 62 was 6 days. The chitinase was purified from the culture medium by fractionation with ammonium sulfate and affinity chromatography. The molecular mass of the purified enzyme was 43 kDa. The highest activity was obtained at 40 °C for both crude and purified enzymes. The crude chitinase activity was stable during 180 min incubation at 40 °C, but purified chitinase lost about 25 % of its activity under these conditions. Optimal pH for chitinase activity was pH 6-6.5. The activity of crude and purified enzyme was stabilized by Mg(2+) and Ca(2+) ions, but inhibited by Hg(2+) and Pb(2+) ions. Chitinase isolated from Aspergillus niger LOCK 62 inhibited the growth of the fungal phytopathogens: Fusarium culmorum, Fusarium solani and Rhizoctonia solani. The growth of Botrytis cinerea, Alternaria alternata, and Fusarium oxysporum was not affected. PMID:22922773

Brzezinska, Maria Swiontek; Jankiewicz, Urszula

2012-12-01

371

High-level expression of aspergillus niger b-galactosidase in ashbya gossypii.  

PubMed

Ashbya gossypii has been recently considered as a host for the expression of recombinant proteins. The production levels achieved thus far were similar to those obtained with Saccharomyces cerevisiae for the same proteins. Here, the b-galactosidase from Aspergillus niger was successfully expressed and secreted by A. gossypii from 2-mm plasmids carrying the native signal sequence at higher levels than those secreted by S. cerevisiae laboratorial strains. Four different constitutive promoters were used to regulate the expression of bgalactosidase: A. gossypii AgTEF and AgGPD promoters, and S. cerevisiae ScADH1 and ScPGK1 promoters. The native AgTEF promoter drove the highest expression levels of recombinant b-galactosidase in A. gossypii, leading to 2- and 8-fold higher extracellular activity than the AgGPD promoter and the heterologous promoters, respectively. In similar production conditions, the levels of active b-galactosidase secreted by A. gossypii were up to 37 times higher than those secreted by recombinant S. cerevisiae and 2.5 times higher than those previously reported for the b-galactosidase-high producing S. cerevisiae NCYC869-A3/pVK1.1. The substitution of glucose by glycerol in the production medium led to a 1.5-fold increase in the secretion of active b-galactosidase by A. gossypii. Recombinant b-galactosidase secreted by A. gossypii was extensively glycosylated, as are the native A. niger b-galactosidase and recombinant b-galactosidase produced by yeast. These results highlight the potential of A. gossypii as a recombinant protein producer and open new perspectives to further optimize recombinant protein secretion in this fungus. PMID:24851247

Magalhes, Frederico; Aguiar, Tatiana Q; Oliveira, Carla; Domingues, Lucília

2014-01-01

372

Production and characterization of recombinant glucose oxidase from Aspergillus niger expressed in Pichia pastoris.  

PubMed

Recombinant glucose oxidase from Aspergillus niger expressed in Pichia pastoris by fed-batch fermentation was purified and assessed with 1·26 purification fold to homogeneity using Q-Sepharose F.F. chromatography. The enzyme was determined by SDS-PAGE and gradient PAGE, which showed a dimeric form of 150 kDa. The purified rGOD was proved to be a glycoprotein, and the content of which was estimated to be 36·7 and 25·14% by phenol-sulfuric acid and anthrone-sulfuric acid methods. Characteristics demonstrated that the highest activity was in pH 6·0 at 40°C and was stable at a broad pH range from 4·0 to 9·0 at 55°C or below. The optimum substrate for this enzyme was d-glucose, and the Km was 21·06 mmol l(-1) as well as the Vmax was 359 ?mol min(-1) mg(-1). rGOD possessed high resistance to various chemicals except for Hg(2+), Fe(2+), Ag(+), Cu(2+), 1,4-dithiothreitol, sodium dodecyl sulfate and ascorbic acid. In addition, the inhibitors also exhibited intensive fluorescence quenching effect on rGOD. Significance and impact of the study: Glucose oxidase is a very important enzyme produced by several species. However, large-scale applications have always been postponed by its complexity in fermentation and purification. Our research focused on developing new purification strategy of recombinant GOD from A. niger expressed in P. pastoris. Here, we described this novel one-step purification method and subsequent research in the characteristics of rGOD which showed different results from previous work. These can open new opportunities to increase its application. PMID:24283586

Meng, Y; Zhao, M; Yang, M; Zhang, Q; Hao, J; Meng, Y

2014-04-01

373

Biochar Enhances Aspergillus niger Rock Phosphate Solubilization by Increasing Organic Acid Production and Alleviating Fluoride Toxicity.  

PubMed

During fungal rock phosphate (RP) solubilization, a significant quantity of fluoride (F(-)) is released together with phosphorus (P), strongly inhibiting the process. In the present study, the effect of two F(-) adsorbents [activated alumina (Al2O3) and biochar] on RP solubilization by Aspergillus niger was examined. Al2O3 adsorbed part of the F(-) released but also adsorbed soluble P, which makes it inappropriate for microbial RP solubilization systems. In contrast, biochar adsorbed only F(-) while enhancing phosphate solubilization 3-fold, leading to the accumulation of up to 160 mg of P per liter. By comparing the values of F(-) measured in solution at the end of incubation and those from a predictive model, it was estimated that up to 19 mg of F(-) per liter can be removed from solution by biochar when added at 3 g liter(-1) to the culture medium. Thus, biochar acted as an F(-) sink during RP solubilization and led to an F(-) concentration in solution that was less inhibitory to the process. In the presence of biochar, A. niger produced larger amounts of citric, gluconic, and oxalic acids, whether RP was present or not. Our results show that biochar enhances RP solubilization through two interrelated processes: partial removal of the released F(-) and increased organic acid production. Given the importance of organic acids for P solubilization and that most of the RPs contain high concentrations of F(-), the proposed solubilization system offers an important technological improvement for the microbial production of soluble P fertilizers from RP. PMID:24610849

Mendes, Gilberto de Oliveira; Zafra, David Lopez; Vassilev, Nikolay Bojkov; Silva, Ivo Ribeiro; Ribeiro, José Ivo; Costa, Maurício Dutra

2014-05-01

374

Bimutation breeding of Aspergillus niger strain for enhancing ?-mannanase production by solid-state fermentation.  

PubMed

A parent strain Aspergillus niger LW-1 was mutated by the compound mutagenesis of vacuum microwave (VMW) and ethyl methane sulfonate (EMS). A mutant strain, designated as A. niger E-30, with high- and stable-yield ?-mannanase was obtained through a series of screening. The ?-mannanase activity of the mutant strain E-30, cultivated on the basic fermentation medium at 32°C for 96 h, reached 36,675 U/g dried koji, being 1.98-fold higher than that (18,50 1U/g dried koji) of the parent strain LW-1. The purified E-30 ?-mannanase, a glycoprotein with a carbohydrate content of 19.6%, had an apparent molecular weight of about 42.0 kDa by SDS-PAGE. Its optimal pH and temperature were 3.5 and 65°C, respectively. It was highly stable at a pH range of 3.5-7.0 and at a temperature of 60°C and below. The kinetic parameters K(m) and V(max), toward locust bean gum and at pH 4.8 and 50°C, were 3.68 mg/mL and 1067.5 U/mg, respectively. The ?-mannanase activity was not significantly affected by an array of metal ions and EDTA, but strongly inhibited by Ag(+) and Hg(2+). In addition, the hydrolytic conditions of konjak glucomannan using the purified E-30 ?-mannanase were optimized as follows: konjak gum solution 240 g/L (dissolved in deionized water), hydrolytic temperature 50°C, ?-mannanase dosage 120 U/g konjak gum, and hydrolytic time 8 h. PMID:21867993

Wu, Minchen; Tang, Cunduo; Li, Jianfang; Zhang, Huimin; Guo, Jing

2011-10-18

375

Pectinase production by solid fermentation from Aspergillus niger by a new prescription experiment.  

PubMed

The Ordos Plateau in China is covered with up to 300,000 ha of peashrub (Caragana) which is the dominant natural vegetation and ideal for fodder production. To exploit peashrub fodder, it is crucially important to optimize the culture conditions, especially culture substrate to produce pectinase complex. In this study, a new prescription process was developed. The process, based on a uniform experimental design, first optimizes the solid substrate and second, after incubation, applies two different temperature treatments (30 degrees C for the first 30 h and 23 degrees C for the second 42 h) in the fermentation process. A multivariate regression analysis is applied to a number of independent variables (water, wheat bran, rice dextrose, ammonium sulfate, and Tween 80) to develop a predictive model of pectinase activity. A second-degree polynomial model is developed which accounts for an excellent proportion of the explained variation (R(2)=97.7%). Using unconstrained mathematical programming, an optimized substrate prescription for pectinase production is subsequently developed. The mathematical analysis revealed that the optimal formula for pectinase production from Aspergillus niger by solid fermentation under the conditions of natural aeration, natural substrate pH (about 6.5), and environmental humidity of 60% is rice dextrose 8%, wheat bran 24%, ammonium sulfate ((NH(4))(2)SO(4)) 6%, and water 61%. Tween 80 was found to have a negative effect on the production of pectinase in solid substrate. With this substrate prescription, pectinase produced by solid fermentation of A. niger reached 36.3 IU/(gDM). Goats fed on the pectinase complex obtain an incremental increase of 0.47 kg day(-1) during the initial 25 days of feeding, which is a very promising new feeding prospect for the local peashrub. It is concluded that the new formula may be very useful for the sustainable development of arid and semiarid pastures such as those of the Ordos Plateau. PMID:16406599

Debing, Jing; Peijun, Li; Stagnitti, Frank; Xianzhe, Xiong; Li, Ling

2006-06-01

376

Multi-objective optimization in Aspergillus niger fermentation for selective product enhancement.  

PubMed

A multi-objective optimization formulation that reflects the multi-substrate optimization in a multi-product fermentation is proposed in this work. This formulation includes the application of epsilon-constraint to generate the trade-off solution for the enhancement of one selective product in a multi-product fermentation, with simultaneous minimization of the other product within a threshold limit. The formulation has been applied to the fed-batch fermentation of Aspergillus niger that produces a number of enzymes during the course of fermentation, and of these, catalase and protease enzyme expression have been chosen as the enzymes of interest. Also, this proposed formulation has been applied in the environment of three control variables, i.e. the feed rates of sucrose, nitrogen source and oxygen and a set of trade-off solutions have been generated to develop the pareto-optimal curve. We have developed and experimentally evaluated the optimal control profiles for multiple substrate feed additions in the fed-batch fermentation of A. niger to maximize catalase expression along with protease expression within a threshold limit and vice versa. An increase of about 70% final catalase and 31% final protease compared to conventional fed-batch cultivation were obtained. Novel methods of oxygen supply through liquid-phase H2O2 addition have been used with a view to overcome limitations of aeration due to high gas-liquid transport resistance. The multi-objective optimization problem involved linearly appearing control variables and the decision space is constrained by state and end point constraints. The proposed multi-objective optimization is solved by differential evolution algorithm, a relatively superior population-based stochastic optimization strategy. PMID:16217656

Mandal, Chaitali; Gudi, Ravindra D; Suraishkumar, G K

2005-12-01

377

Structural Features of Sugars That Trigger or Support Conidial Germination in the Filamentous Fungus Aspergillus niger  

PubMed Central

The asexual spores (conidia) of Aspergillus niger germinate to produce hyphae under appropriate conditions. Germination is initiated by conidial swelling and mobilization of internal carbon and energy stores, followed by polarization and emergence of a hyphal germ tube. The effects of different pyranose sugars, all analogues of d-glucose, on the germination of A. niger conidia were explored, and we define germination as the transition from a dormant conidium into a germling. Within germination, we distinguish two distinct stages, the initial swelling of the conidium and subsequent polarized growth. The stage of conidial swelling requires a germination trigger, which we define as a compound that is sensed by the conidium and which leads to catabolism of d-trehalose and isotropic growth. Sugars that triggered germination and outgrowth included d-glucose, d-mannose, and d-xylose. Sugars that triggered germination but did not support subsequent outgrowth included d-tagatose, d-lyxose, and 2-deoxy-d-glucose. Nontriggering sugars included d-galactose, l-glucose, and d-arabinose. Certain nontriggering sugars, including d-galactose, supported outgrowth if added in the presence of a complementary triggering sugar. This division of functions indicates that sugars are involved in two separate events in germination, triggering and subsequent outgrowth, and the structural features of sugars that support each, both, or none of these events are discussed. We also present data on the uptake of sugars during the germination process and discuss possible mechanisms of triggering in the absence of apparent sugar uptake during the initial swelling of conidia.

Hayer, Kimran; Stratford, Malcolm

2013-01-01

378

Secretion and properties of a hybrid Kluyveromyces lactis-Aspergillus niger ?-galactosidase  

PubMed Central

Background The ?-galactosidase from Kluyveromyces lactis is a protein of outstanding biotechnological interest in the food industry and milk whey reutilization. However, due to its intracellular nature, its industrial production is limited by the high cost associated to extraction and downstream processing. The yeast-system is an attractive method for producing many heterologous proteins. The addition of a secretory signal in the recombinant protein is the method of choice to sort it out of the cell, although biotechnological success is not guaranteed. The cell wall acting as a molecular sieve to large molecules, culture conditions and structural determinants present in the protein, all have a decisive role in the overall process. Protein engineering, combining domains of related proteins, is an alternative to take into account when the task is difficult. In this work, we have constructed and analyzed two hybrid proteins from the ?-galactosidase of K. lactis, intracellular, and its Aspergillus niger homologue that is extracellular. In both, a heterologous signal peptide for secretion was also included at the N-terminus of the recombinant proteins. One of the hybrid proteins obtained has interesting properties for its biotechnological utilization. Results The highest levels of intracellular and extracellular ?-galactosidase were obtained when the segment corresponding to the five domain of K. lactis ?-galactosidase was replaced by the corresponding five domain of the A. niger ?-galactosidase. Taking into account that this replacement may affect other parameters related to the activity or the stability of the hybrid protein, a thoroughly study was performed. Both pH (6.5) and temperature (40°C) for optimum activity differ from values obtained with the native proteins. The stability was higher than the corresponding to the ?-galactosidase of K. lactis and, unlike this, the activity of the hybrid protein was increased by the presence of Ni2+. The affinity for synthetic (ONPG) or natural (lactose) substrates was higher in the hybrid than in the native K. lactis ?-galactosidase. Finally, a structural-model of the hybrid protein was obtained by homology modelling and the experimentally determined properties of the protein were discussed in relation to it. Conclusion A hybrid protein between K. lactis and A. niger ?-galactosidases was constructed that increases the yield of the protein released to the growth medium. Modifications introduced in the construction, besides to improve secretion, conferred to the protein biochemical characteristics of biotechnological interest.

Rodriguez, Angel Pereira; Leiro, Rafael Fernandez; Trillo, M Cristina; Cerdan, M Esperanza; Siso, M Isabel Gonzalez; Becerra, Manuel

2006-01-01

379

Niger.  

PubMed

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

1987-06-01

380

Co-inoculation of aflatoxigenic and non-aflatoxigenic strains of Aspergillus flavus to study fungal invasion, colonization, and competition in maize kernels.  

PubMed

A currently utilized pre-harvest biocontrol method involves field inoculations with non-aflatoxigenic Aspergillus flavus strains, a tactic shown to strategically suppress native aflatoxin-producing strains and effectively decrease aflatoxin contamination in corn. The present in situ study focuses on tracking the invasion and colonization of an aflatoxigenic A. flavus strain (AF70), labeled with green fluorescent protein (GFP), in the presence of a non-aflatoxigenic A. flavus biocontrol strain (AF36), to better understand the competitive interaction between these two strains in seed tissue of corn (Zea mays). Corn kernels that had been co-inoculated with GFP-labeled AF70 and wild-type AF36 were cross-sectioned and observed under UV and blue light to determine the outcome of competition between these strains. After imaging, all kernels were analyzed for aflatoxin levels. There appeared to be a population difference between the co-inoculated AF70-GFP+AF36 and the individual AF70-GFP tests, both visually and with pixel count analysis. The GFP allowed us to observe that AF70-GFP inside the kernels was suppressed up to 82% when co-inoculated with AF36 indicating that AF36 inhibited progression of AF70-GFP. This was in agreement with images taken of whole kernels where AF36 exhibited a more robust external growth compared to AF70-GFP. The suppressed growth of AF70-GFP was reflected in a corresponding (upto 73%) suppression in aflatoxin levels. Our results indicate that the decrease in aflatoxin production correlated with population depression of the aflatoxigenic fungus by the biocontrol strain supporting the theory of competitive exclusion through robust propagation and fast colonization by the non-aflatoxigenic fungus. PMID:24734028

Hruska, Zuzana; Rajasekaran, Kanniah; Yao, Haibo; Kincaid, Russell; Darlington, Dawn; Brown, Robert L; Bhatnagar, Deepak; Cleveland, Thomas E

2014-01-01

381

Co-inoculation of aflatoxigenic and non-aflatoxigenic strains of Aspergillus flavus to study fungal invasion, colonization, and competition in maize kernels  

PubMed Central

A currently utilized pre-harvest biocontrol method involves field inoculations with non-aflatoxigenic Aspergillus flavus strains, a tactic shown to strategically suppress native aflatoxin-producing strains and effectively decrease aflatoxin contamination in corn. The present in situ study focuses on tracking the invasion and colonization of an aflatoxigenic A. flavus strain (AF70), labeled with green fluorescent protein (GFP), in the presence of a non-aflatoxigenic A. flavus biocontrol strain (AF36), to better understand the competitive interaction between these two strains in seed tissue of corn (Zea mays). Corn kernels that had been co-inoculated with GFP-labeled AF70 and wild-type AF36 were cross-sectioned and observed under UV and blue light to determine the outcome of competition between these strains. After imaging, all kernels were analyzed for aflatoxin levels. There appeared to be a population difference between the co-inoculated AF70-GFP+AF36 and the individual AF70-GFP tests, both visually and with pixel count analysis. The GFP allowed us to observe that AF70-GFP inside the kernels was suppressed up to 82% when co-inoculated with AF36 indicating that AF36 inhibited progression of AF70-GFP. This was in agreement with images taken of whole kernels where AF36 exhibited a more robust external growth compared to AF70-GFP. The suppressed growth of AF70-GFP was reflected in a corresponding (upto 73%) suppression in aflatoxin levels. Our results indicate that the decrease in aflatoxin production correlated with population depression of the aflatoxigenic fungus by the biocontrol strain supporting the theory of competitive exclusion through robust propagation and fast colonization by the non-aflatoxigenic fungus.

Hruska, Zuzana; Rajasekaran, Kanniah; Yao, Haibo; Kincaid, Russell; Darlington, Dawn; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

2014-01-01

382

Fate and Role of Ammonium Ions during Fermentation of Citric Acid by Aspergillus niger  

PubMed Central

Stoichiometric modeling of the early stages of the citric acid fermentation process by Aspergillus niger revealed that ammonium ions combine with a carbon-containing metabolite inside the cell, in a ratio 1:1, to form a nitrogen compound which is then excreted by the mycelium. High-performance liquid chromatography analysis identified glucosamine as the product of the relationship between glucose and ammonium during the early stages of the citric acid fermentation process. Slightly acidic internal pHs, extremely low ammonium ion concentrations inside the cell, and glucosamine synthesis come into direct contradiction with the earlier theory of the ammonium pool inside the cell, regarded as responsible for inhibition of the enzyme phosphofructokinase. At later fermentation stages, when the mycelium is involved in a process of fragmentation and regrowth, the addition of ammonium sulfate leads to a series of events: the formation and secretion of glucosamine in elevated amounts, the short inhibition of citrate synthesis, growth enhancement, the utilization of glucosamine, and finally, the enhancement of citric acid production rates. Obviously, the enzymatic processes underlining the phenomena need to be reexamined. As a by-product of the citric acid fermentation, glucosamine is reported for the first time here. Suitable process manipulations of the system described in this work could lead to successful glucosamine recovery at the point of its highest yield before degradation by the fungus occurs.

Papagianni, Maria; Wayman, Frank; Mattey, Michael

2005-01-01

383

Antifungal agents against Aspergillus niger for rearing rice leaffolder larvae (Lepidoptera: Pyralidae) on artificial diet.  

PubMed

Mold contamination is an important issue in insect mass rearing. Frequently used antifungal agents such as sorbic acid and methylparaben have negative impact on many lepidopteran larvae, which might be one of the reasons for the difficulty in rearing rice leaffolder, Cnaphalocrocis medinalis (Güenée). In this study, 19 antifungal agents, including 7 food preservatives, 6 antifungal drugs, and 6 agricultural fungicides, were screened for their inhibitory activities on Aspergillus niger in diets. The results demonstrated that most of the tested chemicals are unsuitable as mold inhibitors in the diets of the rice leaffolder, and the rice leaffolder neonate is sensitive to sorbic acid and methylparaben. These two mold inhibitors at commonly used concentrations were shown to impact the survival of rice leaffolder larvae fed on artificial diets. Among the tested mold inhibitors, natamycin was the safest for the rice leaffolder larvae. Much higher larva survival was observed for the larvae fed on diets containing natamycin as an antifungal agent (59 and 72% at 200 and 400 ppm, respectively). Two agricultural fungicides, tebuconazole and azoxystrobin, are also potent as mold inhibitors when used in insect diets. The mixed use of natamycin and sorbic acid, or methylparaben, and the mixed use of sorbic acid and azoxystrobin resulted in significantly higher larva survival than sorbic acid + methylparaben. Natamycin + azoxystrobin and sorbic acid + tebuconazole resulted in larva survival similar to that of sorbic acid + methylparaben. The ternary combination of natamycin, sorbic acid, and methylparaben was the best combination for the rearing of rice leaffolder. PMID:25026669

Su, Jianya; Wang, Ye-Cheng; Zhang, Shu-Kun; Ren, Xiu-Bei

2014-06-01

384

Development of miconazole nitrate containing chitosan microcapsules and their anti-Aspergillus niger activity.  

PubMed

In this article, we report the development of chitosan/miconazole nitrate microcapsules. Four miconazole nitrate ratios including 12.5, 25, 50 and 100?mg were performed in the chitosan-based microencapsulation system. Chitosan microcapsules with the drug input of 25?mg showed the highest encapsulation efficiency (52.47%) and acceptable mean particle size (5.65?µm) when compared with those of 12.5, 50 and 100?mg. Fourier transform infrared spectroscopic spectrum proved the entrapment of miconazole nitrate into chitosan microcapsules. The antifungal result demonstrated that microcapsules containing 75?µg miconazole nitrate possessed comparable anti-Aspergillus niger activity as the commercial ointment. The growth inhibition of miconazole nitrate containing chitosan microcapsules towards human skin keratinocytes was found to be dose dependent. A total of 75?µg of miconazole nitrate containing microcapsules revealed about 25% of growth inhibition while that of 150?µg showed approximately 70% of growth inhibition. Special monitoring should be taken if a higher dose of miconazole nitrate was used to develop the microcapsules. PMID:22172026

Yuen, C W M; Kan, C W; Cheuk, K L; Cheung, H C; Cheng, S Y; Yip, J; Lam, P L

2012-01-01

385

Production and extraction optimization of xylanase from Aspergillus niger DFR-5 through solid-state-fermentation.  

PubMed

The effects of solid substrates, initial moisture content, moistening medium, temperature and incubation time on xylanase production by Aspergillus niger DFR-5 was studied and the highest activity (2596 IU/g dry substrate (gds)) was achieved in medium that contained wheat bran (WB) and soybean cake (SBC) at a ratio of 70:30, was moistened to 70% with MSS-2 mineral salt solution, and incubated for 6 days at 40 degrees C. Water at 37 degrees C was suitable for efficient recovery of enzyme from moldy WB-SBC medium. The extraction parameters for xylanase were optimized with respect to minimum volume of extractant using a central composite rotatable design (CCRD). The maximum recovery of xylanase (4465+/-52 IU/gds) with 92.5% desirability was obtained employing water (10 ml/gds) as extractant at 200 rpm for 60 min. The result shows that an overall 5.4-fold increase in xylanase production was obtained in concentrated form by optimizing medium components and extraction conditions. PMID:20478705

Pal, Ajay; Khanum, Farhath

2010-10-01

386

The effect of natamycin on the transcriptome of conidia of Aspergillus niger  

PubMed Central

The impact of natamycin on Aspergillus niger was analysed during the first 8 h of germination of conidia. Polarisation, germ tube formation, and mitosis were inhibited in the presence of 3 and 10 ?M of the anti-fungal compound, while at 10 ?M also isotropic growth was affected. Natamycin did not have an effect on the decrease of microviscosity during germination and the concomitant reduction in mannitol and trehalose levels. However, it did abolish the increase of intracellular levels of glycerol and glucose during the 8 h period of germination. Natamycin hardly affected the changes that occur in the RNA profile during the first 2 h of germination. During this time period, genes related to transcription, protein synthesis, energy and cell cycle and DNA processing were particularly up-regulated. Differential expression of 280 and 2586 genes was observed when 8 h old germlings were compared with conidia that had been exposed to 3 ?M and 10 ?M natamycin, respectively. For instance, genes involved in ergosterol biosynthesis were down-regulated. On the other hand, genes involved in endocytosis and the metabolism of compatible solutes, and genes encoding protective proteins were up-regulated in natamycin treated conidia.

van Leeuwen, M.R.; Krijgsheld, P.; Wyatt, T.T.; Golovina, E.A.; Menke, H.; Dekker, A.; Stark, J.; Stam, H.; Bleichrodt, R.; Wosten, H.A.B.; Dijksterhuis, J.

2013-01-01

387

The effect of natamycin on the transcriptome of conidia of Aspergillus niger.  

PubMed

The impact of natamycin on Aspergillus niger was analysed during the first 8 h of germination of conidia. Polarisation, germ tube formation, and mitosis were inhibited in the presence of 3 and 10 ?M of the anti-fungal compound, while at 10 ?M also isotropic growth was affected. Natamycin did not have an effect on the decrease of microviscosity during germination and the concomitant reduction in mannitol and trehalose levels. However, it did abolish the increase of intracellular levels of glycerol and glucose during the 8 h period of germination.Natamycin hardly affected the changes that occur in the RNA profile during the first 2 h of germination. During this time period, genes related to transcription, protein synthesis, energy and cell cycle and DNA processing were particularly up-regulated. Differential expression of 280 and 2586 genes was observed when 8 h old germlings were compared with conidia that had been exposed to 3 ?M and 10 ?M natamycin, respectively. For instance, genes involved in ergosterol biosynthesis were down-regulated. On the other hand, genes involved in endocytosis and the metabolism of compatible solutes, and genes encoding protective proteins were up-regulated in natamycin treated conidia. PMID:23449730

van Leeuwen, M R; Krijgsheld, P; Wyatt, T T; Golovina, E A; Menke, H; Dekker, A; Stark, J; Stam, H; Bleichrodt, R; Wösten, H A B; Dijksterhuis, J

2013-03-15

388

Magnetically recyclable, antimicrobial, and catalytically enhanced polymer-assisted "green" nanosystem-immobilized Aspergillus niger amyloglucosidase.  

PubMed

The present work reports the integration of polymer matrix-supported nanomaterial and enzyme biotechnology for development of industrially feasible biocatalysts. Aqueous leaf extract of Mesua ferrea L. was used to prepare silver nanoparticles distributed within a narrow size range (1-12 nm). In situ oxidative technique was used to obtain poly(ethylene glycol)-supported iron oxide nanoparticles (3-5 nm). Sonication-mediated mixing of above nanoparticles generated the immobilization system comprising of polymer-supported silver-iron oxide nanoparticles (20-30 nm). A commercially important enzyme, Aspergillus niger amyloglucosidase was coupled onto the immobilization system through sonication. The immobilization enzyme registered a multi-fold increment in the specific activity (807 U/mg) over the free counterpart (69 U/mg). Considerable initial activity of the immobilized enzyme was retained even after storing the system at room temperature as well as post-repeated magnetic recycling. Evaluation of the commendable starch saccharification rate, washing performance synergy with a panel of commercial detergents, and antibacterial potency strongly forwards the immobilized enzyme as a multi-functional industrially feasible system. PMID:20490787

Konwarh, Rocktotpal; Kalita, Dipankar; Mahanta, Charulata; Mandal, Manabendra; Karak, Niranjan

2010-08-01

389

Production and characterization of alpha-amylase from Aspergillus niger JGI 24 isolated in Bangalore.  

PubMed

Five fungal isolates were screened for the production of alpha-amylase using both solid-state and submerged fermentations. The best amylase producer among them, Aspergillus niger JGI 24, was selected for enzyme production by solid-state fermentation (SSF) on wheat bran. Different carbon and nitrogen supplements were used to enhance enzyme production and maximum amount of enzyme was obtained when SSF was carried out with soluble starch and beef extract (1% each) as supplements. Further attempts to enhance enzyme production by UV induced mutagenesis were carried out. Survival rate decreased with increase in duration of UV exposure. Partial purification of the enzyme using ammonium sulphate fractionation resulted in 1.49 fold increase in the enzyme activity. The enzyme showed a molecular weight of 43 kDa by SDS-PAGE. Metal ions Ca2+ and Co2+ increased the enzyme activity. The enzyme was optimally active at 30 degrees C and pH 9.5. PMID:19469283

Varalakshmi, K N; Kumudini, B S; Nandini, B N; Solomon, J; Suhas, R; Mahesh, B; Kavitha, A P

2009-01-01

390

Xylanase production by Aspergillus niger FTCC 5003 using palm kernel cake in fermentative bioprocess.  

PubMed

The production of xylanase from palm kernel cake as a substrate was studied in solid substrate fermentation. The simultaneous effects of three independent variables, namely incubation temperature, initial moisture content of substrate and air flow rate on xylanase production were evaluated by response surface methodology using central composite face centered design. A total of 18 experiments were carried out in which Aspergillus niger FTCC 5003 was cultivated on palm kernel cake in a column bioreactor for 7 days under incubation temperature, moisture level and aeration rate determined. Test results showed that the highest xylanase activity of 174.88 U g(-1) was produced at incubation temperature, initial moisture level and aeration rate of 25 degrees C, 60% and 1.5 L min(-1), respectively. The statistical analysis of the experimental results revealed that the linear effect of incubation temperature and quadratic term of initial moisture content had highly significant effects on xylanase production (p<0.01). Statistical results also showed that interaction effect between incubation temperature and initial moisture content as well as interaction effect between moisture level and aeration rate influenced the yield ofxylanase at probability levels of 95%. Optimum conditions determined by statistical model for attaining maximum xylanase production were incubation temperature of 25 degrees C, initial moisture level of 63% and aeration rate of 1.76 L min(-1). The xylanase activity of 192.50 U g(-1) was obtained when solid substrate fermentation was performed under the optimal circumstances. PMID:19943460

Abdeshahian, P; Samat, N; Yusoff, W M Wan

2009-08-01

391

The effects of bioprocess parameters on extracellular proteases in a recombinant Aspergillus niger B1-D.  

PubMed

Although host proteases are often considered to have a negative impact upon heterologous protein production by filamentous fungi, relatively little is known about the pattern of their appearance in recombinant fungal bioprocesses. In the present study, we investigated extracellular proteases from a filamentous fungus, Aspergillus niger B1-D, genetically modified to secrete hen egg white lysozyme (HEWL). Our findings indicate that extracellular protease activity is only detected after the carbon source is completely utilised in batch cultures. The proteases are predominantly acid proteases and have optimal temperature for activity at around 45 degrees C. Their activity could be partially inhibited by protease inhibitors, indicating the existence of at least four kinds of proteases in these culture fluids, aspartic-, serine-, cysteine-, and metallo-proteases. Oxygen enrichment does not have any noticeable effects on extracellular protease activity except that the onset of protease activity appears earlier in oxygen enrichment runs. Oxygen enrichment stimulates HEWL production substantially, and we propose that it is related to fungal morphology. Thermal stress imposed by raising process temperature (from 25 to 30 and 35 degrees C) in early exponential phase, led to appearance of protease activity in the medium following the heat shock. Continued cultivation at high temperatures significantly reduced HEWL production, which was associated with increased activity of the extracellular proteases in these cultures. PMID:18074130

Li, Qiang; Harvey, Linda M; McNeil, Brian

2008-02-01

392

Optimization of xylanase production from Aspergillus niger for biobleaching of eucalyptus pulp.  

PubMed

A crude endo-xylanase produced by Aspergillus niger BCC14405 was investigated for its potential in pre-bleaching of chemical pulp from eucalyptus. The optimal fermentation conditions on the basis of optimization using response surface methodology included cultivation in a complex medium comprising wheat bran, rice bran, and soybean meal supplemented with yeast extract, glucose, peptone, and lactose with a starting pH of 6.0 for 7 d. This resulted in production of 89.5 IU/mL of xylanase with minor cellulase activity. Proteomic analysis using LC/MS/MS revealed that the crude enzyme was a composite of hemicellulolytic enzymes, including endo-?-1,4-xylanase and other hemicellulolytic enzymes attacking arabinoxylan and mannan. Pretreatment of the pulp at a xylanase dosage of 10 IU/g increased the brightness ceiling after the C-Eop-H bleaching step up to 3.0% using a chlorine charge with a C-factor of 0.16-0.20. Xylanase treatment also led to reduction in chlorine charge of at least 20%, with an acceptable brightness level. The enzyme pretreatment resulted in a slight increase in pulp viscosity, suggesting an increase in relative cellulose content. The crude enzyme was potent in the enzyme-aided bleaching of chemical pulp in an environmentally friendly pulping process. PMID:21670524

Khonzue, Parichart; Laothanachareon, Thanaporn; Rattanaphan, Nakul; Tinnasulanon, Phungjai; Apawasin, Saowanee; Paemanee, Atchara; Ruanglek, Vasimon; Tanapongpipat, Sutipa; Champreda, Verawat; Eurwilaichitr, Lily

2011-01-01

393

Sudden substrate dilution induces a higher rate of citric acid production by Aspergillus niger.  

PubMed Central

On the basis of the present knowledge of Aspergillus niger metabolism during citric acid fermentation, an idea on how to improve the process was formed. Initially, a higher sucrose concentration was used for the germination of spores, which caused a higher intracellular level of the osmoregulator, glycerol, to be present. When citric acid started to be excreted into the medium, the substrate was suddenly diluted. Optimization of this procedure resulted in a nearly tripled volumetric rate (grams per liter per hour) of acid production, while the overall fermentation time was halved compared with the usual batch process. Yet, a characteristic delay was observed at the start of the acid excretion after the dilution. Hypo-osmotic shock caused a prominent elevation of intracellular cyclic AMP levels. Simultaneously, the specific activity of 6-phosphofructo-1-kinase increased significantly, probably due to phosphorylation of the protein molecule by cyclic AMP-dependent protein kinase. Specific 6-phosphofructo-1-kinase activity was much higher in the treated than in the normally growing mycelium. The metabolic flow through glycolysis was expected to be higher, which should contribute to a higher volumetric rate of acid production.

Legisa, M; Gradisnik-Grapulin, M

1995-01-01

394

Production of catalases by Aspergillus niger isolates as a response to pollutant stress by heavy metals  

SciTech Connect

Isolates of Aspergillus niger, selected from the coal dust of a mine containing arsenic (As; 400 mg/kg) and from the river sediment of mine surroundings (As, 1651 mg/kg, Sb, 362 mg/kg), growing in minimal nitrate medium in the phase of hyphal development and spore formation, exhibited much higher levels of total catalase activity than the same species from the culture collection or a culture adapted to soil contaminated with As (5 mg/L). Electrophoretic resolution of catalases in cell-free extracts revealed three isozymes of catalases and production of individual isozymes was not significantly affected by stress environments. Exogenously added stressors (As{sup 5+}, Cd{sup 2+}, Cu{sup 2+}) at final concentrations of 25 and 50 mg/L and H{sub 2}O{sub 2} (20 or 40 m(M)) mostly stimulated production of catalases only in isolates from mines surroundings, and H{sub 2}O{sub 2} and Hg{sup 2+} caused the disappearance of the smallest catalase I. Isolates exhibited a higher tolerance of the toxic effects of heavy metals and H{sub 2}O{sub 2}, as monitored by growth, than did the strain from the culture collection.

Buckova, M.; Godocikova, J.; Simonovicova, A.; Polek, B. [Slovakian Academy of Science, Bratislava (Slovakia)

2005-04-15

395

Purification and characterization of a beta-glucuronidase from Aspergillus niger.  

PubMed

A beta-glucuronidase from Pectinex Ultra SP-L, a commercial pectolytic enzyme preparation from Aspergillus niger, was purified 170-fold by ion-exchange chromatography and gel filtration. Apparent M(r) of the purified enzyme, estimated by denaturing gel electrophoresis and size-exclusion chromatography, were 68,000 and 71,000, respectively, indicating that the enzyme is a monomeric protein. It released uronic acids not only from p-nitrophenyl beta-glucosiduronic acid (PNP-GlcA) but also from acidic galactooligosaccharides carrying either beta-D-glucosyluronic or 4-O-methyl-beta-D-glucosyluronic residues at the nonreducing termini through beta-(1-->6)-glycosidic linkages. The enzyme exhibited a maximal activity toward these substrates at pH 3.0. A regioisomer, 3-O-beta-glucosyluronic acid-galactose, was unsusceptible to the enzyme. The enzyme did act on a polymer substrate, releasing uronic acid from the carbohydrate portion of a radish arabinogalactan-protein modified by treatment with fungal alpha-L-arabinofuranosidase. The enzyme produced acidic oligosaccharides by transglycosylation, catalyzing the transfer of uronic acid residues of PNP-GlcA and 6-O-beta-glucosyluronic acid-galactose to certain exogenous acceptor sugars such as Gal, N-acetylgalactosamine, Glc, and xylose. PMID:11423108

Kuroyama, H; Tsutsui, N; Hashimoto, Y; Tsumuraya, Y

2001-06-22

396

Purification and properties of three cellobiases from Aspergillus niger A20.  

PubMed

Three cellobiases, here called cellobiase A, B, and C, from the culture filtrate of Aspergillus niger A20, were purified by precipitation with ammonium sulphate, gel filtration through Sephadex G-75, and column chromatography of DEAE-cellulose. The purified enzymes were homogeneous on polyacrylamide disk electrophoresis. The mol wt of the purified enzymes were estimated by SDS-gel electrophoresis to be 88,000, 80,000, and 71,000 for cellobiases A, B, and C, respectively. The enzymes were active at pH 4.5 and 55-60 degrees C. The pattern of their amino acid compositions showed high contents of aspartic acid, glutamic acid, threonine, serine, and glycine. The apparent K(m) values for cellobiose were 0.9, 1.63, and 1.0 mM for cellobiases A, B, and C, respectively. Calcium ions stimulated cellobiases B and C, and Co2+ and Mg2+ ions stimulated cellobiase A. The purified enzymes hydrolyzed cellobiose and aryl-beta-D-glucosides, but they had no action on sucrose, maltose, and cellulose. The three cellobiases catalyzed transglycosylase reaction, and the major product formed from cellobiose was tetramer of glucose. PMID:10327588

Abdel-Naby, M A; Osman, M Y; Abdel-Fattah, A F

1999-01-01

397

Aspergillus Niger peritonitis in a peritoneal dialysis patient treated with eculizumab.  

PubMed

The complement system plays a vital role in preventing life-threatening infections by ensuring optimal functioning of the host immune system. Its dysregulation has been implicated in causing glomerular, hematological, and transplant-related disorders. Eculizumab a novel monoclonal antibody against complement component C5 has emerged in the recent past as the standard of care offering an effective rescue and maintenance therapy against many of these disorders. Its use has been associated with increased risk of infections predominantly with encapsulated organisms. There is no data in the literature on its effects in end-stage kidney disease (ESKD) or dialysis patients. We describe here a very rare case of Aspergillus Niger peritonitis in an ESKD patient on peritoneal dialysis (PD) receiving maintenance eculizumab therapy for atypical hemolytic uremic syndrome. Given that murine models with the same defect as that induced by eculizumab is vulnerable to invasive Aspergillosis, it is suggested that the fungal peritonitis in this patient was the result of the eculizumab therapy. PMID:24512095

Vellanki, Venkat S; Bargman, Joanne M

2014-05-01

398

Production of catalases by Aspergillus niger isolates as a response to pollutant stress by heavy metals.  

PubMed

Isolates of Aspergillus niger, selected from the coal dust of a mine containing arsenic (As; 400 mg/kg) and from the river sediment of mine surroundings (As, 1651 mg/kg, Sb, 362 mg/kg), growing in minimal nitrate medium in the phase of hyphal development and spore formation, exhibited much higher levels of total catalase activity than the same species from the culture collection or a culture adapted to soil contaminated with As (5 mg/L). Electrophoretic resolution of catalases in cell-free extracts revealed three isozymes of catalases and production of individual isozymes was not significantly affected by stress environments. Exogenously added stressors (As(5+), Cd(2+), Cu(2+)) at final concentrations of 25 and 50 mg/L and H(2)O(2) (20 or 40 mM) mostly stimulated production of catalases only in isolates from mines surroundings, and H(2)O(2) and Hg(2+) caused the disappearance of the smallest catalase I. Isolates exhibited a higher tolerance of the toxic effects of heavy metals and H(2)O(2), as monitored by growth, than did the strain from the culture collection. PMID:15902463

Bucková, Maria; Godocíková, Jana; Simonovicová, Alexandra; Polek, Bystrík

2005-04-01

399

The Effect of organic nitrogen sources on recombinant glucoamylase production by Aspergillus niger in chemostat culture.  

PubMed

Aspergillus niger B1, a recombinant strain carrying 20 extra copies of the native glucoamylase gene, was grown in glucose-limited chemostat cultures supplemented with various organic nitrogen sources (dilution rate 0.12 +/- 0.01 h(-1), pH 5.4). In cultures supplemented with l-alanine, l-methionine, casamino acids, or peptone, specific glucoamylase (GAM) production rapidly decreased to less than 20% of the initial level. Reducing the pH of the culture to 4.0 resulted in stable GAM production for up to 400 h. Morphological mutants (a light brown and a dark brown mutant) appeared in each fermentation and generally displaced B1. Light brown mutants had higher selection coefficients relative to B1 than dark brown mutants and became the dominant strain in all fermentations except those maintained at pH 4.0. Several mutants isolated from these cultures had reduced ability to produce GAM in batch culture, although few had lost copies of the glaA gene. Some mutants had methylated DNA. PMID:11170742

Swift, R J; Karandikar, A; Griffen, A M; Punt, P J; van den Hondel, C A; Robson, G D; Trinci, A P; Wiebe, M G

2000-11-01

400

Role of functional groups on Aspergillus niger biomass in the detoxification of hexavalent chromium.  

PubMed

Chromium (VI) contamination is not uncommon, especially near industries involved in leather tanning, chrome painting, metal cleaning and processing, wood preservation and alloy preparation. The mutagenic and carcinogenic properties of Chromium (VI) necessitate effective remedial processes. Difficulties associated with chemical and physical techniques to remediate a Chromium (VI) contaminated site to EPA recommended level (50 ppm), in addition to higher costs involved, assert the need for bioremedial measures. Biosorption can be one such solution to clean up heavy metal contamination. The objective of this study was to examine the main aspects of a possible strategy for the removal of Chromium (VI), employing Aspergillus niger biomass. The roles played by amines, carboxylic acids, phosphates, in Chromium (VI) biosorption were studied. Amino and the carboxy groups on the fungal cell wall play an important role in sorption. However, the role of carboxy group was far less than amino group. Surface adsorption of Chromium (VI) was also seen by scanning electron microscopy (SEM) thus indicating involvement of ion-exchange and surface adsorption mechanism in removal of Chromium (VI) ions. PMID:21117413

Narvekar, Sneha; Vaidya, Varsha K

2009-10-01

401

Metabolism of 2-ketoaldehydes in mold: purification and characterization of glyoxalase I from Aspergillus niger.  

PubMed

Glyoxalase I catalyzing the conversion of methylglyoxal into S-lactoylglutathione in the presence of glutathione was purified approximately 1,400-fold with 2.9% activity yield from mold, Aspergillus niger. The enzyme consisted of a single polypeptide chain with a relative molecular weight of 36,000 on both SDS-polyacrylamide gel electrophoresis and Sephadex G-150 gel filtration. The enzyme was most active at pH 7.0, 35-37 degrees C. Among the various aldehydes tested, the enzyme was active on methylglyoxal and 4,5-dioxovalerate with Km values of 1.25 and 0.87 mM, respectively. The activity of the enzyme was completely inhibited by Zn2+ at 0.5 mM. An equimolar amount of EDTA (0.5 mM) protected the enzyme from inactivation by Zn2+. EDTA competitively (K1 = 1.3 mM) inhibited the activity of the enzyme. Fe2+ was a potent activator for the enzyme, the activation being approximately 2.4-fold at 0.5 mM. PMID:3123469

Inoue, Y; Rhee, H; Watanabe, K; Murata, K; Kimura, A

1987-09-01

402

The Transcriptional Activator XlnR Regulates Both Xylanolytic and Endoglucanase Gene Expression in Aspergillus niger  

PubMed Central

The expression of genes encoding enzymes involved in xylan degradation and two endoglucanases involved in cellulose degradation was studied at the mRNA level in the filamentous fungus Aspergillus niger. A strain with a loss-of-function mutation in the xlnR gene encoding the transcriptional activator XlnR and a strain with multiple copies of this gene were investigated in order to define which genes are controlled by XlnR. The data presented in this paper show that the transcriptional activator XlnR regulates the transcription of the xlnB, xlnC, and xlnD genes encoding the main xylanolytic enzymes (endoxylanases B and C and ?-xylosidase, respectively). Also, the transcription of the genes encoding the accessory enzymes involved in xylan degradation, including ?-glucuronidase A, acetylxylan esterase A, arabinoxylan arabinofuranohydrolase A, and feruloyl esterase A, was found to be controlled by XlnR. In addition, XlnR also activates transcription of two endoglucanase-encoding genes, eglA and eglB, indicating that transcriptional regulation by XlnR goes beyond the genes encoding xylanolytic enzymes and includes regulation of two endoglucanase-encoding genes.

van Peij, Noel N. M. E.; Gielkens, Marco M. C.; de Vries, Ronald P.; Visser, Jaap; de Graaff, Leo H.

1998-01-01

403

Exploring Sequence Characteristics Related to High-Level Production of Secreted Proteins in Aspergillus niger  

PubMed Central

Protein sequence features are explored in relation to the production of over-expressed extracellular proteins by fungi. Knowledge on features influencing protein production and secretion could be employed to improve enzyme production levels in industrial bioprocesses via protein engineering. A large set, over 600 homologous and nearly 2,000 heterologous fungal genes, were overexpressed in Aspergillus niger using a standardized expression cassette and scored for high versus no production. Subsequently, sequence-based machine learning techniques were applied for identifying relevant DNA and protein sequence features. The amino-acid composition of the protein sequence was found to be most predictive and interpretation revealed that, for both homologous and heterologous gene expression, the same features are important: tyrosine and asparagine composition was found to have a positive correlation with high-level production, whereas for unsuccessful production, contributions were found for methionine and lysine composition. The predictor is available online at http://bioinformatics.tudelft.nl/hipsec. Subsequent work aims at validating these findings by protein engineering as a method for increasing expression levels per gene copy.

van den Berg, Bastiaan A.; Reinders, Marcel J. T.; Hulsman, Marc; Wu, Liang; Pel, Herman J.; Roubos, Johannes A.; de Ridder, Dick

2012-01-01

404

Purification and characterization of endo-xylanases from Aspergillus Niger. III. An enzyme of PL 365  

SciTech Connect

An endo-xylanase (1,4-..beta..-D-xylan xylanohydrolase, EC 3.2.1.8) from Aspergillus niger was purified to homogeneity by chromatography with Ultrogel AcA 54, SP-Sephadex C-25 at pH 4.5, DEAE-Sephadex A-25 at pH 5.4, Sephadex G-50, and DEAE-Sephadex A-25 at pH 5.15. The enzyme was active on soluble xylan, on insoluble xylan only after arabinosyl-initiated branch points were removed, and on xylooligosaccharides longer than xylotetraose. There was slight activity on carboxymethyl-cellulose, arabinogalactan, glucomannan, and p-nitrophenyl-..beta..-D- glucopyranoside. The main products of the hydrolysis of soluble and insoluble xylan were oligosaccharides of intermediate length, especially the tri- and pentasaccharides. The isolectric point of the enzyme was 3.65. It had a molecular weight of 2.8 x 10/sup 4/ by SDS-gel electrophoresis, and was high in acidic amino acids but low in those containing sulfur. Highest activity in a 20-min assay at pH 5 was between 40 and 45 degrees C, with an activation energy up to 40 degrees C of 11.1 kJ/mol. The optimum pH for activity was at 5.0. The enzyme was strongly activated by Ca/sup 2 +/. 15 references.

Fournier, R.A.; Frederick, M.M.; Frederick, J.R.; Reilly, P.J.

1985-04-01

405

Purification and characterisation of an extracellular phytase from Aspergillus niger 11T53A9  

PubMed Central

An extracellular phytase from Aspergillus niger 11T53A9 was purified about 51-fold to apparent homogeneity with a recovery of 20.3% referred to the phytase activity in the crude extract. Purification was achieved by ammonium sulphate precipitation, ion chromataography and gel filtration. The purified enzyme behaved as a monomeric protein with a molecular mass of about 85 kDa and exhibited maximal phytate-degrading activity at pH 5.0. Optimum temperature for the degradation of phytate was 55°C. The kinetic parameters for the hydrolysis of sodium phytate were determined to be KM = 54 µmol l-1 and kcat = 190 sec-1 at pH 5.0 and 37°C. The purified enzyme was rather specific for phytate dephosphorylation. It was shown that the phytase preferably dephosphorylates myo-inositol hexakisphosphate in a stereospecific way by sequential removal of phosphate groups via D-Ins(1,2,4,5,6)P5, D-Ins(1,2,5,6)P4, D-Ins(1,2,6)P3, D-Ins(1,2)P2 to finally Ins(2)P.

Greiner, Ralf; da Silva, Lucineia Gomes; Couri, Sonia

2009-01-01

406

Purification and Characterization of a Ginsenoside Rb1-Hydrolyzing ?-Glucosidase from Aspergillus niger KCCM 11239  

PubMed Central

Rb1-hydrolyzing ?-glucosidase from Aspergillus niger KCCM 11239 was studied to develop a bioconversion process for minor ginsenosides. The specific activity of the purified enzyme was 46.5 times greater than that of the crude enzyme. The molecular weight of the native enzyme was estimated to be approximately 123 kDa. The optimal pH of the purified enzyme was pH 4.0, and the enzyme proved highly stable over a pH range of 5.0–10.0. The optimal temperature was 70 °C, and the enzyme became unstable at temperatures above 60 °C. The enzyme was inhibited by Cu2+, Mg2+, Co2+, and acetic acid (10 mM). In the specificity tests, the enzyme was found to be active against ginsenoside Rb1, but showed very low levels of activity against Rb2, Rc, Rd, Re, and Rg1. The enzyme hydrolyzed the 20-C,?-(1?6)-glucoside of ginsenoside Rb1 to generate ginsenoside Rd and Rg3, and hydrolyzed 3-C,?-(1?2)-glucoside to generate F2. The properties of the enzyme indicate that it could be a useful tool in biotransformation applications in the ginseng industry, as well as in the development of novel drug compounds.

Chang, Kyung Hoon; Jo, Mi Na; Kim, Kee-Tae; Paik, Hyun-Dong

2012-01-01

407

Microbial leaching of chromite overburden from Sukinda mines, Orissa, India using Aspergillus niger  

NASA Astrophysics Data System (ADS)

Leaching of nickel and cobalt from two physical grades (S1, 125-190 ?m, coarser and S3, 53-75 ?m, finer) of chromite overburden was achieved by treating the overburden (2% pulp density) with 21-d culture filtrate of an Aspergillus niger strain grown in sucrose medium. Metal dissolution increases with ore roasting at 600°C and decreasing particle size due to the alteration of microstructural properties involving the conversion of goethite to hematite and the increase in surface area and porosity as evident from X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (DT-TGA), and field emission scanning electron microscopy (FESEM). About 65% Ni and 59% Co were recovered from the roasted S3 ore employing bioleaching against 26.87% Ni and 31.3% Co using an equivalent amount of synthetic oxalic acid under identical conditions. The results suggest that other fungal metabolites in the culture filtrate played a positive role in the bioleaching process, making it an efficient green approach in Ni and Co recovery from lateritic chromite overburden.

Biswas, Supratim; Samanta, Saikat; Dey, Rajib; Mukherjee, Siddhartha; Banerjee, Pataki C.

2013-08-01

408

Bioleaching of nickel and cobalt from lateritic chromite overburden using the culture filtrate of Aspergillus niger.  

PubMed

Extraction of metals (Ni, Co) from chromite overburden of Sukinda mines of Orissa, India, with the culture filtrate of Aspergillus niger was studied. Results showed that the amounts of metals leached varied directly with reaction temperature and period of fermentation. The culture filtrate was analyzed for citric and oxalic acids, and contained only oxalic acid-the concentration of which increased with time. Although this acid played the major role in leaching of metals, other unidentified metabolites present in the culture filtrate influenced the dissolution of the metals significantly. Maximum recovery of metals from raw and roasted ore samples was achieved at 80 °C with the 21-day culture filtrate containing the highest amount of oxalic acid. Under identical experimental conditions, much higher amounts of the metals were leached from roasted ore. Microstructures of the ore particles were studied by scanning electron microscopy and transmission electron microscopy; the bonding behaviors of metal compounds were identified by Fourier transform infrared spectroscopy which showed that the metals were leached after chelation with oxalic acid. PMID:23700146

Biswas, Supratim; Dey, Rajib; Mukherjee, Siddhartha; Banerjee, Pataki C

2013-08-01

409

Purification and biochemical characterisation of glucoamylase from a newly isolated Aspergillus niger: Relation to starch processing.  

PubMed

Herein, we investigate a glucoamylase from newly isolated Aspergillus niger. The enzyme was purified, using fractionation, followed by anion-exchange chromatography and then characterised. The molecular mass of the enzyme was estimated to be ?62,000Da, using SDS-PAGE and 57151Da, based on mass spectrometry results. The pI of the protein, and optimum pH/temperature of enzyme activity were 4.4, 5 and 70°C, respectively and the kinetic parameters (Km, Vmax and kcat) were determined to be 0.33 (mgml(-1)), 0.095 (U?g(-1)min(-1)) and 158.3 (s(-1)) for soluble starch, respectively. The glucoamylase nature of the enzyme was also confirmed using TLC and a specific substrate. Metal ions Fe(3+), Al(3+) and Hg(2+) had the highest inhibitory effect, while Ag(2)(+), Ca(2+), Zn(2+), Mg(2+) and Cd(2+) and EDTA showed no significant effect on the enzyme activity. In addition, thermal stability of the enzyme increased in the presence of starch and calcium ion. Based on the results, the purified glucoamylase appeared to be a newly isolated enzyme. PMID:24837950

Bagheri, Ahmad; Khodarahmi, Reza; Mostafaie, Ali

2014-10-15

410

Unfolding and refolding of Aspergillus niger PhyB phytase: role of disulfide bridges.  

PubMed

The role of disulfide bridges in the folding of Aspergillus niger phytase pH 2.5-optimum (PhyB) was investigated using dynamic light scattering (DLS). Guanidinium chloride (GuCl) at 1.0 M unfolded phytase; however, its removal by dialysis refolded the protein. The thiol reagent tris(2-carboxyethyl)phosphine (TCEP) reduces the refolding activity by 68%. The hydrodynamic radius (R(H)) of PhyB phytase decreased from 5.5 to 4.14 nm when the protein was subjected to 1.0 M GuCl concentration. The active homodimer, 183 kDa, was reduced to a 92 kDa monomer. The DLS data taken together with activity measurements could indicate whether refolding took place or not in PhyB phytase. The correlation between molecular mass and the state of unfolding and refolding is a very strong one in fungal phytase belonging to histidine acid phosphatase (HAP). Unlike PhyA phytase, for which sodium chloride treatment boosted the activity at 0.5 M salt concentration, PhyB phytase activity was severely inhibited under identical condition. Thus, PhyA and PhyB phytases are structurally very different, and their chemical environment in the active site and substrate-binding domain may be different to elicit such an opposite reaction to monovalent cations. PMID:18683944

Ullah, Abul H J; Sethumadhavan, Kandan; Mullaney, Edward J

2008-09-10

411

Sorption of heavy metals by the soil fungi 'Aspergillus niger' and Mucor rouxii  

SciTech Connect

Sorption of the nitrate salts of cadmium(II), copper(II), lanthanum(III) and silver(I) by two fungi, Aspergillus niger and Mucor rouxii, was evaluated using Freundlich adsorption isotherms and energy dispersive X-ray electron microscopy. The linearized Freundlich isotherm described the metal sorption data well for metal concentrations of 5 microM-1 mM metal. Differences in metal binding were observed among metals, as well as between fungal species. Calculated Freundlich K values indicated that metal binding decreased in the order La(3+) > or = Ag(+) > Cu(2+) > Cd(2+). However, sorption of Ag(+) was greater than that of La(3+) from solutions of 0.1 and 1 mM metal and likely due to precipitation at the cell wall surface. At the 1 mM initial concentration, there were no significant differences between the two fungi in metal sorption, except for Ag(+) binding. At the 5 microM concentration, there was no difference between the fungi in their sorption capacities for the four metals. Electron microscopy-energy dispersive X-ray analysis indicated that silver precipitated onto cells as colloidal silver. The results indicate that Freundlich isotherms may be useful for describing short-term metal sorption by fungal biomass and for comparison with other soil constituents in standardized systems. (Copyright (c) 1992 Pergamon Press plc.)

Mullen, M.D.; Wolf, D.C.; Beveridge, T.J.; Bailey, G.W.

1992-01-01

412

Citric acid production from Aspergillus niger MT-4 using hydrolysate extract of the insect Locusta migratoria.  

PubMed

Citric acid (CA) is the most important organic acid used in the food and other industries. Locusta migratoria is an insect species, which has rich nutritional composition (especially protein) and cultivated in some countries. Therefore, the present study investigated the usability of hydrolysate extract of L. migratoria biomass as substrate for the production of CA from Aspergillus niger MT-4. The insect extract (IE) was found to be rich in ash (34.9 g/100 g), protein (35.6 g/100 g) and mineral contents. Yeast extract was found to be the most favorable substrate for biomass production, whereas the maximum production of CA (41.8 g/L) was achieved in the medium containing IE. Besides, uniform pellets with the smallest size (4 mm) were observed in IE medium. It was thought that rich magnesium (6.78 g/100 g) and manganese (1.14 g/100 g) contents of IE increased the production of CA, resulting in the formation of small uniform pellets. This is the first report on the effect of protein-rich insect biomasses on the production of CA. In this regard, L. migratoria biomass was tested for the first time as a CA-production substrate. PMID:22323475

Taskin, Mesut; Tasar, Gani Erhan; Incekara, Umit

2013-06-01

413

Production of Alkaline Protease by a New Aspergillus flavus Isolate under Solid-Substrate Fermentation Conditions for Use as a Depilation Agent  

PubMed Central

The production of alkaline protease by an Aspergillus flavus strain isolated in our laboratory by solid-substrate fermentation for use as a depilation agent and the influence of various factors on enzyme production are reported. The optimum conditions for maximum production were a growth temperature of 32°C, 63% substrate moisture, and a growth period of 48 h. Enrichment with corn steep liquor or Casitone increased productivity. Scaling-up experiments indicated that flask-scale results could be reproduced at 1 and 30 kg of substrate. The enzyme preparation exhibited maximum activity at both pH 7.5 and pH 9.5. The use of this enzyme as a depilation agent was confirmed by experiments in a tannery.

Malathi, S.; Chakraborty, R.

1991-01-01

414

Efficacy of the combined application of chitosan and Locust Bean Gum with different citrus essential oils to control postharvest spoilage caused by Aspergillus flavus in dates.  

PubMed

This study reports the efficacy of the combined application of chitosan (CH) and Locust Bean Gum (LBG) in combination with different citrus essential oils (EOs) to inhibit Aspergillus flavus in vitro and on artificially infected dates for a storage period of 12 days. The effect of these treatments on the fruits' sensory characteristics was evaluated to verify the complete absence of off-odours and off-flavours. Bergamot EO was the most effective in reducing mycelial growth, followed by bitter orange EO. Both bergamot and bitter orange oils significantly reduced conidial germination and a complete inhibition was obtained at concentrations higher than 2%. The mixtures based on CH-2% (v/v) bergamot EO or CH-2% (v/v) bitter orange EO proved to be the most effective coatings to reduce conidial germination resulting in an 87-90% inhibition compared with the control. In fruit decay assays coatings based on CH incorporating citrus oils were able to reduce fungal decay in the range of 52-62% at day 12. The study results and the complete absence of off-flavours and off-odours demonstrate the potential of CH coatings carrying citrus EOs at sub-inhibitory concentrations to control postharvest growth of A. flavus in dates. PMID:24291176

Aloui, Hajer; Khwaldia, Khaoula; Licciardello, Fabio; Mazzaglia, Agata; Muratore, Giuseppe; Hamdi, Moktar; Restuccia, Cristina

2014-01-17

415

Heterologous expression, purification and characterization of nitrilase from Aspergillus niger K10  

PubMed Central

Background Nitrilases attract increasing attention due to their utility in the mild hydrolysis of nitriles. According to activity and gene screening, filamentous fungi are a rich source of nitrilases distinct in evolution from their widely examined bacterial counterparts. However, fungal nitrilases have been less explored than the bacterial ones. Nitrilases are typically heterogeneous in their quaternary structures, forming short spirals and extended filaments, these features making their structural studies difficult. Results A nitrilase gene was amplified by PCR from the cDNA library of Aspergillus niger K10. The PCR product was ligated into expression vectors pET-30(+) and pRSET B to construct plasmids pOK101 and pOK102, respectively. The recombinant nitrilase (Nit-ANigRec) expressed in Escherichia coli BL21-Gold(DE3)(pOK101/pTf16) was purified with an about 2-fold increase in specific activity and 35% yield. The apparent subunit size was 42.7 kDa, which is approx. 4 kDa higher than that of the enzyme isolated from the native organism (Nit-ANigWT), indicating post-translational cleavage in the enzyme's native environment. Mass spectrometry analysis showed that a C-terminal peptide (Val327 - Asn356) was present in Nit-ANigRec but missing in Nit-ANigWT and Asp298-Val313 peptide was shortened to Asp298-Arg310 in Nit-ANigWT. The latter enzyme was thus truncated by 46 amino acids. Enzymes Nit-ANigRec and Nit-ANigWT differed in substrate specificity, acid/amide ratio, reaction optima and stability. Refolded recombinant enzyme stored for one month at 4°C was fractionated by gel filtration, and fractions were examined by electron microscopy. The late fractions were further analyzed by analytical centrifugation and dynamic light scattering, and shown to consist of a rather homogeneous protein species composed of 12-16 subunits. This hypothesis was consistent with electron microscopy and our modelling of the multimeric nitrilase, which supports an arrangement of dimers into helical segments as a plausible structural solution. Conclusions The nitrilase from Aspergillus niger K10 is highly homologous (?86%) with proteins deduced from gene sequencing in Aspergillus and Penicillium genera. As the first of these proteins, it was shown to exhibit nitrilase activity towards organic nitriles. The comparison of the Nit-ANigRec and Nit-ANigWT suggested that the catalytic properties of nitrilases may be changed due to missing posttranslational cleavage of the former enzyme. Nit-ANigRec exhibits a lower tendency to form filaments and, moreover, the sample homogeneity can be further improved by in vitro protein refolding. The homogeneous protein species consisting of short spirals is expected to be more suitable for structural studies.

2011-01-01

416

Gene encoding a novel invertase from a xerophilic Aspergillus niger strain and production of the enzyme in Pichia pastoris.  

PubMed

?-Fructofuranosidases or invertases (EC 3.2.1.26) are enzymes that are widely used in the food industry, where fructose is preferred over sucrose, because it is sweeter and does not crystallize easily. Since Aspergillus niger GH1, an xerophilic fungus from the Mexican semi-desert, has been reported to be an invertase producer, and because of the need for new enzymes with biotechnological applications, in this work, we describe the gene and amino acid sequence of the invertase from A. niger GH1, and the use of a synthetic gene to produce the enzyme in the methylotrophic yeast Pichia pastoris. In addition, the produced invertase was characterized biochemically. The sequence of the invertase gene had a length of 1770bp without introns, encodes a protein of 589 amino acids, and presented an identity of 93% and 97% with invertases from Aspergillus kawachi IFO 4308 and A. niger B60, respectively. A 4.2L culture with the constructed recombinant P. pastoris strain showed an extracellular and periplasmic invertase production at 72h induction of 498 and 3776 invertase units (U), respectively, which corresponds to 1018U/L of culture medium. The invertase produced had an optimum pH of 5.0, optimum temperature of 60°C, and specific activity of 3389U/mg protein, and after storage for 96h at 4°C showed 93.7% of its activity. This invertase could be suitable for producing inverted sugar used in the food industry. PMID:25039056

Veana, Fabiola; Fuentes-Garibay, José Antonio; Aguilar, Cristóbal Noé; Rodríguez-Herrera, Raúl; Guerrero-Olazarán, Martha; Viader-Salvadó, José María

2014-09-01

417

Genomic analysis of the secretion stress response in the enzyme-producing cell factory Aspergillus niger  

PubMed Central

Background Filamentous fungi such as Aspergillus niger have a high capacity secretory system and are therefore widely exploited for the industrial production of native and heterologous proteins. However, in most cases the yields of non-fungal proteins are significantly lower than those obtained for fungal proteins. One well-studied bottleneck appears to be the result of mis-folding of heterologous proteins in the ER during early stages of secretion, with related stress responses in the host, including the unfolded protein response (UPR). This study aims at uncovering transcriptional and translational responses occurring in A. niger exposed to secretion stress. Results A genome-wide transcriptional analysis of protein secretion-related stress responses was determined using Affymetrix DNA GeneChips and independent verification for selected genes. Endoplasmic reticulum (ER)-associated stress was induced either by chemical treatment of the wild-type cells with dithiothreitol (DTT) or tunicamycin, or by expressing a human protein, tissue plasminogen activator (t-PA). All of these treatments triggered the UPR, as shown by the expression levels of several well-known UPR target genes. The predicted proteins encoded by most of the up-regulated genes function as part of the secretory system including chaperones, foldases, glycosylation enzymes, vesicle transport proteins, and ER-associated degradation proteins. Several genes were down-regulated under stress conditions and these included several genes that encode secreted enzymes. Moreover, translational regulation under ER stress was investigated by polysomal fractionation. This analysis confirmed the post-transcriptional control of hacA expression and highlighted that differential translation also occurs during ER stress, in particular for some genes encoding secreted proteins or proteins involved in ribosomal biogenesis and assembly. Conclusion This is first genome-wide analysis of both transcriptional and translational events following protein secretion stress. Insight has been gained into the molecular basis of protein secretion and secretion-related stress in an effective protein-secreting fungus, and provides an opportunity to identify target genes for manipulation in strain improvement strategies.

Guillemette, Thomas; van Peij, Noel NME; Goosen, Theo; Lanthaler, Karin; Robson, Geoffrey D; van den Hondel, Cees AMJJ; Stam, Hein; Archer, David B

2007-01-01

418

Value addition of vegetable wastes by solid-state fermentation using Aspergillus niger for use in aquafeed industry.  

PubMed

Vegetable waste typically has high moisture content and high levels of protein, vitamins and minerals. Its value as an agricultural feed can be enhanced through solid-state fermentation (SSF). Two experiments were conducted to evaluate the nutritional status of the products derived by SSF of a mixture of dried vegetable waste powder and oil cake mixture (soybean flour, wheat flour, groundnut oil cake and sesame oil cake at 4:3:2:1 ratio) using fungi Aspergillus niger S(1)4, a mangrove isolate, and A. niger NCIM 616. Fermentation was carried out for 9 days at 35% moisture level and neutral pH. Significant (p<0.05) increase in crude protein and amino acids were obtained in both the trials. The crude fat and crude fibre content showed significant reduction at the end of fermentation. Nitrogen free extract (NFE) showed a gradual decrease during the fermentation process. The results of the study suggest that the fermented product obtained on days 6 and 9 in case of A. niger S(1)4 and A. niger NCIM 616 respectively contained the highest levels of crude protein. PMID:20100652

Rajesh, N; Imelda-Joseph; Raj, R Paul

2010-11-01

419

Utilization of ram horn peptone in the production of glucose oxidase by a local isolate Aspergillus niger OC-3.  

PubMed

Glucose oxidase (GO) is an enzyme that is used in many fields. In this study, ram horn peptone (RHP) was utilized as the nitrogen source and compared with other nitrogen sources in the production of GO by Aspergillus niger. To obtain higher GO activity, 14 A. niger strains were isolated from soil samples around Erzurum, Turkey. Among these strains, the isolate that was named A. niger OC-3 achieved the highest GO production. The production of GO was carried out in 100 mL scaled batch culture. The fermentation conditions such as initial pH, temperature, agitation speed, and time were investigated in order to improve GO production. The results showed that the cultivation conditions would significantly affect the formation of GO, and the utilization of the RHP achieved the highest enzyme production (48.6 U/mL) if compared to other nitrogen sources. On the other hand, the maximum biomass was obtained by using the fish peptone (7.2 g/L), while RHP yielded 6.4 g/L. These results suggest that RHP from waste ram horns could effectively be used in the production of GO by A. niger OC-3. PMID:21229465

Canli, Ozden; Kurbanoglu, Esabi Basaran

2011-01-01

420

Improvement of Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-Protein Response  

PubMed Central

Unfolded-protein response (UPR) denotes the upregulation of endoplasmic reticulum (ER)-resident chaperone and foldase genes and numerous other genes involved in secretory functions during the accumulation of unfolded proteins into the ER. Overexpression of individual foldases and chaperones has been used in attempts to improve protein production in different production systems. We describe here a novel strategy to improve foreign-protein production. We show that the constitutive induction of the UPR pathway in Aspergillus niger var. awamori can be achieved by expressing the activated form of the transcription factor hacA. This induction enhances the production of Trametes versicolor laccase by up to sevenfold and of bovine preprochymosin by up to 2.8-fold in this biotechnically important fungus. The regulatory range of UPR was studied by analyzing the mRNA levels of novel A. niger var. awamori genes involved in different secretory functions. This revealed both similarities and differences to corresponding studies in Saccharomyces cerevisiae.

Valkonen, Mari; Ward, Michael; Wang, Huaming; Penttila, Merja; Saloheimo, Markku

2003-01-01

421

A new group of exo-acting family 28 glycoside hydrolases of Aspergillus niger that are involved in pectin degradation.  

PubMed

The fungus Aspergillus niger 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 new gene group, which we show to encode exoacting pectinolytic glycoside hydrolases. This group includes four exo-polygalacturonan hydrolases (PGAX, PGXA, PGXB and PGXC) and three putative exo-rhamnogalacturonan hydrolases (RGXA, RGXB and RGXC). Biochemical identification using polygalacturonic acid and xylogalacturonan as substrates demonstrated that indeed PGXB and PGXC act as exo-polygalacturonases, whereas PGXA acts as an exo-xylogalacturonan hydrolase. The expression levels of all 21 genes were assessed by microarray analysis. The results from the present study demonstrate that exo-acting glycoside hydrolases play a prominent role in pectin degradation. PMID:16822232

Martens-Uzunova, Elena S; Zandleven, Joris S; Benen, Jaques A E; Awad, Hanem; Kools, Harrie J; Beldman, Gerrit; Voragen, Alphons G J; Van den Berg, Johan A; Schaap, Peter J

2006-11-15

422

Tandem mass spectrometric analysis of aspergillus niger pectin methylesterase: mode of action on fully methyl-esterified oligogalacturonates.  

PubMed Central

The substrate specificity and the mode of action of Aspergillus niger pectin methylesterase (PME) was determined using both fully methyl-esterified oligogalacturonates with degrees of polymerization (DP) 2-6 and chemically synthesized monomethyl trigalacturonates. The enzymic activity on the different substrates and a preliminary characterization of the reaction products were performed by using high-performance anion-exchange chromatography at neutral pH. Electrospray ionization tandem MS (ESI-MS/MS) was used to localize the methyl esters on the (18)O-labelled reaction products during the course of the enzymic reaction. A. niger PME is able to hydrolyse the methyl esters of fully methyl-esterified oligogalacturonates with DP 2, and preferentially hydrolyses the methyl esters located on the internal galacturonate residues, followed by hydrolysis of the methyl esters towards the reducing end. This PME is unable to hydrolyse the methyl ester of the galacturonate moiety at the non-reducing end.

Kester, H C; Benen, J A; Visser, J; Warren, M E; Orlando, R; Bergmann, C; Magaud, D; Anker, D; Doutheau, A

2000-01-01

423

Activity stabilization of Aspergillus niger and Escherichia coli phytases immobilized on allophanic synthetic compounds and montmorillonite nanoclays.  

PubMed

The aim of this work was to study the stabilization of the activity of two commercial microbial phytases (Aspergillus niger and Escherichia coli) after immobilization on nanoclays and to establish optimal conditions for their immobilization. Synthetic allophane, synthetic iron-coated allophanes and natural montmorillonite were chosen as solid supports for phytase immobilization. Phytase immobilization patterns at different pH values were strongly dependent on both enzyme and support characteristics. After immobilization, the residual activity of both phytases was higher under acidic conditions. Immobilization of phytases increased their thermal stability and improved resistance to proteolysis, particularly on iron-coated allophane (6% iron oxide), which showed activation energy (E(a)) and activation enthalpy (?H(#)) simi