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1

Xylanolytic enzyme production by an Aspergillus niger isolate  

Microsoft Academic Search

Production of xylanolytic enzymes by anAspergillus niger CCMI 850 isolate was investigated in batch cultures. The effect of the composition of a fermentation medium that did not\\u000a include chemical inducers, on ?-xylanase, ?-xylosidase, ?-l-arabinofuranosidase, and total cellulase activity was studied. With 4% xylan as the carbon source, about 65 U\\/mL of ?-xylanase\\u000a was obtained, whereas the total cellulase activity was

M. Costa-Ferreira; A. Dias; C. Maximo; M. J. Morgado; G. Sena-Martins; J. Cardoso Duarte

1994-01-01

2

Isolation and characterization of mutants of Aspergillus niger deficient in extracellular proteases  

Microsoft Academic Search

In the present study, the extracellular protease activity in a strain of the filamentous fungus Aspergillus niger was investigated and mutant strains deficient in the production of extracellular proteases were isolated. The major protease, which is responsible for 80–85% of the total activity, is aspergillopepsin A, a protein of ca. 43 kDa, the activity of which is inhibited by pepstatin.

Ineke E. Mattern; Johannes M. van Noort; Paul van den Berg; David B. Archer; Ian N. Roberts; Cees A. M. J. J. Hondel

1992-01-01

3

Isolation and NMR characterization of fumonisin B2 and a new fumonisin B6 from Aspergillus niger.  

PubMed

A new fumonisin, fumonisin B(6) (1), has been isolated by cation-exchange and reverse-phase chromatography, together with fumonisin B(2) (2), from stationary cultures of the fungus Aspergillus niger NRRL 326. Analysis of mass spectrometric and NMR data determined that FB(6) is a positional isomer of FB(1) and iso-FB(1), having hydroxyl functions at C3, C4, and C5. Analysis of the NMR data for FB(2) showed very similar chemical shift values when compared to an authentic Fusarium FB(2) standard, strongly indicating identical molecules despite that an absolute stereochemical assignment of FB(2) from A. niger was not possible. PMID:20028011

Månsson, Maria; Klejnstrup, Marie Louise; Phipps, Richard K; Nielsen, Kristian F; Frisvad, Jens C; Gotfredsen, Charlotte H; Larsen, Thomas O

2010-01-27

4

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

5

Aspergillus niger lipases: induction, isolation and characterization of two lipases from a MZKI A116 strain  

Microsoft Academic Search

Aspergillus niger strain MZKI A116 was used to produce lipolytic enzymes in submerged culture. Lipase production was induced by addition of olive oil to a complex medium with an initial pH of 5.0. Maximal activity was reached after 70 h in a 15 1 bioreactor at 30 °C with aeration of 0.5 vvm and agitation 400 rpm. Optimal temperature and

D. Pokorny; A. Cimerman; W. Steiner

1997-01-01

6

Response surface optimization for enhanced production of cellulases with improved functional characteristics by newly isolated Aspergillus niger HN-2.  

PubMed

Fungi isolated from partially decayed wood log samples showing characteristic diversity for spore colour, colony morphology and arrangement of spores were assessed for cellulolytic enzyme production. Isolates showing a cellulolytic index of ?2.0 were assayed for filter paper (FP) cellulase and ?-glucosidase (BGL) production. Molecular characterization confirmed the identity of the selected cellulolytic isolate as a strain of Aspergillus niger (A. niger HN-2). Addition of 2 % (w/v) urea enhanced FP and BGL activity by about 20 and 60 %, respectively. Validation studies conducted at parameters (29 °C, pH 5.4, moisture content 72 % and 66 h) optimized through response surface methodology in a solid-state static tray fermentation resulted in FP, BGL, cellobiohydrolase I (CBHI), endoglucanase (EG), xylanase activity and protein content of 25.3 FPU/g ds, 750 IU/g ds, 13.2 IU/g ds, 190 IU/g ds, 2890 IU/g ds and 0.9 mg/ml, respectively. In comparison, A. niger N402 which is a model organism for growth and development studies, produced significantly lower FP, BGL, CBHI, EG, xylanase activity and protein content of 10.0 FPU/g ds, 100 IU/g ds, 2.3 IU/g ds, 50 IU/g ds, 500 IU/g ds and 0.75 mg/ml, respectively under the same process conditions as were used for A. niger HN-2. Process optimization led to nearly 1.8- and 2.2-fold increase in FP and BGL activity, respectively showing promise for cellulase production by A. niger HN-2 at a higher scale of operation. Zymogram analysis revealed two isoforms each for EG and cellobiohydrolase and three isoforms for BGL. Crude cellulase complex produced by A. niger HN-2 exhibited thermostability under acidic conditions showing potential for use in biofuel industry. PMID:24158534

Oberoi, Harinder Singh; Rawat, Rekha; Chadha, Bhupinder Singh

2014-01-01

7

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

8

Isolation of a Aspergillus niger lipase from a solid culture medium with aqueous two-phase systems.  

PubMed

The aim of this work is to find the best conditions to isolate lipase from a solid culture medium of Aspergillus niger NRRL3 strains using aqueous two-phase systems formed with polyethylene glycol and potassium phosphate or polyethylene glycol and sodium citrate. We studied the partitioning of a commercial lyophilizate from A. niger. Also, the lipase enzymatic activity was studied in all the phases of the systems and the results indicate that citrate anion increases lipase activity. An analysis by fluorescence spectroscopy of the interaction between lipase and the bottom and top phases of the systems shows that the protein tryptophan-environments are modified by the presence of PEG and salts. Separation of the enzyme from the rest of the proteins that make up the lyophilized was achieved with good yield and separation factor by ATPS formed by PEG 1000/Pi at pH 7, PEG 2000/Ci at pH 5.2 and PEG 4000/Ci at pH 5.2. The above mentioned systems were used in order to isolate extracellular lipase from a strain of A. niger in submerged culture and solid culture. The best system for solid culture, with high purification factor (30.50), is the PEG 4000/Ci at pH 5.2. The enzyme was produced in a solid culture medium whose production is simple and recovered in a phase poor in polymer, bottom phase. An additional advantage is that the citrate produces less pollution than the phosphate. This methodology could be used as a first step for the isolation of the extracellular lipase from A. niger. PMID:21689997

Marini, Analía; Imelio, Natalia; Picó, Guillermo; Romanini, Diana; Farruggia, Beatriz

2011-07-15

9

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

10

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. PMID:21816052

2011-01-01

11

Kitchens as a source of Aspergillus niger infection  

Microsoft Academic Search

In this study we investigated the epidemiology of a cluster of cutaneous infections owing to Aspergillus niger, which occurred in neutropenic patients in a bone marrow transplant unit. Heavy environmental contamination with the mould was found in the ward kitchen adjacent to the unit. The clinical and environmental isolates were typed by random amplification of polymorphic DNA (RAPD), which showed

K. W. Loudon; A. P. Coke; J. P. Burnie; A. J. Shaw; B. A. Oppenheim; C. Q. Morris

1996-01-01

12

Purification and Characterization of a Dimethoate-Degrading Enzyme of Aspergillus niger ZHY256, Isolated from Sewage  

PubMed Central

A dimethoate-degrading enzyme from Aspergillus niger ZHY256 was purified to homogeneity with a specific activity of 227.6 U/mg of protein. The molecular mass of the purified enzyme was estimated to be 66 kDa by gel filtration and 67 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The isoelectric point was found to be 5.4, and the enzyme activity was optimal at 50°C and pH 7.0. The activity was inhibited by most of the metal ions and reagents, while it was induced by Cu2+. The Michaelis constant (Km) and Vmax for dimethoate were 1.25 mM and 292 ?mol min?1 mg of protein?1, respectively. PMID:11472959

Liu, Yu-Huan; Chung, Ying-Cheng; Xiong, Ya

2001-01-01

13

Induction of glucose oxidase, catalase, and lactonase in Aspergillus niger  

Microsoft Academic Search

The induction of glucose oxidase, catalase, and lactonase activities was studied both in wild-type and in glucose oxidase regulatory and structural mutants of Aspergillus niger. The structural gene for glucose oxidase was isolated and used for Northern analysis and in transformation experiments using various gox mutations. Wild-type phenotype could be restored in the glucose oxidase-negative mutant (goxC) by transformation with

Cor F. B. Witteveen; Hetty C. van den Broeck; Frank A. C. van Engelenburg; Leo H. de Graaff; Marcel H. B. C. Hillebrand; Peter J. Schaap; Jaap Visser

1993-01-01

14

?????????????????????????????????????????????????????????? Aspergillus niger ATCC 20611 Inulin and sucrose affecting on inulinase production from Aspergillus niger ATCC 20611  

Microsoft Academic Search

???????????????????????????? ??????????????????????????????????????????????????????????????? ?????????????????????????? Aspergillus niger ATCC 20611 ????????????????????????????????? (????\\/????) ?????????????????????????? 25 : 2, 25 : 4,12.5 : 4 ??? 6.25 : 4 ???????????????????????????????????????? ??????? 5.48, 2.56, 1.67 ??? 1.22 ?????\\/????????? ??????? 8, 12, 6 ??? 7.5 ??. ????? ???? ?????????????? ???????????????? (YE) ??????? 0.59, 0.84, 0.98 ??? 0.59 ?????\\/???????????? ?????????? ??????????????? ??????? (qE) ??????? 0.07, 0.10, 0.16 ??? 0.08 ?????\\/?????????

Sarote Sirisansaneeyakul; Thikumporn Tantivimongkol; Sittiwat Lertsiri

15

Fingernail Onychomycosis Due to Aspergillus niger.  

PubMed

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. PMID:23197914

Kim, Dong Min; Suh, Moo Kyu; Ha, Gyoung Yim; Sohng, Seung Hyun

2012-11-01

16

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

17

Characterization of phytase produced by Aspergillus niger  

Microsoft Academic Search

The extracellular activity ofAspergillus niger phytase at the end of the growth phase was 132 nkat\\/mL in a laboratory bioreactor. The purified enzyme has molar mass approximately\\u000a 100 kDa, pH optimum at 5.0, temperature optimum at 55°C and high pH and temperature stability. TheK\\u000a m for dodecasodium phytate, calcium phytate and 4-nitrophenyl phosphate are 0.44, 0.45 and 1.38 mmol\\/L, respectively.

J. Dvo?áková; O. Volfová; J. Kopecký

1997-01-01

18

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

19

Microbial transformations of 3-methoxyflavone by strains of Aspergillus niger.  

PubMed

Microbial transformation of 3-methoxyflavone into 3'-hydroxyflavon-3-yloxymethyl myristate was presented. Six filamentous fungi were used as biocatalysts: a wild strain of Aspergillus niger KB, its four UV mutants (A. niger MB, SBP, SBJ, 13/5) and the strain of Penicillium chermesinum 113. The highest yields were observed for the strains of A. niger KB and A. niger SBP (69.8% and 63.1%, respectively). PMID:25033671

Kostrzewa-Sus?ow, Edyta; Dymarska, Monika; Janeczko, Tomasz

2014-01-01

20

Characterization of two forms of glucoamylase from aspergillus niger  

Microsoft Academic Search

Aspergillus niger glucoamylases GI and GII (E.C. 3.2.1.3) were isolated from a commercial enzyme preparation by ammonium sulfate\\u000a precipitation followed by DEAE-cellulose ion exchange chromatography. Both enzymes consist of a single glycosylated polypeptide\\u000a chain. The molecular weights of GI and GII were determined by sedimentation equilibrium ultracentrifugation to 52,000 and\\u000a 46,000, respectively, and by molecular sieving to 65,000 and 55,000.

Birte Svensson; Torben Graves Svendsen; IB Svendsen; Takuo Sakai; Martin Ottesen

1982-01-01

21

Isolation and growth characterization of chlorate and/or bromate resistant mutants generated by spontaneous and induced foreword mutations at several gene loci in aspergillus niger  

PubMed Central

We aimed her mainly to evaluate the contribution of newly employed bromate selection system, in obtaining new Aspergillus niger nitrate/nitrite assimilation defective mutants, through Ultraviolet treatment (UV), 1, 2, 7, 8-Diepoxyoctane (DEO), phenols mixture (Phx)) and spontaneous treatments. The newly employed bromate selection system was able to specify only two putative novel mutant types designated brn (bromate resistant but chlorate sensitive (RS) strain, which may specify nitrite specific transporter) and cbrn mutants (bromate resistant and chlorate resistant strain, which may specify nitrate/nitrite bispecific system). The most relevant and innovative findings of this research work involve the isolation of the RR ( cbrn) mutants (a new type of nitrate assimilation defective mutants), that could be useful for studying the bispecific nitrate /nitrite transporter system. The majority of obtained bromate resistant mutants (93.3% of the total mutants obtained by all treatments) were of the brn type, whereas the remaining percentage (6.76%) was given to cbrn strains. The highest percentages of brn mutant strains (48% and 58.6% of the total RS strains) were obtained with UA after spontaneous and Phx treatment, whereas Trp has generated 29% and 42% of RS strains after UV and DEO treatments, respectively. The obtained ratios of cbrn mutants were higher (i.e. in the range of 8.4%-11.64% of the total bromate mutants) with chemical treatments, especially when U.A or Pro was serving as sole N-sources at 25ºC rather than 37ºC. A 69% mutants` yield of Aspergillus niger mutant strains representing nine gene loci ( niaD, cnx-6 loci , nrt and nirA) were selected on the bases of chlorate (600 mM) toxicity. All chlorate resistant mutants were completely sensitive to bromate (250 mM). The niaD mutants showed the highest percentage (73.97%) of chlorate resistant mutants obtained with all tested treatments. The UV treatment has generated the highest ratio (86.9%) of niaD mutants, whereas, the least (61%) was obtained with Phx treatment. The highest percentage of cnx mutants (32%) was obtained with Phx treatment. The DEO treatment as compared to other tested treatments was the best to use for obtaining the highest ratios of either nrt (13.8%) mutants or nirA (1.9%) mutants. PMID:24031593

Kanan, Ghassan J. M.; Al-Najjar, Heyam E.

2010-01-01

22

Isolation and Characterization of a Xylan-Degrading Enzyme from Aspergillus niger van Tieghem LPM 93 with Potential for Industrial Applications  

Microsoft Academic Search

Aspergillus niger van Tieghem LPM 93 was shown in an earlier study to produce the most thermostable ?-xylanase, which was effective for improving\\u000a brightness and delignification of non-delignified and oxygen-bleached samples of eucalyptus kraft pulp. Here, we report the\\u000a production, purification, and characterization of a xylan-degrading enzyme (XynI) from this strain grown in submerged liquid\\u000a cultivation on medium containing sugar

Natália von Gal Milanezi; Diana Paola Gómez Mendoza; Félix Gonçalves de Siqueira; Luciano Paulino Silva; Carlos André Ornelas Ricart; Edivaldo Ximenes Ferreira Filho

23

On the safety of Aspergillus niger – a review  

Microsoft Academic Search

.   \\u000a Aspergillus niger is one of the most important microorganisms used in biotechnology. It has been in use already for many decades to produce\\u000a extracellular (food) enzymes and citric acid. In fact, citric acid and many A. niger enzymes are considered GRAS by the United States Food and Drug Administration. In addition, A. niger is used for biotransformations and waste

E. Schuster; N. Dunn-Coleman; J. Frisvad; P. van Dijck

2002-01-01

24

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

25

Antifungal activity of strains of lactic acid bacteria isolated from a semolina ecosystem against Penicillium roqueforti, Aspergillus niger and Endomyces fibuliger contaminating bakery products.  

PubMed

Thirty samples of Italian durum wheat semolina and whole durum wheat semolina, generally used for the production of Southern Italy's traditional breads, were subjected to microbiological analysis in order to explore their lactic acid bacteria (LAB) diversity and to find strains with antifungal activity. A total of 125 presumptive LAB isolates (Gram-positive and catalase-negative) were characterized by repetitive extragenic palindromic-PCR (REP-PCR) and sequence analysis of the 16S rRNA gene, leading to the identification of the following species: Weissella confusa, Weissella cibaria, Leuconostoc citreum, Leuconostoc mesenteroides, Lactococcus lactis, Lactobacillus rossiae and Lactobacillus plantarum. The REP-PCR results delineated 17 different patterns whose cluster analysis clearly differentiated W. cibaria from W. confusa isolates. Seventeen strains, each characterized by a different REP-PCR pattern, were screened for their antifungal properties. They were grown in a flour-based medium, comparable to a real food system, and the resulting fermentation products (FPs) were tested against fungal species generally contaminating bakery products, Aspergillus niger, Penicillium roqueforti and Endomyces fibuliger. The results of the study indicated a strong inhibitory activity - comparable to that obtained with the common preservative calcium propionate (0.3% w/v) - of ten LAB strains against the most widespread contaminant of bakery products, P. roqueforti. The screening also highlighted the unexplored antifungal activity of L. citreum, L. rossiae and W. cibaria (1 strain), which inhibited all fungal strains to the same or a higher extent compared with calcium propionate. The fermentation products of these three strains were characterized by low pH values, and a high content of lactic and acetic acids. PMID:19243908

Valerio, Francesca; Favilla, Mara; De Bellis, Palmira; Sisto, Angelo; de Candia, Silvia; Lavermicocca, Paola

2009-09-01

26

Heterogeneity of Aspergillus niger microcolonies in liquid shaken cultures.  

PubMed

The fungus Aspergillus niger forms (sub)millimeter microcolonies within a liquid shaken culture. Here, we show that such microcolonies are heterogeneous with respect to size and gene expression. Microcolonies of strains expressing green fluorescent protein (GFP) from the promoter of the glucoamlyase gene glaA or the ferulic acid esterase gene faeA were sorted on the basis of diameter and fluorescence using the Complex Object Parametric Analyzer and Sorter (COPAS) technology. Statistical analysis revealed that the liquid shaken culture consisted of two populations of microcolonies that differ by 90 ?m in diameter. The population of small microcolonies of strains expressing GFP from the glaA or faeA promoter comprised 39% and 25% of the culture, respectively. Two populations of microcolonies could also be distinguished when the expression of GFP in these strains was analyzed. The population expressing a low level of GFP consisted of 68% and 44% of the culture, respectively. We also show that mRNA accumulation is heterogeneous within microcolonies of A. niger. Central and peripheral parts of the mycelium were isolated with laser microdissection and pressure catapulting (LMPC), and RNA from these samples was used for quantitative PCR analysis. This analysis showed that the RNA content per hypha was about 45 times higher at the periphery than in the center of the microcolony. Our data imply that the protein production of A. niger can be improved in industrial fermentations by reducing the heterogeneity within the culture. PMID:21169437

de Bekker, Charissa; van Veluw, G Jerre; Vinck, Arman; Wiebenga, L Ad; Wösten, Han A B

2011-02-01

27

Influence of environmental factors and salinity on phosphate solubilization by a newly isolated Aspergillus niger F7 from agricultural soil  

Microsoft Academic Search

solubilisation efficiency on PVK medium with 0.5% (w\\/v) TCP and 285, 187.5, 258 and 70.5 ? ? ? ?g\\/ml phosphate, respectively from 0.5% (w\\/v) TCP in liquid broth in 5 days of growth. A. niger (F7), showed 107.7% phosphate solubilization efficiency on PVK agar medium and 285 ? ? ? ?g\\/ml phosphate, in solid and liquid medium respectively from 0.5%

28

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

Code of Federal Regulations, 2014 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...

2014-04-01

29

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

Code of Federal Regulations, 2011 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...

2011-04-01

30

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

31

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

Code of Federal Regulations, 2012 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...

2012-04-01

32

Phytase production and phytic acid reduction in rapeseed meal by Aspergillus niger during solid state fermentation  

Microsoft Academic Search

The effect of moisture content of media, glucose, phosphate, some surfactants and gamma irradiation on the production of phytase and reduction of phytic acid in rapeseed meal by Aspergillus niger A-98 (local isolate) during solid state fermentation have been considered. Optimum moisture content of media for these processes was 60%. Glucose concentrations of up to 6% in solid state culture

A. I El-Batal; H Abdel Karem

2001-01-01

33

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

34

[Hypersensitivity pneumonitis induced by Aspergillus niger--a case report].  

PubMed

A 52-year-old woman was hospitalized because of severe cough in August 1994. She had engaged in culturing roses in greenhouses since 1968, and had developed a cough during the summer of 1990. Chest radiography showed diffuse ground-glass opacity in both lung fields, and she suffered from hypoxemia (PaO2 = 45.6 torr) while breathing room air. The lymphocyte count in the bronchoalveolar lavage fluid was increased, and transbronchial lung biopsy specimens showed lymphocyte alveolitis in the alveolar spaces. After admission, the patient's symptoms improved rapidly without medication. However, on her return to work, the cough and hypoxemia reappeared. In her rose culture, she had used Rockwool, and Aspergillus niger was detected predominantly in the Rockwool. Precipitins against the extracts of Aspergillus niger were detected with the double immunodiffusion test and the inhalation provocation test yielded clinical symptoms. Our diagnosis was hypersensitivity pneumonitis caused by Aspergillus niger. PMID:15357273

Miyazaki, Hiroo; Gemma, Hitoshi; Uemura, Keiichi; Ono, Takahisa; Masuda, Masafumi; Sano, Takehisa; Sato, Masaki; Koshimizu, Naoki; Suda, Takafumi; Chida, Kingo

2004-07-01

35

Location of glucose oxidase during production by Aspergillus niger  

Microsoft Academic Search

The production of the enzyme glucose oxidase by Aspergillus niger is well documented. However, its distribution within the fungal culture is less well defined. Since the enzyme location impacts\\u000a significantly on enzyme recovery, this study quantifies the enzyme distribution between the extracellular fluid, cell wall,\\u000a cytoplasm and slime mucilage fractions in an A. niger NRRL-3. The culture was separated into

K. G. Clarke; M. Johnstone-Robertson; B. Price; S. T. L. Harrison

2006-01-01

36

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

37

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. PMID:21892240

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

2011-01-01

38

Screening a strain of Aspergillus niger and optimization of fermentation conditions for degradation of aflatoxin B1.  

PubMed

Aflatoxin B1, a type of highly toxic mycotoxin produced by some species belonging to the Aspergillus genus, such as Aspergillus flavus and Aspergillus parasiticus, is widely distributed in feed matrices. Here, coumarin was used as the sole carbon source to screen microorganism strains that were isolated from types of feed ingredients. Only one isolate (ND-1) was able to degrade aflatoxin B1 after screening. ND-1 isolate, identified as a strain of Aspergillus niger using phylogenetic analysis on the basis of 18S rDNA, could remove 26.3% of aflatoxin B1 after 48 h of fermentation in nutrient broth (NB). Optimization of fermentation conditions for aflatoxin B1 degradation by selected Aspergillus niger was also performed. These results showed that 58.2% of aflatoxin B1 was degraded after 24 h of culture under the optimal fermentation conditions. The aflatoxin B1 degradation activity of Aspergillus niger supernatant was significantly stronger than cells and cell extracts. Furthermore, effects of temperature, heat treatment, pH, and metal ions on aflatoxin B1 degradation by the supernatant were examined. Results indicated that aflatoxin B1 degradation of Aspergillus niger is enzymatic and this process occurs in the extracellular environment. PMID:25401962

Zhang, Wei; Xue, Beibei; Li, Mengmeng; Mu, Yang; Chen, Zhihui; Li, Jianping; Shan, Anshan

2014-11-01

39

Absorbed substrate fermentation for pectinase production with Aspergillus niger  

Microsoft Academic Search

A 130 litre packed-bed bioreactor was used for pectinase production with Aspergillus niger using absorbed substrate fermentation techniques. Pectinolytic enzyme activity and relative CO2 production were used as indicators of metabolic activity. Absorbed substrate fermentation is an efficient process for pectinase production and is also an interesting model because the culture medium, water, nutrients and specific inducers, can be designed

S. Huerta; E. Favela; R. López-Ulibarri; A. Fonseca; G. Viniegra-González; M. Gutiérrez-Rojas

1994-01-01

40

Factors regulating production of glucose oxidase by Aspergillus niger  

Microsoft Academic Search

Certain factors affecting production of extracellular and cell-bound glucose oxidase by Aspergillus niger were investigated. The intention was to maximize total glucose oxidase activity of academic and potential commercial application by the selection of the appropriate strain and consecutive optimization of growth media and conditions. It was possible to identify combinations resulting in the utilization of molasses as the best

D. G. Hatzinikolaou; B. J. Macris

1995-01-01

41

Hydrolase production by Aspergillus niger in solid-state cultivation  

Microsoft Academic Search

A production of macerating enzymes which liquefy and hydrolyze the mandarin orange peel was studied in a solid state cultivation of Aspergillus niger on wheat bran substrate. Solid state cultivation in a 2 l drum fermenter capable of interchangeable operation under dynamic or static conditions were carried out maintaining the moisture content of the substrate at 32, 39, 46, 56,

Naomichi Nishio; Kiyoshi Tai; Shiro Nagai

1979-01-01

42

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

43

Genetic analysis of resistance to fenpropimorph in Aspergillus niger.  

PubMed

Resistance to the morpholine-fungicide fenpropimorph was studied in Aspergillus niger and A. nidulans. Mass selection of conidia of A. nidulans on agar amended with the fungicide at different concentrations did not yield of resistant mutants, even after UV-treatment of the conidia. In contrast, similar experiments with A. niger generated many fenpropimorph-resistant mutants. The mutants displayed cross-resistance to fenpropidin and generally showed wild-type sensitivity to the unrelated toxicants fenarimol and cycloheximide. Genetic analysis of fenpropimorph resistance in A. niger was carried out by means of the parasexual cycle. In the mutants tested, two genes located on linkage group II were involved in fenpropimorph resistance. Dominance tests showed that resistance to fenpropimorph in A. niger is recessive. PMID:9506903

Engels, A J; Holub, E F; Swart, K; De Waard, M A

1998-02-01

44

Performance of Aspergillus niger B 03 ?-xylosidase immobilized on polyamide membrane support  

Microsoft Academic Search

The dynamics of ?-xylosidase biosynthesis from Aspergillus niger B 03 was investigated in laboratory bioreactor. Maximum xylosidase activity 5.5U\\/ml was achieved after 80h fermentation at medium pH 4.0. The isolated ?-xylosidase was immobilized on polyamide membrane support and the basic characteristics of the immobilized enzyme were determined. Maximum immobilization and activity yield obtained was 30.0 and 6.8%, respectively. A shift

Ginka Delcheva; Georgi Dobrev; Ivan Pishtiyski

2008-01-01

45

Production of fructooligosaccharides from sucrose by a transfructosylase from Aspergillus niger  

Microsoft Academic Search

A strain of Aspergillus niger isolated from sugarcane fields, produced an extracellular transfructosylase in the culture medium. Sucrose and raffinose induced the production to the enzyme, which was purified by 138-fold. The optimum pH for activity and stability were 5.5 and 6.5, respectively. Its optimum temperature was 55°C. The enzyme hydrolysed sucrose rapidly and simultaneously formed fructooligosaccharides by transfructosylation.

Y. K. Park; M. M. Almeida

1991-01-01

46

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

47

Metabolism of the polycyclic aromatic hydrocarbon pyrene by Aspergillus niger SK 9317  

Microsoft Academic Search

The metabolism of pyrene, a polycyclic aromatic hydrocarbon consisting of four rings, by Aspergillus niger SK 9317 was investigated. The metabolites formed were isolated and identified as 1-hydroxypyrene, 1,6- and 1,8-pyrenequinone, 1,6- and 1,8-dihydroxypyrene, 1-pyrenyl sulphate and 1-hydroxy-8-pyrenyl sulphate. This is the first report of 1-hydroxy-8-pyrenyl as a metabolite in the microbial metabolism of pyrene. The results suggest that A.

T. Wunder; S. Kremer; O. Sterner; H. Anke

1994-01-01

48

Production of inulinase using tap roots of dandelion ( Taraxacum officinale) by Aspergillus niger  

Microsoft Academic Search

Various inulin containing vegetal substrates were evaluated for inulinase production by an indigenous isolate, Aspergillus niger NK-126. Highest inulinase activity was observed with dandelion tap root extract (52.3IU\\/ml). The enzyme activity was fourfold higher than that observed in media containing pure chicory inulin (12.3IU\\/ml). The fungus showed good growth on a medium containing 40% (v\\/v) of dandelion tap root extract

Naveen Kango

2008-01-01

49

Immunochemical relationship between glucoamylases I and II of Aspergillus niger  

Microsoft Academic Search

Rabbit antisera were prepared against the purified glucoamylases I and II ofAspergillus niger. Relationships between the two enzyme forms were investigated by using the antisera in immunodiffusion and immunoinhibition\\u000a experiments. Both the forms of glucoamylase gave a single continuous precipitin band demonstrating very close structural resemblance.\\u000a They gave almost identical immunoprecipitation patterns and had the same equivalence points indicating that

P. Manjunath; M. R. Raghavendra Rao

1980-01-01

50

Optimized bioprocess for production of fructofuranosidase by recombinant Aspergillus niger  

Microsoft Academic Search

A comprehensive approach of bioprocess design at various levels was used to optimize microbial production of extracellular\\u000a fructofuranosidase, important as biocatalyst to derive fructooligosaccharides with broad application in food or pharmaceutical\\u000a industry. For production, the recombinant strain Aspergillus niger SKAn1015 was used, which expresses the fructofuranosidase encoding gene suc1 under control of a strong constitutive promoter. In a first screening

Habib Driouch; Andreas Roth; Petra Dersch; Christoph Wittmann

2010-01-01

51

Metabolic peculiarities of Aspergillus niger disclosed by comparative metabolic genomics  

PubMed Central

Background Aspergillus niger is an important industrial microorganism for the production of both metabolites, such as citric acid, and proteins, such as fungal enzymes or heterologous proteins. Despite its extensive industrial applications, the genetic inventory of this fungus is only partially understood. The recently released genome sequence opens a new horizon for both scientific studies and biotechnological applications. Results Here, we present the first genome-scale metabolic network for A. niger and an in-depth genomic comparison of this species to seven other fungi to disclose its metabolic peculiarities. The raw genomic sequences of A. niger ATCC 9029 were first annotated. The reconstructed metabolic network is based on the annotation of two A. niger genomes, CBS 513.88 and ATCC 9029, including enzymes with 988 unique EC numbers, 2,443 reactions and 2,349 metabolites. More than 1,100 enzyme-coding genes are unique to A. niger in comparison to the other seven fungi. For example, we identified additional copies of genes such as those encoding alternative mitochondrial oxidoreductase and citrate synthase in A. niger, which might contribute to the high citric acid production efficiency of this species. Moreover, nine genes were identified as encoding enzymes with EC numbers exclusively found in A. niger, mostly involved in the biosynthesis of complex secondary metabolites and degradation of aromatic compounds. Conclusion The genome-level reconstruction of the metabolic network and genome-based metabolic comparison disclose peculiarities of A. niger highly relevant to its biotechnological applications and should contribute to future rational metabolic design and systems biology studies of this black mold and related species. PMID:17784953

Sun, Jibin; Lu, Xin; Rinas, Ursula; Zeng, An Ping

2007-01-01

52

Expression of the Aspergillus terreus itaconic acid biosynthesis cluster in Aspergillus niger  

PubMed Central

Background Aspergillus terreus is a natural producer of itaconic acid and is currently used to produce itaconic acid on an industrial scale. The metabolic process for itaconic acid biosynthesis is very similar to the production of citric acid in Aspergillus niger. However, a key enzyme in A. niger, cis-aconitate decarboxylase, is missing. The introduction of the A. terreus cadA gene in A. niger exploits the high level of citric acid production (over 200 g per liter) and theoretically can lead to production levels of over 135 g per liter of itaconic acid in A. niger. Given the potential for higher production levels in A. niger, production of itaconic acid in this host was investigated. Results Expression of Aspergillus terreus cis-aconitate decarboxylase in Aspergillus niger resulted in the production of a low concentration (0.05 g/L) of itaconic acid. Overexpression of codon-optimized genes for cis-aconitate decarboxylase, a mitochondrial transporter and a plasma membrane transporter in an oxaloacetate hydrolase and glucose oxidase deficient A. niger strain led to highly increased yields and itaconic acid production titers. At these higher production titers, the effect of the mitochondrial and plasma membrane transporters was much more pronounced, with levels being 5–8 times higher than previously described. Conclusions Itaconic acid can be produced in A. niger by the introduction of the A. terreus cis-aconitate decarboxylase encoding cadA gene. This results in a low itaconic acid production level, which can be increased by codon-optimization of the cadA gene for A. niger. A second crucial requirement for efficient production of itaconic acid is the expression of the A. terreus mttA gene, encoding a putative mitochondrial transporter. Expression of this transporter results in a twenty-fold increase in the secretion of itaconic acid. Expression of the A. terreus itaconic acid cluster consisting of the cadA gene, the mttA gene and the mfsA gene results in A. niger strains that produce over twenty five-fold higher levels of itaconic acid and show a twenty-fold increase in yield compared to a strain expressing only CadA. PMID:24438100

2014-01-01

53

Transcriptome analysis of Aspergillus niger grown on sugarcane bagasse  

PubMed Central

Background Considering that the costs of cellulases and hemicellulases contribute substantially to the price of bioethanol, new studies aimed at understanding and improving cellulase efficiency and productivity are of paramount importance. Aspergillus niger has been shown to produce a wide spectrum of polysaccharide hydrolytic enzymes. To understand how to improve enzymatic cocktails that can hydrolyze pretreated sugarcane bagasse, we used a genomics approach to investigate which genes and pathways are transcriptionally modulated during growth of A. niger on steam-exploded sugarcane bagasse (SEB). Results Herein we report the main cellulase- and hemicellulase-encoding genes with increased expression during growth on SEB. We also sought to determine whether the mRNA accumulation of several SEB-induced genes encoding putative transporters is induced by xylose and dependent on glucose. We identified 18 (58% of A. niger predicted cellulases) and 21 (58% of A. niger predicted hemicellulases) cellulase- and hemicellulase-encoding genes, respectively, that were highly expressed during growth on SEB. Conclusions Degradation of sugarcane bagasse requires production of many different enzymes which are regulated by the type and complexity of the available substrate. Our presently reported work opens new possibilities for understanding sugarcane biomass saccharification by A. niger hydrolases and for the construction of more efficient enzymatic cocktails for second-generation bioethanol. PMID:22008461

2011-01-01

54

Production of l -asparaginase, an anticancer agent, from Aspergillus niger using agricultural waste in solid state fermentation  

Microsoft Academic Search

This article reports the production of high levels of l-asparaginase from a new isolate of Aspergillus niger in solid state fermentation (SSF) using agrowastes from three leguminous crops (bran of Cajanus cajan, Phaseolus mungo, and Glycine max). When used as the sole source for growth in SSF, bran of G. max showed maximum enzyme production followed by that of P.

Abha Mishra

2006-01-01

55

Effect of culture conditions on the biosynthesis of Aspergillus niger phytase and acid phosphatase  

Microsoft Academic Search

The reduction of phytate content in plant feeds is advisable for increasing of their nutritional values. The dephosphorylation of phytates is believed to be mainly effected by phytase. A strain of Aspergillus niger shows a high potential for phytase production. In this study the possibilities to increase the enzyme production by alteration of the growth conditions of Aspergillus niger 307

S Gargova; M Sariyska

2003-01-01

56

Induction of extracellular arabinases on monomeric substrates in Aspergillus niger.  

PubMed

The induction of extracellular arabinases by pentose sugars and polyols generated by the metabolic pathway of L-arabinose and D-xylose catabolism in Aspergillus niger was investigated. Induction occurred with L-arabinose and L-arabitol but not with D-xylose or xylitol. L-arabitol in particular was found to be a good inducer for alpha-L-arabinofuranosidase and endo-arabinase activities. Western blotting analysis showed both alpha-L-arabinofuranosidase A and B to be present. No induction was observed using D-arabitol. Unlike the wild type A. niger N402 strain, the A. niger xylulose kinase negative mutant N572 also showed induction of alpha-L-arabinofuranosidases A and B and endo-arabinase activity on D-xylose and xylitol. This is due to metabolic conversion of these compounds leading to the accumulation of both xylitol and L-arabitol in this mutant, the latter of which then acts as inducer. The induction of the two alpha-L-arabinofuranosidases and endo-arabinase is under the control of two regulatory systems namely pathway specific induction and carbon catabolite repression. Under derepressing conditions in the wild type only alpha-L-arabinofuranosidase B could be detected by Western blotting analysis. This indicates that alpha-L-arabinofuranosidase B is of importance in the initiation of specific induction of the various arabinose activities in A. niger grown on arabinose containing structural polysaccharides. PMID:8427548

v d Veen, P; Flipphi, M J; Voragen, A G; Visser, J

1993-01-01

57

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

58

FluG affects secretion in colonies of Aspergillus niger.  

PubMed

Colonies of Aspergillus niger are characterized by zonal heterogeneity in growth, sporulation, gene expression and secretion. For instance, the glucoamylase gene glaA is more highly expressed at the periphery of colonies when compared to the center. As a consequence, its encoded protein GlaA is mainly secreted at the outer part of the colony. Here, multiple copies of amyR were introduced in A. niger. Most transformants over-expressing this regulatory gene of amylolytic genes still displayed heterogeneous glaA expression and GlaA secretion. However, heterogeneity was abolished in transformant UU-A001.13 by expressing glaA and secreting GlaA throughout the mycelium. Sequencing the genome of UU-A001.13 revealed that transformation had been accompanied by deletion of part of the fluG gene and disrupting its 3' end by integration of a transformation vector. Inactivation of fluG in the wild-type background of A. niger also resulted in breakdown of starch under the whole colony. Asexual development of the ?fluG strain was not affected, unlike what was previously shown in Aspergillus nidulans. Genes encoding proteins with a signal sequence for secretion, including part of the amylolytic genes, were more often downregulated in the central zone of maltose-grown ?fluG colonies and upregulated in the intermediate part and periphery when compared to the wild-type. Together, these data indicate that FluG of A. niger is a repressor of secretion. PMID:25370014

Wang, Fengfeng; Krijgsheld, Pauline; Hulsman, Marc; de Bekker, Charissa; Müller, Wally H; Reinders, Marcel; de Vries, Ronald P; Wösten, Han A B

2015-01-01

59

Production of glucose oxidase using Aspergillus niger and corn steep liquor.  

PubMed

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, ammonium, potassium and yeast extract, malt extract, and peptone) was beneficial to the enzyme synthesis. Aeration and agitation enhanced enzyme synthesis to 850 +/- 45 units/ml. Glucose oxidase has numerous applications in food industry and clinical fields. PMID:11333029

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

2001-06-01

60

Biotransformation of the diperpenoid, isosteviol, by Aspergillus niger, Penicillium chrysogenum and Rhizopus arrhizus.  

PubMed

The biotransformation of isosteviol (ent-16-ketobeyeran-19-oic acid) by three fungi is described. Aspergillus niger produced the 7 beta-OH derivative, ent-7 alpha-hydroxy-16-ketobeyeran-19-oic, and the 1 alpha, 7 beta-diOH derivative, ent-1 beta, 7 alpha-dihydroxy-16-ketobeyeran-19-oic acid. The 17-OH compound, ent-17-hydroxy-16-ketobeyeran-19-oic acid, was obtained with Penicillium chrysogenum. Rhizopus arrhizus produced the 7 beta-OH derivative, ent-7 alpha-hydroxy-16-ketobeyeran-19-oic acid. The isolated metabolites were characterised by IR, NMR and MS. PMID:10389273

de Oliveira, B H; dos Santos, M C; Leal, P C

1999-07-01

61

ADOPTING SELECTED HYDROGEN BONDING AND IONIC INTERACTIONS FROM ASPERGILLUS FUMIGATUS PHYTASE STRUCTURE IMPROVES THE THERMOSTABILITY OF ASPERGILLUS NIGER PHYA PHYTASE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Although it has been widely used as a feed supplement to reduce manure phosphorus pollution of swine and poultry, Aspergillus niger PhyA phytase is unable to withstand heat inactivation during feed pelleting. Crystal structure comparisons with its close homolog, the thermostable Aspergillus fumigatu...

62

Morphology engineering of Aspergillus niger for improved enzyme production.  

PubMed

Supplementation with silicate microparticles was used as novel approach to control the morphological development of Aspergillus niger, important as the major world source of citric acid and higher-value enzymes, in submerged culture. With careful variation of size and concentration of the micromaterial added, a number of distinct morphological forms including pellets of different size, free dispersed mycelium, and short hyphae fragments could be reproducibly created. Aluminum oxide particles similarly affected morphology, showing that this effect is largely independent of the chemical particle composition. Image analysis of morphological development of A. niger during the cultivation process showed that the microparticles influence the morphology by collision-induced disruption of conidia aggregates and probably also the hindrance of new spore-spore interactions in the very early stage of the process. Exemplified for different recombinant A. niger strains enzyme production could be strongly enhanced by the addition of microparticles. Linked to the formation of freely dispersed mycelium, titers for glucoamylase (GA) expressed as intracellular enzyme (88 U/mL) and fructofuranosidase secreted into the supernatant (77 U/mL), were up to fourfold higher in shake flasks. Moreover, accumulation of the undesired by-product oxalate was suppressed by up to 90%. The microparticle strategy could be successfully transferred to fructofuranosidase production in bioreactor, where a final titer of 160 U/mL could be reached. Using co-expression of GA with green fluorescent protein, enzyme production was localized in the cellular aggregates of A. niger. For pelleted growth, protein production was maximal only within a thin layer at the pellet surface and markedly decreased in the pellet interior, whereas the interaction with the microparticles created a highly active biocatalyst with the dominant fraction of cells contributing to production. PMID:19953678

Driouch, Habib; Sommer, Becky; Wittmann, Christoph

2010-04-15

63

Expression of human ?1-proteinase inhibitor in Aspergillus niger  

PubMed Central

Background Human ?1-proteinase inhibitor (?1-PI), also known as antitrypsin, is the most abundant serine protease inhibitor (serpin) in plasma. Its deficiency is associated with development of progressive, ultimately fatal emphysema. Currently in the United States, ?1-PI is available for replacement therapy as an FDA licensed plasma-derived (pd) product. However, the plasma source itself is limited; moreover, even with efficient viral inactivation steps used in manufacture of plasma products, the risk of contamination from emerging viruses may still exist. Therefore, recombinant ?1-PI (r-?1-PI) could provide an attractive alternative. Although r-?1-PI has been produced in several hosts, protein stability in vitro and rapid clearance from the circulation have been major issues, primarily due to absent or altered glycosylation. Results We have explored the possibility of expressing the gene for human ?1-PI in the filamentous fungus Aspergillus niger (A. niger), a system reported to be capable of providing more "mammalian-like" glycosylation patterns to secretable proteins than commonly used yeast hosts. Our expression strategy was based on fusion of ?1-PI with a strongly expressed, secreted leader protein (glucoamylase G2), separated by dibasic processing site (N-V-I-S-K-R) that provides in vivo cleavage. SDS-PAGE, Western blot, ELISA, and ?1-PI activity assays enabled us to select the transformant(s) secreting a biologically active glycosylated r-?1-PI with yields of up to 12 mg/L. Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) analysis further confirmed that molecular mass of the r-?1-PI was similar to that of the pd-?1-PI. In vitro stability of the r-?1-PI from A. niger was tested in comparison with pd-?1-PI reference and non-glycosylated human r-?1-PI from E. coli. Conclusion We examined the suitability of the filamentous fungus A. niger for the expression of the human gene for ?1-PI, a medium size glycoprotein of high therapeutic value. The heterologous expression of the human gene for ?1-PI in A. niger was successfully achieved to produce the secreted mature human r-?1-PI in A. niger as a biologically active glycosylated protein with improved stability and with yields of up to 12 mg/L in shake-flask growth. PMID:17967194

Karnaukhova, Elena; Ophir, Yakir; Trinh, Loc; Dalal, Nimish; Punt, Peter J; Golding, Basil; Shiloach, Joseph

2007-01-01

64

Two-stage statistical medium optimization for augmented cellulase production via solid-state fermentation by newly isolated Aspergillus niger HN-1 and application of crude cellulase consortium in hydrolysis of rice straw.  

PubMed

Cellulolytic enzyme production by newly isolated Aspergillus niger HN-1 was statistically optimized using Plackett-Burman and central composite design (CCD). Optimum concentrations of 2, 0.40, 0.01, and 0.60 g L (-1) for KH2PO4, urea, trace elements solution, and CaCl2·2H2O, respectively, were suggested by Design-Expert software. The two-stage optimization process led to a 3- and 2-fold increases in the filter paper cellulase (FP) and ?-glucosidase activities, respectively. FP, ?-glucosidase, endoglucanase, exopolygalaturonase, cellobiohydrolase, xylanase, ?-l-arabinofuranosidase, ?-xylosidase, and xylan esterase activities of 36.7 ± 1.54 FPU gds(-1), 252.3 ± 7.4 IU gds(-1), 416.3 ± 22.8 IU gds(-1), 111.2 ± 5.4 IU gds(-1), 8.9 ± 0.50 IU gds(-1), 2593.5 ± 78.9 IU gds(-1), 79.4 ± 4.3 IU gds(-1), 180.8 ± 9.3 IU gds(-1), and 288.7 ± 11.8 IU gds(-1), respectively, were obtained through solid-state fermentation during the validation studies. Hydrolysis of alkali-treated rice straw with crude cellulases resulted in about 84% glucan to glucose, 89% xylan to xylose, and 91% arabinan to arabinose conversions, indicating potential for biomass hydrolysis by the crude cellulase consortium obtained in this study. PMID:24328069

Sandhu, Simranjeet Kaur; Oberoi, Harinder Singh; Babbar, Neha; Miglani, Kanupriya; Chadha, Bhupinder Singh; Nanda, Dhiraj Kumar

2013-12-26

65

Increased Heterologous Protein Production in Aspergillus niger Fermentation through Extracellular Proteases Inhibition by  

E-print Network

Increased Heterologous Protein Production in Aspergillus niger Fermentation through Extracellular in filamentous fungal fermentation and thereby to enhance heterologous protein production. Introduction with efficient heterologous protein production in the fungal fermentation industry (1, 2). Current strategies

Gu, Tingyue

66

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

67

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; Magaña-Ortíz, Denis; Coconi-Linares, Nancy; Ortíz-Vázquez, Elizabeth; Gómez-Lim, Miguel A

2014-08-01

68

Aminopeptidase C of Aspergillus niger Is a Novel Phenylalanine Aminopeptidase  

PubMed Central

A novel enzyme with a specific phenylalanine aminopeptidase activity (ApsC) from Aspergillus niger (CBS 120.49) has been characterized. The derived amino acid sequence is not similar to any previously characterized aminopeptidase sequence but does share similarity with some mammalian acyl-peptide hydrolase sequences. ApsC was found to be most active towards phenylalanine ?-naphthylamide (F-?NA) and phenylalanine para-nitroanilide (F-pNA), but it also displayed activity towards other amino acids with aromatic side chains coupled to ?NA; other amino acids with nonaromatic side chains coupled to either pNA or ?NA were not hydrolyzed or were poorly hydrolyzed. ApsC was not able to hydrolyze N-acetylalanine-pNA, a substrate for acyl-peptide hydrolases. PMID:12571053

Basten, Daniëlle E. J. W.; Dekker, Peter J. T.; Schaap, Peter J.

2003-01-01

69

Categorisation of sugar acid dehydratases in Aspergillus niger.  

PubMed

In the genome of Aspergillus niger five genes were identified coding for proteins with homologies to sugar acid dehydratases. The open reading frames were expressed in Saccharomyces cerevisiae and the activities tested with a library of sugar acids. Four genes were identified to code for proteins with activities with sugar acids: an l-galactonate dehydratase (gaaB), two d-galactonate dehydratases (dgdA, dgdB) and an l-rhamnonate dehydratase (lraC). The specificities of the proteins were characterised. The l-galactonate dehydratase had highest activity with l-fuconate, however it is unclear whether the enzyme is involved in l-fuconate catabolism. None of the proteins showed activity with galactaric acid or galactarolactone. PMID:24382357

Motter, Francine A; Kuivanen, Joosu; Keränen, Hanna; Hilditch, Satu; Penttilä, Merja; Richard, Peter

2014-03-01

70

Nanosulfur: A Potent Fungicide Against Food Pathogen, Aspergillus niger  

NASA Astrophysics Data System (ADS)

Elemental sulfur (S0), 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; Nair, Kishore K.; Kumar, Rajesh; Gogoi, Robin; Srivastava, Chitra; Gopal, Madhuban; Subhramanyam, B. S.; devakumar, C.; Goswami, Arunava

2010-10-01

71

Application of maltitol to improve production of raw starch digesting glucoamylase by Aspergillus niger F-08  

Microsoft Academic Search

The effect of the addition of maltitol on the production of raw starch digesting glucoamylase (RSDG) by Aspergillus niger F-08 was studied in the paper. The activity of RSDG formed by Aspergillus niger F-08 was enhanced dramatically by the addition of maltitol to the medium and it was confirmed that maltitol acted as a very\\u000a efficient inducer for RSDG production.

Haiyan Sun; Pingjuan Zhao; Ming Peng

2008-01-01

72

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

73

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

74

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

75

Biotransformation of geraniol, nerol and citral by sporulated surface cultures of Aspergillus niger and Penicillium sp  

Microsoft Academic Search

The biotransformation of geraniol, nerol and citral by Aspergillus niger was studied. A comparison was made between submerged liquid, sporulated surface cultures and spore suspensions. This bioconversion was also carried out with surface cultures of Penicillium sp. The main bioconversion products obtained from geraniol and nerol by liquid cultures of A. niger were linalool and ?-terpineol. Linalool, ?-terpineol and limonene

Jan C. R. Demyttenaere; M. del Carmen Herrera; Norbert De Kimpe

2000-01-01

76

Optimization of medium composition for the production of glucosyltransferase by Aspergillus niger with response surface methodology  

Microsoft Academic Search

Aspergillus niger CCRC 31494 produced an extracellular glucosyltransferase (EC 2.4.1.24) with a high transglucosylating activity. For production of glucosyltransferase by A. niger, yeast extract was the best nitrogen source after cultivation for 7 days. Addition of minerals to the medium showed no significant increase in the production of glucosyltransferase. A significant decrease in the production of glycosyltransferase was obtained when

Shiow-Ling Lee; Wen-Chang Chen

1997-01-01

77

Induced Autolysis of Aspergillus oryzae (A. niger group)  

PubMed Central

The examination of substances formed during induced autolysis by Aspergillus niger was continued in this work, which dealt in particular with carbohydrates. The autolysate contained a large amount of d-glucose (14 to 20% dry wt) and traces of glycolic aldehyde, dihydroxyacetone, ribose, xylose, and fructose. It also contained glycopeptides (about 10% dry wt), which were split from the cell wall during autolysis and which differed from one another in their level of polymerization and their composition. They were constituted by glucose and mannose, glucose and galactose, or mannose, glucose, and galactose (mannose being the most abundant in this case), and amino acids (chiefly alanine, serine, glutamic acid, and aspartic acid). During autolysis, only a part of the cell wall was dissolved, since it retained its shape. Upon further chemical hydrolysis, it produced mostly glucose and glucosamine, and smaller amounts of mannose, galactose, and amino acids. Presumably, glucomannoproteins and glucogalactoproteins were present in the intact cell as a macromolecular complex, constituting, together with chitin, the major part of the cell wall of Aspergillus. PMID:16349623

Emiliani, Ezio; de Davie, I. Ucha

1962-01-01

78

[A case of hypersensitivity pneumonitis resulting from inhalation of Aspergillus niger in a greenhouse worker who raised roses].  

PubMed

A 57-year-old woman was referred because of exertional dyspnea, fever, and cough in June 2006. She had been employed to culture roses in greenhouses since 1991 and had developed a cough during the summer from 2003. Chest CT scan revealed diffuse centrilobular micronodules. Transbronchial lung biopsy specimens demonstrated alveolitis with lymphocytes and non-necrotizing epithelioid cell granulomas. After admission, both the patient's symptoms and laboratory data improved without medication. However, upon her return to work in the greenhouse, cough and exertional dyspnea reappeared. Aspergillus niger was detected in the greenhouse. Her serum was assayed for precipitating antibodies against various antigens, and precipitating antibodies against Aspergillus fumigatus, Aspergillus flavus, Aspergillus glaucus, and Aspergillus niger were demonstrated. In a double immunodiffusion test, cross-reactivity between Aspergillus niger and other Aspergillus species was indicated. Consequently, she was diagnosed as having hypersensitivity pneumonitis resulting from the inhalation of Aspergillus niger. PMID:19348267

Hamaguchi, Reo; Saito, Hiroaki; Kegasawa, Kyoko; Nakagawa, Atsushi; Ryujin, Yasushi; Noguchi, Saiko; Sugimoto, Hideyasu; Kobayashi, Akiko; Yamazaki, Keiichi; Jin, Yasuto; Yoshimura, Nobuyuki; Tsurikisawa, Naomi; Akiyama, Kazuo

2009-03-01

79

Spatial Differentiation in the Vegetative Mycelium of Aspergillus niger? †  

PubMed Central

Fungal mycelia are exposed to heterogenic substrates. The substrate in the central part of the colony has been (partly) degraded, whereas it is still unexplored at the periphery of the mycelium. We here assessed whether substrate heterogeneity is a main determinant of spatial gene expression in colonies of Aspergillus niger. This question was addressed by analyzing whole-genome gene expression in five concentric zones of 7-day-old maltose- and xylose-grown colonies. Expression profiles at the periphery and the center were clearly different. More than 25% of the active genes showed twofold differences in expression between the inner and outermost zones of the colony. Moreover, 9% of the genes were expressed in only one of the five concentric zones, showing that a considerable part of the genome is active in a restricted part of the colony only. Statistical analysis of expression profiles of colonies that had either been or not been transferred to fresh xylose-containing medium showed that differential expression in a colony is due to the heterogeneity of the medium (e.g., genes involved in secretion, genes encoding proteases, and genes involved in xylose metabolism) as well as to medium-independent mechanisms (e.g., genes involved in nitrate metabolism and genes involved in cell wall synthesis and modification). Thus, we conclude that the mycelia of 7-day-old colonies of A. niger are highly differentiated. This conclusion is also indicated by the fact that distinct zones of the colony grow and secrete proteins, even after transfer to fresh medium. PMID:17951513

Levin, Ana M.; de Vries, Ronald P.; Conesa, Ana; de Bekker, Charissa; Talon, Manuel; Menke, Hildegard H.; van Peij, Noel N. M. E.; Wösten, Han A. B.

2007-01-01

80

Biopelículas de Aspergillus niger para la producción de celulasas: algunos aspectos estructurales y fisiológicos Aspergillus niger biofilms for celulasas production: some structural and physiological aspects  

Microsoft Academic Search

Aspergillus niger biofilms developed on polyester cloth were evaluated considering two aspects related to the growth on surfaces: structure and physiological behavior focused on cellulase production. The biofilm structure was assessed by using electron scanning microphotographs from inoculation and adsorption to 120 h growth. The microphotographs show that biofilm formation can be divided into three phases: 1) Adhesion, which is

Gretty K. Villena; Marcel Gutiérrez-Correa

2003-01-01

81

Improved enzyme production by co-cultivation of Aspergillus niger and Aspergillus oryzae and with other fungi  

Microsoft Academic Search

Aspergillus niger and Aspergillus oryzae were co-cultivated with each other and with Magnaporthe grisea or Phanerochaete chrysosporium, respectively. Enzyme assays for plant polysaccharide and lignin-degrading enzymes showed that co-cultivation can improve extracellular enzyme production. Highest ?-glucosidase, ?-cellobiohydrolase, ?-galactosidase, and laccase activities were found for A. oryzae in combination with other fungi, in particular with P. chrysosporium. Highest ?-xylosidase activity was

H. L. Hu; J. van den Brink; B. S. Gruben; H. A. B. Wösten; J.-D. Gu; R. P. de Vries

2011-01-01

82

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. PMID:24294255

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

2013-01-01

83

Genome shuffling of Aspergillus niger for improving transglycosylation activity.  

PubMed

Isomaltooligosaccharides (IMO), the glucosylsaccharides used as food additives, are made from saccharified starch by enzymes or microbial cells with transglycosylation activity. This study aimed to generate shuffled futants of Aspergillus niger with enhanced transglycosylation activity for industrial IMO production. The starting mutant population was generated by (60)Co-? radiation; mutants with higher transglycosylation activity were selected and subjected to recursive protoplast fusion. The resulting fusants were screened by a novel high-throughput method based on detecting non-fermentable reducing sugar. After three rounds of genome shuffling, the best performing strain GS3-3 was obtained, its transglycosylation activity (14.91 U/mL) was increased by 194.1 % compared to that of original strain C-6181. In fermentor test, transglycosylation activity of GS3-3 was obtained at 16.61 U/mL. The mycelia of GS3-3 were reused ten times to produce IMO syrup from liquefied cassava starch containing about 280 g/L total sugar within 4 days. The conversion of liquefied cassava starch to IMO was at 71.3-72.1 %, which was higher than the best conversion (68 %) ever reported. GS3-3 shows a great potential for industrial IMO production. PMID:24043449

Li, Wei; Chen, Guiguang; Gu, Lingli; Zeng, Wei; Liang, Zhiqun

2014-01-01

84

Flavone Biotransformation by Aspergillus niger and the Characterization of Two Newly Formed Metabolites  

PubMed Central

Aspergillus niger isolated from Allium sativum was used at large scale fermentation (150 mg flavone/200 ml medium) to obtain suitable amounts of the products, efficient for identification. Then spectral analysis (UV, IR, 1H-NMR, 13C-NMR) and mass spectrometry were performed for the two products, which contributed to the identification process. The metabolite (1) was identified as 2'-hydroxydihydrochalcone, and the metabolite (2) was identified as 2'-hydroxyphenylmethylketone, which were more active than flavone itself. Antioxidant activities of the two isolated metabolites were tested compared with ascorbic acid. Antioxidant activity of metabolite (1) was recorded 64.58% which represented 79% of the antioxidant activity of ascorbic acid, and metabolite (2) was recorded 54.16% (67% of ascorbic acid activity). However, the antioxidant activity of flavone was recorded 37.50% which represented 46% of ascorbic acid activity. The transformed products of flavone have antimicrobial activity against Pseudomonas aeruginosa, Aspergillus flavus and Candida albicans, with MIC was recorded 250 µg/ml for metabolite (2) against all three organism and 500, 300, and 300 µg/ml for metabolite (1) against tested microorganisms (P. aeruginosa, Escherichia coli, Bacillus subtilis, and Klebsiella pneumonia, Fusarium moniliforme, A. flavus, Saccharomyces cerviceae, Kluveromyces lactis and C. albicans) at this order. PMID:23990746

Assawah, Suzan W.; El-Sharkawy, Saleh H.; Abdel-Salam, Amal

2008-01-01

85

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

Microsoft Academic Search

A flocculent Saccharomyces cerevisiae strain secreting Aspergillus niger ?-galactosidase activity was constructed by transforming S. cerevisiae NCYC869-A3 strain with plasmid pVK1.1 harboring the A. niger ?-ga- lactosidase 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 ?-galactosidase activity. In shake- flask cultures, the

J. A. Teixeira; M. Penttilä; N. Lima

2002-01-01

86

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

87

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

88

Genome sequencing and analysis of the versatile cell factory Aspergillus niger CBS 513.88  

Microsoft Academic Search

The filamentous fungus Aspergillus niger is widely exploited by the fermentation industry for the production of enzymes and organic acids, particularly citric acid. We sequenced the 33.9-megabase genome of A. niger CBS 513.88, the ancestor of currently used enzyme production strains. A high level of synteny was observed with other aspergilli sequenced. Strong function predictions were made for 6,506 of

Herman J Pel; Johannes H de Winde; David B Archer; Paul S Dyer; Gerald Hofmann; Peter J Schaap; Geoffrey Turner; Ronald P de Vries; Richard Albang; Kaj Albermann; Mikael R Andersen; Jannick D Bendtsen; Jacques A E Benen; Marco van den Berg; Stefaan Breestraat; Mark X Caddick; Roland Contreras; Michael Cornell; Pedro M Coutinho; Etienne G J Danchin; Alfons J M Debets; Peter Dekker; Piet W M van Dijck; Alard van Dijk; Lubbert Dijkhuizen; Arnold J M Driessen; Christophe d'Enfert; Steven Geysens; Coenie Goosen; Gert S P Groot; Piet W J de Groot; Thomas Guillemette; Bernard Henrissat; Marga Herweijer; Johannes P T W van den Hombergh; Cees A M J J van den Hondel; Rene T J M van der Heijden; Rachel M van der Kaaij; Frans M Klis; Harrie J Kools; Christian P Kubicek; Patricia A van Kuyk; Jürgen Lauber; Xin Lu; Marc J E C van der Maarel; Rogier Meulenberg; Hildegard Menke; Martin A Mortimer; Jens Nielsen; Stephen G Oliver; Maurien Olsthoorn; Karoly Pal; Arthur F J Ram; Ursula Rinas; Johannes A Roubos; Cees M J Sagt; Monika Schmoll; Jibin Sun; David Ussery; Janos Varga; Wouter Vervecken; Holger Wedler; Han A B Wösten; An-Ping Zeng; Albert J J van Ooyen; Jaap Visser; Hein Stam

2007-01-01

89

Cellulase production from Aspergillus niger MS82: effect of temperature and pH.  

PubMed

Fungal cellulases are well-studied enzymes and are used in various industrial processes. Much of the knowledge of enzymatic depolymerization of cellulosic material has come from Trichoderma cellulase system. Species of Trichoderma can produce substantial amounts of endoglucanase and exoglucanase but very low levels of b-glucosidase. This deficiency necessitates screening of fungi for cellulytic potential. A number of indigenously isolated fungi were screened for cellulytic potential. In the present study, the kinetics of cellulase production from an indigenous strain of Aspergillus niger MS82 is reported. Product formation parameters of endoglucanase and beta-glucosidase (Qp + Y(p/s)) indicate that A.niger MS82 is capable of producing moderate to high levels of both endoglucanase and beta-glucosidase when grown on different carbon containing natural substrates, for example, grass, corncob, bagasse along side purified celluloses. Furthermore, it was observed that the production of endoglucanase reaches its maximum during exponential phase of growth, while b-glucosidase during the Stationary phase. Enzyme production by solid-state fermentation was also investigated and found to be promising.Highest production of cellulase was noted at pH 4.0 at 35 degrees C under submerged conditions. Growth and enzyme production was affected by variations in temperature and pH. PMID:19552887

Sohail, Muhammad; Siddiqi, Roquya; Ahmad, Aqeel; Khan, Shakeel Ahmed

2009-09-01

90

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

91

Beneficiation of iron ore slime using Aspergillus niger and Bacillus circulans.  

PubMed

Studies were carried out on the removal of alumina from iron ore slime containing (%) Fe(2)O(3) 75.7, Al(2)O(3) 9.95, SiO(2) 6.1, Fe (total) 52.94 with the help of Bacillus circulans and Aspergillus niger. B. circulans and A. niger showed 39% and 38% alumina removal after six and 15 days of in situ leaching at 10% pulp density, respectively. Culture filtrate leaching with A. niger removed 20% alumina at 2% pulp density with 13 day old culture filtrate. B. circulans was more efficient than A. niger for selective removal of alumina. In case of A. niger in situ leaching rather than culture filtrate leaching was found to be more effective. PMID:16531043

Pradhan, N; Das, B; Gahan, C S; Kar, R N; Sukla, L B

2006-10-01

92

Characterization of filamentous fungi isolated from Moroccan olive and olive cake: toxinogenic potential of Aspergillus strains.  

PubMed

During the 2003 and 2004 olive oil production campaigns in Morocco, 136 samples from spoiled olive and olive cake were analyzed and 285 strains were isolated in pure culture. Strains included 167 mesophilic strains belonging to ten genera: Penicillium, Aspergillus, Geotrichum, Mucor, Rhizopus, Trichoderma, Alternaria, Acremonium, Humicola, Ulocladium as well as 118 thermophilic strains isolated in 2003 and 2004, mainly belonging to six species: Aspergillus fumigatus, Paecilomyces variotii, Mucor pusillus, Thermomyces lanuginosus, Humicola grisea, and Thermoascus aurantiacus. Penicillium and Aspergillus, respectively, 32.3 and 26.9% of total isolates represented the majority of mesophilic fungi isolated. When considering total strains (including thermotolerant strains) Aspergillus were the predominant strains isolated; follow-up studies on mycotoxins therefore focused primarily on aflatoxins (AFs) and ochratoxin A (OTA) from the latter strains. All isolated Aspergillus flavus strains (9) and Aspergillus niger strains (36) were studied in order to evaluate their capacity to produce AFs and OTA, respectively, when grown on starch-based culture media. Seven of the nine tested A. flavus strains isolated from olive and olive cake produced AF B1 at concentrations between 48 and 95 microg/kg of dry rice weight. As for the A. niger strains, 27 of the 36 strains produced OTA. PMID:16715545

Roussos, Sevastianos; Zaouia, Nabila; Salih, Ghislane; Tantaoui-Elaraki, Abdelrhafour; Lamrani, Khadija; Cheheb, Mostafa; Hassouni, Hicham; Verhé, Fréderic; Perraud-Gaime, Isabelle; Augur, Christopher; Ismaili-Alaoui, Mustapha

2006-05-01

93

Selection and characterisation of a xylitol-derepressed Aspergillus niger mutant that is apparently impaired in xylitol transport.  

PubMed

Aspergillus niger is known for its biotechnological applications, such as the use of xylanase enzyme for the degradation of hemicellulose. Depending on culture conditions, several polyols may also be accumulated, such as xylitol during D: -xylose oxidation. Also during industrial fermentation of xylose for the production of fuel ethanol by recombinant yeast, xylitol is a by-product. We studied xylitol metabolism by isolating mutants that have impaired xylitol-mediated repression. Genetic and biochemical characterisation revealed that one of these mutants was affected not only in xylitol-mediated carbon repression, but also had impaired xylitol transport. PMID:16932954

van de Vondervoort, Peter J I; de Groot, Marco J L; Ruijter, George J G; Visser, Jaap

2006-12-01

94

Effect of polyols on heat inactivation of Aspergillus niger van Teighem inulinase.  

PubMed

The effect of polyols (ethylene glycol, glycerol, erythritol, xylitol and sorbitol) on partially purified inulinase from Aspergillus niger van Teighem mutant grown on Kuth (Saussurea lappa) root as source of inulin was determined. Seventy per cent of inulinase activity was retained in the presence of 4 mol l-1 sorbitol at 75 degrees C. PMID:7576522

Viswanathan, P; Kulkarni, P R

1995-11-01

95

Biosorption of chromium from aqueous solutions by pretreated Aspergillus niger: Batch and column studies  

Microsoft Academic Search

This study involved the investigation of enhancement of chromium biosorption capacity of dead Aspergillus niger fungal biomass by pretreatment and its use in a column mode. Cetyl trimethyl ammonium bromide (CTAB) pretreatment exhibited maximum chromium removal. An initial factorial design of experiments showed that factors such as pH of the solution, temperature and biomass mass were important. The kinetics of

Deepa Prabhu Mungasavalli; Thiruvenkatachari Viraraghavan; Yee-Chung Jin

2007-01-01

96

Biosorption of an Azo Dye by Aspergillus niger and Trichoderma sp. Fungal Biomasses.  

PubMed

Biosorption is an eco-friendly and cost-effective method for treating the dye house effluents. Aspergillus niger and Trichoderma sp. were cultivated in bulk and biomasses used as biosorbents for the biosorption of an azo dye Orange G. Batch biosorption studies were performed for the removal of Orange G from aqueous solutions by varying the parameters like initial aqueous phase pH, biomass dosage, and initial dye concentration. It was found that the maximum biosorption was occurred at pH 2. Experimental data were analyzed by model equations such as Langmuir and Freundlich isotherms, and it was found that both the isotherm models best fitted the adsorption data. The monolayer saturation capacity was 0.48 mg/g for Aspergillus niger and 0.45 mg/g for Trichoderma sp. biomasses. The biosorption kinetic data were tested with pseudo first-order and pseudo second-order rate equations, and it was found that the pseudo second-order model fitted the data well for both the biomasses. The rate constant for the pseudo second-order model was found to be 10-0.8 (g/mg min?¹) for Aspergillus niger and 8-0.4 (g/mg min?¹) for Trichoderma sp. by varying the initial dye concentrations from 5 to 25 mg/l. It was found that the biomass obtained from Aspergillus niger was a better biosorbent for the biosorption of Orange G dye when compared to Trichoderma sp. PMID:20644933

Sivasamy, Arumugam; Sundarabal, Nethaji

2011-02-01

97

Production of gluconic acid from glucose by Aspergillus niger: growth and non-growth conditions  

Microsoft Academic Search

Batch fermentation of glucose to gluconic acid was conducted using Aspergillus niger under growth and non-growth conditions using pure oxygen and air as a source of oxygen for the fermentation in 2 and 5l stirred tank reactors (batch reactor). Production of gluconic acid under growth conditions was conducted in a 5l batch reactor. Production and growth rates were higher during

H. Znad; J. Markoš; V. Baleš

2004-01-01

98

Submerged production of pectolytic enzymes by Aspergillus niger : effect of different aeration\\/agitation regimes  

Microsoft Academic Search

The production of a pectolytic enzyme complex in a 10-l strirred tank bioreactor was studied using the Aspergillus niger mutant A 138. A time course of the fermentation showed that the enzyme synthesis is not associated with growth. Maximal activity was reached after 95 h and from that time on it remained constant. Redox potential and pH values proved to

Jožica Friedrich; Aleksa Cimerman; Walter Steiner

1989-01-01

99

Morphologically structured model for growth and citric acid accumulation by Aspergillus niger  

Microsoft Academic Search

A morphologically structured model for the batch process of biomass growth and citric acid accumulation by Aspergillus niger is presented in this paper. The model consists of ten ordinary differential equations, which balance biomass and four physiological zones of hyphae, and includes the most important medium components, such as carbon sources, nitrogen source and citric acid. Digital analysis of microscopic

Marcin Bizukojc; Stanislaw Ledakowicz

2003-01-01

100

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

101

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

102

Production of Aspergillus niger pectolytic enzymes by solid state bioprocessing of apple pomace  

Microsoft Academic Search

The aim of this work was to develop a low cost process for apple pomace utilisation. Accordingly this production of pectynolitic enzymes based on solid state bioprocessing of this actual waste, was developed. Production of pectolytic enzymes of Aspergillus niger, pectinesterase and polygalacturonase as well as the activity of pectolytic enzymatic complex by solid state bioprocessing were studied. The results

M. Berovi?; H. Ostroveršnik

1997-01-01

103

Comparative study of amylolytic enzymes production by Aspergillus niger in liquid and solid-state cultivation  

Microsoft Academic Search

Summary Amylolytic enzymes produced by a strain ofAspergillus niger cultivated on cassava starch in liquid or solid culture were found to be mainly glucoamylases. For the same initial amount of substrate, the glucoamylase activity increased even after 60 h of culture on solid medium whereas it decreased in liquid culture. Some characteristics of the amylases produced in both culture conditions

Didier Alazard; Maurice Raimbault

1981-01-01

104

Morphological patterns of Aspergillus niger biofilms and pellets related to lignocellulolytic enzyme productivities  

Microsoft Academic Search

Aims: To study the morphological patterns of Aspergillus niger during biofilm formation on polyester cloth by using cryo-scanning electron microscopy rela- ted to lignocellulolytic enzyme productivity. Methods and Results: Biofilm and pellet samples obtained from flask cultures were examined at )80? C in a LEO PV scanning electron microscope. Spore adhesion depends on both its rough surface and adhesive substances

G. K. Villena; M. Gutiérrez-Correa

2007-01-01

105

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. PMID:23533852

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

2013-01-01

106

Solution structure of the granular starch binding domain of Aspergillus niger glucoamylase bound to -cyclodextrin  

E-print Network

the catalytic domains of hydrolytic enzymes. Glucoamylase 1 (G1) from Aspergillus niger, an enzyme used widely the enzyme to noncrystalline (more hydrolyzable) areas of starch. The region of the SBD where the linker of the starch granules. Introduction Starch-degrading and related enzymes are abundant in animals, bacteria

Williamson, Mike P.

107

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

108

Gram-scale production of a basidiomycetous laccase in Aspergillus niger.  

PubMed

We report on the expression in Aspergillus niger of a laccase gene we used to produce variants in Saccharomyces cerevisiae. Grams of recombinant enzyme can be easily obtained. This highlights the potential of combining this generic laccase sequence to the yeast and fungal expression systems for large-scale productions of variants. PMID:23867099

Mekmouche, Yasmina; Zhou, Simeng; Cusano, Angela M; Record, Eric; Lomascolo, Anne; Robert, Viviane; Simaan, A Jalila; Rousselot-Pailley, Pierre; Ullah, Sana; Chaspoul, Florence; Tron, Thierry

2014-01-01

109

Xylanase production in solid state fermentation by Aspergillus niger mutant using statistical experimental designs  

Microsoft Academic Search

. The initial moisture content, cultivation time, inoculum size and concentration of basal medium were optimized in solid state fermentation (SSF) for the production of xylanase by an Aspergillus niger mutant using statistical experimental designs. The cultivation time and concentration of basal medium were the most important factors affecting xylanase activity. An inoculum size of 5쎹 spores\\/g, initial moisture content

Y. S. Park; S. W. Kang; J. S. Lee; S. I. Hong; S. W. Kim

2002-01-01

110

Cloning and characterization of a type III polyketide synthase from Aspergillus niger  

E-print Network

Cloning and characterization of a type III polyketide synthase from Aspergillus niger Jinglin Li in plant, bacteria, and fungi. Here we report the cloning and characterization of a putative type III PKS-pyrone synthase, and benzalacetone synthase have been cloned and characterized.4­6 They deviate from

Zhao, Huimin

111

Incidence of fumonisin B2 production within Aspergillus section Nigri populations isolated from California raisins.  

PubMed

Fungi belonging to Aspergillus section Nigri occur frequently and in high populations on grapes. Species within this section include Aspergillus niger, A. tubingensis, and A. carbonarius, and they are potential sources for mycotoxins including ochratoxin A and fumonisin B(2) (FB(2)) in grapes and grape products. Aspergillus section Nigri strains were isolated from California raisins to examine the frequency and extent of FB(2) production. Of 392 strains isolated, 197 strains were identified as A. niger, 131 of which produced FB(2). These strains produced from 1.2 to 27 ?g/ml FB(2) in culture. PCR amplification of fum1 and fum19 gene fragments showed that all FB(2)-producing strains and nearly all nonproducing strains of A. niger contain these genes. An additional 175 strains were identified as A. tubingensis, none of which produced FB(2). PCR with fum1 and fum19 primers amplified gene fragments of 14 and 25% of A. tubingensis strains, respectively, suggesting that putative orthologs of A. niger fumonisin biosynthetic genes might occur in A. tubingensis. These results indicate that FB(2) production is common among field isolates of A. niger and suggest that the potential for FB(2) contamination of California raisins should be addressed further. PMID:21477486

Palumbo, Jeffrey D; O'Keeffe, Teresa L; McGarvey, Jeffery A

2011-04-01

112

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

113

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. PMID:24688383

Shivanna, Gunashree B.; Venkateswaran, Govindarajulu

2014-01-01

114

VeA of Aspergillus niger increases spore dispersing capacity by impacting conidiophore architecture.  

PubMed

Aspergillus species are highly abundant fungi worldwide. Their conidia are among the most dominant fungal spores in the air. Conidia are formed in chains on the vesicle of the asexual reproductive structure called the conidiophore. Here, it is shown that the velvet protein VeA of Aspergillus niger maximizes the diameter of the vesicle and the spore chain length. The length and width of the conidiophore stalk and vesicle were reduced nearly twofold in a ?veA strain. The latter implies a fourfold reduced surface area to develop chains of spores. Over and above this, the conidial chain length was approximately fivefold reduced. The calculated 20-fold reduction in formation of conidia by ?veA fits the 8- to 17-fold decrease in counted spore numbers. Notably, morphology of the ?veA conidiophores of A. niger was very similar to that of wild-type Aspergillus sydowii. This suggests that VeA is key in conidiophore architecture diversity in the fungal kingdom. The finding that biomass formation of the A. niger ?veA strain was reduced twofold shows that VeA not only impacts dispersion capacity but also colonization capacity of A. niger. PMID:25367340

Wang, Fengfeng; Dijksterhuis, Jan; Wyatt, Timon; Wösten, Han A B; Bleichrodt, Robert-Jan

2015-01-01

115

The intra- and extracellular proteome of Aspergillus niger growing on defined medium with xylose or maltose as carbon substrate  

Microsoft Academic Search

BACKGROUND: The filamentous fungus Aspergillus niger is well-known as a producer of primary metabolites and extracellular proteins. For example, glucoamylase is the most efficiently secreted protein of Aspergillus niger, thus the homologous glucoamylase (glaA) promoter as well as the glaA signal sequence are widely used for heterologous protein production. Xylose is known to strongly repress glaA expression while maltose is

Xin Lu; Jibin Sun; Manfred Nimtz; Josef Wissing; An-Ping Zeng; Ursula Rinas

2010-01-01

116

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

117

Purification and characterization of a ferulic acid esterase (FAE-III) from Aspergillus niger: specificity for the phenolic moiety and binding to microcrystalline cellulose  

Microsoft Academic Search

An inducible ferulic acid esterase (FAE-Ill) has been isolated, purified and partially characterized from Aspergillus niger after growth on oat spelt xylan. The purification procedure utilized ammonium sulphate precipitation, hydrophobic interaction and anion-exchange chromatography. The purified enzyme appeared almost pure by SDS-PAGE, with an apparent M, of 36000. A single band, corresponding to a pl of 3.3 was observed on

Craig B. Faulds; Gary Williamson

1994-01-01

118

Understanding thermostability factors of Aspergillus niger PhyA phytase: a molecular dynamics study.  

PubMed

Molecular dynamics simulation was used to study the dynamic differences between native Aspergillus niger PhyA phytase and a mutant with 20 % greater thermostability. Atomic root mean square deviation, radius of gyration, and number of hydrogen bonds and salt bridges are examined to determine thermostability factors. The results suggest that, among secondary structure elements, loops have the most impact on the thermal stability of A. niger phytase. In addition, the location rather than the number of hydrogen bonds is found to have an important contribution to thermostability. The results also show that salt bridges may have stabilizing or destabilizing effect on the enzyme and influence its thermostability accordingly. PMID:23636517

Noorbatcha, I A; Sultan, A M; Salleh, H M; Amid, Azura

2013-04-01

119

Transcriptomic comparison of Aspergillus niger growing on two different sugars reveals coordinated regulation of the secretory pathway  

Microsoft Academic Search

BACKGROUND: The filamentous fungus, Aspergillus niger, responds to nutrient availability by modulating secretion of various substrate degrading hydrolases. This ability has made it an important organism in industrial production of secreted glycoproteins. The recent publication of the A. niger genome sequence and availability of microarrays allow high resolution studies of transcriptional regulation of basal cellular processes, like those of glycoprotein

Thomas R Jørgensen; Theo Goosen; Cees AMJJ van den Hondel; Arthur FJ Ram; Jens JL Iversen

2009-01-01

120

Regulation of pentose utilisation by AraR, but not XlnR, differs in Aspergillus nidulans and Aspergillus niger.  

PubMed

Filamentous fungi are important producers of plant polysaccharide degrading enzymes that are used in many industrial applications. These enzymes are produced by the fungus to liberate monomeric sugars that are used as carbon source. Two of the main components of plant polysaccharides are L-arabinose and D-xylose, which are metabolized through the pentose catabolic pathway (PCP) in these fungi. In Aspergillus niger, the regulation of pentose release from polysaccharides and the PCP involves the transcriptional activators AraR and XlnR, which are also present in other Aspergilli such as Aspergillus nidulans. The comparative analysis revealed that the regulation of the PCP by AraR differs in A. nidulans and A. niger, whereas the regulation of the PCP by XlnR was similar in both species. This was demonstrated by the growth differences on L-arabinose between disruptant strains for araR and xlnR in A. nidulans and A. niger. In addition, the expression profiles of genes encoding L-arabinose reductase (larA), L-arabitol dehydrogenase (ladA) and xylitol dehydrogenase (xdhA) differed in these strains. This data suggests evolutionary changes in these two species that affect pentose utilisation. This study also implies that manipulating regulatory systems to improve the production of polysaccharide degrading enzymes, may give different results in different industrial fungi. PMID:21484208

Battaglia, Evy; Hansen, Sara Fasmer; Leendertse, Anne; Madrid, Susan; Mulder, Harm; Nikolaev, Igor; de Vries, Ronald P

2011-07-01

121

Comparing phosphorus mobilization strategies using Aspergillus niger for the mineral dissolution of three phosphate rocks.  

PubMed

Phosphorus deficiencies are limiting crop production in agricultural soils worldwide. Locally available sources of raw phosphate rock (PR) are being recognized for their potential role in soil fertility improvement. Phosphorus bioavailability is essential for the efficiency of PRs and can be increased by acid treatments. The utilization of organic acid producing micro-organisms, notably Aspergillus niger, presents a sustainable alternative to the use of strong inorganic acids, but acid production of A. niger strongly depends on the mineral content of the growth media. This study compared the phosphorus mobilization efficiency of two biological treatments, namely addition of acidic cell-free supernatants from A. niger cultivations to PRs and the direct cultivation of A. niger with PRs. The results show that addition of PR to cultivations leads to significant differences in the profile of organic acids produced by A. niger. Additions of PR, especially igneous rocks containing high amounts of iron and manganese, lead to reduced citric acid concentrations. In spite of these differences, phosphorus mobilization was similar between treatments, suggesting that the simpler direct cultivation method was not inferior. In addition to citric acid, it is suggested that oxalic acid contributes to PR solubilization in direct cultivations with A. niger, which would benefit farmers in developing countries where conventional fertilizers are not adequately accessible. PMID:19709342

Schneider, K D; van Straaten, P; de Orduña, R Mira; Glasauer, S; Trevors, J; Fallow, D; Smith, P S

2010-01-01

122

Sub-inhibitory concentration of biogenic selenium nanoparticles lacks post antifungal effect for Aspergillus niger and Candida albicans and stimulates the growth of Aspergillus niger  

PubMed Central

Background The antifungal activity of selenium nanoparticles (Se NPs) prepared by Klebsiella pneumoniae has been reported previously for different fungi. In the present study, freshly prepared Se NPs produced by K. pneumoniae were purified and characterized by transmission electron microscopy and Energy-Dispersive X-ray spectroscopy (EDS) and its post antifungal effects for two fungi were evaluated. Materials and Methods The minimum inhibitory concentrations (MICs) of Se NPs, determined by serial dilution were 250 µg/ml for Aspergillus niger and 2,000 µg/ml for Candida albicans. The effect of exposure of A. niger and C. albicans to Se NPs on later growth was evaluated by incubating the fungi for 1 hour at 25 °C in media containing 0, 1, 2 and 4 x MIC of Se NPs and diluting the cultures 100 times with Se free medium. The kinetics of growth of the fungi in control cultures and in non-toxic Se NPs concentration of, 0.01 × MIC, 0.02 × MIC or 0.04 × MIC were measured. Results The exposure of A. niger and C. albicans to 2 and 4 x MIC of Se NPs stimulated the growth of both fungi in the absence of toxic concentrations of Se. The strongest stimulation was observed for A. niger. Conclusion It is concluded that exposure to high concentration of the Se NPs did not have any post-inhibitory effect on A. niger and C. albicans and that trace amounts of this element promoted growth of both fungi in a dose- dependent-manner. The role of nanoparticles serving as needed trace elements and development of microorganism tolerance to nanoparticles should not be dismissed while considering therapeutic potential. PMID:23466957

Kazempour, Zahra Bahri; Yazdi, Mohammad Hossein; Rafii, Fatemeh; Shahverdi, Ahmad Reza

2013-01-01

123

Biosynthesis, purification and characterization of endoglucanase from a xylanase producing strain Aspergillus niger B03  

PubMed Central

An extracellular endoglucanase was isolated from the culture liquid of xylanase producing strain Aspergillus niger B03. The enzyme was purified to a homogenous form, using consecutive ultrafiltration, anion exchange chromatography, and gel filtration. Endoglucanase was a monomer protein with a molecular weight of 26,900 Da determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and 28,800 Da determined by gel filtration. The optimal pH and temperature values for the enzyme action were 3.5 and 65 °C respectively. Endoglucanase was stable at 40 °C, pH 3.0 for 210 min. The substrate specificity of the enzyme was determined with carboxymethyl cellulose, filter paper, and different glycosides. Endoglucanase displayed maximum activity in the case of carboxymethyl cellulose, with a Km value of 21.01 mg/mL. The substrate specificity and the pattern of substrate degradation suggested that the enzyme is an endoglucanase. Endoglucanase showed a synergism with endoxylanase in corn cobs hydrolysis. PMID:24031805

Dobrev, Georgi Todorov; Zhekova, Boriana Yordanova

2012-01-01

124

Production of Protease from Rice Mill Wastes by Aspergillus niger in Solid State Fermentation  

Microsoft Academic Search

The production of enzymes by bioprocesses is a good value added to agro industry residues. A comparative study was carried out on the production of protease using different varieties of Rice brokens (PONNI, IR-20, CR-1009, ADT-36 and ADT-66) from Rice mill wastes as substrates in solid-state fermentation (SSF) by Aspergillus niger. Among the all tested varieties of rice broken PONNI

R. Paranthaman; K. Alagusundaram; J. Indhumathi

125

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

Microsoft Academic Search

Convenient expression systems for efficient heterologous production of different laccases are needed for their characterization\\u000a 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\\u000a directing catalytically active laccase to the medium. P. pastoris batch cultures in

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

2006-01-01

126

Increased NADPH concentration obtained by metabolic engineering of the pentose phosphate pathway in Aspergillus niger  

Microsoft Academic Search

Many biosynthetic reactions and bioconversions are limited by low availability of NADPH. With the purpose of increasing the NADPH concentration and\\/or the flux through the pentose phosphate pathway in Aspergillus niger, the genes encoding glucose 6-phosphate dehydrogenase (gsdA), 6-phosphogluconate dehydrogenase (gndA) and transketolase (tktA) were cloned and overexpressed in separate strains. Intracellular NADPH concentration was increased two- to ninefold as

B. R. Poulsen; J. Nohr; S. Douthwaite; L. V. Hansen; J. J. L. Iversen; J. Visser; G. J. G. Ruijter

2005-01-01

127

Aspergillus niger ?-galactosidase production by yeast in a continuous high cell density reactor  

Microsoft Academic Search

The continuous production of extracellular heterologous ?-galactosidase by a recombinant flocculating Saccharomyces cerevisiae, expressing the lacA gene (coding for ?-galactosidase) of Aspergillus niger was investigated. A continuous operation was run in a 6.5l airlift bioreactor with a concentric draft tube using lactose as substrate. Data on the operation with semi-synthetic medium with 50 and 100g\\/l initial lactose concentrations are presented.

Luc??lia Domingues; Nelson Lima; José A. Teixeira

2005-01-01

128

Effect of Media Composition and Growth Conditions on Production of ?-Glucosidase by Aspergillus niger C-6  

Microsoft Academic Search

The hydrolytic activity of fungal originated ?-glucosidase is exploited in several biotechnological processes to increase\\u000a the rate and extent of saccha-rification of several cellulosic materials by hydrolyzing the cellobiose which inhibits cellulases.\\u000a In a previous presentation, we reported the screening and liquid fermentation with Aspergillus niger, strain C-6 for p-glucosidase production at shake flask cultures in a basal culture medium

O. García-Kirchner; M. Segura-Granados; P. Rodríguez-Pascual

129

Optimization of glucose oxidase production by Aspergillus niger using genetic-and process-engineering techniques  

Microsoft Academic Search

Wild-type Aspergillus niger NRRL-3 was transformed with multiple copies of the glucose oxidase structural gene (god). The gene was placed under the control of the gpd A promoter of A. nidulans. For more efficient secretion the a-amylase signal peptide from A oryzae was inserted in front of god. Compared to the wild type, the recombinant strain NRRL-3 (GOD3-18) produced up

K. Hellmuth; S. Pluschkell; J.-K. Jung; E. Ruttkowski; U. Rinas

1995-01-01

130

Induced reactive oxygen species improve enzyme production from Aspergillus niger cultivation  

Microsoft Academic Search

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 a-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

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

2003-01-01

131

Application of kaolin to improve citric acid production by a thermophilic Aspergillus niger  

Microsoft Academic Search

Citric acid production by a thermophilic strain of the filamentous fungus Aspergillus niger IIB-6 in a medium containing blackstrap cane molasses was improved by the addition of kaolin to the fermentation medium. The fermentation was run in a 7.5-l stirred bioreactor (60% working volume). The optimal sugar concentration was found to be 150 g\\/l. Kaolin (1.0 ml) was added to the fermentation

Sikander Ali

2006-01-01

132

Genomic analysis of the secretion stress response in the enzyme-producing cell factory Aspergillus niger  

Microsoft Academic Search

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

Thomas Guillemette; Noël NME van Peij; Theo Goosen; Karin Lanthaler; Geoffrey D Robson; Cees AMJJ van den Hondel; Hein Stam; David B Archer

2007-01-01

133

Heterologous Expression of Trametes versicolor Laccase in Pichia pastoris and Aspergillus niger  

Microsoft Academic Search

Convenient expression systems for efficient heterologous production of different laccases are needed for their characterization\\u000a 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\\u000a directing catalytically active laccase to the medium. P. pastoris batch cultures in

Christina Bohlin; Leif J. Jönsson; Robyn Roth; WILLEM H. VAN ZYL

134

Comparative studies on extracellular protease secretion and glucoamylase production by free and immobilized Aspergillus niger cultures  

Microsoft Academic Search

  The effects of cell immobilization on the secretion of extracellular proteases and glucoamylase production by Aspergillus niger were investigated under a variety of immobilization techniques and culture conditions. Immobilization was achieved by means\\u000a of cell attachment on metal surfaces or spore entrapment and subsequent growth on porous Celite beads. Free-suspension cultures\\u000a were compared with immobilized mycelium under culture conditions that

M Papagianni; N Joshi; M Moo-Young

2002-01-01

135

Performance of a column bioreactor for glucoamylase synthesis by Aspergillus niger in SSF  

Microsoft Academic Search

A novel bioreactor was developed for glucoamylase production in solid state fermentation using Aspergillus niger. Glass columns of different diameter were placed vertically and packed with pre-inoculated substrate and with substrate bed heights in the range 4.5–22.0 cm. Moist air was passed through the bottom of the bioreactor at 1–1.5 vvm and fermentation was carried out for 48 h at

Ashok Pandey; P. Selvakumar; L. Ashakumary

1996-01-01

136

Continuous production of citric acid from dairy wastewater using immobilized Aspergillus niger ATCC 9142  

Microsoft Academic Search

The continuous production of citric acid from dairy wastewater was investigated using calcium-alginate immobilizedAspergillus niger ATCC 9142. The citric acid productivity and yield were strongly affected by the culture conditions. The optimal pH, temperature,\\u000a and dilution rate were 3.0, 30°C, and 0.025 h?1, respectively. Under optimal culture conditions, the maximum productivity, concentration, and yield of citric acid produced\\u000a by the

Se-Kwon Kim; Pyo-Jam Park; Hee-Guk Byun

2002-01-01

137

Effect of media composition and growth conditions on production of ?-glucosidase by Aspergillus niger C-6  

Microsoft Academic Search

The hydrolytic activity of fungal originated ?-glucosidase is exploited in several biotechnological processes to increase\\u000a the rate and extent of saccharification of several cellulosic materials by hydrolyzing the cellobiose which inhibits cellulases.\\u000a In a previous presentation, we reported the screening and liquid fermentation with Aspergillus niger, strain C-6 for ?-glucosidase production at shake flask cultures in a basal culture medium

O. García-Kirchner; M. Segura-Granados; P. Rodríguez-Pascual

2005-01-01

138

Fed-batch Production of Gluconic Acid by Terpene-treated Aspergillus niger Spores  

Microsoft Academic Search

Aspergillus niger spores were used as catalyst in the bioconversion of glucose to gluconic acid. Spores produced by solid-state fermentation\\u000a were treated with 15 different terpenes including monoterpenes and monoterpenoids to permeabilize and inhibit spore germination.\\u000a It was found that spore membrane permeability is significantly increased by treatment with terpenoids when compared to monoterpenes.\\u000a Best results were obtained with citral

Sumitra Ramachandran; Pierre Fontanille; Ashok Pandey; Christian Larroche

2008-01-01

139

Aeration as a factor in textile dye bioremoval by Aspergillus niger  

Microsoft Academic Search

Experiments were done to study the bioremoval\\/ biosorption of dis-azo dye by Aspergillus niger strain 20 in two concentrations using 5 liter bioreactor at five aeration rates. The experimental results are compared for various operating conditions. The dye used was direct brown and the inlet air flow rate was: 1\\/8, º, ?, 1, 2 v\\/v\\/min. The aeration rate of ?

Wafaa M. Abd El-Rahim; Ola Ahmed; M. El-Ardy; Hassan Moawad

140

Tannase enzyme production by entrapped cells of Aspergillus niger FETL FT3 in submerged culture system  

Microsoft Academic Search

The ability of immobilized cell cultures of Aspergillus niger FETL FT3 to produce extracellular tannase was investigated. The production of enzyme was increased by entrapping the fungus\\u000a in scouring mesh cubes compared to free cells. Using optimized parameters of six scouring mesh cubes and inoculum size of\\u000a 1 × 106 spores\\/mL, the tannase production of 3.98 U\\/mL was obtained from the immobilized cells

I. Darah; G. Sumathi; K. Jain; S. H. Lim

141

The use of Aspergillus niger for the bioconversion of olive mill waste-waters  

Microsoft Academic Search

Olive mill waste-water was used for protein production in small-scale experiments, using non-sterilized medium without pH control. A 14 g\\/1 concentration of proteins, 61% chemical oxygen demand removal and a 58% reduction in total phenolic compounds were obtained using an Aspergillus niger strain. The removal of phenolic compounds resulted in a change in the colour of the waste-water from black

Moktar Hamdi; Abdelkader Khadir; Jean-Louis Garcia

1991-01-01

142

Production of pectinesterase and polygalacturonase by Aspergillus niger in submerged and solid state systems  

Microsoft Academic Search

  Production of pectinesterase and polygalacturonase by Aspergillus niger was studied in submerged and solid-state fermentation systems. With pectin as a sole carbon source, pectinesterase and polygalacturonase\\u000a production were four and six times higher respectively in a solid state system than in a submerged fermentation system and\\u000a required a shorter time for enzyme production. The addition of glucose increased pectinesterase and

M C Maldonado; A M Strasser de Saad

1998-01-01

143

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

144

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

145

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

146

Optimization of process parameters for the production of naringinase by Aspergillus niger MTCC 1344  

Microsoft Academic Search

Aspergillus niger MTCC 1344 was used to produce extracellular naringinase in a complex (molasses, yeast extract and salts) medium. An initial medium pH 4.5 and cultivation temperature 30°C were optimal for enzyme production. Among various carbon and organic nitrogen sources used, molasses and peptone were the most effective for enzyme yield. The rate of enzyme production was enhanced when metal

Munish Puri; Anirban Banerjee; U. C. Banerjee

2005-01-01

147

Optimization of glucoamylase production by Aspergillus niger in solid-state fermentation  

Microsoft Academic Search

Glucoamylase production by Aspergillus niger in solid-state fermentation was optimized using factorial design and response surface techniques. The variables evaluated\\u000a were pH and bed thickness in tray, having as response enzyme production and productivity. The bed thickness in tray was the\\u000a most significant variable for both responses. The highest values for glucoamylase production occurred using pH 4.5 and bed\\u000a thickness

Silvana T. Silveira; Melissa S. Oliveira; Jorge A. V. Costa; Susana J. Kalil

2006-01-01

148

Dephosphorylation of Phytate by Using the Aspergillus niger Phytase with a High Affinity for Phytate  

Microsoft Academic Search

A phytase (EC 3.1.3.8) with a high affinity for phytic acid was found in Aspergillus niger SK-57 and purified to homogeneity in four steps by using ion-exchange chromatography (two types), gel filtration, and chromato- focusing. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of the purified enzyme gave a single stained band at a molecular mass of approximately 60 kDa. The Michaelis constant

TADASHI NAGASHIMA; TATSUYA TANGE; HIDEHARU ANAZAWA

1999-01-01

149

Enantioselective behavior of lipases from Aspergillus niger immobilized in different supports  

Microsoft Academic Search

Considering the extraordinary microbial diversity and importance of fungi as enzyme producers, the search for new biocatalysts\\u000a with special characteristics and possible applications in biocatalysis is of great interest. Here, we report the performance\\u000a 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,

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

2009-01-01

150

Production of ascorbic acid glucoside by alginate-entrapped mycelia of Aspergillus niger  

Microsoft Academic Search

The mycelia of Aspergillus niger, cultivated in a medium containing 45 g l?1 maltose, 66 g l?1 yeast extract, and 5 g l?1 K2HPO4 at 30°C and 200 rpm, were used as a biocatalyst in the glucosylation of ascorbic acid. Free mycelia from 3-day-old culture,\\u000a when used in a 6-h reaction with maltose as the acyl donor, gave 16.07 g l?1 ascorbic acid glucoside corresponding

Hsin-Ju Hsieh; Kai-Yu Tung; Giridhar R. Nair; I-Ming Chu; Wen-Teng Wu

2007-01-01

151

Mycobization with Glomus mosseae and Aspergillus niger in Lycopersicon esculentum plants  

Microsoft Academic Search

The effect of mycobization with both an arbuscular mycorrhizal fungus, Glomus mosseae, and a phosphorus-solubilizing microorganism, Aspergillus niger, was evaluated on tomato plants grown on steamed perlite-vermiculite-sand substrate added either with or without rock phosphate in six greenhouse treatments. Plant aerial biomass, phosphorus concentration in plant tissue, and P available in the substrate were evaluated upon 60-day-old harvested plants. Mycorrhizal

152

Hydrolytic enzyme production in solid-state fermentation by Aspergillus niger 3T5B8  

Microsoft Academic Search

A mixture containing polygalacturonase, cellulase, xylanase and protease enzymes was produced using Aspergillus niger 3T5B8 on different agroindustrial residues by solid-state fermentation and tested for vegetable oil extraction. The enzymic activities were evaluated using second-order empirical models from experimental data as a function of fermentation time and cellobiose concentration in the fermentation medium. The use of wheat bran as substrate

Sonia Couri; Selma da Costa Terzi; Gustavo A Saavedra Pinto; Suely Pereira Freitas; Antonio Carlos Augusto da Costa

2000-01-01

153

Citric acid production from carob pod extract by cell recycle of Aspergillus niger atcc 9142  

Microsoft Academic Search

The production of citric acid from carob pod extract by cell recycle of Aspergillus niger at different pHs was investigated. Best results in terms of citric acid concentration, productivity, yield and sugar utilization were obtained with a substrate pH of 5.0. The citric acid concentration (85.5 g\\/l) and the productivity (4 g\\/ld) remained constant up to the second and third

T. Roukas

1998-01-01

154

Overproduction of the Aspergillus niger feruloyl esterase for pulp bleaching application  

Microsoft Academic Search

A well-known industrial fungus for enzyme production, Aspergillus niger, was selected to produce the feruloyl esterase FAEA by homologous overexpression for pulp bleaching application. The gpd gene promoter was used to drive FAEA expression. Changing the nature and concentration of the carbon source nature (maltose to glucose; from 2.5 to 60 g l -1), improved FAEA activity 24.5-fold and a yield of

E. Record; M. Asther; C. Sigoillot; S. Pagès; P. J. Punt; M. Delattre; M. Haon; C. A. M. J. J. van den Hondel; J.-C. Sigoillot; L. Lesage-Meessen

2003-01-01

155

Evidence for a cytoplasmic pathway of oxalate biosynthesis in Aspergillus niger  

SciTech Connect

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 P/sub i/ and a nitrogen source and was inhibited by the protein synthesis inhibitor cycloheximide. Exogenously added /sup 14/CO/sub 2/ 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 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.; Woehrer, W.; Roehr, M.

1988-03-01

156

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. PMID:23270588

2012-01-01

157

Production of the Aspergillus aculeatus endo-1,4-beta-mannanase in A. niger.  

PubMed

The beta-mannanase gene (man1) from Aspergillus aculeatus MRC11624 (Izuka) was patented for application in the coffee industry. For production of the enzyme, the gene was originally cloned and expressed in Saccharomyces cerevisiae. However the level of production was found to be economically unfeasible. Here we report a 13-fold increase in enzyme production through the successful expression of beta-mannanase of Aspergillus aculeatus MRC11624 in Aspergillus niger under control of the A. niger glyceraldehyde-3-phosphate dehydrogenase promoter (gpd (P)) and the A. awamori glucoamylase terminator (glaA(T)). The effect of medium composition on mannanase production was evaluated, and it was found that the glucose concentration and the organic nitrogen source had an effect on both the volumetric enzyme activity and the specific enzyme activity. The highest mannanase activity levels of 16,596 nkat ml(-1) and 574 nkat mg(-1) dcw were obtained for A. niger D15[man1] when cultivated in a process-viable medium containing corn steep liquor as the organic nitrogen source and high glucose concentrations. PMID:19277742

van Zyl, Petrus J; Moodley, V; Rose, S H; Roth, R L; van Zyl, W H

2009-04-01

158

Targeting enzymes to the right compartment: metabolic engineering for itaconic acid production by Aspergillus niger.  

PubMed

Itaconic acid is an unsaturated dicarboxylic acid which has a high potential as a biochemical building block. It can be microbially produced from some Aspergillus species, such as Aspergillus itaconicus and Aspergillus terreus. However, the achieved titers are significantly lower as compared to the citric acid production by A. niger. Heterologous expression of cis-aconitate decarboxylase in A. niger leads to the accumulation of small amounts of itaconic acid. Additional expression of aconitase, the second enzyme metabolically linking citric acid and itaconic acid improves productivity. However, proper organelle targeting of the enzymes appears to be an important point to consider. Here we compare the mitochondrial expression with the cytosolic expression of cis-aconitate decarboxylase or aconitase in A. niger. Heterologous expression of both enzymes in the mitochondria doubles the productivity compared to strains which express the enzymes in the cytosol. It is essential to target enzymes to the correct compartment in order to establish a proper flux through a compartmentalized pathway. PMID:23727192

Blumhoff, Marzena L; Steiger, Matthias G; Mattanovich, Diethard; Sauer, Michael

2013-09-01

159

Germination of Aspergillus niger conidia is triggered by nitrogen compounds related to L-amino acids.  

PubMed

Conidial germination is fundamentally important to the growth and dissemination of most fungi. It has been previously shown (K. Hayer, M. Stratford, and D. B. Archer, Appl. Environ. Microbiol. 79:6924-6931, 2013, http://dx.doi.org/10.1128/AEM.02061-13), using sugar analogs, that germination is a 2-stage process involving triggering of germination and then nutrient uptake for hyphal outgrowth. In the present study, we tested this 2-stage germination process using a series of nitrogen-containing compounds for the ability to trigger the breaking of dormancy of Aspergillus niger conidia and then to support the formation of hyphae by acting as nitrogen sources. Triggering and germination were also compared between A. niger and Aspergillus nidulans using 2-deoxy-D-glucose (trigger), D-galactose (nontrigger in A. niger but trigger in A. nidulans), and an N source (required in A. niger but not in A. nidulans). Although most of the nitrogen compounds studied served as nitrogen sources for growth, only some nitrogen compounds could trigger germination of A. niger conidia, and all were related to L-amino acids. Using L-amino acid analogs without either the amine or the carboxylic acid group revealed that both the amine and carboxylic acid groups were essential for an L-amino acid to serve as a trigger molecule. Generally, conidia were able to sense and recognize nitrogen compounds that fitted into a specific size range. There was no evidence of uptake of either triggering or nontriggering compounds over the first 90 min of A. niger conidial germination, suggesting that the germination trigger sensors are not located within the spore. PMID:25063657

Hayer, Kimran; Stratford, Malcolm; Archer, David B

2014-10-01

160

Cloning and molecular characterization of a soluble epoxide hydrolase from Aspergillus niger that is related to mammalian microsomal epoxide hydrolase.  

PubMed Central

Aspergillus niger strain LCP521 harbours a highly processive epoxide hydrolase (EH) that is of particular interest for the enantioselective bio-organic synthesis of fine chemicals. In the present work, we report the isolation of the gene and cDNA for this EH by use of inverse PCR. The gene is composed of nine exons, the first of which is apparently non-coding. The deduced protein of the A. niger EH shares significant sequence similarity with the mammalian microsomal EHs (mEH). In contrast to these, however, the protein from A. niger lacks the common N-terminal membrane anchor, in line with the fact that this enzyme is, indeed, soluble in its native environment. Recombinant expression of the isolated cDNA in Escherichia coli yielded a fully active EH with similar characteristics to the fungal enzyme. Sequence comparison with mammalian EHs suggested that Asp(192), Asp(348) and His(374) constituted the catalytic triad of the fungal EH. This was subsequently substantiated by the analysis of respective mutants constructed by site-directed mutagenesis. The presence of an aspartic acid residue in the charge-relay system of the A. niger enzyme, in contrast to a glutamic acid residue in the respective position of all mEHs analysed to date, may be one important contributor to the exceptionally high turnover number of the fungal enzyme when compared with its mammalian relatives. Recombinant expression of the enzyme in E. coli offers a versatile tool for the bio-organic chemist for the chiral synthesis of a variety of fine chemicals. PMID:10548561

Arand, M; Hemmer, H; Dürk, H; Baratti, J; Archelas, A; Furstoss, R; Oesch, F

1999-01-01

161

Induction of mutation in Aspergillus niger for conversion of cellulose into glucose  

SciTech Connect

Plant wastes are very important part of biomass used and investigated for energy, chemical, and fuel production. Cellulose is the major renewable form of carbohydrate in the world, about 10{sup 11} tons of which is synthesized annually. For general use, it must be hydrolyzed first, either chemically or by cellulases derived from a few specialized microorganisms. Enzymes are acceptable environmentally but expensive to produce. Certainly, induction of mutations and selection of high cellulose microbial strains with significant adaptability to degrade cellulose to glucose is promising solutions. Induction of mutations in other fungi and Aspergillus sp. rather than Aspergillus niger was reported. Aspergillus ustus and Trichoderma harzianum were induced by gamma irradiation indicating mutants that excrete higher cellulose yields, particularly exocellobiohydrolase (Avicelase) than their respective wild types. Mutants from the celluiolytic fungus Penicillium pinophilum were induced by chemical and UV-irradiation. Enhancing the production of endo-1,4-{Beta}-D-glucanase (CMCase) and particularly {Beta}-glucosidase was obtained by gamma irradiation of Altemaria alternate. To overcome the lower activity of {beta}-glucosidase in certain fungi species rather than A. niger, mixed cultures of different species were tried. Thus, Aspergillus phonicis with Trichoderma reesei Rut 30, produced a cellulose complex that improved activity twofold over cellulose from Trichoderma alone.

Helmi, S.; Khalil, A.E.; Tahoun, M.K.; Khairy, A.H. [Univ. of Alexandria Research Centre, Alexandria (Egypt)

1991-12-31

162

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. PMID:21210990

2011-01-01

163

Phylogenetic characterization and ochratoxin A--fumonisin profile of black Aspergillus isolated from grapes in Argentina.  

PubMed

Aspergillus section Nigri populations isolated from seven growing regions from Argentina were characterized by sequencing in order to identify species responsible for production of ochratoxin A (OTA) and fumonisins (FB(s)). Sequences of genes encoding calmodulin, ?-tubulin, the second largest subunit of RNA polymerase II and translation elongation factor 1 alpha were analysed. The phylogenetic analysis showed the presence of six lineages: A. carbonarius, A. tubingensis, A. niger, A. japonicus, A. homomorphus and A. foetidus grouped in four major clusters. The molecular tools used allowed the identification for the first time of A. homomorphus from vineyards. OTA production confirmed the importance of A. carbonarius as the main ochratoxigenic species isolated and, to a variable degree, of A. niger and A. tubingensis, which were by far the most commonly occurring species on grapes in Argentina. The only strains able to produce OTA and fumonisins (B(2)-B(4)) belong to the A. niger cluster. PMID:21723640

Chiotta, M L; Susca, A; Stea, G; Mulè, G; Perrone, G; Logrieco, A; Chulze, S N

2011-09-15

164

Optimization of Ellagitannase Production by Aspergillus niger GH1 by Solid-State Fermentation.  

PubMed

Ellagic acid is one of the most bioactive antioxidants with important applications in pharmaceutical, cosmetic, and food industries. However, there are few biotechnological processes developed for its production, because it requires precursors (ellagitannins) and the corresponding biocatalyst (ellagitannase). The aim of this study was to optimize the culture conditions for ellagitannase production by Aspergillus niger in solid-state fermentation (SSF). The bioprocess was carried out into a column bioreactor packed with polyurethane foam impregnated with an ellagitannins solution as carbon source. Four strains of Aspergillus niger (PSH, GH1, HT4, and HC2) were evaluated for ellagitannase production. The study was performed in two experimental steps. A Plackett-Burman design was used to determine the influencing parameters on ellagitannase production. Ellagitannins concentration, KCl, and MgSO4 were determined to be the most significant parameters. Box-Behnken design was used to define the interaction of the selected parameters. The highest enzyme value was obtained by A. niger PSH at concentrations of 7.5 g/L ellagitannins, 3.04 g/L KCl, and 0.76 g/L MgSO4. The methodology followed here allowed increasing the ellagitannase activity 10 times over other researcher results (938.8 U/g ellagitannins). These results are significantly higher than those reported previously and represent an important contribution for the establishment of a new bioprocess for ellagic acid and ellagitannase production. PMID:25085574

de la Cruz, Reynaldo; Ascacio, Juan A; Buenrostro, Juan; Sepúlveda, Leonardo; Rodríguez, Raúl; Prado-Barragán, Arely; Contreras, Juan C; Aguilera, Antonio; Aguilar, Cristóbal N

2015-10-01

165

Mutualistic interaction between Salmonella enterica and Aspergillus niger and its effects on Zea mays colonization  

PubMed Central

Salmonella?Typhimurium inhabits a variety of environments and is able to infect a broad range of hosts. Throughout its life cycle, some hosts can act as intermediates in the path to the infection of others. Aspergillus niger is a ubiquitous fungus that can often be found in soil or associated to plants and microbial consortia. Recently, S. Typhimurium was shown to establish biofilms on the hyphae of A. niger. In this work, we have found that this interaction is stable for weeks without a noticeable negative effect on either organism. Indeed, bacterial growth is promoted upon the establishment of the interaction. Moreover, bacterial biofilms protect the fungus from external insults such as the effects of the anti-fungal agent cycloheximide. Thus, the Salmonella–Aspergillus interaction can be defined as mutualistic. A tripartite gnotobiotic system involving the bacterium, the fungus and a plant revealed that co-colonization has a greater negative effect on plant growth than colonization by either organism in dividually. Strikingly, co-colonization also causes a reduction in plant invasion by S. Typhimurium. This work demonstrates that S. Typhimurium and A. niger establish a mutualistic interaction that alters bacterial colonization of plants and affects plant physiology. PMID:25351041

Balbontín, Roberto; Vlamakis, Hera; Kolter, Roberto

2014-01-01

166

Mutualistic interaction between Salmonella enterica and Aspergillus niger and its effects on Zea mays colonization.  

PubMed

Salmonella?Typhimurium inhabits a variety of environments and is able to infect a broad range of hosts. Throughout its life cycle, some hosts can act as intermediates in the path to the infection of others. Aspergillus niger is a ubiquitous fungus that can often be found in soil or associated to plants and microbial consortia. Recently, S.?Typhimurium was shown to establish biofilms on the hyphae of A.?niger. In this work, we have found that this interaction is stable for weeks without a noticeable negative effect on either organism. Indeed, bacterial growth is promoted upon the establishment of the interaction. Moreover, bacterial biofilms protect the fungus from external insults such as the effects of the anti-fungal agent cycloheximide. Thus, the Salmonella-Aspergillus interaction can be defined as mutualistic. A tripartite gnotobiotic system involving the bacterium, the fungus and a plant revealed that co-colonization has a greater negative effect on plant growth than colonization by either organism in dividually. Strikingly, co-colonization also causes a reduction in plant invasion by S.?Typhimurium. This work demonstrates that S.?Typhimurium and A.?niger establish a mutualistic interaction that alters bacterial colonization of plants and affects plant physiology. PMID:25351041

Balbontín, Roberto; Vlamakis, Hera; Kolter, Roberto

2014-11-01

167

Gene cloning and soluble expression of Aspergillus niger phytase in E. coli cytosol via chaperone co-expression.  

PubMed

A phytase gene from Aspergillus niger was isolated and two Escherichia coli expression systems, based on T7 RNA polymerase promoter and tac promoter, were used for its recombinant expression. Co-expression of molecular chaperone, GroES/EL, aided functional cytosolic expression of the phytase in E. coli BL21 (DE3). Untagged and maltose-binding protein-tagged recombinant phytase showed an activity band of ~49 and 92 kDa, respectively, on a zymogram. Heterologously-expressed phytase was fractionated from endogenous E. coli phytase by (NH4)2SO4 precipitation. The enzyme had optimum activity at 50 °C and pH 6.5. PMID:24078121

Ushasree, Mrudula Vasudevan; Vidya, Jalaja; Pandey, Ashok

2014-01-01

168

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

169

An Antifungal Role of Hydrogen Sulfide on the Postharvest Pathogens Aspergillus niger and Penicillium italicum  

PubMed Central

In this research, the antifungal role of hydrogen sulfide (H2S) on the postharvest pathogens Aspergillus niger and Penicillium italicum growing on fruits and under culture conditions on defined media was investigated. Our results show that H2S, released by sodium hydrosulfide (NaHS) effectively reduced the postharvest decay of fruits induced by A. niger and P. italicum. Furthermore, H2S inhibited spore germination, germ tube elongation, mycelial growth, and produced abnormal mycelial contractions when the fungi were grown on defined media in Petri plates. Further studies showed that H2S could cause an increase in intracellular reactive oxygen species (ROS) in A. niger. In accordance with this observation we show that enzyme activities and the expression of superoxide dismutase (SOD) and catalase (CAT) genes in A. niger treated with H2S were lower than those in control. Moreover, H2S also significantly inhibited the growth of Saccharomyces cerevisiae, Rhizopus oryzae, the human pathogen Candida albicans, and several food-borne bacteria. We also found that short time exposure of H2S showed a microbicidal role rather than just inhibiting the growth of microbes. Taken together, this study suggests the potential value of H2S in reducing postharvest loss and food spoilage caused by microbe propagation. PMID:25101960

Li, Yan-Hong; Hu, Liang-Bin; Yan, Hong; Liu, Yong-Sheng; Zhang, Hua

2014-01-01

170

Salmonella biofilm formation on Aspergillus niger involves cellulose--chitin interactions.  

PubMed

Salmonella cycles between host and nonhost environments, where it can become an active member of complex microbial communities. The role of fungi in the environmental adaptation of enteric pathogens remains relatively unexplored. We have discovered that S. enterica Typhimurium rapidly attaches to and forms biofilms on the hyphae of the common fungus, Aspergillus niger. Several Salmonella enterica serovars displayed a similar interaction, whereas other bacterial species were unable to bind to the fungus. Bacterial attachment to chitin, a major constituent of fungal cell walls, mirrored this specificity. Pre-incubation of S. Typhimurium with N-acetylglucosamine, the monomeric component of chitin, reduced binding to chitin beads by as much as 727-fold and inhibited attachment to A. niger hyphae considerably. A cellulose-deficient mutant of S. Typhimurium failed to attach to chitin beads and to the fungus. Complementation of this mutant with the cellulose operon restored binding to chitin beads to 79% of that of the parental strain and allowed for attachment and biofilm formation on A. niger, indicating that cellulose is involved in bacterial attachment to the fungus via the chitin component of its cell wall. In contrast to cellulose, S. Typhimurium curli fimbriae were not required for attachment and biofilm development on the hyphae but were critical for its stability. Our results suggest that cellulose-chitin interactions are required for the production of mixed Salmonella-A. niger biofilms, and support the hypothesis that encounters with chitinaceous alternate hosts may contribute to the ecological success of human pathogens. PMID:22003399

Brandl, Maria T; Carter, Michelle Q; Parker, Craig T; Chapman, Matthew R; Huynh, Steven; Zhou, Yaguang

2011-01-01

171

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

172

Development of a serial bioreactor system for direct ethanol production from starch using Aspergillus niger and Saccharomyces cerevisiae  

Microsoft Academic Search

Aspergillus niger hyphae were found to grow with unliquefied potato starch under aerobic conditions, but did not grow under anaerobic conditions.\\u000a The raw culture ofA. niger catalyzed saccharification of potato starch to glucose, producing approximately 12 g glucose\\/L\\/day\\/ The extracellular enzyme\\u000a activity was decreased in proportion to incubation time, and approximately 64% of initial activity was maintained after 3\\u000a days.

Bo Young Jeon; Soo Jin Kim; Dae Hee Kim; Byung Kwan Na; Doo Hyun Park; Hung Thuan Tran; Ruihong Zhang; Dae Hee Ahn

2007-01-01

173

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

174

Purification and characterization of endo-xylanases from Aspergillus Niger. III. An enzyme of PL 365  

Microsoft Academic Search

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.

R. A. Fournier; M. M. Frederick; J. R. Frederick; P. J. Reilly

1985-01-01

175

Crystallization and preliminary X-ray diffraction data of ?-galactosidase from Aspergillus niger.  

PubMed

?-Galactosidase from Aspergillus niger (An-?-Gal), belonging to the family 35 glycoside hydrolases, hydrolyzes the ?-galactosidase linkages in lactose and other galactosides. It is extensively used in industry owing to its high hydrolytic activity and safety. The enzyme has been expressed in yeasts and purified by immobilized metal-ion affinity chromatography for crystallization experiments. The recombinant An-?-Gal, deglycosylated to avoid heterogeneity of the sample, has a molecular mass of 109?kDa. Rod-shaped crystals grew using PEG 3350 as the main precipitant agent. A diffraction data set was collected to 1.8?Å resolution. PMID:25372823

Rico-Díaz, Agustín; Vizoso Vázquez, Ángel; Cerdán, M Esperanza; Becerra, Manuel; Sanz-Aparicio, Julia

2014-11-01

176

Biosorption of Cr(VI) onto marine Aspergillus niger : experimental studies and pseudo-second order kinetics  

Microsoft Academic Search

The removal of hexavalent chromium from aqueous solution was studied in batch experiments using dead biomass of three different\\u000a species of marine Aspergillus after alkali treatment. All the cultures exhibited potential to remove Cr(VI), out of which, Aspergillus niger was found to be the most promising one. This culture was further studied employing variation in pH, temperature, metal ion\\u000a concentration

Yasmin Khambhaty; Kalpana Mody; Shaik Basha; Bhavanath Jha

2009-01-01

177

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

178

Genome mining and functional genomics for siderophore production in Aspergillus niger.  

PubMed

Iron is an essential metal for many organisms, but the biologically relevant form of iron is scarce because of rapid oxidation resulting in low solubility. Simultaneously, excessive accumulation of iron is toxic. Consequently, iron uptake is a highly controlled process. In most fungal species, siderophores play a central role in iron handling. Siderophores are small iron-specific chelators that can be secreted to scavenge environmental iron or bind intracellular iron with high affinity. A second high-affinity iron uptake mechanism is reductive iron assimilation (RIA). As shown in Aspergillus fumigatus and Aspergillus nidulans, synthesis of siderophores in Aspergilli is predominantly under control of the transcription factors SreA and HapX, which are connected by a negative transcriptional feedback loop. Abolishing this fine-tuned regulation corroborates iron homeostasis, including heme biosynthesis, which could be biotechnologically of interest, e.g. the heterologous production of heme-dependent peroxidases. Aspergillus niger genome inspection identified orthologues of several genes relevant for RIA and siderophore metabolism, as well as sreA and hapX. Interestingly, genes related to synthesis of the common fungal extracellular siderophore triacetylfusarinine C were absent. Reverse-phase high-performance liquid chromatography (HPLC) confirmed the absence of triacetylfusarinine C, and demonstrated that the major secreted siderophores of A. niger are coprogen B and ferrichrome, which is also the dominant intracellular siderophore. In A. niger wild type grown under iron-replete conditions, the expression of genes involved in coprogen biosynthesis and RIA was low in the exponential growth phase but significantly induced during ascospore germination. Deletion of sreA in A. niger resulted in elevated iron uptake and increased cellular ferrichrome accumulation. Increased sensitivity toward phleomycin and high iron concentration reflected the toxic effects of excessive iron uptake. Moreover, SreA-deficiency resulted in increased accumulation of heme intermediates, but no significant increase in heme content. Together with the upregulation of several heme biosynthesis genes, these results reveal a complex heme regulatory mechanism. PMID:25062661

Franken, Angelique C W; Lechner, Beatrix E; Werner, Ernst R; Haas, Hubertus; Lokman, B Christien; Ram, Arthur F J; van den Hondel, Cees A M J J; de Weert, Sandra; Punt, Peter J

2014-11-01

179

Removal and recovery of uranium (VI) from aqueous solutions by immobilized Aspergillus niger powder beads.  

PubMed

The immobilized Aspergillus niger powder beads were obtained by entrapping nonviable A. niger powder into Ca-alginate gel. The effects of pH, contact time, initial uranium (VI) concentration and biomass dosage on the biosorption of uranium (VI) onto the beads from aqueous solutions were investigated in a batch system. Biosorption equilibrium data were agreeable with Langmuir isotherm model and the maximum biosorption capacity of the beads for uranium (VI) was estimated to be 649.4 mg/g at 30 °C. The biosorption kinetics followed the pseudo-second-order model and intraparticle diffusion equation. The variations in enthalpy (26.45 kJ/mol), entropy (0.167 kJ/mol K) and Gibbs free energy were calculated from the experimental data. SEM and EDS analysis indicated that the beads have strong adsorption capability for uranium (VI). The adsorbed uranium (VI) on the beads could be released with HNO(3) or HCl. The results showed that the immobilized A. niger powder beads had great potential for removing and recovering uranium (VI) from aqueous solutions. PMID:22580796

Ding, De-Xin; Tan, Xiang; Hu, Nan; Li, Guang-Yue; Wang, Yong-Dong; Tan, Yan

2012-11-01

180

EglC, a New Endoglucanase from Aspergillus niger with Major Activity towards Xyloglucan  

PubMed Central

A novel gene, eglC, encoding an endoglucanase, was cloned from Aspergillus niger. Transcription of eglC is regulated by XlnR, a transcriptional activator that controls the degradation of polysaccharides in plant cell walls. EglC is an 858-amino-acid protein and contains a conserved C-terminal cellulose-binding domain. EglC can be classified in glycoside hydrolase family 74. No homology to any of the endoglucanases from Trichoderma reesei was found. In the plant cell wall xyloglucan is closely linked to cellulose fibrils. We hypothesize that the EglC cellulose-binding domain anchors the enzyme to the cellulose chains while it is cleaving the xyloglucan backbone. By this action it may contribute to the degradation of the plant cell wall structure together with other enzymes, including hemicellulases and cellulases. EglC is most active towards xyloglucan and therefore is functionally different from the other two endoglucanases from A. niger, EglA and EglB, which exhibit the greatest activity towards ?-glucan. Although the mode of action of EglC is not known, this enzyme represents a new enzyme function involved in plant cell wall polysaccharide degradation by A. niger. PMID:11916668

Hasper, Alinda A.; Dekkers, Ester; van Mil, Marc; van de Vondervoort, Peter J. I.; de Graaff, Leo H.

2002-01-01

181

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

182

Physiological characterization of xylose metabolism in Aspergillus niger under oxygen-limited conditions.  

PubMed

The physiology of Aspergillus niger was studied under different aeration conditions. Five different aeration rates were investigated in batch cultivations of A. niger grown on xylose. Biomass, intra- and extra-cellular metabolites profiles were determined and ten different enzyme activities in the central carbon metabolism were assessed. The focus was on organic acid production with a special interest in succinate production. The fermentations revealed that oxygen limitation significantly changes the physiology of the micro-organism. Changes in extra cellular metabolite profiles were observed, that is, there was a drastic increase in polyol production (erythritol, xylitol, glycerol, arabitol, and mannitol) and to a lesser extent in the production of reduced acids (malate and succinate). The intracellular metabolite profiles indicated changes in fluxes, since several primary metabolites, like the intermediates of the TCA cycle accumulated during oxygen limitation (on average three fold increase). Also the enzyme activities showed changes between the exponential growth phase and the oxygen limitation phase. In general, the oxygen availability has a significant impact on the physiology of this fungus causing dramatic alterations in the central carbon metabolism that should be taken into account in the design of A. niger as a succinate cell factory. PMID:17335061

Meijer, S; Panagiotou, G; Olsson, L; Nielsen, J

2007-10-01

183

Heterogenic expression of genes encoding secreted proteins at the periphery of Aspergillus niger colonies.  

PubMed

Colonization of a substrate by fungi starts with the invasion of exploring hyphae. These hyphae secrete enzymes that degrade the organic material into small molecules that can be taken up by the fungus to serve as nutrients. We previously showed that only part of the exploring hyphae of Aspergillus niger highly express the glucoamylase gene glaA. This was an unexpected finding since all exploring hyphae are exposed to the same environmental conditions. Using GFP as a reporter, we here demonstrate that the acid amylase gene aamA, the ?-glucuronidase gene aguA, and the feruloyl esterase gene faeA of A. niger are also subject to heterogenic expression within the exploring mycelium. Coexpression studies using GFP and dTomato as reporters showed that hyphae that highly express one of these genes also highly express the other genes encoding secreted proteins. Moreover, these hyphae also highly express the amylolytic regulatory gene amyR, and the glyceraldehyde-3-phosphate dehydrogenase gene gpdA. In situ hybridization demonstrated that the high expressers are characterized by a high 18S rRNA content. Taken together, it is concluded that two subpopulations of hyphae can be distinguished within the exploring mycelium of A. niger. The experimental data indicate that these subpopulations differ in their transcriptional and translational activity. PMID:20722697

Vinck, Arman; de Bekker, Charissa; Ossin, Adam; Ohm, Robin A; de Vries, Ronald P; Wösten, Han A B

2011-01-01

184

[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

185

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

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

2014-04-01

186

Solubilisation of some naturally occurring metal-bearing minerals, limescale and lead phosphate by Aspergillus niger.  

PubMed

The ability of the soil fungus Aspergillus niger to tolerate and solubilise seven naturally occurring metal-bearing minerals, limescale and lead phosphate was investigated. A. niger was able to solubilise four of the test insoluble compounds when incorporated into solid medium: cuprite (CuO2), galena (PbS), rhodochrosite (Mn(CO3)x) and limescale (CaCO3). A. niger was able to grow on all concentrations of all the test compounds, whether solubilisation occurred or not, with no reduction in growth rate from the control. In some cases, stimulation of growth occurred, most marked with the phosphate-containing mineral, apatite. Precipitation of insoluble copper and manganese oxalate crystals under colonies growing on agar amended with cuprite and rhodochrosite was observed after 1-2 days growth at 25 degrees C. This process of oxalate formation represents a reduction in bioavailability of toxic cations, and could represent an important means of toxic metal immobilisation of physiological and environmental significance. PMID:9297818

Sayer, J A; Kierans, M; Gadd, G M

1997-09-01

187

Deletion of a Chitin Synthase Gene in a Citric Acid Producing Strain of Aspergillus niger  

SciTech Connect

Citric acid production by the filamentous fungus Aspergillus niger is carried out in a process that causes the organism to drastically alter its morphology. This altered morphology includes hyphal swelling and highly limited polar growth resulting in clumps of swollen cells that eventually aggregate into pellets of approximately 100 microns in diameter. In this pelleted form, A. niger has increased citric acid production as compared to growth in filamentous form. Chitin is a crucial component of the cell wall of filamentous fungi. Alterations in the deposition or production of chitin may have profound effects on the morphology of the organism. In order to study the role of chitin synthesis in pellet formation we have deleted a chitin synthase gene (csmA) in Aspergillus niger strain ATCC 11414 using a PCR based deletion construct. This class of chitin synthases is only found in filamentous fungi and is not present in yeasts. The csmA genes contain a myosin motor domain at the N-terminus and a chitin synthesis domain at the C-terminus. They are believed to contribute to the specialized polar growth observed in filamentous fungi that is lacking in yeasts. The csmA deletion strain (csmA?) was subjected to minimal media with and without osmotic stabilizers as well as tested in citric acid production media. Without osmotic stabilizers, the mutant germlings were abnormally swollen, primarily in the subapical regions, and contained large vacuoles. However, this swelling is ultimately not inhibitory to growth as the germlings are able to recover and undergo polar growth. Colony formation was largely unaffected in the absence of osmotic stabilizers. In citric acid production media csmA? was observed to have a 2.5 fold increase in citric acid production. The controlled expression of this class of chitin synthases may be useful for improving production of organic acids in filamentous fungi.

Rinker, Torri E.; Baker, Scott E.

2007-01-29

188

VOCs removal from waste gases: gas-phase bioreactor for the abatement of hexane by Aspergillus niger  

Microsoft Academic Search

In this study, a biofilter reactor was successfully applied to remove hexane (a volatile organic compound) from contaminated air streams. Since hexane is very poorly water soluble and hardly metabolized by most bacteria, because of its short hydrocarbon chain, a gas-phase bioreactor inoculated by Aspergillus niger was adopted. In fact, filamentous fungi include many paraffin-degrading species and develop aerial structures

Giorgia Spigno; Claudio Pagella; M Daria Fumi; Roberto Molteni; D Marco De Faveri

2003-01-01

189

Comparison of different inoculating methods to evaluate the pathogenicity and virulence of Aspergillus niger on two maize hybrids  

Technology Transfer Automated Retrieval System (TEKTRAN)

A two-year field study was conducted to determine the effects of inoculation techniques on the aggressiveness of Aspergillus niger kernel infection in A. flavus resistant and susceptible maize hybrids. Ears were inoculated with the silk-channel, side-needle, and spray techniques 7 days after midsilk...

190

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

191

Cellular localization and metabolic function of n -butylamine-induced amine oxidases in the fungus Aspergillus niger AKU 3302  

Microsoft Academic Search

Using transmission electron microscopy, the amine oxidase activity in Aspergillus niger AKU 3302 was localized to the outer side of the cell wall but not inside the cell using the cerium perhydroxide deposition method. The presence of cerium in the deposit was confirmed by energy-dispersive microanalysis of X-rays. Interestingly, immunocytochemical localization using gold labeling with a specific antibody indicated the

Ivo Frébort; Shuhei Tanaka; Kazunobu Matsushita; Osao Adachi

2000-01-01

192

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

193

Production and Optimization of Cellulase Enzyme Using Aspergillus niger USM AI 1 and Comparison with Trichoderma reesei via Solid State Fermentation System.  

PubMed

Novel design solid state bioreactor, FERMSOSTAT, had been evaluated in cellulase production studies using local isolate Aspergillus niger USM AI 1 grown on sugarcane bagasse and palm kernel cake at 1?:?1 (w/w) ratio. Under optimised SSF conditions of 0.5?kg substrate; 70% (w/w) moisture content; 30°C; aeration at 4?L/h · g fermented substrate for 5?min and mixing at 0.5?rpm for 5?min, about 3.4?U/g of Filter paper activity (FPase) was obtained. At the same time, comparative studies of the enzymes production under the same SSF conditions indicated that FPase produced by A. niger USM AI 1 was about 35.3% higher compared to Trichoderma reesei. This shows that the performance of this newly designed SSF bioreactor is acceptable and potentially used as prototype for larger-scale bioreactor design. PMID:21350665

Lee, C K; Darah, I; Ibrahim, C O

2011-01-01

194

Development of an Unmarked Gene Deletion System for the Filamentous Fungi Aspergillus niger and Talaromyces versatilis  

PubMed Central

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

2014-01-01

195

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

196

Optimization of glucose oxidase production by Aspergillus niger using genetic- and process-engineering techniques.  

PubMed

Wild-type Aspergillus niger NRRL-3 was transformed with multiple copies of the glucose oxidase structural gene (god). The gene was placed under the control of the gpdA promoter of A. nidulans. For more efficient secretion the alpha-amylase signal peptide from A. oryzae was inserted in front of god. Compared to the wild type, the recombinant strain NRRL-3 (GOD3-18) produced up to four times more extracellular glucose oxidase under identical culture conditions. Addition of yeast extract (2 gl-1) to a mineral salts medium containing only glucose as carbon source increased volumetric and specific extracellular glucose oxidase activities by 130% and 50% respectively. With the same medium composition and inoculum size, volumetric and specific extracellular glucose oxidase activities increased more than ten times in bioreactor cultivations compared to shake-flask cultures. PMID:8590664

Hellmuth, K; Pluschkell, S; Jung, J K; Ruttkowski, E; Rinas, U

1995-11-01

197

Optimisation of different physical parameters for bioleaching of phosphate by Aspergillus niger from Indian rock phosphate.  

PubMed

A mutant strain of Aspergillus niger AB100 was incubated with samples of rock phosphate. Mutation resulted in a greater amount of solubilisation (30 to 35%) as against the parent strain (10 to 15%). The influence of leaching parameters such as ore concentration (pulp density), particle size, initial pH of the medium, temperature, volume of the medium in 250 ml flasks, inoculum concentration and age of inoculum was studied. When low quantity of rock phosphate is applied (0.1%) the solubilisation of phosphorus was optimal (40.5%). Optimum particle size was--200 to 240 mesh, initial pH of the medium 4.0, optimum volume of the fermentation medium 160 ml, time period of incubation was 8 days, inoculum volume was 7.5 ml, and age of inoculum 7 days. The maximum leaching of phosphorus by using these optimum physical parameters is 45 to 50%. PMID:9782785

Ghosh, R; Banik, A K

1998-07-01

198

Selection of amylolytically active Aspergillus niger mutants to 2-deoxy-D-glucose.  

PubMed

As a result of mutagenization and passaging on 2-deoxy-D-glucose containing medium, 10 Aspergillus niger strains resistant to this agent were obtained. These showed (with one exception) an increase in the activity of glucoamylse, the level of which ranged widely in individual cases from several to over 200% in comparison with the parent strain. A weaker rate of glucose accumulation in derepressed strains may account for the fact that the mechanism of their resistance to deoxyglucose is connected with disturbance of the system of glucose transport. However, it is possible that a high activity of acid phosphatase, which the obtained deoxyglucose-resistant cultures showed, may be involved here. Apart from the biochemical character of the catabolic derepression, it seems that it can already be successfully utilized to increase the productivity of industrial mould cultures. PMID:3122460

Fiedurek, J; Paszczy?ski, A; Ginalska, G; Ilczuk, Z

1987-01-01

199

[Overexpression of artificial synthetic gene of Aspergillus niger NRRL3135 phytase in Pichia pastoris].  

PubMed

The phytase gene of Aspergillus niger NRRL3135 was modified with a deletion of intron and signal coding sequence. Then, according to the codon preference of Pichia pastoris, modified phyA gene was artificially synthesized and cloned into expression vector of pPICZ alpha A. The recombinant plasmid was transformed into chromosome of Pichia pastoris X-33 strain by electroporation. The results of SDS-PAGE and enzymatic kinetic analysis proved that the recombinant phytase was secreted into culture medium with nearly same character of natural phytase. After screening for high level productive yeast strains, a strain named SPAN-III produced recombinant phytase with 165,000 u/mL under the condition of shake cultivation. It will satisfy the demand for industrialized production in some degree. PMID:11517595

Bei, J L; Chen, Z; Yang, L; Liao, L; Wang, X Z; Jiang, Z Y

2001-05-01

200

Production, purification, and characterization of human alpha1 proteinase inhibitor from Aspergillus niger.  

PubMed

Human alpha one proteinase inhibitor (alpha1-PI) was cloned and expressed in Aspergillus niger, filamentious fungus that can grow in defined media and can perform glycosylation. Submerged culture conditions were established using starch as carbon source, 30% dissolved oxygen concentration, pH 7.0 and 28 degrees C. Eight milligrams per liter of active alpha1-PI were secreted to the growth media in about 40 h. Controlling the protein proteolysis was found to be an important factor in the production. The effects of various carbon sources, pH and temperature on the production and stability of the protein were tested and the product was purified and characterized. Two molecular weights variants of the recombinant alpha1-PI were produced by the fungus; the difference is attributed to the glycosylated part of the molecule. The two glycoproteins were treated with PNGAse F and the released glycans were analyzed by HPAEC, MALDI/TOF-MS, NSI-MS(n), and GC-MS. The MALDI and NSI- full MS spectra of permethylated N-glycans revealed that the N-glycans of both variants contain a series of high-mannose type glycans with 5-20 hexose units. Monosaccharide analysis showed that these were composed of N-acetylglucos-amine, mannose, and galactose. Linkage analysis revealed that the galactosyl component was in the furanoic conformation, which was attaching in a terminal non-reducing position. The Galactofuranose-containing high-mannnose type N-glycans are typical structures, which recently have been found as part of several glycoproteins produced by Aspergillus niger. PMID:18828177

Chill, Liat; Trinh, Loc; Azadi, Parastoo; Ishihara, Mayumi; Sonon, Roberto; Karnaukhova, Elena; Ophir, Yakir; Golding, Basil; Shiloach, Joseph

2009-02-15

201

Morphology of Filamentous Fungi: Linking Cellular Biology to Process Engineering Using Aspergillus niger  

NASA Astrophysics Data System (ADS)

In various biotechnological processes, filamentous fungi, e.g. Aspergillus niger, are widely applied for the production of high value-added products due to their secretion efficiency. There is, however, a tangled relationship between the morphology of these microorganisms, the transport phenomena and the related productivity. The morphological characteristics vary between freely dispersed mycelia and distinct pellets of aggregated biomass. Hence, advantages and disadvantages for mycel or pellet cultivation have to be balanced out carefully. Due to this inadequate understanding of morphogenesis of filamentous microorganisms, fungal morphology, along with reproducibility of inocula of the same quality, is often a bottleneck of productivity in industrial production. To obtain an optimisation of the production process it is of great importance to gain a better understanding of the molecular and cell biology of these microorganisms as well as the approaches in biochemical engineering and particle technique, in particular to characterise the interactions between the growth conditions, cell morphology, spore-hyphae-interactions and product formation. Advances in particle and image analysis techniques as well as micromechanical devices and their applications to fungal cultivations have made available quantitative morphological data on filamentous cells. This chapter provides the ambitious aspects of this line of action, focussing on the control and characterisation of the morphology, the transport gradients and the approaches to understand the metabolism of filamentous fungi. Based on these data, bottlenecks in the morphogenesis of A. niger within the complex production pathways from gene to product should be identified and this may improve the production yield.

Krull, Rainer; Cordes, Christiana; Horn, Harald; Kampen, Ingo; Kwade, Arno; Neu, Thomas R.; Nörtemann, Bernd

202

Optimization of the production of Aspergillus niger ?-glucosidase expressed in Pichia pastoris.  

PubMed

The ?-glucosidase (AGL) from Aspergillus niger has been applied to produce isomaltooligosaccharides. In the present study, various factors which affect the yield of recombinant AGL, produced by engineered Pichia pastoris, were investigated. The expression level reached 5.5 U ml(-1) in bioreactor after optimization of parameters of initial induction cell density, induction temperature and methanol concentration. In addition, it was found that coexpression of protein disulfide isomerase (PDI) inhibited the growth of the engineered P. pastoris strains and had an adverse effect on the production of AGL, while codon optimization of native A. niger ?-glucosidase encoding gene (aglu) resulted in a significant enhancement of enzyme production, which reached 10.1 U ml(-1). We believe that yield of AGL is increased by codon optimization as a result of enhanced translation efficiency as well as more stable mRNA secondary structure. In contrast, PDI coexpression under the control of alcohol oxidase promoter (PAOX1) seems to be less efficient in helping disulfide bond formation in AGL while probably induce unfolded protein response, which further leads to cell apoptosis and increased protein degradation. PMID:23132254

Liu, Xu; Wu, Dan; Wu, Jing; Chen, Jian

2013-03-01

203

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

204

Bacillus subtilis attachment to Aspergillus niger hyphae results in mutually altered metabolism.  

PubMed

Interaction between microbes affects the growth, metabolism and differentiation of members of the microbial community. While direct and indirect competition, like antagonism and nutrient consumption have a negative effect on the interacting members of the population, microbes have also evolved in nature not only to fight, but in some cases to adapt to or support each other, while increasing the fitness of the community. The presence of bacteria and fungi in soil results in various interactions including mutualism. Bacilli attach to the plant root and form complex communities in the rhizosphere. Bacillus subtilis, when grown in the presence of Aspergillus niger, interacts similarly with the fungus, by attaching and growing on the hyphae. Based on data obtained in a dual transcriptome experiment, we suggest that both fungi and bacteria alter their metabolism during this interaction. Interestingly, the transcription of genes related to the antifungal and putative antibacterial defence mechanism of B.?subtilis and A.?niger, respectively, are decreased upon attachment of bacteria to the mycelia. Analysis of the culture supernatant suggests that surfactin production by B.?subtilis was reduced when the bacterium was co-cultivated with the fungus. Our experiments provide new insights into the interaction between a bacterium and a fungus. PMID:25040940

Benoit, Isabelle; van den Esker, Marielle H; Patyshakuliyeva, Aleksandrina; Mattern, Derek J; Blei, Felix; Zhou, Miaomiao; Dijksterhuis, Jan; Brakhage, Axel A; Kuipers, Oscar P; de Vries, Ronald P; Kovács, Akos T

2014-07-15

205

Release of ferulic acid from agroindustrial by-products by the cell wall-degrading enzymes produced by Aspergillus niger I-1472  

Microsoft Academic Search

Aspergillus niger I-1472 was grown on sugar beet pulp to produce cell wall polysaccharide-degrading enzymes, including feruloyl esterases. Compared to enzymatic activities measured in commercially available mixtures previously used for the release of ferulic acid, the A. niger enzymes were more various. These enzymes were tested to release ferulic acid from sugar beet pulp, maize bran, or autoclaved maize bran.

Estelle Bonnin; Luc Saulnier; Magali Brunel; Cécile Marot; Laurence Lesage-Meessen; Marcel Asther; Jean-François Thibault

2002-01-01

206

The Weak-Acid Preservative Sorbic Acid Is Decarboxylated and Detoxified by a Phenylacrylic Acid Decarboxylase, PadA1, in the Spoilage Mold Aspergillus niger? †  

PubMed Central

Resistance to sorbic and cinnamic acids is mediated by a phenylacrylic acid decarboxylase (PadA1) in Aspergillus niger. A. niger ?padA1 mutants are unable to decarboxylate sorbic and cinnamic acids, and the MIC of sorbic acid required to inhibit spore germination was reduced by ?50% in ?padA1 mutants. PMID:18039817

Plumridge, Andrew; Stratford, Malcolm; Lowe, Kenneth C.; Archer, David B.

2008-01-01

207

The weak-acid preservative sorbic acid is decarboxylated and detoxified by a phenylacrylic acid decarboxylase, PadA1, in the spoilage mold Aspergillus niger.  

PubMed

Resistance to sorbic and cinnamic acids is mediated by a phenylacrylic acid decarboxylase (PadA1) in Aspergillus niger. A. niger DeltapadA1 mutants are unable to decarboxylate sorbic and cinnamic acids, and the MIC of sorbic acid required to inhibit spore germination was reduced by approximately 50% in DeltapadA1 mutants. PMID:18039817

Plumridge, Andrew; Stratford, Malcolm; Lowe, Kenneth C; Archer, David B

2008-01-01

208

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

209

Biochemical properties of Cu/Zn-superoxide dismutase from fungal strain Aspergillus niger 26  

NASA Astrophysics Data System (ADS)

The fungal strain Aspergillus niger produces two superoxide dismutases, Cu/Zn-SOD and Mn-SOD. The primary structure of the Cu/Zn-SOD has been determined by Edman degradation of peptide fragments derived from proteolytic digests. A single chain of the protein, consisting of 153 amino acid residues, reveals a very high degree of structural homology with the amino acid sequences of other Aspergillus Cu/Zn-SODs. The molecular mass of ANSOD, measured by MALDI-MS and ESI-MS, and calculated by its amino acid sequence, was determined to be 15 821 Da. Only one Trp residue, at position 32, and one disulfide bridge were identified. However, neither a Tyr residue nor a carbohydrate chain occupying an N-linkage site (-Asn-Ile-Thr-) were found. Studies on the temperature and pH dependence of fluorescence, and on the temperature dependence of CD spectroscopic properties, confirmed that the enzyme is very stable, which can be explained by the stabilising effect of the disulfide bridge. The enzyme retains about 53% of its activity after incubation for a period of 30 min at 60 °C, and 15% at 85 °C.

Dolashki, Aleksandar; Abrashev, Radoslav; Stevanovic, Stefan; Stefanova, Lilyana; Ali, Syed Abid; Velkova, Ludmila; Hristova, Rumyana; Angelova, Maria; Voelter, Wolfgang; Devreese, Bart; Van Beeumen, Jozef; Dolashka-Angelova, Pavlina

2008-12-01

210

Heterologous Expression of Aspergillus niger ?-d-Xylosidase (XlnD): Characterization on Lignocellulosic Substrates  

NASA Astrophysics Data System (ADS)

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 max was determined using differential scanning microcalorimetry (DSC) to be 78.2 °C; the K m and k cat were found to be 255 ?M and 13.7 s-1, respectively, using pNP-?-d-xylopyranoside as substrate. End-product inhibition by d-xylose was also verified and shown to be competitive; the K 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, Michael J.; Knoshaug, Eric P.; Decker, Stephen R.; Baker, John O.; Himmel, Michael E.; Adney, William S.

211

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

212

Isolation of Bacterial Antagonists of Aspergillus flavus from Almonds  

Microsoft Academic Search

Bacteria were isolated from California almond orchard samples to evaluate their potential antifungal activity against aflatoxin-producing Aspergillus flavus. Fungal populations from the same samples were examined to determine the incidence of aflatoxigenic Aspergillus species. Antagonistic activities of the isolated bacterial strains were screened against a nonaflatoxigenic nor mutant of A. flavus, which accumulates the pigmented aflatoxin precursor norsolorinic acid (NOR)

Jeffrey D. Palumbo; James L. Baker; Noreen E. Mahoney

2006-01-01

213

Bioconversion of Agave tequilana fructans by exo-inulinases from indigenous Aspergillus niger CH-A-2010 enhances ethanol production from raw Agave tequilana juice.  

PubMed

Agave tequilana fructans are the source of fermentable sugars for the production of tequila. Fructans are processed by acid hydrolysis or by cooking in ovens at high temperature. Enzymatic hydrolysis is considered an alternative for the bioconversion of fructans. We previously described the isolation of Aspergillus niger CH-A-2010, an indigenous strain that produces extracellular inulinases. Here we evaluated the potential application of A. niger CH-A-2010 inulinases for the bioconversion of A. tequilana fructans, and its impact on the production of ethanol. Inulinases were analyzed by Western blotting and thin layer chromatography. Optimal pH and temperature conditions for inulinase activity were determined. The efficiency of A. niger CH-A-2010 inulinases was compared with commercial enzymes and with acid hydrolysis. The hydrolysates obtained were subsequently fermented by Saccharomyces cerevisiae to determine the efficiency of ethanol production. Results indicate that A. niger CH-A-2010 predominantly produces an exo-inulinase activity. Optimal inulinase activity occurred at pH 5.0 and 50 °C. Hydrolysis of raw agave juice by CH-A-2010 inulinases yielded 33.5 g/l reducing sugars, compared with 27.3 g/l by Fructozyme(®) (Novozymes Corp, Bagsværd, Denmark) and 29.4 g/l by acid hydrolysis. After fermentation of hydrolysates, we observed that the conversion efficiency of sugars into ethanol was 97.5 % of the theoretical ethanol yield for enzymatically degraded agave juice, compared to 83.8 % for acid-hydrolyzed juice. These observations indicate that fructans from raw Agave tequilana juice can be efficiently hydrolyzed by using A. niger CH-A-2010 inulinases, and that this procedure impacts positively on the production of ethanol. PMID:23160922

Huitrón, Carlos; Pérez, Rosalba; Gutiérrez, Luís; Lappe, Patricia; Petrosyan, Pavel; Villegas, Jesús; Aguilar, Cecilia; Rocha-Zavaleta, Leticia; Blancas, Abel

2013-01-01

214

Genomic analysis of the aconidial and high-performance protein producer, industrially relevant Aspergillus niger SH2 strain.  

PubMed

Aspergillus niger is usually regarded as a beneficial species widely used in biotechnological industry. Obtaining the genome sequence of the widely used aconidial A. niger SH2 strain is of great importance to understand its unusual production capability. In this study we assembled a high-quality genome sequence of A. niger SH2 with approximately 11,517 ORFs. Relatively high proportion of genes enriched for protein expression related FunCat items verify its efficient capacity in protein production. Furthermore, genome-wide comparative analysis between A. niger SH2 and CBS513.88 reveals insights into unique properties of A. niger SH2. A. niger SH2 lacks the gene related with the initiation of asexual sporulation (PrpA), leading to its distinct aconidial phenotype. Frame shift mutations and non-synonymous SNPs in genes of cell wall integrity signaling, ?-1,3-glucan synthesis and chitin synthesis influence its cell wall development which is important for its hyphal fragmentation during industrial high-efficiency protein production. PMID:24630962

Yin, Chao; Wang, Bin; He, Pan; Lin, Ying; Pan, Li

2014-05-15

215

Production of tissue plasminogen activator (t-PA) in Aspergillus niger.  

PubMed

A protease-deficient strain of Aspergillus niger has been used as a host for the production of human tissue plasminogen activator (t-PA). In defined medium, up to 0.07 mg t-PA (g biomass)(-1) was produced in batch and fed-batch cultures and production was increased two- to threefold in two-phase batch cultures in which additional glucose was provided as a single pulse at the end of the first batch growth phase. Production was increased [up to 1.9 mg t-PA (g biomass)(-1)] by the addition of soy peptone to the defined medium. The rate of t-PA production in batch cultures supplemented with soy peptone (0.2 to 0.6 mg t-PA L(-1) h(-1)) was comparable to rates observed previously in high-producing mammalian or insect cell cultures. In glucose-limited chemostat culture supplemented with soy peptone, t-PA was produced at a rate of 0.7 mg t-PA L(-1) h(-1). Expression of t-PA in A. niger resulted in increased expression of genes (bipA, pdiA, and cypB) involved in the unfolded protein response (UPR). However, when cypB was overexpressed in a t-PA-producing strain, t-PA production was not increased. The t-PA produced in A. niger was cleaved into two chains of similar molecular weight to two-chain human melanoma t-PA. The two chains appeared to be stable for at least 16 h in culture supernatant of the host strain. However, in general, <1% of the t-PA produced in A. niger was active, and active t-PA disappeared from the culture supernatant during the stationary phase of batch cultures, suggesting that the two-chain t-PA may have been incorrectly processed or that initial proteolytic cleavage occurred within the proteolytic domain of the protein. Total t-PA (detected by enzyme-linked immunoassay) also eventually disappeared from culture supernatants, confirming significant extracellular proteolytic activity, even though the host strain was protease-deficient. PMID:11505386

Wiebe, M G; Karandikar, A; Robson, G D; Trinci, A P; Candia, J L; Trappe, S; Wallis, G; Rinas, U; Derkx, P M; Madrid, S M; Sisniega, H; Faus, I; Montijn, R; van den Hondel, C A; Punt, P J

2001-09-01

216

Production of L-asparaginase, an anticancer agent, from Aspergillus niger using agricultural waste in solid state fermentation.  

PubMed

This article reports the production of high levels of L-asparaginase from a new isolate of Aspergillus niger in solid state fermentation (SSF) using agro-wastes from three leguminous crops (bran of Cajanus cajan, Phaseolus mungo, and Glycine max). When used as the sole source for growth in SSF, bran of G. max showed maximum enzyme production followed by that of P. mungo and C. cajan. A 96-h fermentation time under aerobic condition with moisture content of 70%, 30 min of cooking time and 1205-1405 micro range of particle size in SSF appeared optimal for enzyme production. Enzyme yield was maximum (40.9 +/- 3.35 U/g of dry substrate) at pH 6.5 and temperature 30 +/- 2 degrees C. The optimum temperature and pH for enzyme activity were 40 degrees C and 6.5, respectively. The study suggests that choosing an appropriate substrate when coupled with process level optimization improves enzyme production markedly. Developing an asparaginase production process based on bran of G. max as a substrate in SSF is economically attractive as it is a cheap and readily available raw material in agriculture-based countries. PMID:17057254

Mishra, Abha

2006-10-01

217

Uncovering the Genome-Wide Transcriptional Responses of the Filamentous Fungus Aspergillus niger to Lignocellulose Using RNA Sequencing  

PubMed Central

A key challenge in the production of second generation biofuels is the conversion of lignocellulosic substrates into fermentable sugars. Enzymes, particularly those from fungi, are a central part of this process, and many have been isolated and characterised. However, relatively little is known of how fungi respond to lignocellulose and produce the enzymes necessary for dis-assembly of plant biomass. We studied the physiological response of the fungus Aspergillus niger when exposed to wheat straw as a model lignocellulosic substrate. Using RNA sequencing we showed that, 24 hours after exposure to straw, gene expression of known and presumptive plant cell wall–degrading enzymes represents a huge investment for the cells (about 20% of the total mRNA). Our results also uncovered new esterases and surface interacting proteins that might form part of the fungal arsenal of enzymes for the degradation of plant biomass. Using transcription factor deletion mutants (xlnR and creA) to study the response to both lignocellulosic substrates and low carbon source concentrations, we showed that a subset of genes coding for degradative enzymes is induced by starvation. Our data support a model whereby this subset of enzymes plays a scouting role under starvation conditions, testing for available complex polysaccharides and liberating inducing sugars, that triggers the subsequent induction of the majority of hydrolases. We also showed that antisense transcripts are abundant and that their expression can be regulated by growth conditions. PMID:22912594

Gaddipati, Sanyasi; Kokolski, Matthew; Malla, Sunir; Blythe, Martin J.; Ibbett, Roger; Campbell, Maria; Liddell, Susan; Aboobaker, Aziz; Tucker, Gregory A.; Archer, David B.

2012-01-01

218

Application of response surface methodology for optimization of lead biosorption in an aqueous solution by Aspergillus niger  

Microsoft Academic Search

Response surface methodology was applied to optimize the removal of lead ion by Aspergillus niger in an aqueous solution. Experiments were conducted based on a rotatable central composite design (CCD) and analyzed using response surface methodology (RSM). The biosorption process was investigated as a function of three independent factors viz. initial solution pH (2.8–7.2), initial lead concentration (8–30mg\\/l) and biomass

Malihe Amini; Habibollah Younesi; Nader Bahramifar; Ali Akbar Zinatizadeh Lorestani; Farshid Ghorbani; Ali Daneshi; Mazyar Sharifzadeh

2008-01-01

219

Production of pectolytic enzymes by Aspergillus niger: effect of inoculum size and potassium hexacyanoferrate II-trihydrate  

Microsoft Academic Search

The effect of inoculum size and potassium hexacyanoferrate II-trihydrate, K4[Fe(CN)6]·3 H2O (KHCF), on pectinase synthesis by Aspergillus niger in submerged conditions were studied. Experiments were performed in shake flasks and in a 10-1 stirred bioreactor. Spore concentrations in the range 102-108 spores\\/1 of substrate were tested. Enzyme activity measured by the Apple Juice Depectinizing Assay (AJDA) showed the highest values

Jožica Friedrich; Aleksa Cimerman; Walter Steiner

1990-01-01

220

Glucoamylase production in batch, chemostat and fed-batch cultivations by an industrial strain of Aspergillus niger  

Microsoft Academic Search

The Aspergillus niger strain BO-1 was grown in batch, continuous (chemostat) and fed-batch cultivations in order to study the production of the\\u000a extracellular enzyme glucoamylase under different growth conditions. In the pH range 2.5–6.0, the specific glucoamylase productivity\\u000a and the specific growth rate of the fungus were independent of pH when grown in batch cultivations. The specific glucoamylase\\u000a producivity increased

H. Pedersen; M. Beyer; J. Nielsen

2000-01-01

221

Biotransformation of glucose to gluconic acid by Aspergillus niger—study of mass transfer in an airlift bioreactor  

Microsoft Academic Search

A glucose–gluconic acid biotransformation system was suggested for the experimental study of oxygen transfer in bioreactors. This biosystem was used for the investigation of the effect of the flow rate and biomass concentration on the volumetric oxygen transfer coefficient kLa in a 10dm3 internal-loop airlift bioreactor. For this purpose, the fermentation broth of the mycelial strain Aspergillus niger was employed,

Jaroslav Klein; Michal Rosenberg; Jozef Markoš; Ondrej Dolgoš; Marek Krošlák; L’udmila Krištof??ková

2002-01-01

222

Oxidative stress response of a recombinant Aspergillus niger to exogenous menadione and H 2O 2 addition  

Microsoft Academic Search

A recombinant strain of Aspergillus niger (B1-D), engineered to produce the marker protein hen egg white lysozyme (HEWL), was investigated with regard to its susceptibility to oxidative stress. The culture response to oxidative stress, produced either by menadione (MD) or by H2O2, was characterised in terms of the intracellular activities of two key defensive enzymes, catalase (CAT) and superoxide dismutase

Michaela Kreiner; Linda M Harvey; Brian McNeil

2002-01-01

223

Optimization of culture conditions for the production of an extracellular ribonuclease by Aspergillus niger in a benchtop bioreactor  

Microsoft Academic Search

SummarySelf-directing optimization was successfully employed to determine the optimal combination of engineering parameters, viz., pH, aeration rate and agitation rate, for extracellular ribonuclease production by Aspergillus niger SA-13-20 in a batch bioreactor. Maximal RNase production of 5.38 IU ml-1 was obtained at controlled pH of 2.33, aeration rate of 1.67 v\\/v\\/m and agitation rate of 850 rev\\/min. The effect of

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

2004-01-01

224

Continuous production of polygalacturonases (PGases) using Aspergillus niger in a surface culture bioreactor and modeling the process  

Microsoft Academic Search

The feasibility of continuous production of PGases by a strain of Aspergillus niger was investigated in a surface culture bioreactor. Pectin was used as the substrate. The fermentation started in batch mode\\u000a until the medium was covered with the mycelia of the microorganism and after that it turned to continuous mode by introducing\\u000a the fresh feed. The process continued for

Haidar Abbasi; Mohammad Hassan Fazaelipoor

2010-01-01

225

A cinnamoyl esterase from Aspergillus niger can break plant cell wall cross-links without release of free diferulic acids  

Microsoft Academic Search

A cinnamoyl esterase, ferulic acid esterase A, from Aspergillus niger releases ferulic acid and 5-5- and 8-O-4-dehydrodiferulic acids from plant cell walls. The breakage of one or both ester bonds from dehydrodimer cross-links between plant cell wall polymers is essential for optimal action of carbohydrases on these substrates, but it is not known if cinnamoyl esterases can break these cross-links

Maria-Teresa Garcia-Conesa; Paul A. Kroon; John Ralph; Fred A. Mellon; Ian J. Colquhoun; Luc Saulnier; Jean-Francois Thibault; Gary Williamson

1999-01-01

226

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

227

Gamma radiation induced mutagenesis in Aspergillus niger to enhance its microbial fermentation activity for industrial enzyme production  

Microsoft Academic Search

?- and ?-Galactosidases find application in food processing, health and nutrition. Aspergillus niger is one of the potent producer of these enzymes and was genotypically improved using gamma-ray induced mutagenesis. The mutant-derivative\\u000a produced two-fold higher ?- and ?-galactosidases. For testing genetic variability and its relationship with phenotypic properties\\u000a of the two organisms, DNA samples of the mutant and parental strains

M. Siddique Awan; Nabila Tabbasam; N. Ayub; M. E. Babar; Shahid Mahboob Rana; M. I. Rajoka

2011-01-01

228

Optimization of amylase production by Aspergillus niger in solid-state fermentation using sugarcane bagasse as solid support material  

Microsoft Academic Search

Synthesis of amylase by Aspergillus niger strain UO-01 under solid-state fermentation with sugarcane bagasse was optimized by using response surface methodology and\\u000a empirical modelling. The process parameters tested were particle size of sugarcane bagasse, incubation temperature and pH,\\u000a moisture level of solid support material and the concentrations of inoculum, total sugars, nitrogen and phosphorous. The optimum\\u000a conditions for high amylase

Renato Pérez Rosés; Nelson Pérez Guerra

2009-01-01

229

Study of Spanish grape mycobiota and ochratoxin A production by Isolates of Aspergillus tubingensis and other members of Aspergillus section Nigri.  

PubMed

The native mycobiota of five grape varieties grown in Spain has been studied. Four (Bobal, Tempranillo, Garnacha, and Monastrell) were red varieties and one (Moscatel) was white. The main fungal genera isolated were Alternaria, Cladosporium, and Aspergillus. The isolation frequency of Aspergillus spp. section Nigri in contaminated samples was 82%. Ochratoxin A (OTA) production was assessed using yeast extract-sucrose broth supplemented with 5% bee pollen. Cultures of 205 isolates from this section showed that 74.2% of Aspergillus carbonarius and 14.3% of Aspergillus tubingensis isolates produced OTA at levels ranging from 1.2 to 3,530 ng/ml and from 46.4 to 111.5 ng/ml, respectively. No Aspergillus niger isolate had the ability to produce this toxin under the conditions assayed. Identification of the A. niger aggregate isolates was based on PCR amplification of 5.8S rRNA genes and its two intergenic spacers, internal transcribed spacer 1 (ITS1) and ITS2, followed by digestion with restriction endonuclease RsaI of the PCR products. The restriction patterns were compared with those from strains of A. niger CECT 2807 and A. tubingensis CECT 20393, held at the Spanish Collection of Type Cultures. DNA sequencing of the ITS1-5.8S rRNA gene-ITS2 region of the OTA-producing isolates of A. tubingensis matched 99 to 100% with the nucleotide sequence of strain A. tubingensis CBS 643.92. OTA determination was accomplished by liquid chromatography with fluorescence detection. OTA confirmation was carried out by liquid chromatography coupled to ion trap mass spectrometry. The results showed that there are significant differences with regard to the isolation frequency of ochratoxinogenic fungi in the different grape varieties. These differences were uncorrelated to berry color. The ability of A. tubingensis to produce OTA and the influence of grape variety on the occurrence of OTA-producing fungi in grapes are described in this report for the first time. PMID:16085865

Medina, Angel; Mateo, Rufino; López-Ocaña, Laura; Valle-Algarra, Francisco Manuel; Jiménez, Misericordia

2005-08-01

230

Citric acid production by selected mutants of Aspergillus niger from cane molasses.  

PubMed

The present investigation deals with citric acid production by some selected mutant strains of Aspergillus niger from cane molasses in 250 ml Erlenmeyer flasks. For this purpose, a conidial suspension of A. niger GCB-75, which produced 31.1 g/l citric acid from 15% (w/v) molasses sugar, was subjected to UV-induced mutagenesis. Among the 3 variants, GCM-45 was found to be a better producer of citric acid (50.0 +/- 2a) and it was further improved by chemical mutagenesis using N-methyl, N-nitro-N-nitroso-guanidine (MNNG). Out of 3,2-deoxy-D-glucose resistant variants, GCMC-7 was selected as the best mutant, which produced 96.1 +/- 1.5 g/l citric acid 168 h after fermentation of potassium ferrocyanide and H2SO4 pre-treated blackstrap molasses in Vogel's medium. On the basis of kinetic parameters such as volumetric substrate uptake rate (Qs), and specific substrate uptake rate (qs), the volumetric productivity, theoretical yield and specific product formation rate, it was observed that the mutants were faster growing organisms and produced more citric acid. The mutant GCMC-7 has greater commercial potential than the parental strain with regard to citrate synthase activity. The addition of 2.0 x 10(-5) M MgSO4 x 5H2O into the fermentation medium reduced the Fe2+ ion concentration by counter-acting its deleterious effect on mycelial growth. The magnesium ions also induced a loose-pelleted form of growth (0.6 mm, diameter), reduced the biomass concentration (12.5 g/l) and increased the volumetric productivity of citric acid monohydrate (113.6 +/- 5 g/l). PMID:15051073

Ikram-Ul, Haq; Ali, Sikander; Qadeer, M A; Iqbal, Javed

2004-06-01

231

Fed-batch production of gluconic acid by terpene-treated Aspergillus niger spores.  

PubMed

Aspergillus niger spores were used as catalyst in the bioconversion of glucose to gluconic acid. Spores produced by solid-state fermentation were treated with 15 different terpenes including monoterpenes and monoterpenoids to permeabilize and inhibit spore germination. It was found that spore membrane permeability is significantly increased by treatment with terpenoids when compared to monoterpenes. Best results were obtained with citral and isonovalal. Studies were carried out to optimize spores concentration (10(7)-10(10) spores/mL), terpene concentrations in the bioconversion medium and time of exposure (1-18 h) needed for permeabilization of spores. Fed-batch production of gluconate was done in a bioreactor with the best conditions [10(9) spores/mL of freeze-thawed spores treated with citral (3% v/v) for 5 h] followed by sequential additions of glucose powder and pH-regulated with a solution containing 2 mol/L of either NaOH or KOH. Bioconversion performance of the spore enzyme was compared with the commercial glucose oxidase at 50, 60, and 70 degrees C. Results showed that the spore enzyme was comparatively stable at 60 degrees C. It was also found that the spores could be reutilized for more than 14 cycles with almost similar reaction rate. Similar biocatalytic activity was rendered by spores even after its storage of 1 year at -20 degrees C. This study provided an experimental evidence of the significant catalytic role played by A. niger spore in bioconversion of glucose to gluconic acid with high yield and stability, giving protection to glucose oxidase. PMID:18427736

Ramachandran, Sumitra; Fontanille, Pierre; Pandey, Ashok; Larroche, Christian

2008-12-01

232

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

233

The effect of pH on glucoamylase production, glycosylation and chemostat evolution of Aspergillus niger.  

PubMed

The effect of ambient pH on production and glycosylation of glucoamylase (GAM) and on the generation of a morphological mutant produced by Aspergillus niger strain B1 (a transformant containing an additional 20 copies of the homologous GAM glaA gene) was studied. We have shown that a change in the pH from 4 to 5.4 during continuous cultivation of the A. niger B1 strain instigates or accelerates the spontaneous generation of a morphological mutant (LB). This mutant strain produced approx. 50% less extracellular protein and GAM during both chemostat and batch cultivation compared to another strain with parental-type morphology (PS). The intracellular levels of GAM were also lower in the LB strain. In addition, cultivation of the original parent B1 strain in a batch-pulse bioreactor at pH 5.5 resulted in a 9-fold drop in GAM production and a 5-fold drop in extracellular protein compared to that obtained at pH 4. Glycosylation analysis of the glucoamylases purified from shake-flask cultivation showed that both principal forms of GAM secreted by the LB strain possessed enhanced galactosylation (2-fold), compared to those of the PS. Four diagnostic methods (immunostaining, mild methanolysis, mild acid hydrolysis and beta-galactofuranosidase digestion) provided evidence that the majority of this galactose was of the furanoic conformation. The GAMs produced during batch-pulse cultivation at pH 5.5 similarly showed an approx. 2-fold increase in galactofuranosylation compared to pH 4. Interestingly, in both cases the increased galactofuranosylation appears primarily restricted to the O-linked glycan component. Ambient pH therefore regulates both GAM production and influences its glycosylation. PMID:11479027

Wallis, G L; Swift, R J; Atterbury, R; Trappe, S; Rinas, U; Hemming, F W; Wiebe, M G; Trinci, A P; Peberdy, J F

2001-08-15

234

Aspergillus niger ?-Glucosidase Has a Cellulase-like Tadpole Molecular Shape  

PubMed Central

Aspergillus niger is known to secrete large amounts of ?-glucosidases, which have a variety of biotechnological and industrial applications. Here, we purified an A. niger ?-glucosidase (AnBgl1) and conducted its biochemical and biophysical analyses. Purified enzyme with an apparent molecular mass of 116 kDa forms monomers in solution as judged by native gel electrophoresis and has a pI value of 4.55, as found for most of the fungi of ?-glucosidases. Surprisingly, the small angle x-ray experiments reveal that AnBgl1 has a tadpole-like structure, with the N-terminal catalytic domain and C-terminal fibronectin III-like domain (FnIII) connected by the long linker peptide (?100 amino acid residues) in an extended conformation. This molecular organization resembles the one adopted by other cellulases (such as cellobiohydrolases, for example) that frequently contain a catalytic domain linked to the cellulose-binding module that mediates their binding to insoluble and polymeric cellulose. The reasons why AnBgl1, which acts on the small soluble substrates, has a tadpole molecular shape are not entirely clear. However, our enzyme pulldown assays with different polymeric substrates suggest that AnBgl1 has little or no capacity to bind to and to adsorb cellulose, xylan, and starch, but it has high affinity to lignin. Molecular dynamics simulations suggested that clusters of residues located in the C-terminal FnIII domain interact strongly with lignin fragments. The simulations showed that numerous arginine residues scattered throughout the FnIII surface play an important role in the interaction with lignin by means of cation-? stacking with the lignin aromatic rings. These results indicate that the C-terminal FnIII domain could be operational for immobilization of the enzyme on the cell wall and for the prevention of unproductive binding of cellulase to the biomass lignin. PMID:24064212

Lima, Marisa A.; Oliveira-Neto, Mario; Kadowaki, Marco Antonio S.; Rosseto, Flavio R.; Prates, Erica T.; Squina, Fabio M.; Leme, Adriana F. P.; Skaf, Munir S.; Polikarpov, Igor

2013-01-01

235

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

236

Biochar Enhances Aspergillus niger Rock Phosphate Solubilization by Increasing Organic Acid Production and Alleviating Fluoride Toxicity  

PubMed Central

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

2014-01-01

237

Molecular characterization of a glycosyl hydrolase family 10 xylanase from Aspergillus niger.  

PubMed

A gene coding for an endo-?-1,4-xylanase (XlnA) (glycosyl hydrolase family 10) from Aspergillus niger DSM 1957 was cloned and sequenced. The cDNA sequence (984 bp) and its putative endoxylanase (327 aa protein with a predicted molecular mass of 35.5 kDa and pI 6.23) showed 91.3-99.5% and 96.3-99.1% identities with cDNA sequences and their corresponding endoxylanases from A. niger strains from GenBank, respectively. The cDNA was expressed in Pichia pastoris GS115 under the control of AOX1 promoter at a level of 46.4 U/ml culture supernatant, after 144 h of growth at 30°C in YP medium induced with 0.5% (v/v) of methanol. The molecular mass of the purified XlnA determined by SDS-PAGE was 35.5k Da with a specific activity of 808.5 U/mg towards 1% (w/v) of birch wood xylan. Temperature and pH optimum were observed at 50°C and pH 7.0, respectively. The enzyme was stable over a temperature range of 25-40°C and at pH range of 4.5-8.5 and resistant to Tween 80 and acetone. The K(m) and V(max) value obtained for the purified xylanase were 25.5mg/ml and 5000 ?mol/min/mg protein with birch wood xylan as substrate, respectively. The xylanase was free of cellulase and mannanase activity but highly active towards birch wood xylan. The major products of the birch wood xylan hydrolysis were predicted as xylotriose, xylotetraose, and xylopentose. The biochemical characteristics suggested that the recombinant xylanase has a potential application, including use as a feed enzyme. PMID:24084008

Do, Thi Tuyen; Quyen, Dinh Thi; Nguyen, Thi Nuong; Nguyen, Van Thuat

2013-12-01

238

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

239

Effect of Aspergillus niger xylanase on dough characteristics and bread quality attributes.  

PubMed

The present study was conducted to investigate the impact of various treatments of xylanase produced by Aspergillus niger applied in bread making processes like during tempering of wheat kernels and dough mixing on the dough quality characteristics i.e. dryness, stiffness, elasticity, extensibility, coherency and bread quality parameters i.e. volume, specific volume, density, moisture retention and sensory attributes. Different doses (200, 400, 600, 800 and 1,000 IU) of purified enzyme were applied to 1 kg of wheat grains during tempering and 1 kg of flour (straight grade flour) during mixing of dough in parallel. The samples of wheat kernels were agitated at different intervals for uniformity in tempering. After milling and dough making of both types of flour (having enzyme treatment during tempering and flour mixing) showed improved dough characteristics but the improvement was more prominent in the samples receiving enzyme treatment during tempering. Moreover, xylanase decreased dryness and stiffness of the dough whereas, resulted in increased elasticity, extensibility and coherency and increase in volume & decrease in bread density. Xylanase treatments also resulted in higher moisture retention and improvement of sensory attributes of bread. From the results, it is concluded that dough characteristics and bread quality improved significantly in response to enzyme treatments during tempering as compared to application during mixing. PMID:25328183

Ahmad, Zulfiqar; Butt, Masood Sadiq; Ahmed, Anwaar; Riaz, Muhammad; Sabir, Syed Mubashar; Farooq, Umar; Rehman, Fazal Ur

2014-10-01

240

Polyol synthesis in Aspergillus niger: influence of oxygen availability, carbon and nitrogen sources on the metabolism.  

PubMed

Polyol production has been studied in Aspergillus niger under different conditions. Fermentations have been run using high concentration of glucose or xylose as carbon source and ammonium or nitrate as nitrogen source. The growth of biomass, as freely dispersed hyphae, led to an increase of medium viscosity and hereby a decrease in mass transfer, especially oxygen transfer. The consequence was a decrease in DOT and the occurrence of a switch between fully aerobic conditions and oxygen-limited conditions. Metabolite quantification showed that polyols were the main metabolic products formed and represented up to 22% of the carbon consumed in oxygen-limited conditions. The polyol concentration and the polyol pattern depended strongly on the environmental conditions. This is due to a complex regulation of polyol production and to the fact that each polyol can fulfill different functions. In this study, erythritol, xylitol, and arabitol were produced as carbon storage compounds when the flux through the PP pathway exceeded the need in ribulose-5-phosphate for the biomass synthesis. Glycerol, erythritol, and xylitol seem to be involved in osmoregulation. Mannitol was produced when the catabolic reduction of charge was high. Its production involves the enzyme NAD-dependent mannitol-1-phosphate dehydrogenase and seems to be the main cytosolic route for the NADH reoxidation during oxygen limitation. PMID:16718677

Diano, A; Bekker-Jensen, S; Dynesen, J; Nielsen, J

2006-08-01

241

Medium optimization for hen egg white lysozyme production by recombinant Aspergillus niger using statistical methods.  

PubMed

Statistics-based experimental design was used to investigate the effect of medium components (starch, peptone, ammonium sulfate, yeast extract, and CaCl2.2H2O) on hen's egg white lysozyme production by Aspergillus niger HEWL WT-13-16. A 2(5-1) fractional factorial design augmented with center points revealed that peptone, starch, and ammonium sulfate were the most significant factors, whereas the other factors were not important within the levels tested. The method of steepest ascent was used to approach the proximity of optimum. This task was followed by a central composite design to develop a response surface for medium optimization. The optimum medium composition for lysozyme production was found to be: starch 34 g L-1, peptone 34 g L-1, ammonium sulfate 11.9 g L-1, yeast extract 0.5 g L-1, and CaCl2.2H2O 0.5 g L-1. This medium was projected to produce, theoretically, 212 mg L-1 lysozyme. Using this medium, an experimental maximum lysozyme concentration of 209+/-18 mg L-1 verified the applied methodology. PMID:15806549

Gheshlaghi, R; Scharer, J M; Moo-Young, M; Douglas, P L

2005-06-20

242

Response surface optimization of fermentation conditions for producing xylanase by Aspergillus niger SL-05.  

PubMed

Fermentation conditions were statistically optimized for producing extracellular xylanase by Aspergillus niger SL-05 using apple pomace and cotton seed meal. The primary study shows that culture medium with a 1:1 ratio of apple pomace and cotton seed meal (carbon and nitrogen sources) yielded maximal xylanase activity. Three significant factors influencing xylanase production were identified as urea, KH(2)PO(4), and initial moisture content using Plackett-Burman design study. The effects of these three factors were further investigated using a design of rotation-regression-orthogonal combination. The optimized conditions by response surface analysis were 2.5% Urea, 0.09% KH(2)PO(4), and 62% initial moisture content. The analysis of variance indicated that the established model was significant (P < 0.05), "while" or "and" the lack of fit was not significant. Under the optimized conditions, the model predicted 4,998 IU/g dry content, whereas validation experiments produced an enzymatic activity of xylanase at 5,662 IU/g dry content after 60 h fermentation. This study innovatively developed a fermentation medium and process to utilize inexpensive agro-industrial wastes to produce a high yield of xylanase. PMID:18309527

Liu, Cheng; Sun, Zhong-Tao; Du, Jin-Hua; Wang, Jian

2008-07-01

243

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

244

Comparative studies on extracellular protease secretion and glucoamylase production by free and immobilized Aspergillus niger cultures.  

PubMed

The effects of cell immobilization on the secretion of extracellular proteases and glucoamylase production by Aspergillus niger were investigated under a variety of immobilization techniques and culture conditions. Immobilization was achieved by means of cell attachment on metal surfaces or spore entrapment and subsequent growth on porous Celite beads. Free-suspension cultures were compared with immobilized mycelium under culture conditions that included growth in shake flasks and an airlift bioreactor. Cell attachment on metal surfaces minimized the secretion of proteases while enhancing glucoamylase production by the fungus. Growth on Celite beads in shake-flask cultures reduced the specific activity of the secreted proteases from 128 to 61 U g(-1), while glucoamylase specific activity increased from 205 to 350 U g(-1). The effect was more pronounced in bioreactor cultures. A reduction of six orders of magnitude in protease specific activities was observed when the fungus grew immobilized on a rolled metal screen, which served as the draft tube of an airlift bioreactor. PMID:12407460

Papagianni, M; Joshi, N; Moo-Young, M

2002-11-01

245

Increased NADPH concentration obtained by metabolic engineering of the pentose phosphate pathway in Aspergillus niger.  

PubMed

Many biosynthetic reactions and bioconversions are limited by low availability of NADPH. With the purpose of increasing the NADPH concentration and/or the flux through the pentose phosphate pathway in Aspergillus niger, the genes encoding glucose 6-phosphate dehydrogenase (gsdA), 6-phosphogluconate dehydrogenase (gndA) and transketolase (tktA) were cloned and overexpressed in separate strains. Intracellular NADPH concentration was increased two- to ninefold as a result of 13-fold overproduction of 6-phosphogluconate dehydrogenase. Although overproduction of glucose 6-phosphate dehydrogenase and transketolase changed the concentration of several metabolites it did not result in increased NADPH concentration. To establish the effects of overexpression of the three genes, wild-type and overexpressing strains were characterized in detail in exponential and stationary phase of bioreactor cultures containing minimal media, with glucose as the carbon source and ammonium or nitrate as the nitrogen source and final cell density limiting substrate. Enzymes, intermediary metabolites, polyol pools (intra- and extracellular), organic acids, growth rates and rate constant of induction of acid production in postexponential phase were measured. None of the modified strains had a changed growth rate. Partial least square regressions showed the correlations between NADPH and up to 40 other variables (concentration of enzymes and metabolites) and it was possible to predict the intracellular NADPH concentration from relatively easily obtainable data (the concentration of enzymes, polyols and oxalate). This prediction might be used in screening for high NADPH levels in engineered strains or mutants of other organisms. PMID:15752350

R Poulsen, Bjarne; Nøhr, Jane; Douthwaite, Stephen; Hansen, Line V; Iversen, Jens J L; Visser, Jaap; Ruijter, George J G

2005-03-01

246

Development of stable flocculent Saccharomyces cerevisiae strain for continuous Aspergillus niger beta-galactosidase production.  

PubMed

A flocculent Saccharomyces cerevisiae strain was engineered to stably secrete Aspergillus niger beta-galactosidase in a continuous high-cell-density bioreactor. The delta-sequences from the yeast retrotransposon Ty1 were used as target sites for the integration of the beta-galactosidase expression cassette. High-copy-number transformants were successfully obtained using the delta-integration system together with the dominant selection antibiotic, G418. The integration of multiple copies was confirmed by genomic Southern blot analysis. Integrants with the highest beta-galactosidase levels (approximately eight gene copies) had similar beta-galactosidase activities as a recombinant strain carrying the beta-galactosidase expression cassette in a YEp-based vector. The beta-galactosidase expression cassettes integrated into the yeast genome were stably maintained after eight sequential batch cultures in a nonselective medium. In continuous high-cell-density culture under the same operating conditions, the integrant strain was more stable than the plasmid-carrying strain. To our knowledge, this is the first study of multicopy delta-integrant stability in a continuous bioreactor operating at different dilution rates. PMID:17502272

Oliveira, Carla; Teixeira, José A; Lima, Nelson; Da Silva, Nancy A; Domingues, Lucília

2007-04-01

247

Cellulase production by Aspergillus niger in biofilm, solid-state, and submerged fermentations.  

PubMed

Cellulase production by Aspergillus niger was compared in three different culture systems: biofilm, solid-state, and submerged fermentation. Biofilm and solid-state fermentations were carried out on perlite as inert support, and lactose was used as a carbon source in the three culture systems. In cryo-scanning electron microscopy, biofilm and solid-state cultures gave similar morphological patterns and confirmed that both spore first attachment and hyphal adhered growth are helped by the production of an adhesive extracellular matrix. Biofilm cultures produced higher cellulase activities than those in submerged and solid-state cultures (1,768, 1,165, and 1,174 U l(-1), respectively). Although biofilm cultures grew less than the other cultures, they produced significantly higher cellulase yields (370, 212, and 217 U g(-1) lactose, respectively) and volumetric productivities (24, 16, and 16 U l(-1) h(-1), respectively). Likewise, endoglucanase and xylanase activities were higher in biofilm cultures. Under the conditions tested, it seems that fungal attached growth on perlite may favor better enzyme production. Biofilms are efficient systems for cellulase production and may replace solid-state fermentation. Biofilm fermentation holds promise for further optimization and development. The results of this work reveal that fungal biofilms may be used for the commercial production of cellulase employing the technology developed for submerged fermentation at high cell densities. PMID:20354693

Gamarra, Norma N; Villena, Gretty K; Gutiérrez-Correa, Marcel

2010-06-01

248

Fungal morphology in submerged cultures and its relation to glucose oxidase excretion by recombinant Aspergillus niger.  

PubMed

The effect of culture conditions such as medium composition and shear stress on the fungal pellet morphology in shake-flask cultures and its relation to glucose oxidase (GOD) excretion by recombinant Aspergillus niger NRRL 3 (GOD 3-18) was investigated. It was shown that culture conditions resulting in the formation of smaller fungal pellets with an increased mycelial density result in higher yields of exocellular GOD. The pellets obtained in shake-flask cultures showed distinct layers of mycelial density with only the thin outer layer consisting of a dense mycelial network. The performance of the recombinant strain and the process of pellet formation was also analyzed during batch cultivation in a stirred-tank bioreactor. It was shown that the process of pellet formation occurred in two steps: (1) aggregation of free spores to spore clusters with subsequent germination and formation of small aggregates surrounded by a loose hyphal network, and (2) aggregation of the primary aggregates to the final full-size pellets. The fungal pellets formed during bioreactor cultivation were smaller, did not show large differences in mycelial density, and were more efficient with respect to the production of exocellular GOD. The decreasing pellet size also correlated with an increased mycelial density, indicating an improvement of the transport of nutrients to the inner parts of the pellet. PMID:10533711

el-Enshasy, H; Hellmuth, K; Rinas, U

1999-07-01

249

Effective bioconversion of sophoricoside to genistein from Fructus sophorae using immobilized Aspergillus niger and Yeast.  

PubMed

In this study, sophoricoside from Fructus sophorae was highly bioconversed to genistein by co-immobilized Aspergillus niger and Yeast. Bioconversion conditions for genistein were optimized with single-factor experiments. The optimal conditions were as follows: microbial concentration 1.5 × 10(7) cells/mL, wet weight of microorganisms beads 10.0 g/g material, pH 5, ratio of liquid to solid 25:1 (mL/g), temperature 32 °C and time 24 h. Under these conditions, a 34.45-fold increase in production of genistein was observed with a bioreactor. Moreover, the antioxidant activities of the extracts from the fermented and untreated F. sophorae were 0.287 ± 0.11, 0.384 ± 0.08 mg/mL (IC50) and 1.84 ± 0.13, 1.28 ± 0.25 mmol Fe(II)/g, according to the DPPH test and FRAP assay, respectively. The results indicated that the method described in the current work were valuable procedure for the production of genistein, which is of most importance for industrial scale applications as well as food industry. PMID:25392205

Feng, Chen; Jin, Shuang; Xia, Xin-Xin; Guan, Yue; Luo, Meng; Zu, Yuan-Gang; Fu, Yu-Jie

2015-01-01

250

Degradation of phytates in distillers' grains and corn gluten feed by Aspergillus niger phytase.  

PubMed

Distillers' dried grains with solubles (DDGS) and corn gluten feed (CGF) are major coproducts of ethanol production from corn dry grind and wet milling facilities, respectively. These coproducts contain important nutrients and high levels of phytates. The phytates in these products cannot be digested by nonruminant animals; consequently, large quantities of phytate phosphorus (P) are deposited into the soil with the animal wastes which potentially could cause P pollution in soil and underground water resources. To reduce phytates in DDGS and CGF, a phytase from Aspergillus niger, PhyA, was investigated regarding its capability to catalyze the hydrolysis of phytates in light steep water (LSW) and whole stillage (WS). LSW and WS streams are the intermediate streams in the production of CGF and DDGS, respectively, and contribute to most of the P in these streams. Enzyme loadings with activity of 0.1, 1, 2, and 4 FTU/g substrate and temperatures of 35 and 45 degrees C were investigated regarding their influences on the degree of hydrolysis. The analysis of the hydrolyzate suggested to a sequentially degradation of phytates to lower order myo-inositol phosphate isomers. Approximately 90% phytate P of LSW and 66% phytate P of WS were released, suggesting myo-inositol monophosphate as the end product. The maximum amount of released P was 4.52 +/- 0.03 mg/g LSW and 0.86 +/- 0.01 mg/g WS. PMID:18815903

Noureddini, H; Dang, J

2009-10-01

251

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

252

Fluoride-tolerant mutants of Aspergillus niger show enhanced phosphate solubilization capacity.  

PubMed

P-solubilizing microorganisms are a promising alternative for a sustainable use of P against a backdrop of depletion of high-grade rock phosphates (RPs). Nevertheless, toxic elements present in RPs, such as fluorine, can negatively affect microbial solubilization. Thus, this study aimed at selecting Aspergillus niger mutants efficient at P solubilization in the presence of fluoride (F-). The mutants were obtained by exposition of conidia to UV light followed by screening in a medium supplemented with Ca3(PO4)2 and F-. The mutant FS1-555 showed the highest solubilization in the presence of F-, releasing approximately 70% of the P contained in Ca3(PO4)2, a value 1.7 times higher than that obtained for the wild type (WT). The mutant FS1-331 showed improved ability of solubilizing fluorapatites, increasing the solubilization of Araxá, Catalão, and Patos RPs by 1.7, 1.6, and 2.5 times that of the WT, respectively. These mutants also grew better in the presence of F-, indicating that mutagenesis allowed the acquisition of F- tolerance. Higher production of oxalic acid by FS1-331 correlated with its improved capacity for RP solubilization. This mutant represents a significant improvement and possess a high potential for application in solubilization systems with fluoride-rich phosphate sources. PMID:25310310

Silva, Ubiana de Cássia; Mendes, Gilberto de Oliveira; Silva, Nina Morena R M; Duarte, Josiane Leal; Silva, Ivo Ribeiro; Tótola, Marcos Rogério; Costa, Maurício Dutra

2014-01-01

253

Effects of Temperature and Additives on the Thermal Stability of Glucoamylase from Aspergillus niger.  

PubMed

GAM-1 and GAM-2, two themostable glucoamylases from Aspergillus niger B-30, possess different molecular masses, glycosylation, and thermal stability. In the present study, the effects of additives on the thermal inactivation of GAM-1 and GAM-2 were investigated. The half-lives of GAM-1 and GAM-2 at 70°C were 45 and 216 min, respectively. Data obtained from fluorescence spectroscopy, circular dichroism spectroscopy, UV absorption spectroscopy, and dynamic light scattering demonstrated that during the thermal inactivation progress, combined with the loss of the helical structure and a majority of the tertiary structure, tryptophan residues were partially exposed and further led to glucoamylases aggregating. The thermal stability of GAM-1 and GAM-2 was largely improved in the presence of sorbitol and trehalose. Results from spectroscopy and Native-PAGE confirmed that sorbitol and trehalose maintained the native state of glucoamylases and prevented their thermal aggregation. The loss of hydrophobic bonding and helical structure was responsible for the decrease of glucoamylase activity. Additionally, sorbitol and trehalose significantly increased the substrate affinity and catalytic efficiency of the two glucoamylases. Our results display an insight into the thermal inactivation of glucoamylases and provide an important base for industrial applications of the thermally stable glucoamylases. PMID:25179903

Liu, Yang; Meng, Zhaoli; Shi, Ruilin; Zhan, Le; Hu, Wei; Xiang, Hongyu; Xie, Qiuhong

2015-01-28

254

Expression of an Aspergillus niger phytase gene (phyA) in Saccharomyces cerevisiae.  

PubMed

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) in Saccharomyces 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 was inserted into the expression vector pYES2 and was expressed in S. cerevisiae as an active, extracellular phytase. The yield of total extracellular phytase activity was affected by the signal peptide and the medium composition. The expressed phytase had two pH optima (2 to 2.5 and 5 to 5.5) and a temperature optimum between 55 and 60 degrees C, and it cross-reacted with a rabbit polyclonal antibody against the wild-type enzyme. Due to the heavy glycosylation, the expressed phytase had a molecular size of approximately 120 kDa and appeared to be more thermostable than the commercial enzyme. Deglycosylation of the phytase resulted in losses of 9% of its activity and 40% of its thermostability. The recombinant phytase was effective in hydrolyzing phytate phosphorus from corn or soybean meal in vitro. In conclusion, the phyA gene was expressed as an active, extracellular phytase in S. cerevisiae, and its thermostability was affected by glycosylation. PMID:10223979

Han, Y; Wilson, D B; Lei, X G

1999-05-01

255

Improved phytate phosphorus utilization by Japanese medaka transgenic for the Aspergillus niger phytase gene.  

PubMed

The inefficient digestion of phytate phosphorus by fish has created environmental concerns associated with phosphorus pollution from aquaculture production facilities. To further complicate this situation, phytate is known to chelate minerals and proteins, making them nutritionally unavailable. The enzyme phytase degrades phytate into inorganic phosphorus, which can be directly utilized by fish. As a model to examine the feasibility and efficacy of producing fish capable of degrading phytate, Japanese medaka (Oryzias latipes) transgenic for an Aspergillus niger phytase gene were produced and their ability to utilize phytate phosphorus tested. Cell culture techniques, including transfection, RT-PCR, Northern blot, Western blot, and enzyme activity analysis demonstrated that the protein was expressed, active, and secreted. Survival of transgenic fish was significantly greater on all examined diets than their nontransgenic siblings and up to six-fold higher on a diet with phytate as the main phosphorus source. Similar results were obtained with nontransgenic fish when fed the same diet supplemented with phytase, suggesting that phytase, whether ingested or produced by the fish, is effective in degrading phytate and overcoming many of the known antinutritional factors. PMID:18248176

Hostetler, Heather A; Collodi, Paul; Devlin, Robert H; Muir, William M

2005-01-01

256

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

PubMed Central

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) in Saccharomyces 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 was inserted into the expression vector pYES2 and was expressed in S. cerevisiae as an active, extracellular phytase. The yield of total extracellular phytase activity was affected by the signal peptide and the medium composition. The expressed phytase had two pH optima (2 to 2.5 and 5 to 5.5) and a temperature optimum between 55 and 60°C, and it cross-reacted with a rabbit polyclonal antibody against the wild-type enzyme. Due to the heavy glycosylation, the expressed phytase had a molecular size of approximately 120 kDa and appeared to be more thermostable than the commercial enzyme. Deglycosylation of the phytase resulted in losses of 9% of its activity and 40% of its thermostability. The recombinant phytase was effective in hydrolyzing phytate phosphorus from corn or soybean meal in vitro. In conclusion, the phyA gene was expressed as an active, extracellular phytase in S. cerevisiae, and its thermostability was affected by glycosylation. PMID:10223979

Han, Yanming; Wilson, David B.; Lei, Xin gen

1999-01-01

257

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

258

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

259

Influence of dietary components on Aspergillus niger prolyl endoprotease mediated gluten degradation.  

PubMed

Celiac disease (CD) is caused by intolerance to gluten. Oral supplementation with enzymes like Aspergillus niger propyl-endoprotease (AN-PEP), which can hydrolyse gluten, has been proposed to prevent the harmful effects of ingestion of gluten. The influence of meal composition on AN-PEP activity was investigated using an in vitro model that simulates stomach-like conditions. AN-PEP optimal dosage was 20 proline protease units (PPU)/g gluten. The addition of a carbonated drink strongly enhanced AN-PEP activity because of its acidifying effect. While fat did not affect gluten degradation by AN-PEP, the presence of food proteins slowed down gluten detoxification. Moreover, raw gluten was degraded more efficiently by AN-PEP than baked gluten. We conclude that the meal composition influences the amount of AN-PEP needed for gluten elimination. Therefore, AN-PEP should not be used to replace a gluten free diet, but rather to support digestion of occasional and/or inadvertent gluten consumption. PMID:25529703

Montserrat, Veronica; Bruins, Maaike J; Edens, Luppo; Koning, Frits

2015-05-01

260

Fluoride-Tolerant Mutants of Aspergillus niger Show Enhanced Phosphate Solubilization Capacity  

PubMed Central

P-solubilizing microorganisms are a promising alternative for a sustainable use of P against a backdrop of depletion of high-grade rock phosphates (RPs). Nevertheless, toxic elements present in RPs, such as fluorine, can negatively affect microbial solubilization. Thus, this study aimed at selecting Aspergillus niger mutants efficient at P solubilization in the presence of fluoride (F?). The mutants were obtained by exposition of conidia to UV light followed by screening in a medium supplemented with Ca3(PO4)2 and F?. The mutant FS1-555 showed the highest solubilization in the presence of F?, releasing approximately 70% of the P contained in Ca3(PO4)2, a value 1.7 times higher than that obtained for the wild type (WT). The mutant FS1-331 showed improved ability of solubilizing fluorapatites, increasing the solubilization of Araxá, Catalão, and Patos RPs by 1.7, 1.6, and 2.5 times that of the WT, respectively. These mutants also grew better in the presence of F?, indicating that mutagenesis allowed the acquisition of F? tolerance. Higher production of oxalic acid by FS1-331 correlated with its improved capacity for RP solubilization. This mutant represents a significant improvement and possess a high potential for application in solubilization systems with fluoride-rich phosphate sources. PMID:25310310

Silva, Ubiana de Cássia; Mendes, Gilberto de Oliveira; Silva, Nina Morena R. M.; Duarte, Josiane Leal; Silva, Ivo Ribeiro; Tótola, Marcos Rogério; Costa, Maurício Dutra

2014-01-01

261

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 1770 bp 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 4.2 L culture with the constructed recombinant P. pastoris strain showed an extracellular and periplasmic invertase production at 72 h induction of 498 and 3776 invertase units (U), respectively, which corresponds to 1018 U/L of culture medium. The invertase produced had an optimum pH of 5.0, optimum temperature of 60 °C, and specific activity of 3389 U/mg protein, and after storage for 96 h 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

262

Two Cellobiohydrolase-Encoding Genes from Aspergillus niger Require d-Xylose and the Xylanolytic Transcriptional Activator XlnR for Their Expression  

PubMed Central

Two cellobiohydrolase-encoding genes, cbhA and cbhB, have been isolated from the filamentous fungus Aspergillus niger. The deduced amino acid sequence shows that CbhB has a modular structure consisting of a fungus-type cellulose-binding domain (CBD) and a catalytic domain separated by a Pro/Ser/Thr-rich linker peptide. CbhA consists only of a catalytic domain and lacks a CBD and linker peptide. Both proteins are homologous to fungal cellobiohydrolases in family 7 of the glycosyl hydrolases. Northern blot analysis showed that the transcription of the cbhA and cbhB genes is induced by d-xylose but not by sophorose and, in addition, requires the xylanolytic transcriptional activator XlnR. PMID:10508057

Gielkens, Marco M. C.; Dekkers, Ester; Visser, Jaap; de Graaff, Leo H.

1999-01-01

263

Two cellobiohydrolase-encoding genes from Aspergillus niger require D-xylose and the xylanolytic transcriptional activator XlnR for their expression.  

PubMed

Two cellobiohydrolase-encoding genes, cbhA and cbhB, have been isolated from the filamentous fungus Aspergillus niger. The deduced amino acid sequence shows that CbhB has a modular structure consisting of a fungus-type cellulose-binding domain (CBD) and a catalytic domain separated by a Pro/Ser/Thr-rich linker peptide. CbhA consists only of a catalytic domain and lacks a CBD and linker peptide. Both proteins are homologous to fungal cellobiohydrolases in family 7 of the glycosyl hydrolases. Northern blot analysis showed that the transcription of the cbhA and cbhB genes is induced by D-xylose but not by sophorose and, in addition, requires the xylanolytic transcriptional activator XlnR. PMID:10508057

Gielkens, M M; Dekkers, E; Visser, J; de Graaff, L H

1999-10-01

264

Utilization of molasses and sugar cane bagasse for production of fungal invertase in solid state fermentation using Aspergillus niger GH1  

PubMed Central

Agro-industrial wastes have been used as substrate-support in solid state fermentation for enzyme production. Molasses and sugarcane bagasse are by-products of sugar industry and can be employed as substrates for invertase production. Invertase is an important enzyme for sweeteners development. In this study, a xerophilic fungus Aspergillus niger GH1 isolated of the Mexican semi-desert, previously reported as an invertase over-producer strain was used. Molasses from Mexico and Cuba were chemically analyzed (total and reducer sugars, nitrogen and phosphorous contents); the last one was selected based on chemical composition. Fermentations were performed using virgin and hydrolyzate bagasse (treatment with concentrated sulfuric acid). Results indicated that, the enzymatic yield (5231 U/L) is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse. The acid hydrolysis promotes availability of fermentable sugars. In addition, maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs. This study presents an alternative method for invertase production using a xerophilic fungus isolated from Mexican semi-desert and inexpensive substrates (molasses and sugarcane bagasse). PMID:25242918

Veana, F.; Martínez-Hernández, J.L.; Aguilar, C.N.; Rodríguez-Herrera, R.; Michelena, G.

2014-01-01

265

Utilization of molasses and sugar cane bagasse for production of fungal invertase in solid state fermentation using Aspergillus niger GH1.  

PubMed

Agro-industrial wastes have been used as substrate-support in solid state fermentation for enzyme production. Molasses and sugarcane bagasse are by-products of sugar industry and can be employed as substrates for invertase production. Invertase is an important enzyme for sweeteners development. In this study, a xerophilic fungus Aspergillus niger GH1 isolated of the Mexican semi-desert, previously reported as an invertase over-producer strain was used. Molasses from Mexico and Cuba were chemically analyzed (total and reducer sugars, nitrogen and phosphorous contents); the last one was selected based on chemical composition. Fermentations were performed using virgin and hydrolyzate bagasse (treatment with concentrated sulfuric acid). Results indicated that, the enzymatic yield (5231 U/L) is higher than those reported by other A. niger strains under solid state fermentation, using hydrolyzate bagasse. The acid hydrolysis promotes availability of fermentable sugars. In addition, maximum invertase activity was detected at 24 h using low substrate concentration, which may reduce production costs. This study presents an alternative method for invertase production using a xerophilic fungus isolated from Mexican semi-desert and inexpensive substrates (molasses and sugarcane bagasse). PMID:25242918

Veana, F; Martínez-Hernández, J L; Aguilar, C N; Rodríguez-Herrera, R; Michelena, G

2014-01-01

266

Multiplex PCR analysis of fumonisin biosynthetic genes in fumonisin-nonproducing Aspergillus niger and A. awamori strains.  

PubMed

To determine the genetic basis for loss of fumonisin B2 (FB2) biosynthesis in FB2-nonproducing Aspergillus niger and A. awamori strains, we developed multiplex PCR primer sets to amplify fragments of eight fumonisin biosynthetic pathway (fum) genes. Fragments of all eight fum genes were amplified from FB2-producing A. niger and A. awamori strains; from FB2-nonproducing strains four amplification patterns arose in which one or more fum gene fragments were absent. Southern hybridization analysis of strains yielding patterns 2 and 3 confirmed that loss of FB2 production in A. awamori is associated with gene deletions within the fumonisin biosynthetic gene cluster. In addition, we observed a fifth multiplex amplification pattern in which all eight fum gene fragments appeared. Reverse transcription-PCR analysis of strains yielding pattern 5 showed that the expression of at least one fum gene was reduced relative to expression in FB2-producing A. niger. This suggests that in these strains loss of FB2 production is a result of structural or regulatory mutations that alter gene expression or function. These results demonstrate a diversity of genotypes within FB2-nonproducing A. niger and A. awamori populations and provide tools useful for identifying certain non-toxigenic strains for industrial or ecological applications. PMID:22962354

Palumbo, Jeffrey D; O'Keeffe, Teresa L; Gorski, Lisa

2013-01-01

267

Highly thermostable and pH-stable cellulases from Aspergillus niger NS-2: properties and application for cellulose hydrolysis.  

PubMed

Optimization of cultural conditions for enhanced cellulase production by Aspergillus niger NS-2 were studied under solid-state fermentation. Significant increase in yields (CMCase 463.9 ± 20.1 U/g, FPase 101.1 ± 3.5 U/g and ?-glucosidase 99 ± 4.0 U/g) were obtained under optimized conditions. Effect of different nutritional parameters was studied to induce the maximum production of cellulase complex. Scale-up studies for enzyme production process were carried out. Characterization studies showed that enzymes produced by A. niger NS-2 were highly temperature- and pH stable. At 50 °C, the half life for CMCase, FPase, ?-glucosidase were approximately 240 h. Cellulases from A. niger NS-2 were stable at 35 °C for 24 h over a broader pH range of 3.0-9.0. We examined the feasibility of using steam pretreatment to increase the saccharification yields from various lignocellulosic residues for sugar release which can potentially be used in bioethanol production. Saccharification of pretreated dry potato peels, carrot peels, composite waste mixture, orange peels, onion peels, banana peels, pineapple peels by crude enzyme extract from A. niger NS-2, resulted in very high cellulose conversion efficiencies of 92-98 %. PMID:24052336

Bansal, Namita; Janveja, Chetna; Tewari, Rupinder; Soni, Raman; Soni, Sanjeev Kumar

2014-01-01

268

Strain improvement and up scaling of phytase production by Aspergillus niger NCIM 563 under submerged fermentation conditions.  

PubMed

Combination of physical and chemical mutagenesis was used to isolate hyper secretory strains of Aspergillus niger NCIM 563 for phytase production. Phytase activity of mutant N-1 and N-79 was about 17 and 47% higher than the parent strain. In shake flask the productivity of phytase in parent, mutant N-1 and N-79 was 6,181, 7,619 and 9,523 IU/L per day, respectively. Up scaling of the fermentation from shake flask to 3 and 14 L New Brunswick fermenter was studied. After optimizing various fermentation parameters like aeration, agitation and carbon source in fermentation medium the fermentation time to achieve highest phytase activity was reduced considerably from 14 days in shake flask to 8 days in 14 L fermenter. Highest phytase activity of 80 IU/ml was obtained in 1% rice bran-3.5% glucose containing medium with aeration 0.2 vvm and agitation 550 rpm at room temperature on 8th day of fermentation. Addition of either bavistin (0.1%), penicillin (0.1%), formalin (0.2%) and sodium chloride (10%) in fermented broth were effective in retaining 100% phytase activity for 8 days at room temperature while these reagents along with methanol (50%) and ethanol (50%) confer 100% stability of phytase activity at 4 degrees C till 20 days. Among various carriers used for application of phytase in feed, wheat bran and rice bran were superior to silica and calcium carbonate. Thermo stabilization studies indicate 100% protection of phytase activity in presence of 12% skim milk at 70 degrees C, which will be useful for its spray drying. PMID:19082644

Shah, P; Bhavsar, K; Soni, S K; Khire, Jayant Malhar

2009-03-01

269

In Vitro Activity of Two Echinocandin Derivatives, LY303366 and MK-0991 (L-743,792), Against Clinical Isolates of Aspergillus, Fusarium, Rhizopus, and Other Filamentous Fungi  

Microsoft Academic Search

LY303366 and MK-0991 (previously L-743,792) are new echinocandin derivatives with excellent broad-spectrum antifungal activity. We investigated the in vitro activity of LY303366, MK-0991, itraconazole, amphotericin B, and 5-flucytosine against 51 clinical isolates of filamentous fungi, including Aspergillus flavus (10), A. fumigatus (12), Fusarium spp. (13), Rhizopus spp. (6), Pseudallescheria boydii (5), and one isolate each of Acremonium spp., A. niger,

M. A Pfaller; F Marco; S. A Messer; R. N Jones

1998-01-01

270

Identification, cloning and analysis of the Aspergillus niger gene pacC , a wide domain regulatory gene responsive to ambient pH  

Microsoft Academic Search

A wide domain regulatory gene implicated in modulating gene expression in response to ambient pH has been cloned and sequenced from the industrially useful filamentous fungusAspergillus niger. This gene,pacC, is able to restore apacC+ phenotype toA. nidulans pacCc11 andpacCc14 mutants with respect to extent of conidiation, conidial pigment intensity and acid phosphatase regulation. ThepacC gene ofA. niger comprises three exons,

A. P. MacCabe; J. P. T. W. Hombergh; J. Visser; J. Tilburn; H. N. Arst

1996-01-01

271

Application of kaolin to improve citric acid production by a thermophilic Aspergillus niger.  

PubMed

Citric acid production by a thermophilic strain of the filamentous fungus Aspergillus niger IIB-6 in a medium containing blackstrap cane molasses was improved by the addition of kaolin to the fermentation medium. The fermentation was run in a 7.5-l stirred bioreactor (60% working volume). The optimal sugar concentration was found to be 150 g/l. Kaolin (1.0 ml) was added to the fermentation medium to enhance volumetric production. The best results in terms of product formation were observed when 15 parts per million (ppm) kaolin was added 24 h after inoculation. With added kaolin, citric acid production was enhanced 2.34-fold, compared to a control fermentation without added kaolin. The length of incubation to attain this product yield was shortened from 168 to 96 h. The comparison of kinetic parameters showed improved citrate synthase activity of the culture (Y (p/x)=7.046 g/g). When the culture grown at various kaolin concentrations was monitored for Q (p), Q (s), and q (p), there was significant improvement in these variables over the control. Specific production by the culture (q (p)=0.073 g/g cells/h) was improved several fold. The addition of kaolin substantially improved the enthalpy (DeltaH (D)=74.5 kJ/mol) and entropy of activation (DeltaS=-174 J/mol/K) for citric acid production, free energies for transition state formation, and substrate binding for sucrose hydrolysis. The performance of fuzzy logic control of the bioreactor was found to be very promising for an improvement ( approximately 4.2-fold) in the production of citric acid (96.88 g/l), which is of value in commercial applications. PMID:16871375

Ali, Sikander

2006-12-01

272

Analysis of regulation of pentose utilisation in Aspergillus niger reveals evolutionary adaptations in Eurotiales  

PubMed Central

Aspergilli are commonly found in soil and on decaying plant material. D-xylose and L-arabinose are highly abundant components of plant biomass. They are released from polysaccharides by fungi using a set of extracellular enzymes and subsequently converted intracellularly through the pentose catabolic pathway (PCP). In this study, the L-arabinose responsive transcriptional activator (AraR) is identified in Aspergillus niger and was shown to control the L-arabinose catabolic pathway as well as expression of genes encoding extracellular L-arabinose releasing enzymes. AraR interacts with the D-xylose-responsive transcriptional activator XlnR in the regulation of the pentose catabolic pathway, but not with respect to release of L-arabinose and D-xylose. AraR was only identified in the Eurotiales, more specifically in the family Trichocomaceae and appears to have originated from a gene duplication event (from XlnR) after this order or family split from the other filamentous ascomycetes. XlnR is present in all filamentous ascomycetes with the exception of members of the Onygenales. Since the Onygenales and Eurotiales are both part of the subclass Eurotiomycetidae, this indicates that strong adaptation of the regulation of pentose utilisation has occurred at this evolutionary node. In Eurotiales a unique two-component regulatory system for pentose release and metabolism has evolved, while the regulatory system was lost in the Onygenales. The observed evolutionary changes (in Eurotiomycetidae) mainly affect the regulatory system as in contrast, homologues for most genes of the L-arabinose/D-xylose catabolic pathway are present in all the filamentous fungi, irrespective of the presence of XlnR and/or AraR. PMID:21892241

Battaglia, E.; Visser, L.; Nijssen, A.; van Veluw, G.J.; Wösten, H.A.B.; de Vries, R.P.

2011-01-01

273

Purification and characterization of endo-xylanases from aspergillus Niger. II. An enzyme of PL 45  

SciTech Connect

A homogeneous endo-xylanase (1,4-..beta..-D-xylan xylano-hydrolase, EC 3.2.1.8) was obtained from a crude Aspergillus niger pentosanase 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 SP-Sephadex C-25 with a gradient from pH 2.8 to pH 4.6. It was much more active on soluble than on insoluble xylan yielding large amounts of unreacted xylan and a mixture of oligosaccharides with chain lengths from two to six. No xylose or L-arabinose was produced. There was high activity on a xylopentaose through xylononaose mixture, but not on xylobiose, xylotriose, or xylotetraose. The enzyme had slight activity on untreated cellulose, carboxymethylcellulose, and pectin. Molecular weight was ca. 1.4 x 10/sup 4/, with an isoelectric point of 4.5 and an amino acid profile high in acidic but low in sulfur-containing residues. In a 25-min assay at pH 4.7, this endo-xylanase was most active at 45 degrees C, with an activation energy from 5 to 35 degrees C of 33.3 kJ/mol. The optimum pH for activity was 4.9. Decay in buffer was first order, with an activation energy at pH 4.7 from 48 to 53 degrees C of 460 kJ/mol. Optimum pH for stability was about 5.6, where the half-life at 48 degrees C in buffer was ca. 40 h.

Shei, J.C.; Fratzke, A.R.; Frederick, M.M.; Frederick, J.R.; Reilly, P.J.

1985-04-01

274

Germination of conidia of Aspergillus niger is accompanied by major changes in RNA profiles  

PubMed Central

The transcriptome of conidia of Aspergillus niger was analysed during the first 8 h of germination. Dormant conidia started to grow isotropically two h after inoculation in liquid medium. Isotropic growth changed to polarised growth after 6 h, which coincided with one round of mitosis. Dormant conidia contained transcripts from 4 626 genes. The number of genes with transcripts decreased to 3 557 after 2 h of germination, after which an increase was observed with 4 780 expressed genes 8 h after inoculation. The RNA composition of dormant conidia was substantially different than all the subsequent stages of germination. The correlation coefficient between the RNA profiles of 0 h and 8 h was 0.46. They were between 0.76–0.93 when profiles of 2, 4 and 6 h were compared with that of 8 h. Dormant conidia were characterised by high levels of transcripts of genes involved in the formation of protecting components such as trehalose, mannitol, protective proteins (e.g. heat shock proteins and catalase). Transcripts belonging to the Functional Gene Categories (FunCat) protein synthesis, cell cycle and DNA processing and respiration were over-represented in the up-regulated genes at 2 h, whereas metabolism and cell cycle and DNA processing were over-represented in the up-regulated genes at 4 h. At 6 h and 8 h no functional gene classes were over- or under-represented in the differentially expressed genes. Taken together, it is concluded that the transcriptome of conidia changes dramatically during the first two h and that initiation of protein synthesis and respiration are important during early stages of germination. PMID:23449598

van Leeuwen, M.R.; Krijgsheld, P.; Bleichrodt, R.; Menke, H.; Stam, H.; Stark, J.; Wösten, H.A.B.; Dijksterhuis, J.

2013-01-01

275

Effect of temperature, water activity, and pH on growth and production of ochratoxin A by Aspergillus niger and Aspergillus carbonarius from Brazilian grapes.  

PubMed

The growth of ochratoxigenic fungus and the presence of ochratoxin A (OTA) in grapes and their derivatives can be caused by a wide range of physical, chemical, and biological factors. The determination of interactions between these factors and fungal species from different climatic regions is important in designing models for minimizing the risk of OTA in wine and grape juice. This study evaluated the influence of temperature, water activity (aw), and pH on the development and production of OTA in a semisynthetic grape culture medium by Aspergillus carbonarius and Aspergillus niger strains. To analyze the growth conditions and production of OTA, an experimental design was conducted using response surface methodology as a tool to assess the effects of these abiotic variables on fungal behavior. A. carbonarius showed the highest growth at temperatures from 20 to 33°C, aw between 0.95 and 0.98, and pH levels between 5 and 6.5. Similarly, for A. niger, temperatures between 24 and 37°C, aw greater than 0.95, and pH levels between 4 and 6.5 were optimal. The greatest toxin concentrations for A. carbonarius and A. niger (10 ?g/g and 7.0 ?g/g, respectively) were found at 15°C, aw 0.99, and pH 5.35. The lowest pH was found to contribute to greater OTA production. These results show that the evaluated fungi are able to grow and produce OTA in a wide range of temperature, aw, and pH. However, the optimal conditions for toxin production are generally different from those optimal for fungal growth. The knowledge of optimal conditions for fungal growth and production of OTA, and of the stages of cultivation in which these conditions are optimal, allows a more precise assessment of the potential risk to health from consumption of products derived from grapes. PMID:25364929

Passamani, Fabiana Reinis Franca; Hernandes, Thais; Lopes, Noelly Alves; Bastos, Sabrina Carvalho; Santiago, Wilder Douglas; Cardoso, Maria das Graças; Batista, Luís Roberto

2014-11-01

276

Foreign DNA sequences are received by a wild-type strain of Aspergillus niger after co-culture with transgenic higher plants.  

PubMed

Different transgenic plants of Brassica napus, Brassica nigra, Datura innoxia and Vicia narbonensis expressing the hph gene under the control of the 35s promoter were co-cultivated with mycelial material of Aspergillus niger in microcosms under sterile conditions. A significantly higher number of hygromycin B-resistant colonies of re-isolated fungi was obtained if compared with co-cultures with non-transgenic plants. The hph gene and other foreign sequences could be detected in some of the resistant strains only for a short time after selection, indicating a rapid loss of foreign DNA. A more stable transgenic strain was obtained after co-culture with transgenic plants of D. innoxia including a high number of hph copies in their genome. DNA with detected pUC sequences was prepared to transform E. coli DH5 alpha. One of the recovered plasmids is shown to include pieces of the plant-transforming vector and a foreign sequence. The 35s-regulated expression of genes is studied in A. niger. PMID:7750149

Hoffmann, T; Golz, C; Schieder, O

1994-12-01

277

Evaluation for rock phosphate solubilization in fermentation and soil-plant system using a stress-tolerant phosphate-solubilizing Aspergillus niger WHAK1.  

PubMed

A strain WHAK1, identified as Aspergillus niger, was isolated from Yichang phosphate mines in Hubei province of China. The fungus developed a phosphate solubilization zone on modified National Botanical Research Institute's phosphate growth (NBRIP) agar medium, supplemented with tricalcium phosphate. The fungus was applied in a repeated-batch fermentation process in order to test its effect on solubilization of rock phosphate (RP). The results showed that A. niger WHAK1 could effectively solubilize RP in NBRIP liquid medium and released soluble phosphate in the broth, which can be illustrated by the observation of scanning electron microscope, energy-dispersive X-ray microanalysis, and Fourier transform infrared spectroscopy. Acidification of the broth seemed to be the major mechanism for RP solubilization by the fungus. Indeed, multiple organic acids (mainly gluconic acid) were detected in the broth by high-performance liquid chromatography analysis. These organic acids caused a significant drop of pH and an obvious rise of titratable acidity in the broth. The fungus also exhibited high levels of tolerance against temperature, pH, salinity, and desiccation stresses, although a significant decline in the fungal growth and release of soluble phosphate was marked under increasing intensity of stress parameters. Further, the fungus was introduced into the soil supplemented with RP to analyze its effect on plant growth and phosphate uptake of wheat plants. The result revealed that inoculation of A. niger WHAK1 significantly increased the growth and phosphate uptake of wheat plants in the RP-amended soil compared to the control soil. PMID:23229476

Xiao, Chunqiao; Zhang, Huaxiang; Fang, Yujuan; Chi, Ruan

2013-01-01

278

The Cu,Zn superoxide dismutases of Aspergillus flavus, Aspergillus niger, Aspergillus nidulans, and Aspergillus terreus: purification and biochemical comparison with the Aspergillus fumigatus Cu,Zn superoxide dismutase.  

PubMed Central

Cu,Zn superoxide dismutases (SODs) have been purified to homogeneity from Aspergillus flavus and A. niger, which are significant causative agents of aspergillosis, and from A. nidulans and A. terreus, which are much rarer causative agents of disease, using a combination of isoelectric focusing and gel filtration fast protein liquid chromatography. The purified enzymes have been compared with the previously described SOD from the most important pathogen in the genus, A. fumigatus (M. D. Holdom, R. J. Hay, and A. J. Hamilton, Free Radical Res. 22:519-531, 1995). The N-terminal amino acid sequences of the four newly purified enzymes were almost identical and demonstrated homology to known Cu,Zn SODs from a range of organisms including that from the previously described SOD from A. fumigatus. SOD activity was detectable in the culture filtrates of all species, and intracellular Cu,Zn SOD activity as a proportion of total protein was highest in early-log-phase cultures. The specific activities of the purified enzymes were similar, and all four of the newly described enzymes were inhibited by potassium cyanide and diethyldithiocarbamate, known Cu,Zn SOD inhibitors. Sodium azide and o-phenanthroline demonstrated inhibition at concentrations from 5 to 30 mM, and EDTA also exhibited a varying degree of inhibition of SOD activity. However, there were differences in the nonreduced molecular masses, the reduced molecular masses, and the isoelectric points of the four newly described SODs and the A. fumigatus enzyme; these varied from 55 to 123 kDa, 17.5 to 19.5 kDa, and 5.0 to 5.9, respectively. Of particular note was the observation that the A. fumigatus enzyme was thermostable compared with the SODs from the other species; in addition, the A.fiumigatus enzyme retained all of its activity at 37 degrees C relative to 20 degrees C, whereas the SODs of A. nidulans and A. terreus lost significant activity at the higher temperature. Aspergillus Cu,Zn SOD plays a hypothetical role in the avoidance of oxidative killing mechanisms, and our data suggest that the thermotolerant A. fumigatus Cu,Zn SOD would be more effective in such a protective system than, for example, the equivalent enzyme from the more rarely pathogenic A. nidulans. PMID:8757871

Holdom, M D; Hay, R J; Hamilton, A J

1996-01-01

279

Characterization of toxigenic and atoxigenic Aspergillus flavus isolates from pistachio  

Technology Transfer Automated Retrieval System (TEKTRAN)

Thirty eight Aspergillus flavus isolates collected from a pistachio orchard in California were analyzed for production of aflatoxin (AF), cyclopiazonic acid (CPA), vegetative compatibility groups (VCGs) and mating types. All toxigenic isolates produced both AFB1 and CPA. Twenty-one percent of the i...

280

Effect of media composition and growth conditions on production of beta-glucosidase by Aspergillus niger C-6.  

PubMed

The hydrolytic activity of fungal originated beta-glucosidase is exploited in several biotechnological processes to increase the rate and extent of saccharification of several cellulosic materials by hydrolyzing the cellobiose which inhibits cellulases. In a previous presentation, we reported the screening and liquid fermentation with Aspergillus niger, strain C-6 for beta-glucosidase production at shake flask cultures in a basal culture medium with mineral salts, corn syrup liquor, and different waste lignocellulosic materials as the sole carbon source obtaining the maximum enzymatic activity after 5-6 d of 8.5 IU/mL using native sugar cane bagasse. In this work we describe the evaluation of fermentation conditions: growth temperature, medium composition, and pH, also the agitation and aeration effects for beta-glucosidase production under submerged culture using a culture media with corn syrup liquor (CSL) and native sugar cane bagasse pith as the sole carbon source in a laboratory fermenter. The maximum enzyme titer of 7.2 IU/mL was obtained within 3 d of fermentation. This indicates that beta-glucosidase productivity by Aspergillus niger C-6 is function of culture conditions, principally temperature, pH, culture medium conditions, and the oxygen supply given in the bioreactor. Results obtained suggest that this strain is a potential microorganism that can reach a major level of enzyme production and also for enzyme characterization. PMID:15917612

García-Kirchner, O; Segura-Granados, M; Rodríguez-Pascual, P

2005-01-01

281

Genome-wide transcriptional response of Trichoderma reesei to lignocellulose using RNA sequencing and comparison with Aspergillus niger  

PubMed Central

Background A major part of second generation biofuel production is the enzymatic saccharification of lignocellulosic biomass into fermentable sugars. Many fungi produce enzymes that can saccarify lignocellulose and cocktails from several fungi, including well-studied species such as Trichoderma reesei and Aspergillus niger, are available commercially for this process. Such commercially-available enzyme cocktails are not necessarily representative of the array of enzymes used by the fungi themselves when faced with a complex lignocellulosic material. The global induction of genes in response to exposure of T. reesei to wheat straw was explored using RNA-seq and compared to published RNA-seq data and model of how A. niger senses and responds to wheat straw. Results In T. reesei, levels of transcript that encode known and predicted cell-wall degrading enzymes were very high after 24 h exposure to straw (approximately 13% of the total mRNA) but were less than recorded in A. niger (approximately 19% of the total mRNA). Closer analysis revealed that enzymes from the same glycoside hydrolase families but different carbohydrate esterase and polysaccharide lyase families were up-regulated in both organisms. Accessory proteins which have been hypothesised to possibly have a role in enhancing carbohydrate deconstruction in A. niger were also uncovered in T. reesei and categories of enzymes induced were in general similar to those in A. niger. Similarly to A. niger, antisense transcripts are present in T. reesei and their expression is regulated by the growth condition. Conclusions T. reesei uses a similar array of enzymes, for the deconstruction of a solid lignocellulosic substrate, to A. niger. This suggests a conserved strategy towards lignocellulose degradation in both saprobic fungi. This study provides a basis for further analysis and characterisation of genes shown to be highly induced in the presence of a lignocellulosic substrate. The data will help to elucidate the mechanism of solid substrate recognition and subsequent degradation by T. reesei and provide information which could prove useful for efficient production of second generation biofuels. PMID:24060058

2013-01-01

282

Stability of Glucose Oxidase Activity of Aspergillus niger Spores Produced by Solid-State Fermentation and Their Role as Biocatalysts in Bioconversion Reaction  

Microsoft Academic Search

Summary The aim of this work is to demonstrate the role of conidial spores as a reservoir of glucose oxidase and their stability as a biocatalyst in the bioconversion reaction for the production of gluconic acid. Solid-state fermentation (SSF) was carried out in fixed-bed column bioreactor for the production of Aspergillus niger spores. Growth parameters, sporulation and kinetics of gluconic

Sumitra Ramachandran; Pierre Fontanille; Ashok Pandey; Christian Larroche

283

Enhanced enzyme production from mixed cultures of Trichoderma reesei RUT-C30 and Aspergillus niger LMA grown as fed batch in a stirred tank bioreactor  

Microsoft Academic Search

For the complete hydrolysis of cellulose, the cellulolytic fungi produce a whole set of commercially important enzymes called cellulases. The aim of this work was to investigate an approach to enhance the production of these enzymes by co-culturing Trichoderma reesei and Aspergillus niger in a bioreactor to convert cellulose substrate into soluble sugars through a synergetic action of enzyme complex

Aftab Ahamed; Patrick Vermette

2008-01-01

284

Control of pellet morphology of filamentous fungi in fluidized bed bioreactors by means of a pulsing flow. Application to Aspergillus niger and Phanerochaete chrysosporium  

Microsoft Academic Search

The application of a pulsing flow to fluidized-bed bioreactors in order to control pellet morphology of filamentous fungi was investigated. The operation at an optimum pulsation frequency allowed two effects: a narrower pellet size distribution which improves fluidization quality, and an enhanced production of citric acid by Aspergillus niger and manganese peroxidase by Phanerochaete chrysosporium. In the case of A.

M. T. Moreira; A. Sanromán; G. Feijoo; J. M. Lema

1996-01-01

285

Comprehensive annotation of secondary metabolite biosynthetic genes and gene clusters of Aspergillus nidulans, A. fumigatus, A. niger and A. oryzae  

PubMed Central

Background Secondary metabolite production, a hallmark of filamentous fungi, is an expanding area of research for the Aspergilli. These compounds are potent chemicals, ranging from deadly toxins to therapeutic antibiotics to potential anti-cancer drugs. The genome sequences for multiple Aspergilli have been determined, and provide a wealth of predictive information about secondary metabolite production. Sequence analysis and gene overexpression strategies have enabled the discovery of novel secondary metabolites and the genes involved in their biosynthesis. The Aspergillus Genome Database (AspGD) provides a central repository for gene annotation and protein information for Aspergillus species. These annotations include Gene Ontology (GO) terms, phenotype data, gene names and descriptions and they are crucial for interpreting both small- and large-scale data and for aiding in the design of new experiments that further Aspergillus research. Results We have manually curated Biological Process GO annotations for all genes in AspGD with recorded functions in secondary metabolite production, adding new GO terms that specifically describe each secondary metabolite. We then leveraged these new annotations to predict roles in secondary metabolism for genes lacking experimental characterization. As a starting point for manually annotating Aspergillus secondary metabolite gene clusters, we used antiSMASH (antibiotics and Secondary Metabolite Analysis SHell) and SMURF (Secondary Metabolite Unknown Regions Finder) algorithms to identify potential clusters in A. nidulans, A. fumigatus, A. niger and A. oryzae, which we subsequently refined through manual curation. Conclusions This set of 266 manually curated secondary metabolite gene clusters will facilitate the investigation of novel Aspergillus secondary metabolites. PMID:23617571

2013-01-01

286

Improved enzyme production by bio-pellets of Aspergillus niger: targeted morphology engineering using titanate microparticles.  

PubMed

The present study describes the design of bio-pellet morphologies of the industrial working horse Aspergillus niger strains in submerged culture. The novel approach recruits the intended addition of titanate microparticles (TiSiO(4), 8 µm) to the growth medium. As tested for two recombinant strains producing fructofuranosidase and glucoamylase, the enzyme titer by the titanate-enhanced cultures in shake flasks was increased 3.7-fold to 150 U/mL (for fructofuranosidase) and 9.5-fold to 190 U/mL (for glucoamylase) as compared to the control. This could be successfully utilized for improved enzyme production in stirred tank reactors. Stimulated by the particles, the achieved final glucoamylase activity of 1,080 U/mL (fed-batch) and 320 U/mL (batch) was sevenfold higher as compared to the conventional processes. The major reason for the enhanced production was the close association between the titanate particles and the fungal cells. Already below 2.5 g/L the micromaterial was found inside the pellets, including single particles embedded as 50-150 µm particle aggregates in the center resulting in core shell pellets. With increasing titanate levels the pellet size decreased from 1,700 µm (control) to 300 µm. Fluorescence based resolution of GFP expression revealed that the large pellets of the control were only active in a 200 µm surface layer. This matches with the critical penetration depth for nutrients and oxygen typically observed for fungal pellets. The biomass within the titanate derived fungal pellets, however, was completely active. This was due a reduced thickness of the biomass layer via smaller pellets as well as the core shell structure. Moreover, also the created loose inner pellet structure enabled a higher mass transfer and penetration depths for up to 500 µm. The creation of core-shell pellets has not been achieved previously by the addition of microparticles, for example, made of talc or alumina. Due to this, the present work opens further possibilities to use microparticles for tailor-made morphology design of filamentous fungi, especially for pellet based processes which have a long and strong industrial relevance for industrial production. PMID:21887774

Driouch, Habib; Hänsch, Robert; Wucherpfennig, Thomas; Krull, Rainer; Wittmann, Christoph

2012-02-01

287

Characterization of a polyketide synthase in Aspergillus niger whose product is a precursor for both dihydroxynaphthalene (DHN) melanin and naphtho-?-pyrone.  

SciTech Connect

The genome sequencing of the fungus Aspergillus niger, an industrial workhorse, uncovered a large cache of genes encoding enzymes thought to be involved in the production of secondary metabolites yet to be identified. Identification and structural characterization of many of these predicted secondary metabolites are hampered by their low concentration relative to the known A. niger metabolites such as the naphtho-?-pyrone family of polyketides. We deleted a nonreducing PKS gene in A. niger strain ATCC 11414, a daughter strain of A. niger ATCC strain 1015 whose genome was sequenced by the DOE Joint Genome Institute. This PKS encoding gene is a predicted ortholog of alb1 from Aspergillus fumigatus which is responsible for production of YWA1, a precursor of fungal DHN melanin. Our results show that the A. niger alb1 PKS is responsible for the production of the polyketide precursor for DHN melanin biosynthesis. Deletion of alb1 elimnates the production of major metabolites, naphtho-?-pyrones. The generation of an A. niger strain devoid of naphtho-?-pyrones will greatly facilitate the elucidation of cryptic biosynthetic pathways in this organism.

Chiang, Yi Ming; Meyer, Kristen M.; Praseuth , Michael; Baker, Scott E.; Bruno, Kenneth S.; Wang, Clay C.

2010-12-06

288

The Weak Acid Preservative Sorbic Acid Inhibits Conidial Germination and Mycelial Growth of Aspergillus niger through Intracellular Acidification  

PubMed Central

The growth of the filamentous fungus Aspergillus niger, a common food spoilage organism, is inhibited by the weak acid preservative sorbic acid (trans-trans-2,4-hexadienoic acid). Conidia inoculated at 105/ml of medium showed a sorbic acid MIC of 4.5 mM at pH 4.0, whereas the MIC for the amount of mycelia at 24 h developed from the same spore inoculum was threefold lower. The MIC for conidia and, to a lesser extent, mycelia was shown to be dependent on the inoculum size. A. niger is capable of degrading sorbic acid, and this ability has consequences for food preservation strategies. The mechanism of action of sorbic acid was investigated using 31P nuclear magnetic resonance (NMR) spectroscopy. We show that a rapid decline in cytosolic pH (pHcyt) by more than 1 pH unit and a depression of vacuolar pH (pHvac) in A. niger occurs in the presence of sorbic acid. The pH gradient over the vacuole completely collapsed as a result of the decline in pHcyt. NMR spectra also revealed that sorbic acid (3.0 mM at pH 4.0) caused intracellular ATP pools and levels of sugar-phosphomonoesters and -phosphodiesters of A. niger mycelia to decrease dramatically, and they did not recover. The disruption of pH homeostasis by sorbic acid at concentrations below the MIC could account for the delay in spore germination and retardation of the onset of subsequent mycelial growth. PMID:15184150

Plumridge, Andrew; Hesse, Stephan J. A.; Watson, Adrian J.; Lowe, Kenneth C.; Stratford, Malcolm; Archer, David B.

2004-01-01

289

Biochemical characterization of Aspergillus niger CfcI, a glycoside hydrolase family 18 chitinase that releases monomers during substrate hydrolysis.  

PubMed

The genome of the industrially important fungus Aspergillus niger encodes a large number of glycoside hydrolase family 18 members annotated as chitinases. We identified one of these putative chitinases, CfcI, as a representative of a distinct phylogenetic clade of homologous enzymes conserved in all sequenced Aspergillus species. Where the catalytic domain of more distantly related chitinases consists of a triosephosphate isomerase barrel in which a small additional (?+?) domain is inserted, CfcI-like proteins were found to have, in addition, a carbohydrate-binding module (CBM18) that is inserted in the (?+?) domain next to the substrate-binding cleft. This unusual domain structure and sequence dissimilarity to previously characterized chitinases suggest that CfcI has a novel activity or function different from chitinases investigated so far. Following its heterologous expression and purification, its biochemical characterization showed that CfcI displays optimal activity at pH 4 and 55-65 °C and degrades chitin oligosaccharides by releasing N-acetylglucosamine from the reducing end, possibly via a processive mechanism. This is the first fungal family 18 exochitinase described, to our knowledge, that exclusively releases monomers. The cfcI expression profile suggests that its physiological function is important in processes that take place during the late stages of the aspergillus life cycle, such as autolysis or sporulation. PMID:22575895

van Munster, Jolanda M; van der Kaaij, Rachel M; Dijkhuizen, Lubbert; van der Maarel, Marc J E C

2012-08-01

290

Comparative study of toxicity of azo dye Procion Red MX-5B following biosorption and biodegradation treatments with the fungi Aspergillus niger and Aspergillus terreus.  

PubMed

Azo dyes are an important class of environmental contaminants and are characterized by the presence of one or more azo bonds (-N=N-) in their molecular structure. Effluents containing these compounds resist many types of treatments due to their molecular complexity. Therefore, alternative treatments, such as biosorption and biodegradation, have been widely studied to solve the problems caused by these substances, such as their harmful effects on the environment and organisms. The aim of the present study was to evaluate biosorption and biodegradation of the azo dye Procion Red MX-5B in solutions with the filamentous fungi Aspergillus niger and Aspergillus terreus. Decolorization tests were performed, followed by acute toxicity tests using Lactuca sativa seeds and Artemia salina larvae. Thirty percent dye removal of the solutions was achieved after 3 h of biosorption. UV-Vis spectroscopy revealed that removal of the dye molecules occurred without major molecular changes. The acute toxicity tests confirmed lack of molecular degradation following biosorption with A. niger, as toxicity to L. sativa seed reduced from 5% to 0%. For A. salina larvae, the solutions were nontoxic before and after treatment. In the biodegradation study with the fungus A. terreus, UV-Vis and FTIR spectroscopy revealed molecular degradation and the formation of secondary metabolites, such as primary and secondary amines. The biodegradation of the dye molecules was evaluated after 24, 240 and 336 h of treatment. The fungal biomass demonstrated considerable affinity for Procion Red MX-5B, achieving approximately 100% decolorization of the solutions by the end of treatment. However, the solutions resulting from this treatment exhibited a significant increase in toxicity, inhibiting the growth of L. sativa seeds by 43% and leading to a 100% mortality rate among the A. salina larvae. Based on the present findings, biodegradation was effective in the decolorization of the samples, but generated toxic metabolites, while biosorption was effective in both decolorization and reducing the toxicity of the solutions. PMID:25048922

Almeida, E J R; Corso, C R

2014-10-01

291

The intra- and extracellular proteome of Aspergillus niger growing on defined medium with xylose or maltose as carbon substrate  

PubMed Central

Background The filamentous fungus Aspergillus niger is well-known as a producer of primary metabolites and extracellular proteins. For example, glucoamylase is the most efficiently secreted protein of Aspergillus niger, thus the homologous glucoamylase (glaA) promoter as well as the glaA signal sequence are widely used for heterologous protein production. Xylose is known to strongly repress glaA expression while maltose is a potent inducer of glaA promoter controlled genes. For a more profound understanding of A. niger physiology, a comprehensive analysis of the intra- and extracellular proteome of Aspergillus niger AB1.13 growing on defined medium with xylose or maltose as carbon substrate was carried out using 2-D gel electrophoresis/Maldi-ToF and nano-HPLC MS/MS. Results The intracellular proteome of A. niger growing either on xylose or maltose in well-aerated controlled bioreactor cultures revealed striking similarities. In both cultures the most abundant intracellular protein was the TCA cycle enzyme malate-dehydrogenase. Moreover, the glycolytic enzymes fructose-bis-phosphate aldolase and glyceraldehyde-3-phosphate-dehydrogenase and the flavohemoglobin FhbA were identified as major proteins in both cultures. On the other hand, enzymes involved in the removal of reactive oxygen species, such as superoxide dismutase and peroxiredoxin, were present at elevated levels in the culture growing on maltose but only in minor amounts in the xylose culture. The composition of the extracellular proteome differed considerably depending on the carbon substrate. In the secretome of the xylose-grown culture, a variety of plant cell wall degrading enzymes were identified, mostly under the control of the xylanolytic transcriptional activator XlnR, with xylanase B and ferulic acid esterase as the most abundant ones. The secretome of the maltose-grown culture did not contain xylanolytic enzymes, instead high levels of catalases were found and glucoamylase (multiple spots) was identified as the most abundant extracellular protein. Surprisingly, the intracellular proteome of A. niger growing on xylose in bioreactor cultures differed more from a culture growing in shake flasks using the same medium than from the bioreactor culture growing on maltose. For example, in shake flask cultures with xylose as carbon source the most abundant intracellular proteins were not the glycolytic and the TCA cycle enzymes and the flavohemoglobin, but CipC, a protein of yet unknown function, superoxide dismutase and an NADPH dependent aldehyde reductase. Moreover, vacuolar proteases accumulated to higher and ER-resident chaperones and foldases to lower levels in shake flask compared to the bioreactor cultures. Conclusions The utilization of xylose or maltose was strongly affecting the composition of the secretome but of minor influence on the composition of the intracellular proteome. On the other hand, differences in culture conditions (pH control versus no pH control, aeration versus no aeration and stirring versus shaking) have a profound effect on the intracellular proteome. For example, lower levels of ER-resident chaperones and foldases and higher levels of vacuolar proteases render shake flask conditions less favorable for protein production compared to controlled bioreactor cultures. PMID:20406453

2010-01-01

292

Optimization of tannase production by Aspergillus niger in solid-state packed-bed bioreactor.  

PubMed

Tannin acyl hydrolase, also known as tannase, is an enzyme with important applications in the food, feed, pharmaceutical, and chemical industries. However, despite a growing interest in the catalytic properties of tannase, its practical use is very limited owing to high production costs. Several studies have already demonstrated the advantages of solid-state fermentation (SSF) for the production of fungal tannase, yet the optimal conditions for enzyme production strongly depend on the microbial strain utilized. Therefore, the aim of this study was to improve the tannase production by a locally isolated A. niger strain in an SSF system. The SSF was carried out in packed-bed bioreactors using polyurethane foam as an inert support impregnated with defined culture media. The process parameters influencing the enzyme production were identified using a Plackett–Burman design, where the substrate concentration, initial pH, and incubation temperature were determined as the most significant. These parameters were then further optimized using a Box-Behnken design. The maximum tannase production was obtained with a high tannic acid concentration (50 g/l), relatively low incubation temperature (30°C), and unique low initial pH (4.0). The statistical strategy aided in increasing the enzyme activity nearly 1.97-fold, from 4,030 to 7,955 U/l. Consequently, these findings can lead to the development of a fermentation system that is able to produce large amounts of tannase in economical, compact, and scalable reactors. PMID:21952373

Rodríguez-Durán, Luis V; Contreras-Esquivel, Juan C; Rodríguez, Raúl; Prado-Barragán, L Arely; Aguilar, Cristóbal N

2011-09-01

293

Influence of agitation speed on tannase production and morphology of Aspergillus niger FETL FT3 in submerged fermentation.  

PubMed

Agitation speed was found to influence the tannase production and fungal growth of Aspergillus niger FETL FT3. The optimal agitation speed was at 200 rpm which produced 1.41 U/ml tannase and 3.75 g/l of fungal growth. Lower or higher agitation speeds than 200 rpm produced lower enzyme production and fungal growth. Based on the SEM and TEM micrograph observation, there was a significant correlation between agitation speed and the morphology of the fungal mycelia. The results revealed an increase of the enzyme production with the change of the fungal growth morphology from filamentous to pelleted growth forms. However, the exposure to higher shear stress with an increasing agitation speed of the shaker also resulted in lower biomass yields as well as enzyme production. PMID:21947762

Darah, I; Sumathi, G; Jain, K; Lim, S H

2011-12-01

294

Sequential solid-state and submerged cultivation of Aspergillus niger on sugarcane bagasse for the production of cellulase.  

PubMed

Sequential solid-state and submerged cultivation with sugarcane bagasse as substrate for cellulase production by Aspergillus niger A12 was assessed by measuring endoglucanase activity. An unconventional pre-culture with an initial fungal growth phase under solid-state cultivation was followed by a transition to submerged fermentation by adding the liquid culture medium to the mycelium grown on solid substrate. For comparison, control experiments were conducted using conventional submerged cultivation. The cultures were carried out in shake flasks and in a 5-L bubble column bioreactor. An endoglucanase productivity of 57 ± 13 IU/L/h was achieved in bubble column cultivations prepared using the new method, representing an approximately 3-fold improvement compared to conventional submerged fermentation. Therefore, the methodology proposed here of a sequential fermentation process offers a promising alternative for cellulase production. PMID:22409979

Cunha, F M; Esperança, M N; Zangirolami, T C; Badino, A C; Farinas, C S

2012-05-01

295

A qualitative and quantitative high-throughput assay for screening of gluconate high-yield strains by Aspergillus niger.  

PubMed

A novel two-step high-throughput strategy was developed for screening of gluconate high-yield strains by Aspergillus niger. The first step was fast qualitative assay according to the indicator color change, the second step was quantitative assay according to the absorbance of chelate formed with Cu(2+) at 810nm. The accuracy of high-throughput assay was comparable to that of high-performance liquid chromatography (HPLC). The correlation coefficient between CuSO4 assay and HPLC assays was exceeding 0.99 by statistical analysis. As a result, 3 high-yield mutants were screened out from 1000 viable single colonies, the mutants II-2-A1, IV-7-C6, and V-11-C5 were further validated in 5L of bioreactor. The average production rates were 15.5%, 32.8%, and 12.1% higher than that of the parental strain, respectively. PMID:25498457

Shi, Fei; Tan, Jun; Chu, Ju; Wang, Yonghong; Zhuang, Yingping; Zhang, Siliang

2015-02-01

296

Partition in aqueous two-phase system: its application in downstream processing of tannase from Aspergillus niger.  

PubMed

Tannase from Aspergillus niger was partitioned in aqueous two-phase systems composed by polyethyleneglycol of molar mass 400, 600 and 1000 and potassium phosphate. Tannase was found to be partitioned toward the salt-rich phase in all systems, with partition coefficients lower than 0.5. Partition coefficients values and low entropic and enthalpic changes associated with tannase partition suggest that the entropic effect may be the driving force of the concentration of the enzyme in the bottom phase due to the high molar mass of the enzyme. The process was significantly influenced by the top phase/bottom phase volume ratio. When the fungal culture broth was partitioned in these systems, a good performance was found, since the enzyme recovery in the bottom phase of the system composed by polyethyleneglycol 1000 was around 96% with a 7.0-fold increase in purity. PMID:23010046

Rodríguez-Durán, Luis V; Spelzini, Darío; Boeris, Valeria; Aguilar, Cristóbal N; Picó, Guillermo A

2013-01-01

297

Identification of an L-arabinose reductase gene in Aspergillus niger and its role in L-arabinose catabolism.  

PubMed

The first enzyme in the pathway for l-arabinose catabolism in eukaryotic microorganisms is a reductase, reducing l-arabinose to l-arabitol. The enzymes catalyzing this reduction are in general nonspecific and would also reduce d-xylose to xylitol, the first step in eukaryotic d-xylose catabolism. It is not clear whether microorganisms use different enzymes depending on the carbon source. Here we show that Aspergillus niger makes use of two different enzymes. We identified, cloned, and characterized an l-arabinose reductase, larA, that is different from the d-xylose reductase, xyrA. The larA is up-regulated on l-arabinose, while the xyrA is up-regulated on d-xylose. There is however an initial up-regulation of larA also on d-xylose but that fades away after about 4 h. The deletion of the larA gene in A. niger results in a slow growth phenotype on l-arabinose, whereas the growth on d-xylose is unaffected. The l-arabinose reductase can convert l-arabinose and d-xylose to their corresponding sugar alcohols but has a higher affinity for l-arabinose. The K(m) for l-arabinose is 54 + or - 6 mm and for d-xylose 155 + or - 15 mm. PMID:20511228

Mojzita, Dominik; Penttilä, Merja; Richard, Peter

2010-07-30

298

Identification of an l-Arabinose Reductase Gene in Aspergillus niger and Its Role in l-Arabinose Catabolism*  

PubMed Central

The first enzyme in the pathway for l-arabinose catabolism in eukaryotic microorganisms is a reductase, reducing l-arabinose to l-arabitol. The enzymes catalyzing this reduction are in general nonspecific and would also reduce d-xylose to xylitol, the first step in eukaryotic d-xylose catabolism. It is not clear whether microorganisms use different enzymes depending on the carbon source. Here we show that Aspergillus niger makes use of two different enzymes. We identified, cloned, and characterized an l-arabinose reductase, larA, that is different from the d-xylose reductase, xyrA. The larA is up-regulated on l-arabinose, while the xyrA is up-regulated on d-xylose. There is however an initial up-regulation of larA also on d-xylose but that fades away after about 4 h. The deletion of the larA gene in A. niger results in a slow growth phenotype on l-arabinose, whereas the growth on d-xylose is unaffected. The l-arabinose reductase can convert l-arabinose and d-xylose to their corresponding sugar alcohols but has a higher affinity for l-arabinose. The Km for l-arabinose is 54 ± 6 mm and for d-xylose 155 ± 15 mm. PMID:20511228

Mojzita, Dominik; Penttilä, Merja; Richard, Peter

2010-01-01

299

Gamma radiation induced mutagenesis in Aspergillus niger to enhance its microbial fermentation activity for industrial enzyme production.  

PubMed

?- and ?-Galactosidases find application in food processing, health and nutrition. Aspergillus niger is one of the potent producer of these enzymes and was genotypically improved using gamma-ray induced mutagenesis. The mutant-derivative produced two-fold higher ?- and ?-galactosidases. For testing genetic variability and its relationship with phenotypic properties of the two organisms, DNA samples of the mutant and parental strains of A. niger were amplified with 28 deca-nucleotide synthetic primers. RAPD analysis showed significantly different pattern between parental and mutant cultures. The mutant derivative yielded homogeneous while parental strain formed heterogeneous amplification patterns. Seven primers identified 42.9% polymorphism in the amplification products, indicating that these primers determined some genetic variability between the two strains. Thus RAPD was found to be an efficient technique to determine genetic variability in the mutant and wild organisms. Both wild and mutant strains were analyzed for their potential to produce galactosidases. Comparison of different carbon sources on enzyme yield revealed that wheat bran is significant (P < 0.01) effective producer and economical source followed by rice bran, rice polishing and lactose. The mutant was significantly better enzyme producer and could be considered for its prospective application in food, nutrition and health and that RAPD can be effectively used to differentiate mutant strain from the parental strain based on the RAPD patterns. PMID:20632114

Awan, M Siddique; Tabbasam, Nabila; Ayub, N; Babar, M E; Mehboob-ur-Rahman; Rana, Shahid Mahboob; Rajoka, M I

2011-02-01

300

Production of cellulose by Aspergillus niger under submerged and solid state fermentation using coir waste as a substrate  

PubMed Central

Aspergillus niger was used for cellulase production in submerged (SmF) and solid state fermentation (SSF). The maximum production of cellulase was obtained after 72 h of incubation in SSF and 96 h in Smf. The CMCase and FPase activities recorded in SSF were 8.89 and 3.56 U per g of dry mycelial bran (DBM), respectively. Where as in Smf the CMase & FPase activities were found to be 3.29 and 2.3 U per ml culture broth, respectively. The productivity of extracellular cellulase in SSF was 14.6 fold higher than in SmF. The physical and nutritional parameters of fermentation like pH, temperature, substrate, carbon and nitrogen sources were optimized. The optimal conditions for maximum biosynthesis of cellulase by A. niger were shown to be at pH 6, temperature 30 °C. The additives like lactose, peptone and coir waste as substrate increased the productivity both in SmF and SSF. The moisture ratio of 1:2 (w/v) was observed for optimum production of cellulase in SSF. PMID:24031730

Mrudula, Soma; Murugammal, Rangasamy

2011-01-01

301

Continuous hydrolysis of 4-cyanopyridine by nitrilases from Fusarium solani O1 and Aspergillus niger K10.  

PubMed

The operational stabilities of nitrilases from Aspergillus niger K10 and Fusarium solani O1 were examined with 4-cyanopyridine as the substrate in continuous-stirred membrane reactors (CSMRs). The former enzyme was fairly stable at 30 degrees C with a deactivation constant (k (d)) and enzyme half-life of 0.014 h(-1) and 50 h, respectively, but the latter exhibited an even higher stability characterized by k (d) = 0.008 h(-1) and half-life of 87 h at 40 degrees C. Another advantage of this enzyme was its high chemoselectivity, i.e., selective transformation of nitriles into carboxylic acids, while the amide formed a high ratio of A. niger K10 nitrilase product. High conversion rates (>90%) were maintained for about 52 h using the nitrilase from F. solani O1 immobilized in cross-linked enzyme aggregates (CLEAs). The purity of isonicotinic acid was increased from 98% to >99.9% by using two CSMRs connected in series, the first one containing the F. solani O1 nitrilase and the second the amidase from Rhodococcus erythropolis A4 (both enzymes as CLEAs), the amidase hydrolyzing the by-product isonicotinamide. PMID:19554325

Malandra, Anna; Cantarella, Maria; Kaplan, Ondrej; Vejvoda, Vojtech; Uhnáková, Bronislava; Stepánková, Barbora; Kubác, David; Martínková, Ludmila

2009-11-01

302

Bioprocessing strategies for improving hen egg-white lysozyme (HEWL) production by recombinant Aspergillus niger HEWL WT-13-16.  

PubMed

Hen egg-white lysozyme (HEWL) production by recombinant Aspergillus niger HEWL WT-13-16 from a cDNA under the control of the A. niger glucoamylase promoter was used as a model system. The fungal mycelium was either immobilized on porous Celite 560 micro-carrier or grown in suspension as pelleted and dispersed forms. The objective was to reduce the protease activity that adversely affects the expressed HEWL. Free suspension culture at uncontrolled pH served as the benchmark. The control of pH during growth at pH 4.0 gave rise to a greater than five-fold reduction of protease activity in suspension culture. An additional 38.5% decrease in protease activity was achieved in mycelial-pellet cultures in comparison to a 40.9% decrease in protease activity obtained with Celite 560 beads in an airlift vessel at controlled pH. The specific HEWL yields were 5.8, 5.0 and 4.1 mg/g dry wt. for the free suspension, mycelial-pellet, and Celite-560-immobilized cultures, respectively. PMID:12466879

Gyamerah, M; Merichetti, G; Adedayo, O; Scharer, J M; Moo-Young, M

2002-12-01

303

Monoclinic crystal form of Aspergillus niger ?-­amylase in complex with maltose at 1.8?Å resolution  

PubMed Central

Aspergillus niger ?-amylase catalyses the hydrolysis of ?-1,4-glucosidic bonds in starch. It shows 100% sequence identity to the A. oryzae homologue (also called TAKA-amylase), three crystal structures of which have been published to date. Two of them belong to the orthorhombic space group P212121 with one molecule per asymmetric unit and one belongs to the monoclinic space group P21 with three molecules per asymmetric unit. Here, the purification, crystallization and structure determination of A. niger ?-amylase crystallized in the monoclinic space group P21 with two molecules per asymmetric unit in complex with maltose at 1.8?Å resolution is reported. Furthermore, a novel 1.6?Å resolution orthorhombic crystal form (space group P21212) of the native enzyme is presented. Four maltose molecules are observed in the maltose–?-amylase complex. Three of these occupy active-site subsites ?2 and ?1, +1 and +2 and the hitherto unobserved subsites +4 (Asp233, Gly234) and +5 (Asp235). The fourth maltose molecule binds at the distant binding sites d1 (Tyr382) and d2 (Trp385), also previously unobserved. Furthermore, it is shown that the active-site groove permits different binding modes of sugar units at subsites +1 and +2. This flexibility of the active-site cleft close to the catalytic centre might be needed for a productive binding of substrate chains and/or release of products. PMID:16880540

Vuji?i?-Žagar, A.; Dijkstra, B. W.

2006-01-01

304

Mechanism of Cr(VI) reduction by Aspergillus niger: enzymatic characteristic, oxidative stress response, and reduction product.  

PubMed

Bioremediation of hexavalent chromium by Aspergillus niger was attributed to the reduction product (trivalent chromium) that could be removed in precipitation and immobilized inside the fungal cells and on the surface of mycelium. The site location of reduction was conducted with assays of the permeabilized cells, cell-free extracts, and cell debris, which confirmed that the chromate reductase was mainly located in the soluble fraction of cells. The oxidation-reduction process was accompanied by the increase of reactive oxygen species and antioxidant levels after hexavalent chromium treatment. Michaelis-Menten constant (K m) and maximum reaction rate (V max), obtained from the Lineweaver-Burk plot were 14.68 ?M and 434 ?M min(-1) mg(-1) of protein, respectively. Scanning electron microscopy and Raman spectra analyses manifested that both Cr(VI) and Cr(III) species were present on the mycelium. Fourier transform-infrared spectroscopy analysis suggested that carboxyl, hydroxide, amine, amide, cyano-group, and phosphate groups from the fungal cell wall were involved in chromium binding by the complexation with the Cr(III) and Cr(VI) species. A Cr(VI) removal mechanism of Cr(VI) reduction followed by the surface immobilization and intracellular accumulation of Cr(III) in living A. niger was present. PMID:25408081

Gu, Yanling; Xu, Weihua; Liu, Yunguo; Zeng, Guangming; Huang, Jinhui; Tan, Xiaofei; Jian, Hao; Hu, Xi; Li, Fei; Wang, Dafei

2014-11-20

305

Growth Kinetics and Mechanistic Action of Reactive Oxygen Species Released by Silver Nanoparticles from Aspergillus niger on Escherichia coli  

PubMed Central

Silver Nanoparticles (AgNPs), the real silver bullet, are known to have good antibacterial properties against pathogenic microorganisms. In the present study AgNPs were prepared from extracellular filtrate of Aspergillus niger. Characterization of AgNPs by UV-Vis spectrum reveals specific surface plasmon resonance at peak 416?nm; TEM photographs revealed the size of the AgNPs to be 20–55?nm. Average diameter of the produced AgNPs was found to be 73?nm with a zeta potential that was ?24?mV using Malvern Zetasizer. SEM micrographs showed AgNPs to be spherical with smooth morphology. EDS revealed the presence of pure metallic AgNPs along with carbon and oxygen signatures. Of the different concentrations (0, 2.5, 5, 10, and 15??g/mL) used 10??g/mL were sufficient to inhibit 107?CFU/mL of E. coli. ROS production was measured using DCFH-DA method and the the free radical generation effect of AgNPs on bacterial growth inhibition was investigated by ESR spectroscopy. This paper not only deals with the damage inflicted on microorganisms by AgNPs but also induces cell death through the production of ROS released by AgNPs and also growth kinetics of E. coli supplemented with AgNPs produced by A. niger. PMID:25028666

Ninganagouda, Shivaraj; Rathod, Vandana; Singh, Dattu; Hiremath, Jyoti; Singh, Ashish Kumar; Mathew, Jasmine; ul-Haq, Manzoor

2014-01-01

306

Conversion of orange peel to L-galactonic acid in a consolidated process using engineered strains of Aspergillus niger  

PubMed Central

Citrus processing waste is a leftover from the citrus processing industry and is available in large amounts. Typically, this waste is dried to produce animal feed, but sometimes it is just dumped. Its main component is the peel, which consists mostly of pectin, with D-galacturonic acid as the main monomer. Aspergillus niger is a filamentous fungus that efficiently produces pectinases for the hydrolysis of pectin and uses the resulting D-galacturonic acid and most of the other components of citrus peel for growth. We used engineered A. niger strains that were not able to catabolise D-galacturonic acid, but instead converted it to L-galactonic acid. These strains also produced pectinases for the hydrolysis of pectin and were used for the conversion of pectin in orange peel to L-galactonic acid in a consolidated process. The D-galacturonic acid in the orange peel was converted to L-galactonic acid with a yield close to 90%. Submerged and solid-state fermentation processes were compared. PMID:24949267

2014-01-01

307

An acidothermophilic functionally active novel GH12 family endoglucanase from Aspergillus niger HO: purification, characterization and molecular interaction studies.  

PubMed

Endoglucanase (EG) from Aspergillus niger HO was sequentially purified through ultrafiltration, ion exchange and size exclusion chromatography to homogeneity, with an overall recovery of 18 %. The purified EG was a monomeric protein with a molecular weight of about 55 kDa. The enzyme was optimally active at pH 3.5 and 70 °C with a half life (t1/2) of 3 h and Km value of 2.5 mg/ml. Metal ions, such as Ca(2+) and Co(2+) helped in enzyme induction, while Hg(2+) and Cu(2+) strongly inhibited the enzyme activity. Peptide mass fingerprinting results revealed that the purified EG is a novel enzyme that belongs to family 12 of glycoside hydrolase (GH12). Molecular docking studies indicated the presence of Glu116 and Glu204 as important determinant residues for the functional interaction with carboxymethylcellulose and showed hydrogen bonding with Asp99, Glu116, Glu204 and hydrophobic interactions with Trp22, Val58, Tyr61, Phe101, Met118, Trp120, Pro129, Ile130, Thr160 and Phe206. Hydrolysis of 2 % CMC with purified acidothermophilic EG at its optimum temperature and pH resulted in complete hydrolysis within 2 h yielding 18 % cellotriose, 72 % cellobiose and 10 % glucose as evident from HPLC analysis. In comparison to most of the EGs reported in literature, EG from A. niger HO exhibited higher thermostability. The acidothermophilic nature of this enzyme makes it potentially useful for industrial applications. PMID:25331339

Rawat, Rekha; Kumar, Sunil; Chadha, Bhupinder Singh; Kumar, Dinesh; Oberoi, Harinder Singh

2015-01-01

308

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

NASA Astrophysics Data System (ADS)

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 palm oils) was investigated to enhance lipase production. The maximum lipase activity was obtained using 2% (m/m) castor oil. In these conditions, the growth was evaluated each 24 h for 5 days by the glycosamine content analysis and digital image processing. Lipase activity was also determined. The results indicated that the digital image process technique can be used to monitor biomass growth in a SSF process and to correlate biomass growth and enzyme activity. In addition, the immobilized esterification lipase activity was determined for the butyl oleate synthesis, with and without 50% v/v hexane, resulting in 650 and 120 U/g, respectively. The enzyme was also used for transesterification of soybean oil and ethanol with maximum yield of 2.4%, after 30 min of reaction.

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

309

Lipase production in solid-state fermentation monitoring biomass growth of aspergillus niger using digital image processing.  

PubMed

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 palm oils) was investigated to enhance lipase production. The maximum lipase activity was obtained using 2% (m/m) castor oil. In these conditions, the growth was evaluated each 24 h for 5 days by the glycosamine content analysis and digital image processing. Lipase activity was also determined. The results indicated that the digital image process technique can be used to monitor biomass growth in a SSF process and to correlate biomass growth and enzyme activity. In addition, the immobilized esterification lipase activity was determined for the butyl oleate synthesis, with and without 50% v/v hexane, resulting in 650 and 120 U/g, respectively. The enzyme was also used for transesterification of soybean oil and ethanol with maximum yield of 2.4%, after 30 min of reaction. PMID:18401753

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

2008-03-01

310

Role of Aspergillus niger acrA in Arsenic Resistance and Its Use as the Basis for an Arsenic Biosensor  

PubMed Central

Arsenic contamination of groundwater sources is a major issue worldwide, since exposure to high levels of arsenic has been linked to a variety of health problems. Effective methods of detection are thus greatly needed as preventive measures. In an effort to develop a fungal biosensor for arsenic, we first identified seven putative arsenic metabolism and transport genes in Aspergillus niger, a widely used industrial organism that is generally regarded as safe (GRAS). Among the genes tested for RNA expression in response to arsenate, acrA, encoding a putative plasma membrane arsenite efflux pump, displayed an over 200-fold increase in gene expression in response to arsenate. We characterized the function of this A. niger protein in arsenic efflux by gene knockout and confirmed that AcrA was located at the cell membrane using an enhanced green fluorescent protein (eGFP) fusion construct. Based on our observations, we developed a putative biosensor strain containing a construct of the native promoter of acrA fused with egfp. We analyzed the fluorescence of this biosensor strain in the presence of arsenic using confocal microscopy and spectrofluorimetry. The biosensor strain reliably detected both arsenite and arsenate in the range of 1.8 to 180 ?g/liter, which encompasses the threshold concentrations for drinking water set by the World Health Organization (10 and 50 ?g/liter). PMID:22467499

Choe, Se-In; Gravelat, Fabrice N.; Al Abdallah, Qusai; Lee, Mark J.; Gibbs, Bernard F.

2012-01-01

311

EFECTO DE LA GLUCOAMILASA DE Aspergillus Niger EN LA DIGESTIBILIDAD in vitro DE MAÍZ Y SORGO, Y EN LA PRODUCTIVIDAD DE BORREGOS EFFECTS OF GLUCOAMYLASE FROM Aspergillus Niger ON in vitroDIGESTIBILITY, OF MAIZE AND SORGHUM AND ON LAMB PERFORMANCE  

Microsoft Academic Search

Treatment of sorghum grain with glucoamylase from Aspergillus niger has increased ruminal starch digestion. An in vitro essay was conducted to determine the effects of the dose of glucoamylase on the digestion of maize (Zea mays L.) and sorghum (Sorghum vulgare) (during 63 d) grain dry matter (DM). Another trial was carried out to measure productive variables in lambs fed

Germán Buendía-Rodriguez; Germán D. Mendoza-Martínez; Ricardo Bárcena-Gama; María E. Ortega-Cerrilla; José Solís-Hernández; Alejandro Lara-Bueno

312

A comparative study on determination of the equilibrium, kinetic and thermodynamic parameters of biosorption of copper(II) and lead(II) ions onto pretreated Aspergillus niger  

Microsoft Academic Search

The kinetics and thermodynamics of copper(II) and lead(II) biosorption onto Aspergillus niger pretreated with NaOH were studied with respect to pH, temperature and initial metal ion concentration. The optimum pH values were determined as 5.0 and 4.0 for copper(II) and lead(II) at 25°C, respectively. Biosorption capacity values of the biomass increased with increasing initial metal ion concentration and temperature. The

Arzu Y. Dursun

2006-01-01

313

Statistical optimization of cellulases production by Aspergillus niger HQ1 in solid-state fermentation and partial enzymatic characterization of cellulases on hydrolyzing chitosan  

Microsoft Academic Search

Cultivation conditions of cellulases production by Aspergillus niger HQ-1 in solid-state fermentation (SSF) were optimized. Furthermore, partial enzymatic characterization of the crude cellulases\\u000a on hydrolyzing chitosan was studied. The moisture content, cultivation temperature, and initial culture pH were identified\\u000a by Plackett-Burman design (PBD) as the significant factors for cellulases activities. The method of steepest ascent was undertaken\\u000a to determine the

Hui Zhang; Qing Sang; Wenhui Zhang

314

Evaluation of glucosidases of Aspergillus niger strain comparing with other glucosidases in transformation of ginsenoside Rb1 to ginsenosides Rg3  

PubMed Central

The transformation of ginsenoside Rb1 into a specific minor ginsenoside using Aspergillus niger KCCM 11239, as well as the identification of the transformed products and the pathway via thin layer chromatography and high performance liquid chromatography were evaluated to develop a new biologically active material. The conversion of ginsenoside Rb1 generated Rd, Rg3, Rh2, and compound K although the reaction rates were low due to the low concentration. In enzymatic conversion, all of the ginsenoside Rb1 was converted to ginsenoside Rd and ginsenoside Rg3 after 24 h of incubation. The crude enzyme (?-glucosidase) from A. niger KCCM 11239 hydrolyzed the ?-(1?6)-glucosidic linkage at the C-20 of ginsenoside Rb1 to generate ginsenoside Rd and ginsenoside Rg3. Our experimental demonstration showing that A. niger KCCM 11239 produces the ginsenoside-hydrolyzing ?-glucosidase reflects the feasibility of developing a specific bioconversion process to obtain active minor ginsenosides. PMID:24558310

Chang, Kyung Hoon; Jo, Mi Na; Kim, Kee-Tae; Paik, Hyun-Dong

2013-01-01

315

Influence of dissolved oxygen concentration on intracellular pH for regulation of Aspergillus niger growth rate during citric acid fermentation in a stirred tank bioreactor.  

PubMed

In this paper we report the regulation of Aspergillus niger growth rate during citric acid fermentation in a stirred tank bioreactor. For this, the influence of dissolved oxygen concentration in a medium on intracellular pH values and consequently on overall microbial metabolism was emphasized. Intracellular pH of mycelium grown under different concentrations of dissolved oxygen in the medium was determined. Sensitivity of proteins toward proton concentration is well recognized, therefore pH influences on the activities of key regulatory enzymes of Aspergillus niger were determined at pH values similar to those detected in the cells grown under lower dissolved oxygen concentrations. The results have shown significantly reduced specific activities of hexokinase, 6-phosphofructokinase and glucose-6-phosphate dehydrogenase in more acidic environment, while pyruvate kinase was found to be relatively insensitive towards higher proton concentration. As expected, due to the reduced specific activities of regulatory enzymes under more acidic conditions, overall metabolism should be hindered in the medium with lower dissolved oxygen concentration which was confirmed by detecting the reduced specific growth rates. From the studies, we conclude that dissolved oxygen concentration affects the intracellular pH and thus growth rate of Aspergillus niger during the fermentation process. PMID:15951848

Haq, Ikram-Ul; Ali, Sikander; Qadeer, M A

2005-01-01

316

Improvement of the Optimum pH of Aspergillus niger Xylanase towards an Alkaline pH by Site-Directed Mutagenesis.  

PubMed

In an attempt to shift the optimal pH of the xylanase B (XynB) from Aspergillus niger towards alkalinity, target mutation sites were selected by alignment between Aspergillus niger xylanase B and other xylanases that have alkalophilic pH optima that highlight charged residues in the eight-residues-longer loop in the alkalophilic xylanase. Multiple engineered XynB mutants were created by site-directed mutagenesis with substitutions Q164K and Q164K+D117N. The variant XynB-117 had the highest optimum pH (at 5.5), which corresponded to a basic 0.5 pH unit shift when compared with the wild-type enzyme. However, the optimal pH of the XynB- 164 mutation was not changed, similar to the wild type. These results suggest that the residues at positions 164 and 117 in the eight-residues-longer loop and the cleft's edge are important in determining the pH optima of XynB from Aspergillus niger. PMID:25152057

Li, Fei; Xie, Jingcong; Zhang, Xuesong; Zhao, Linguo

2015-01-28

317

Identification and characterisation of eroA and ervA, encoding two putative thiol oxidases from Aspergillus niger.  

PubMed

The oxidative folding of proteins in the secretory pathway involves the formation and isomerisation of disulphide bonds and is catalysed by foldases in the lumen of the endoplasmic reticulum (ER). The transfer of reducing equivalents, from disulphide bond formation, to oxygen involves the participation of thiol oxidases. Here, we describe the identification and functional characterisation of the eroA and ervA genes from Aspergillus niger, encoding functional orthologues of S. cerevisiae ERO1 and ERV2, respectively. The eroA gene encodes a product of 600 amino acids, EroA, and the ervA gene encodes a product of 215 amino acids, ErvA, both of which share common motifs and features with their S. cerevisiae orthologues. In contrast to Ero1p in S. cerevisiae, A. niger EroA appears to be retained in the ER lumen by a C-terminal retention motif. Real-time PCR analysis indicated that eroA is transcriptionally up-regulated in response to ER stress, whereas ervA is slightly down-regulated in response to DTT stress yet up-regulated in response to expression of a heterologous protein. Gene disruption studies indicated that, unlike ervA, eroA is essential for viability. When expressed in the thermosensitive S. cerevisiae ero1-1 strain, both eroA and ervA were able to complement the temperature and DTT sensitive phenotype, although a truncated eroA, missing the putative HEEL ER-retention signal was unable to complement as well as the full-length eroA gene. PMID:20438816

Harvey, Anna R; Ward, Michael; Archer, David B

2010-08-01

318

GpdA-promoter-controlled production of glucose oxidase by recombinant Aspergillus niger using nonglucose carbon sources.  

PubMed

The gpdA-promoter-controlled exocellular production of glucose oxidase (GOD) by recombinant Aspergillus niger NRRL-3 (GOD3-18) during growth on glucose and nonglucose carbon sources was investigated. Screening of various carbon substrates in shake-flask cultures revealed that exocellular GOD activities were not only obtained on glucose but also during growth on mannose, fructose, and xylose. The performance of A. niger NRRL-3 (GOD3-18) using glucose, fructose, or xylose as carbon substrate was compared in more detail in bioreactor cultures. These studies revealed that gpdA-promoter-controlled GOD synthesis was strictly coupled to cell growth. The gpdA-promoter was most active during growth on glucose. However, the unfavorable rapid GOD-catalyzed transformation of glucose into gluconic acid, a carbon source not supporting further cell growth and GOD production, resulted in low biomass yields and, therefore, reduced the advantageous properties of glucose. The total (endo- and exocellular) specific GOD activities were lowest when growth occurred on fructose (only a third of the activity that was obtained on glucose), whereas utilization of xylose resulted in total specific GOD activities nearly as high as reached during growth on glucose. Also, the portion of GOD excreted into the culture fluid reached similar high levels (approximately equal to 90%) by using either glucose or xylose as substrate, whereas growth on fructose resulted in a more pelleted morphology with more than half the total GOD activity retained in the fungal biomass. Finally, growth on xylose resulted in the highest biomass yield and, consequently, the highest total volumetric GOD activity. These results show that xylose is the most favorable carbon substrate for gpdA-promoter-controlled production of exocellular GOD. PMID:11257807

el-Enshasy, H; Hellmuth, K; Rinas, U

2001-01-01

319

Chitinases CtcB and CfcI modify the cell wall in sporulating aerial mycelium of Aspergillus niger.  

PubMed

Sporulation is an essential part of the life cycle of the industrially important filamentous fungus Aspergillus niger. The formation of conidiophores, spore-bearing structures, requires remodelling of the fungal cell wall, as demonstrated by the differences in carbohydrate composition of cell walls of vegetative mycelium and spores. Glycoside hydrolases that are involved in this process have so far remained unidentified. Using transcriptome analysis, we have identified genes encoding putative cell-wall-modifying proteins with enhanced expression in sporulating aerial mycelium compared to vegetative mycelium. Among the most strongly induced genes were those encoding a protein consisting of a putative chitin binding module (CBM14) and the chitinolytic enzymes NagA, CfcI and CtcB. Reporter studies showed that the N-acetyl-?-hexosaminidase gene nagA was expressed both in vegetative hyphae and in aerial structures (aerial hyphae, conidiophores and conidia) upon starvation. In contrast, promoter activities of the chitinase genes ctcB and cfcI were specifically localized in the conidiophores and conidia. CtcB is an endo-chitinase and CfcI releases monomers from chitin oligosaccharides: together these enzymes have the potential to degrade chitin of the fungal cell wall. Inactivation of both the cfcI and ctcB genes affected neither radial growth rate, nor formation and germination of spores. The amount of chitin in the spore walls of a ?cfcI?ctcB double deletion strain, however, was significantly increased compared with the wild-type, thus indicating that CfcI and CtcB indeed modify the A. niger cell walls during sporulation. These novel insights in the sporulation process in aspergilli are of strong scientific relevance, and also may aid industrial strain engineering. PMID:23832003

van Munster, Jolanda M; Nitsche, Benjamin M; Krijgsheld, Pauline; van Wijk, Alle; Dijkhuizen, Lubbert; Wösten, Han A; Ram, Arthur F; van der Maarel, Marc J E C

2013-09-01

320

Pathogenicity differences of multiple isolates of Aspergillus fumigatus in turkeys.  

PubMed

Sixteen Aspergillus fumigatus isolates of environmental, mammalian, and avian origin were used to assess: 1) intra-air-sac inoculation as a viable challenge alternative to aerosol exposure, and 2) isolate variability in pathogenicity. Development of lesions, antibody response in survivors, mortality, and weight gains were assessed. Turkey poults were challenged with equal numbers of viable conidia. Total number of conidia given per experimental group varied markedly and did not influence mortality. Antibody response as measured by the enzyme-linked immunosorbent assay and agar gel immunodiffusion test was erratic, although most poults with high antibody scores had marked lesions and low weight. Lesions were characterized by necrogranulomatous pneumonia and airsacculitis with marked visceral involvement. The source of the isolate was not a factor in mortality, although this was biased by the high numbers of isolates from birds with aspergillosis. The single environmental isolate produced no mortality. PMID:1417585

Peden, W M; Rhoades, K R

1992-01-01

321

Production and characterization of in planta transiently produced polygalacturanase from Aspergillus niger and its fusions with hydrophobin or ELP tags  

PubMed Central

Background Pectinases play an important role in plant cell wall deconstruction and have potential in diverse industries such as food, wine, animal feed, textile, paper, fuel, and others. The demand for such enzymes is increasing exponentially, as are the efforts to improve their production and to implement their use in several industrial processes. The goal of this study was to examine the potential of producing polygalacturonase I from Aspergillus niger in plants and to investigate the effects of subcellular compartmentalization and protein fusions on its accumulation and activity. Results Polygalacturonase I from Aspergillus niger (AnPGI) was transiently produced in Nicotiana benthamiana by targeting it to five different cellular compartments: apoplast, endoplasmic reticulum (ER), vacuole, chloroplast and cytosol. Accumulation levels of 2.5%, 3.0%, and 1.9% of total soluble protein (TSP) were observed in the apoplast, ER, and vacuole, respectively, and specific activity was significantly higher in vacuole-targeted AnPGI compared to the same enzyme targeted to the ER or apoplast. No accumulation was found for AnPGI when targeted to the chloroplast or cytosol. Analysis of AnPGI fused with elastin-like polypeptide (ELP) revealed a significant increase in the protein accumulation level, especially when targeted to the vacuole where the protein doubles its accumulation to 3.6% of TSP, while the hydrophobin (HFBI) fusion impaired AnPGI accumulation and both tags impaired activity, albeit to different extents. The recombinant protein showed activity against polygalacturonic acid with optimum conditions at pH 5.0 and temperature from 30 to 50°C, depending on its fusion. In vivo analysis of reducing sugar content revealed a higher release of reducing sugars in plant tissue expressing recombinant AnPGI compared to wild type N. benthamiana leaves. Conclusion Our results demonstrate that subcellular compartmentalization of enzymes has an impact on both the target protein accumulation and its activity, especially in the case of proteins that undergo post-translational modifications, and should be taken into consideration when protein production strategies are designed. Using plants to produce heterologous enzymes for the degradation of a key component of the plant cell wall could reduce the cost of biomass pretreatment for the production of cellulosic biofuels. PMID:24970673

2014-01-01

322

Carob pod: A new substrate for citric acid production by Aspergillus niger  

Microsoft Academic Search

The production of citric acid from carob pod extract byA. niger in surface fermentation was investigated. A maximum citric acid concentration (85.5 g\\/L), citric acid productivity (4.07\\u000a g\\/L\\/d), specific citric acid production rate (0.18 g\\/g\\/d), and specific sugar uptake rate (0.358 g\\/g\\/d) was achieved at an\\u000a initial sugar concentration of 200 g\\/L, pH of 6.5, and a temperature of 30°C.

Triantafyllos Roukas

1998-01-01

323

Probing the determinants of substrate specificity of a feruloyl esterase, AnFaeA, from Aspergillus niger.  

PubMed

Feruloyl esterases hydrolyse phenolic groups involved in the cross-linking of arabinoxylan to other polymeric structures. This is important for opening the cell wall structure making material more accessible to glycoside hydrolases. Here we describe the crystal structure of inactive S133A mutant of type-A feruloyl esterase from Aspergillus niger (AnFaeA) in complex with a feruloylated trisaccharide substrate. Only the ferulic acid moiety of the substrate is visible in the electron density map, showing interactions through its OH and OCH(3) groups with the hydroxyl groups of Tyr80. The importance of aromatic and polar residues in the activity of AnFaeA was also evaluated using site-directed mutagenesis. Four mutant proteins were heterologously expressed in Pichia pastoris, and their kinetic properties determined against methyl esters of ferulic, sinapic, caffeic and p-coumaric acid. The k(cat) of Y80S, Y80V, W260S and W260V was drastically reduced compared to that of the wild-type enzyme. However, the replacement of Tyr80 and Trp260 with smaller residues broadened the substrate specificity of the enzyme, allowing the hydrolysis of methyl caffeate. The role of Tyr80 and Trp260 in AnFaeA are discussed in light of the three-dimensional structure. PMID:16128806

Faulds, Craig B; Molina, Rafael; Gonzalez, Ramón; Husband, Fiona; Juge, Nathalie; Sanz-Aparicio, Julia; Hermoso, Juan A

2005-09-01

324

Production of pectinase from deseeded sunflower head by Aspergillus niger in submerged and solid-state conditions.  

PubMed

Studies were carried out on the production of pectinases using deseeded sunflower head by Aspergillus niger DMF 27 and DMF 45 in submerged fermentation (SmF) and solid-state fermentation (SSF). Higher titres of endo- and exo-pectinases were observed when medium was supplemented with carbon (4% glucose for SmF and 6% sucrose for SSF) and nitrogen (ammonium sulphate, 0.3% for both SmF and SSF) sources. Green gram husk proved to be relatively a better supplement to attain higher yield of endo-pectinase (11.7 U/g) and exo-pectinase (30.0 U/g) in solid-state conditions. Maximum production of endo-pectinase (19.8 U/g) and exo-pectinase (45.9 U/g) by DMF 45 were recorded in SSF when compared to endo-pectinase (18.9 U/ml) and exo-pectinase (30.3 U/ml) by DMF 27 in SmF under optimum process conditions. PMID:16263274

Patil, Sarvamangala R; Dayanand, A

2006-11-01

325

Effect of different cultural conditions for phytase production by Aspergillus niger CFR 335 in submerged and solid-state fermentations.  

PubMed

The present article deals with the studies on the effect of media ingredients, such as carbon, nitrogen, inorganic phosphates, surfactants, and metal salts, on phytase enzyme production by Aspergillus niger CFR 335 in submerged (SmF) and solid-state fermentations (SSF). The results obtained showed a 1.5-fold higher enzyme yield in the presence of sucrose in both SmF and SSF, while peptone was found to be a favorable nitrogen source for SmF. Sodium dihydrogen phosphate (NaH(2)PO(4)) favored 34% higher enzyme yield than the control, which was followed by 19% higher activity in potassium dihydrogen phosphate (KH(2)PO(4)) in SSF at 0.015% w/v. The addition of Tween-20 in SmF showed a maximum yield of 12.6 U/mL while, SDS suppressed the growth of the fungus. None of the surfactants favored the enzyme yield in SSF. Calcium chloride (CaCl(2)) was extensively efficient in stimulating more than 55% higher phytase production in SmF at 0.01% v/v. In SSF, none of the metal salts stimulated phytase production. PMID:18663503

Gunashree, B S; Venkateswaran, G

2008-12-01

326

Effect of oxygen enrichment on morphology, growth, and heterologous protein production in chemostat cultures of Aspergillus niger B1-D.  

PubMed

The response of steady state chemostat cultures of a recombinant Aspergillus niger (B1-D), secreting both a heterologous enzyme (Hen Egg White Lysozyme [HEWL]) and a native enzyme (Glucoamylase), to varying levels of O2 enrichment of the process gas was evaluated. Formation of both the native and the foreign enzyme increased with increasing O2 supply. Conversely, biomass levels and total extracellular protein levels were generally not increased under O2 enriched conditions. Two distinct micromorphologies were apparent in these cultures, one, typically seen under O2 limiting conditions (i. e. at 0 and 10% enrichment levels), tended to be represented by long, sparsely branched hyphal elements, with low percentages of "active" length (i. e. how much of the hypha is cytoplasm filled); whilst, a second micromorphology, typical of O2 enriched cultures at 30 and 50% O2 enrichment, was represented by shorter hyphal elements, with more branching and a higher % "active" length. At these higher O2 levels, formation of a yellow pigment occurred, and signs of culture autolysis were noted. At 50% enrichment, a "stranded" aggregate morphology was apparent, possibly as a response to a hyperoxidant state. Production of both the native enzyme and HEWL correlated well with a simple morphological measure (tip number) or, with % "active" length. It is proposed the morphological changes noted in the cultures were associated with the increased production of both HEWL and glucoamylase. PMID:10506417

Wongwicharn, A; McNeil, B; Harvey, L M

1999-11-20

327

Optimization of date syrup for enhancement of the production of citric acid using immobilized cells of Aspergillus niger.  

PubMed

Date syrup as an economical source of carbohydrates and immobilized Aspergillus niger J4, which was entrapped in calcium alginate pellets, were employed for enhancing the production of citric acid. Maximum production was achieved by pre-treating date syrup with 1.5% tricalcium phosphate to remove heavy metals. The production of citric acid using a pretreated medium was 38.87% higher than an untreated one that consumed sugar. The appropriate presence of nitrogen, phosphate and magnesium appeared to be important in order for citric acid to accumulate. The production of citric acid and the consumed sugar was higher when using 0.1% ammonium nitrate as the best source of nitrogen. The production of citric acid increased significantly when 0.1 g/l of KH2PO4 was added to the medium of date syrup. The addition of magnesium sulfate at the rate of 0.20 g/l had a stimulating effect on the production of citric acid. Maximum production of citric acid was obtained when calcium chloride was absent. One of the most important benefits of immobilized cells is their ability and stability to produce citric acid under a repeated batch culture. Over four repeated batches, the production of citric acid production was maintained for 24 days when each cycle continued for 144 h. The results obtained in the repeated batch cultivation using date syrup confirmed that date syrup could be used as a medium for the industrial production of citric acid. PMID:23961184

Mostafa, Yasser S; Alamri, Saad A

2012-04-01

328

Cloning and functional expression of an acidophilic ?-mannanase gene (Anman5A) from Aspergillus niger LW-1 in Pichia pastoris.  

PubMed

A cDNA fragment of the Anman5A, a gene that encodes an acidophilic ?-mannanase of Aspergillus niger LW-1 (abbreviated as AnMan5A), was cloned and functionally expressed in Pichia pastoris . Homology alignment of amino acid sequences verified that the AnMan5A belongs to the glycoside hydrolase (GH) family 5. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) assay demonstrated that the recombinant AnMan5A (reAnMan5A), a N-glycosylated protein with an apparent molecular weight of 52.0 kDa, was secreted into the medium. The highest reAnMan5A activity expressed by one P. pastoris transformant, labeled as GSAnMan4-12, reached 29.0 units/mL. The purified reAnMan5A displayed the highest activity at pH 3.5 and 70 °C. It was stable at a pH range of 3.0-7.0 and at a temperature of 60 °C or below. Its activity was not significantly affected by an array of metal ions and ethylenediaminetetraacetic acid (EDTA). The K(m) and V(max) of the reAnMan5A, toward locust bean gum, were 1.10 mg/mL and 266.7 units/mg, respectively. PMID:22225502

Li, Jian-Fang; Zhao, Shun-Ge; Tang, Cun-Duo; Wang, Jun-Qing; Wu, Min-Chen

2012-01-25

329

Immobilization of Aspergillus niger F7-02 Lipase in Polysaccharide Hydrogel Beads of Irvingia gabonensis Matrix.  

PubMed

The potential of polysaccharide Irvingia gabonensis matrix as enzyme immobilization support was investigated. Lipase of Aspergillus niger F7-02 was immobilized by entrapment using glutaraldehyde as the cross-linking agent and stabilized in ethanolic-formaldehyde solution. The pH and temperature stability and activity yield of the immobilized enzyme were determined. Such parameters as enzyme load, bead size, number of beads, and bead reusability were also optimized. Adequate gel strength to form stabilized beads was achieved at 15.52% (w/v) Irvingia gabonensis powder, 15% (v/v) partially purified lipase, 2.5% (v/v) glutaraldehyde, and 3?:?1 (v/v) ethanolic-formaldehyde solution. There was 3.93-fold purification when the crude enzyme was partially purified in two-step purification using Imarsil and activated charcoal. Optimum lipase activity 75.3?Ug(-1) was achieved in 50?mL test solution containing 15 beads of 7?mm bead size. Relative activity 80% was retained at eight repeated cycles. The immobilization process gave activity yield of 59.1% with specific activity of 12.3?Umg(-1) and stabilized at optimum pH 4.5 and temperature 55°C. Thus the effectiveness and cost-efficiency of I. gabonensis as a polymer matrix for lipase immobilization have been established. PMID:25614829

Kareem, Safaradeen Olateju; Adio, Olayinka Quadri; Osho, Michael Bamitale

2014-01-01

330

Characterization and constitutive expression of a novel endo-1,4-?-D-xylanohydrolase from Aspergillus niger in Pichia pastoris.  

PubMed

A putative endo-1,4-?-D-xylanohydrolase gene xyl10 from Aspergillus niger, encoding a 308-residue mature xylanase belonging to glycosyl hydrolase family 10, was constitutively expressed in Pichia pastoris. The recombinant Xyl10 exhibited optimal activity at pH 5.0 and 60 °C with more than 50 % of the maximum activity from 40 to 70 °C. It retained more than 90 % of the original activity after incubation at 60 °C (pH 5.0) for 30 min and more than 74 % after incubation at pH 3.0-13.0 for 2 h (25 °C). The specific activity, K m and V max values for purified Xyl10 were, respectively, 3.2 × 10(3) U mg(-1), 3.6 mg ml(-1) and 5.4 × 10(3) ?mol min(-1 )mg(-1) towards beechwood xylan. The enzyme degraded xylan to a series of xylooligosaccharides and xylose. The recombinant enzyme with these properties has the potential for various industrial applications. PMID:23690032

Zheng, Jia; Guo, Ning; Wu, Lishuang; Tian, Jian; Zhou, Hongbo

2013-09-01

331

Immobilization of Aspergillus niger F7-02 Lipase in Polysaccharide Hydrogel Beads of Irvingia gabonensis Matrix  

PubMed Central

The potential of polysaccharide Irvingia gabonensis matrix as enzyme immobilization support was investigated. Lipase of Aspergillus niger F7-02 was immobilized by entrapment using glutaraldehyde as the cross-linking agent and stabilized in ethanolic-formaldehyde solution. The pH and temperature stability and activity yield of the immobilized enzyme were determined. Such parameters as enzyme load, bead size, number of beads, and bead reusability were also optimized. Adequate gel strength to form stabilized beads was achieved at 15.52% (w/v) Irvingia gabonensis powder, 15% (v/v) partially purified lipase, 2.5% (v/v) glutaraldehyde, and 3?:?1 (v/v) ethanolic-formaldehyde solution. There was 3.93-fold purification when the crude enzyme was partially purified in two-step purification using Imarsil and activated charcoal. Optimum lipase activity 75.3?Ug?1 was achieved in 50?mL test solution containing 15 beads of 7?mm bead size. Relative activity 80% was retained at eight repeated cycles. The immobilization process gave activity yield of 59.1% with specific activity of 12.3?Umg?1 and stabilized at optimum pH 4.5 and temperature 55°C. Thus the effectiveness and cost-efficiency of I. gabonensis as a polymer matrix for lipase immobilization have been established.

Kareem, Safaradeen Olateju; Adio, Olayinka Quadri; Osho, Michael Bamitale

2014-01-01

332

Production of phytase (myo-inositolhexakisphosphate phosphohydrolase) by Aspergillus niger van Teighem in laboratory-scale fermenter.  

PubMed

The growth and production pattern of phytase by a filamentous fungus, Aspergillus niger van Teighem, were studied in submerged culture at varying agitation rates and controlled and uncontrolled pH conditions. Allowing the initial culture to grow under neutral condition with subsequent decline in pH resulted in increased phytase productivity. A maximum of 141 nkat/mL phytase was obtained when the broth pH was maintained at pH 2.5 as compared to 17 nkat/mL units at controlled pH 5.5. The culture morphology and rheological properties of the fermentation broth significantly varied with the agitation rate. The volumetric oxygen transfer coefficient was determined at different phases of fungal growth during batch fermentation using static gassing out and dynamic gassing out methods. The oxygen transfer coefficient (k(L)a) of the fermenter was found to be 125 h(-)(1) at 500 rpm as compared to 38 h(-)(1) at 200 rpm. The oxygen transfer rates at different phases of growth were significantly affected by cell mass concentration and fungal morphology. During the course of fermentation there was a gradual decline of k(L)a from 97 h(-)(1) on day 2 to 63 h(-)(1) on day 6 of fermentation, after which no significant change was observed. The degree of agitation considerably influenced the culture morphology where shear thinning of filamentous fungus was observed with the increase in agitation. PMID:15176876

Vats, Purva; Sahoo, D K; Banerjee, U C

2004-01-01

333

The Transcriptomic Signature of RacA Activation and Inactivation Provides New Insights into the Morphogenetic Network of Aspergillus niger  

PubMed Central

RacA is the main Rho GTPase in Aspergillus niger regulating polarity maintenance via controlling actin dynamics. Both deletion and dominant activation of RacA (RacG18V) provoke an actin localization defect and thereby loss of polarized tip extension, resulting in frequent dichotomous branching in the ?racA strain and an apolar growing phenotype for RacG18V. In the current study the transcriptomics and physiological consequences of these morphological changes were investigated and compared with the data of the morphogenetic network model for the dichotomous branching mutant ramosa-1. This integrated approach revealed that polar tip growth is most likely orchestrated by the concerted activities of phospholipid signaling, sphingolipid signaling, TORC2 signaling, calcium signaling and CWI signaling pathways. The transcriptomic signatures and the reconstructed network model for all three morphology mutants (?racA, RacG18V, ramosa-1) imply that these pathways become integrated to bring about different physiological adaptations including changes in sterol, zinc and amino acid metabolism and changes in ion transport and protein trafficking. Finally, the fate of exocytotic (SncA) and endocytotic (AbpA, SlaB) markers in the dichotomous branching mutant ?racA was followed, demonstrating that hyperbranching does not per se result in increased protein secretion. PMID:23894378

Kwon, Min Jin; Nitsche, Benjamin M.; Arentshorst, Mark; Jørgensen, Thomas R.; Ram, Arthur F. J.; Meyer, Vera

2013-01-01

334

Optimization of Acid Protease Production by Aspergillus niger I1 on Shrimp Peptone Using Statistical Experimental Design  

PubMed Central

Medium composition and culture conditions for the acid protease production by Aspergillus niger I1 were optimized by response surface methodology (RSM). A significant influence of temperature, KH2PO4, and initial pH on the protease production was evaluated by Plackett-Burman design (PBD). These factors were further optimized using Box-Behnken design and RSM. Under the proposed optimized conditions, the experimental protease production (183.13?U?mL?1) closely matched the yield predicted by the statistical model (172.57?U?mL?1) with R2 = 0.914. Compared with the initial M1 medium on which protease production was 43.13?U?mL?1, a successful and significant improvement by 4.25 folds was achieved in the optimized medium containing (g/L): hulled grain of wheat (HGW) 5.0; KH2PO4 1.0; NaCl 0.3; MgSO4(7H2O) 0.5; CaCl2 (7H2O) 0.4; ZnSO4 0.1; Na2HPO4 1.6; shrimp peptone (SP) 1.0. The pH was adjusted at 5 and the temperature at 30°C. More interestingly, the optimization was accomplished using two cheap and local fermentation substrates, HGW and SP, which may result in a significant reduction in the cost of medium constituents. PMID:22593695

Siala, Rayda; Frikha, Fakher; Mhamdi, Samiha; Nasri, Moncef; Sellami Kamoun, Alya

2012-01-01

335

The Three-Dimensional Structure of Aspergillus niger Pectin Lyase B at 1.7-? Resolution1  

PubMed Central

The three-dimensional structure of Aspergillus niger pectin lyase B (PLB) has been determined by crystallographic techniques at a resolution of 1.7 ?. The model, with all 359 amino acids and 339 water molecules, refines to a final crystallographic R factor of 16.5%. The polypeptide backbone folds into a large right-handed cylinder, termed a parallel ? helix. Loops of various sizes and conformations protrude from the central helix and probably confer function. The largest loop of 53 residues folds into a small domain consisting of three antiparallel ? strands, one turn of an ? helix, and one turn of a 310 helix. By comparison with the structure of Erwinia chrysanthemi pectate lyase C (PelC), the primary sequence alignment between the pectate and pectin lyase subfamilies has been corrected and the active site region for the pectin lyases deduced. The substrate-binding site in PLB is considerably less hydrophilic than the comparable PelC region and consists of an extensive network of highly conserved Trp and His residues. The PLB structure provides an atomic explanation for the lack of a catalytic requirement for Ca2+ in the pectin lyase family, in contrast to that found in the pectate lyase enzymes. Surprisingly, however, the PLB site analogous to the Ca2+ site in PelC is filled with a positive charge provided by a conserved Arg in the pectin lyases. The significance of the finding with regard to the enzymatic mechanism is discussed. PMID:9449837

Vitali, Jacqueline; Schick, Brian; Kester, Harry C.M.; Visser, Jaap; Jurnak, Frances

1998-01-01

336

Comparison of the EUCAST-AFST broth dilution method with the CLSI reference broth dilution method (M38-A) for susceptibility testing of posaconazole and voriconazole against Aspergillus spp  

Microsoft Academic Search

The susceptibilities of 40 clinical isolates of Aspergillus spp. (Aspergillus fumigatus, Aspergillus flavus, Aspergillus niger, Aspergillus terreus) were determined for posaconazole and voriconazole by the CLSI M38-A and EUCAST-AFST broth dilution methods. Where a discrepancy was observed between the methods, the EUCAST method tended to give higher MIC values. Overall, the level of agreement was 92.5% and the intra-class correlation

E. Chryssanthou; M. Cuenca-Estrella

2006-01-01

337

Kinetic characterization of glucose aerodehydrogenase from Aspergillus niger EMS-150-F after optimizing the dose of mutagen for enhanced production of enzyme  

PubMed Central

In the present study enhanced production of glucose aerodehydrogenase from Aspergillus niger has been achieved after optimizing the dose of chemical mutagen ethyl methane sulfonate (EMS) that has not been reported earlier. Different doses of mutagen were applied and a strain was developed basing upon the best production. The selected strain Aspergillus niger EMS-150-F was optimized for nutrient requirements in order to produce enzyme through fermentation and the results showed the best yield at 2% corn steep liquor (CSL), 36 hours fermentation time, pH 5, 30°C temperature, 0.3% KH2PO4, 0.3% urea and 0.06% CaCO3. The enzyme was then purified and resulted in 57.88 fold purification with 52.12% recovery. On kinetic characterization, the enzyme showed optimum activity at pH 6 and temperature 30°C. The Michaelis-Menton constants (Km, Vmax, Kcat and Kcat/Km) were 20 mM, 45.87 U mL?1, 1118.81 s?1 and 55.94 s?1 mM?1, respectively. The enzyme was found to be thermaly stable and the enthalpy and free energy showed an increase with increase in temperature and ?S* was highly negative proving the enzyme from A. niger EMS-150-F resistant to temperature and showing a very little disorderliness. PMID:24688499

Umbreen, Huma; Zia, Muhammad Anjum; Rasul, Samreen

2013-01-01

338

Induction, production, repression, and de-repression of exoglucanase synthesis in Aspergillus niger.  

PubMed

The influence of carbon and nitrogen sources on the production of cellulases was investigated. The enzyme production was variable according to the carbon source. Levels of beta-cellobiohydrolase (CBH) were minimal in the presence of even low concentrations of glucose. Enzyme production was stimulated by other carbohydrates. The enzyme is subject to carbon source control by easily metabolizable sugars. Wheat bran and cellulose were the most effective promoters of beta-cellobiohydrolase and filter paperase (FPase) activities respectively, followed by rice bran. Exogenously supplied glucose inhibited the synthesis of the enzyme in cultures of A. niger growing on wheat bran. In defined medium with cellobiose, the cellobiohydrolase titres were 2- to 110-fold higher with cells growing on monomeric sugars and 1.5 times higher than cells growing on other disaccharides. It appeared that synthesis of beta-cellobiohydrolase varied under an induction mechanism, and a repression mechanism which changed the rate of synthesis of beta-cellobiohydrolase and FPase in induced over non-induced cultures. In this organism, substantial synthesis of beta-cellobiohydrolase can be induced by cellobiose, cellodextrin, cellulose or cellulose and hemi-cellulose containing substrates which showed low volumetric substrate uptake rate. The organism required limiting concentration of carbon, nitrogen or phosphorous for production of beta-cellobiohydrolase and FPase. During growth of A. niger on wheat bran, maximum volumetric productivities (Qp) of beta-cellobiohydrolase and FPase were 39.6 and 32.5 IU/lh and were significantly higher than the values reported for some other potent fungi and bacteria. The addition of actinomycin D (a repressor of transcription) and cycloheximide, (a repressor of translation) completely repressed CBH/FPase biosynthesis, suggested that the regulation of CBH synthesis in this organism occurs at both transcriptional and translational level. Thermodynamic studies revealed that the culture exerted protection against thermal inactivation when exposed to different fermentation temperatures. PMID:15182839

Hanif, Atif; Yasmeen, Amber; Rajoka, M I

2004-09-01

339

Isolation and Identification of Indigenous Aspergillus oryzae for Saccharification of Rice Starch  

Microsoft Academic Search

A study was undertaken to isolate an indigenous Aspergillus oryzae strain for use in saccharification of high amylose rice starch. Bread, black gram, soya grains, 'kevum', and cooked rice samples assumed to be contaminated with Aspergillus oryzae were used in the isolation. Ten pure cultures obtained by culturing and sub- culturing on Potato Dextrose Agar (PDA) were maintained on PDA

S. S. Sooriyamoorthy; K. F. S. T. Silva; M. H. W. Gunawardhane; C. K. Illeperuma

340

The Aspergillus niger transcriptional activator XlnR, which is involved in the degradation of the polysaccharides xylan and cellulose, also regulates D-xylose reductase gene expression.  

PubMed

Screening of an Aspergillus niger differential cDNA library, constructed by subtracting cDNA fragments of a xlnR loss-of-function mutant from wild-type cDNA fragments, resulted in the cloning of the gene encoding D-xylose reductase (xyrA). Northern blot analysis using an A. niger wild-type strain, a xlnR multiple-copy strain and a xlnR loss-of-function mutant confirmed that the xyrA gene is regulated by XlnR, the transcriptional activator of the xylanolytic enzyme system in A. niger. D-xylose reductase catalyses the NADPH-dependent reduction of D-xylose to xylitol, which is the first step in D-xylose catabolism in fungi. Until now, XlnR was shown to control the transcription of genes encoding extracellular hydrolytic enzymes involved in cellulose and xylan degradation. In the present study, we show that A. niger is able to harmonize its sugar metabolism and extracellular xylan degradation via XlnR by regulating the expression of XyrA. PMID:10760176

Hasper, A A; Visser, J; de Graaff, L H

2000-04-01

341

Overexpression of the Aspergillus niger GatA transporter leads to preferential use of D-galacturonic acid over D-xylose  

PubMed Central

Pectin is a structural heteropolysaccharide of the primary cell walls of plants and as such is a significant fraction of agricultural waste residues that is currently insufficiently used. Its main component, D-galacturonic acid, is an attractive substrate for bioconversion. The complete metabolic pathway is present in the genome of Aspergillus niger, that is used in this study. The objective was to identify the D-galacturonic acid transporter in A. niger and to use this transporter to study D-galacturonic acid metabolism. We have functionally characterized the gene An14g04280 that encodes the D-galacturonic acid transporter in A. niger. In a mixed sugar fermentation it was found that the An14g04280 overexpression strain, in contrast to the parent control strain, has a preference for D-galacturonic acid over D-xylose as substrate. Overexpression of this transporter in A. niger resulted in a strong increase of D-galacturonic acid uptake and induction of the D-galacturonic acid reductase activity, suggesting a metabolite controlled regulation of the endogenous D-galacturonic acid catabolic pathway. PMID:25177540

2014-01-01

342

Mapping N-linked Glycosylation Sites in the Secretome and Whole Cells of Aspergillus niger Using Hydrazide Chemistry and Mass Spectrometry  

SciTech Connect

Protein glycosylation is known to play an essential role in both cellular functions and the secretory pathways; however, little information is available on the dynamics of glycosylated N-linked glycosites of fungi. Herein we present the first extensive mapping of glycosylated N-linked glycosites in industrial strain Aspergillus niger by applying an optimized solid phase enrichment of glycopeptide protocol using hydrazide modified magnetic beads. The enrichment protocol was initially optimized using mouse plasma and A. niger secretome samples, which was then applied to profile N-linked glycosites from both the secretome and whole cell lysates of A. niger. A total of 847 unique N-linked glycosites and 330 N-linked glycoproteins were confidently identified by LC-MS/MS. Based on gene ontology analysis, the identified N-linked glycoproteins in the whole cell lysate were primarily localized in the plasma membrane, endoplasmic reticulum, golgi apparatus, lysosome, and storage vacuoles. The identified N-linked glycoproteins are involved in a wide range of biological processes including gene regulation and signal transduction, protein folding and assembly, protein modification and carbohydrate metabolism. The extensive coverage of glycosylated N-linked glycosites along with identification of partial N-linked glycosylation in those enzymes involving in different biochemical pathways provide useful information for functional studies of N-linked glycosylation and their biotechnological applications in A. niger.

Wang, Lu; Aryal, Uma K.; Dai, Ziyu; Mason, Alisa C.; Monroe, Matthew E.; Tian, Zhixin; Zhou, Jianying; Su, Dian; Weitz, Karl K.; Liu, Tao; Camp, David G.; Smith, Richard D.; Baker, Scott E.; Qian, Weijun

2012-01-01

343

Trehalose synthesis in Aspergillus niger: characterization of six homologous genes, all with conserved orthologs in related species  

PubMed Central

Background The disaccharide trehalose is a major component of fungal spores and is released upon germination. Moreover, the sugar is well known for is protective functions, e.g. against thermal stress and dehydration. The properties and synthesis of trehalose have been well investigated in the bakers’ yeast Saccharomyces cerevisiae. In filamentous fungi, such knowledge is limited, although several gene products have been identified. Results Using Aspergillus niger as a model fungus, the aim of this study was to provide an overview of all genes involved in trehalose synthesis. This fungus has three potential trehalose-6-phosphate synthase encoding genes, tpsA-C, and three putative trehalose phosphate phosphatase encoding genes, tppA-C, of which two have not previously been identified. Expression of all six genes was confirmed using real-time PCR, and conserved orthologs could be identified in related Aspergilli. Using a two-hybrid approach, there is a strong indication that four of the proteins physically interact, as has previously been shown in S. cerevisiae. When creating null mutants of all the six genes, three of them, ?tpsA, ?tppA and ?tppB, had lower internal trehalose contents. The only mutant with a pronounced morphological difference was ?tppA, in which sporulation was severely reduced with abnormal conidiophores. This was also the only mutant with accumulated levels of trehalose-6-phosphate, indicating that the encoded protein is the main phosphatase under normal conditions. Besides ?tppA, the most studied deletion mutant in this work was ?tppB. This gene encodes a protein conserved in filamentous Ascomycota. The ?tppB mutant displayed a low, but not depleted, internal trehalose content, and conidia were more susceptible to thermal stress. Conclusion A. niger contains at least 6 genes putatively involved in trehalose synthesis. Gene expressions related to germination have been quantified and deletion mutants characterized: Mutants lacking tpsA, tppA or tppB have reduced internal trehalose contents. Furthermore, tppA, under normal conditions, encodes the functional trehalose-6-phosphate-phosphatase. PMID:24725382

2014-01-01

344

The transcriptional activators AraR and XlnR from Aspergillus niger regulate expression of pentose catabolic and pentose phosphate pathway genes.  

PubMed

The pentose catabolic pathway (PCP) and the pentose phosphate pathway (PPP) are required for the conversion of pentose sugars in fungi and are linked via d-xylulose-5-phosphate. Previously, it was shown that the PCP is regulated by the transcriptional activators XlnR and AraR in Aspergillus niger. Here we assessed whether XlnR and AraR also regulate the PPP. Expression of two genes, rpiA and talB, was reduced in the ?araR/?xlnR strain and increased in the xylulokinase negative strain (xkiA1) on d-xylose and/or l-arabinose. Bioinformatic analysis of the 1 kb promoter regions of rpiA and talB showed the presence of putative XlnR binding sites. Combining all results in this study, it strongly suggests that these two PPP genes are under regulation of XlnR in A. niger. PMID:25086261

Battaglia, Evy; Zhou, Miaomiao; de Vries, Ronald P

2014-09-01

345

Customization of Aspergillus niger morphology through addition of talc micro particles.  

PubMed

The filamentous fungus A. 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. It ranges from dense spherical pellets to viscous mycelia. Various process parameters and ingredients are known to influence fungal morphology. Since optimal productivity correlates strongly with a specific morphological form, the fungal morphology often represents the bottleneck of productivity in industrial production. A straight forward and elegant approach to precisely control morphological shape is the addition of inorganic insoluble micro particles (like hydrous magnesium silicate, aluminum oxide or titanium silicate oxide) to the culture medium contributing to increased enzyme production. Since there is an obvious correlation between micro particle dependent morphology and enzyme production it is desirable to mathematically link productivity and morphological appearance. Therefore a quantitative precise and holistic morphological description is targeted. Thus, we present a method to generate and characterize micro particle dependent morphological structures and to correlate fungal morphology with productivity which possibly contributes to a better understanding of the morphogenesis of filamentous microorganisms. The recombinant strain A. niger SKAn1015 is cultivated for 72 h in a 3 L stirred tank bioreactor. By addition of talc micro particles in concentrations of 1 g/L, 3 g/L and 10 g/L prior to inoculation a variety of morphological structures is reproducibly generated. Sterile samples are taken after 24, 48 and 72 hours for determination of growth progress and activity of the produced enzyme. The formed product is the high-value enzyme ?-fructofuranosidase, an important biocatalyst for neo-sugar formation in food or pharmaceutical industry, which catalyzes among others the reaction of sucrose to glucose. Therefore, the quantification of glucose after adding sucrose implies the amount of produced ?-fructofuranosidase. Glucose quantification is made by a GOD/POD-Assay, which is modified for high-throughput analysis in 96-well micro titer plates. Fungal morphology after 72 hours is examined by microscope and characterized by digital image analysis. In doing so, particle shape factors for fungal macro morphology like Feret's diameter, projected area, perimeter, circularity, aspect ratio, roundness und solidity are calculated with the open source image processing program ImageJ. Relevant parameters are combined to a dimensionless Morphology number (Mn), which enables a comprehensive characterization of fungal morphology. The close correlation of the Morphology number and productivity are highlighted by mathematical regression. PMID:22453998

Wucherpfennig, Thomas; Lakowitz, Antonia; Driouch, Habib; Krull, Rainer; Wittmann, Christoph

2012-01-01

346

Application of a statistical design to the optimization of culture medium for ?-amylase production by Aspergillus niger ATCC 16404 grown on orange waste powder  

Microsoft Academic Search

The production optimization of ?-amylase (E.C.3.2.1.1.) from Aspergillus niger ATCC 16404 fungus is obtained with statistical experimental designs. The methodology was based on the Plackett–Burman design (N=12) [12 experiments and 11 factors in which seven are real ones (agitation, pH, starch, yeast extract, “corn steep liquor”, CaCl2, and salts: MgCl2, 6H2O, MnSO4 and FeSO4, 7H2O) and four errors]. This design

S. Djekrif-Dakhmouche; Z. Gheribi-Aoulmi; Z. Meraihi; L. Bennamoun

2006-01-01

347

The crystal structure of feruloyl esterase A from Aspergillus niger suggests evolutive functional convergence in feruloyl esterase family.  

PubMed

As a component of the array of enzymes produced by micro-organisms to deconstruct plant cell walls, feruloyl esterases hydrolyze phenolic groups involved in the cross-linking of arabinoxylan to other polymeric structures. This is important for opening the cell wall structure, making material more accessible to glycosyl hydrolases. Here, we describe the first crystal structure of the non-modular type-A feruloyl esterase from Aspergillus niger (AnFaeA) solved at 2.5A resolution. AnFaeA displays an alpha/beta hydrolase fold similar to that found in fungal lipases and different from that reported for other feruloyl esterases. Crystallographic and site-directed mutagenesis studies allow us to identify the catalytic triad (Ser133-His247-Asp194) that forms the catalytic machinery of this enzyme. The active-site cavity is confined by a lid (residues 68-80), on the analogy of lipases, and by a loop (residues 226-244) that confers plasticity to the substrate-binding site. The lid presents a high ratio of polar residues, which in addition to a unique N-glycosylation site stabilises the lid in an open conformation, conferring the esterase character to this enzyme. A putative model for bound 5,5'-diferulic acid-linked arabinoxylan has been built, pointing to the more relevant residues involved in substrate recognition. Comparison with structurally related lipases reveals that subtle amino acid and conformational changes within a highly conserved protein fold may produce protein variants endowed with new enzymatic properties, while comparison with functionally related proteins points to a functional convergence after evolutionary divergence within the feruloyl esterases family. PMID:15081808

Hermoso, Juan A; Sanz-Aparicio, Julia; Molina, Rafael; Juge, Nathalie; González, Ramón; Faulds, Craig B

2004-04-30

348

A novel immobilised design for the production of the heterologous protein lysozyme by a genetically engineered Aspergillus niger strain.  

PubMed

A novel immobilisation design for increasing the final concentration of the heterologous protein lysozyme by a genetically engineered fungus, Aspergillus niger B1, was developed. A central composition design was used to investigate different immobilised polymer types (alginate and pectate), polymer concentration [24% and 4% (w/v)], inoculum support ratios (1:2 and 1:4) and gel-inducing agent concentration [CaCl(2), 2% and 3.5% (w/v)]. Studies of the kinetics of production showed that optimum lysozyme productivity occurred after 10 days. Lysozyme production was significantly affected by polymer type, polymer concentration, and inoculum support ratio. Overall, immobilisation in Ca-pectate resulted in higher lysozyme production compared to that in Ca-alginate. Similar effects were observed when the polymer concentration was reduced. Regardless of polymer type and concentration, increasing the fungal inoculum level increased lysozyme production. A significantly higher lysozyme yield was achieved with Ca-pectate in comparison to Ca-alginate (approximately 20-23 mg l(-1) and 0.5-2 mg l(-1), respectively). The maximum lysozyme yield achieved was about 23 mg l(-1) by immobilisation in Ca-pectate 2% (w/v) with 33% (v/v) mycelium and 3.5% (w/v) gel-inducing agent (CaCl(2)). Response surface methodology was used to investigate the effect of pH and water activity (a(w)). The best medium pH was 4.5-5.0, and bead a(w) for optimum lysozyme yield was 0.94, regardless of polymer type. PMID:15480630

Parra, Roberto; Aldred, David; Magan, Naresh

2005-05-01

349

Physiological responses of chemostat cultures of Aspergillus niger (B1-D) to simulated and actual oxidative stress.  

PubMed

The physiological responses of chemostat cultures of the filamentous fungus, Aspergillus niger (B1-D) to simulated and actual oxidative stress, imposed respectively by addition of exogenous menadione (MD; a superoxide radical generating reagent) and gassing the culture with oxygen enriched air (25%, 50%, 75%, and 100% [v/v]), were examined. Changes in the levels of intracellular superoxide anions and defensive enzyme activities, such as catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx), were monitored, together with glutathione and respiratory activity in both the dynamic phase and when a new steady state was established. Culture response to MD addition was distinct from that upon exposure to enriched oxygen conditions, in that MD caused elevated levels of intracellular protein, whereas oxygen enrichment caused reduced protein content, especially at low dilution rates. An unexpectedly low level of superoxide radical was found in oxygen-enriched steady-state cultures (>/=50%) at a range of dilution rates, which was not caused by elevated SOD activity. Under these conditions, it was noted that the ratio of rotenone-insensitive/total respiration increased, suggesting increased activity of the alternative respiratory pathway. This may have had the effect of reducing the endogenous generation of superoxide radicals under oxygen rich conditions, but also may have reduced the ATP yield due to the non-proton-pumping nature of the alternative respiratory pathway. Thus, the negative culture effects noted in many studies at high oxygen levels may not simply be due to elevated endogenous superoxide generation, but could be in part due to the consequences of metabolic changes in the culture that seek to minimize superoxide generation. The dynamic culture response was characterized by rapid elevation of intracellular superoxide anions and associated protective enzymes, especially SOD, and was clearly distinct from the adaptive response just described. PMID:12673769

Bai, Zhonghu; Harvey, Linda M; McNeil, Brian

2003-06-20

350

Production of GFP and glucoamylase by recombinant Aspergillus niger: effects of fermentation conditions on fungal morphology and protein secretion.  

PubMed

The effect of filamentous fungal morphology on heterologous protein secretion was investigated using the recombinant Aspergillus niger strain AB4.1[pgpdAGLAGFP], which contained the gene coded for the GLA-GFP (glucoamylase-green fluorescence protein) fusion protein. Three culturing systems were studied to develop different morphological forms of the fungus. Free-cell cultures in conventional stirred-tank bioreactors grew in pellet form with various sizes depending on culturing conditions. Cells immobilized on cotton cloth grew in mycelial form in a rotating fibrous bed (RFB) and a static fibrous bed (SFB) bioreactors. The expression of the fusion protein was growth-associated and dependent on the fungal morphology. Immobilized cells produced 10-fold more GFP and glucoamylase than well-oxygenated free-cell pellets. In free-cell cultures, excretion of the fusion protein occurred mainly from cell autolysis, when oxygen or nutrient were depleted, whereas protein secretion took place from the beginning of the fermentation in immobilized-cell cultures. Also, protein secretion was found to be strongly dependent on morphology. Small pellets of a 1-mm size secreted 82% of GFP produced, whereas 43% of GFP remained intracellular in larger pellets of 5 mm. Complete secretion of GFP was obtained with cells immobilized on the fibrous matrix. The improvement in heterologous protein synthesis and secretion can be attributed to the filamentous mycelial morphology since protein secretion occurred predominantly at the tips of growing hyphae. Secretion of proteases occurred mainly in the stationary phase or when cell autolysis were induced by nutrient depletion and was not dependent on morphology, although immobilizing the cells also reduced protease activity. The RFB bioreactor gave the best fermentation performance because of its ability to control the cell morphology that was amenable to efficient oxygen transfer and protein secretion. PMID:16209542

Talabardon, Mylene; Yang, Shang-Tian

2005-01-01

351

Expression of Aspergillus niger IA-001 Endo-?-1,4-xylanase in Pichia pastoris and analysis of the enzymic characterization.  

PubMed

The xylanaseB (XynB) (JX560731.1) gene of Aspergillus niger IA-001 was optimized according to the codon usage of Pichia pastoris and expressed in P. pastoris GS115. The optimized XynB expression level was increased 2.8 times relative to that of the wild-type XynB, and the dual-copy XynB (optimized) expression level was increased 1.9 times relative to that of the single-copy XynB (optimized). The activity of the dual-copy XynB ((XynB-opt)2) was maximized at 15,158.23?±?45.11 U/mL after 120 h of shaking. The optimal temperature and pH of (XynB-opt)2 were 50 °C and 5.0, respectively. (XynB-opt)2 showed a high specific activity of 6,853.00?±?20.08 U/mg. IC analysis of the standard xylooligosaccharides showed that (XynB-opt)2 was an endo-xylanase with X2 as the main degradation product. (XynB-opt)2 was highly specific towards different natural xylans. After 24 h of hydrolysis, more than 90 % of the total hydrolysis products of xylan were X2 and X1, almost no X4?~?X6. In addition, the enzyme exhibited resistance to many metal ions and low pH values. The superior catalytic properties of (XynB-opt)2 suggested its great potential as an effective additive in animal feed industry. PMID:24888408

Gao, He; Yan, Ping; Zhang, Boru; Shan, Anshan

2014-08-01

352

The role of carbon starvation in the induction of enzymes that degrade plant-derived carbohydrates in Aspergillus niger.  

PubMed

Fungi are an important source of enzymes for saccharification of plant polysaccharides and production of biofuels. Understanding of the regulation and induction of expression of genes encoding these enzymes is still incomplete. To explore the induction mechanism, we analysed the response of the industrially important fungus Aspergillus niger to wheat straw, with a focus on events occurring shortly after exposure to the substrate. RNA sequencing showed that the transcriptional response after 6h of exposure to wheat straw was very different from the response at 24h of exposure to the same substrate. For example, less than half of the genes encoding carbohydrate active enzymes that were induced after 24h of exposure to wheat straw, were also induced after 6h exposure. Importantly, over a third of the genes induced after 6h of exposure to wheat straw were also induced during 6h of carbon starvation, indicating that carbon starvation is probably an important factor in the early response to wheat straw. The up-regulation of the expression of a high number of genes encoding CAZymes that are active on plant-derived carbohydrates during early carbon starvation suggests that these enzymes could be involved in a scouting role during starvation, releasing inducing sugars from complex plant polysaccharides. We show, using proteomics, that carbon-starved cultures indeed release CAZymes with predicted activity on plant polysaccharides. Analysis of the enzymatic activity and the reaction products, indicates that these proteins are enzymes that can degrade various plant polysaccharides to generate both known, as well as potentially new, inducers of CAZymes. PMID:24792495

van Munster, Jolanda M; Daly, Paul; Delmas, Stéphane; Pullan, Steven T; Blythe, Martin J; Malla, Sunir; Kokolski, Matthew; Noltorp, Emelie C M; Wennberg, Kristin; Fetherston, Richard; Beniston, Richard; Yu, Xiaolan; Dupree, Paul; Archer, David B

2014-11-01

353

Submerged conidiation and product formation by Aspergillus niger at low specific growth rates are affected in aerial developmental mutants.  

PubMed

Exposure to an aerial environment or severe nutrient limitation induces asexual differentiation in filamentous fungi. Submerged cultivation of Aspergillus niger in carbon- and energy-limited retentostat cultures both induces and fuels conidiation. Physiological and transcriptomic analyses have revealed that this differentiation strongly affects product formation. Since conidiation is inherent in the aerial environment, we hypothesized that product formation near zero growth can be influenced by affecting differentiation or development of aerial hyphae in general. To investigate this idea, three developmental mutants (?fwnA, scl-1, and scl-2 mutants) that have no apparent vegetative growth defects were cultured in maltose-limited retentostat cultures. The secondary-metabolite profile of the wild-type strain defined flavasperone, aurasperone B, tensidol B, and two so far uncharacterized compounds as associated with conidium formation, while fumonisins B(2), B(4), and B(6) were characteristic of early response to nutrient limitation by the vegetative mycelium. The developmental mutants responded differently to the severe substrate limitation, which resulted in distinct profiles of growth and product formation. fwnA encodes the polyketide synthase responsible for melanin biosynthesis during aerial differentiation, and we show that conidial melanin synthesis in submerged retentostat cultures and aurasperone B production are fwnA dependent. The scl-1 and scl-2 strains are two UV mutants generated in the ?fwnA background that displayed reduced asexual conidiation and formed sclerotium-like structures on agar plates. The reduced conidiation phenotypes of the scl-1 and scl-2 strains are reflected in the retentostat cultivation and are accompanied by elimination or severely reduced accumulation of secondary metabolites and distinctly enhanced accumulation of extracellular protein. This investigation shows that submerged conidiation and product formation of a mitosporic fungus cultured at low specific growth rates can be fundamentally affected by interfering with the genetic program for differentiation of aerial hyphae, opening new perspectives for tailoring industrial performance. PMID:21652743

Jørgensen, Thomas R; Nielsen, Kristian F; Arentshorst, Mark; Park, Joohae; van den Hondel, Cees A; Frisvad, Jens C; Ram, Arthur F

2011-08-01

354

Submerged Conidiation and Product Formation by Aspergillus niger at Low Specific Growth Rates Are Affected in Aerial Developmental Mutants ?  

PubMed Central

Exposure to an aerial environment or severe nutrient limitation induces asexual differentiation in filamentous fungi. Submerged cultivation of Aspergillus niger in carbon- and energy-limited retentostat cultures both induces and fuels conidiation. Physiological and transcriptomic analyses have revealed that this differentiation strongly affects product formation. Since conidiation is inherent in the aerial environment, we hypothesized that product formation near zero growth can be influenced by affecting differentiation or development of aerial hyphae in general. To investigate this idea, three developmental mutants (?fwnA, scl-1, and scl-2 mutants) that have no apparent vegetative growth defects were cultured in maltose-limited retentostat cultures. The secondary-metabolite profile of the wild-type strain defined flavasperone, aurasperone B, tensidol B, and two so far uncharacterized compounds as associated with conidium formation, while fumonisins B2, B4, and B6 were characteristic of early response to nutrient limitation by the vegetative mycelium. The developmental mutants responded differently to the severe substrate limitation, which resulted in distinct profiles of growth and product formation. fwnA encodes the polyketide synthase responsible for melanin biosynthesis during aerial differentiation, and we show that conidial melanin synthesis in submerged retentostat cultures and aurasperone B production are fwnA dependent. The scl-1 and scl-2 strains are two UV mutants generated in the ?fwnA background that displayed reduced asexual conidiation and formed sclerotium-like structures on agar plates. The reduced conidiation phenotypes of the scl-1 and scl-2 strains are reflected in the retentostat cultivation and are accompanied by elimination or severely reduced accumulation of secondary metabolites and distinctly enhanced accumulation of extracellular protein. This investigation shows that submerged conidiation and product formation of a mitosporic fungus cultured at low specific growth rates can be fundamentally affected by interfering with the genetic program for differentiation of aerial hyphae, opening new perspectives for tailoring industrial performance. PMID:21652743

Jørgensen, Thomas R.; Nielsen, Kristian F.; Arentshorst, Mark; Park, JooHae; van den Hondel, Cees A.; Frisvad, Jens C.; Ram, Arthur F.

2011-01-01

355

Tailoring fungal morphology of Aspergillus niger MYA 135 by altering the hyphal morphology and the conidia adhesion capacity: biotechnological applications  

PubMed Central

Current problems of filamentous fungi fermentations and their further successful developments as microbial cell factories are dependent on control fungal morphology. In this connection, this work explored new experimental procedures in order to quantitatively check the potential of some culture conditions to induce a determined fungal morphology by altering both hyphal morphology and conidia adhesion capacity. The capacity of environmental conditions to modify hyphal morphology was evaluated by examining the influence of some culture conditions on the cell wall lytic potential of Aspergillus niger MYA 135. The relative value of the cell wall lytic potential was determined by measuring a cell wall lytic enzyme activity such as the mycelium-bound ?-N-acetyl-D-glucosaminidase (Mb-NAGase). On the other hand, the quantitative value of conidia adhesion was considered as an index of its aggregation capacity. Concerning microscopic morphology, a highly negative correlation between the hyphal growth unit length (lHGU) and the specific Mb-NAGase activity was found (r?=?-0.915, P?

2013-01-01

356

Study of Spanish Grape Mycobiota and Ochratoxin A Production by Isolates of Aspergillus tubingensis and Other Members of Aspergillus Section Nigri  

Microsoft Academic Search

The native mycobiota of five grape varieties grown in Spain has been studied. Four (Bobal, Tempranillo, Garnacha, and Monastrell) were red varieties and one (Moscatel) was white. The main fungal genera isolated were Alternaria, Cladosporium, and Aspergillus. The isolation frequency of Aspergillus spp. section Nigri in contaminated samples was 82%. Ochratoxin A (OTA) production was assessed using yeast extract-sucrose broth

Angel Medina; Rufino Mateo; Laura Lopez-Ocana; Francisco Manuel Valle-Algarra; Misericordia Jimenez

2005-01-01

357

Aspergillus niger genome-wide analysis reveals a large number of novel alpha-glucan acting enzymes with unexpected expression profiles  

PubMed Central

The filamentous ascomycete Aspergillus niger is well known for its ability to produce a large variety of enzymes for the degradation of plant polysaccharide material. A major carbon and energy source for this soil fungus is starch, which can be degraded by the concerted action of ?-amylase, glucoamylase and ?-glucosidase enzymes, members of the glycoside hydrolase (GH) families 13, 15 and 31, respectively. In this study we have combined analysis of the genome sequence of A. niger CBS 513.88 with microarray experiments to identify novel enzymes from these families and to predict their physiological functions. We have identified 17 previously unknown family GH13, 15 and 31 enzymes in the A. niger genome, all of which have orthologues in other aspergilli. Only two of the newly identified enzymes, a putative ?-glucosidase (AgdB) and an ?-amylase (AmyC), were predicted to play a role in starch degradation. The expression of the majority of the genes identified was not induced by maltose as carbon source, and not dependent on the presence of AmyR, the transcriptional regulator for starch degrading enzymes. The possible physiological functions of the other predicted family GH13, GH15 and GH31 enzymes, including intracellular enzymes and cell wall associated proteins, in alternative ?-glucan modifying processes are discussed. Electronic supplementary material The online version of this article (doi:10.1007/s00438-008-0332-7) contains supplementary material, which is available to authorized users. PMID:18320228

Yuan, Xiao-Lian; van der Kaaij, Rachel M.; van den Hondel, Cees A. M. J. J.; Punt, Peter J.; van der Maarel, Marc J. E. C.; Dijkhuizen, Lubbert

2008-01-01

358

Impact of alg3 gene deletion on growth, development, pigment production, protein secretion, and functions of recombinant Trichoderma reesei cellobiohydrolases in Aspergillus niger  

SciTech Connect

ALG3 is a Family 58 glycosyltransferase enzyme involved in early N-linked glycan synthesis. Here, we investigated the effect of the alg3 gene disruption on growth, development, metabolism, and protein secretion in Aspergillus niger. The alg3 gene deletion resulted in a significant reduction of growth on complete (CM) and potato dextrose agar (PDA) media and a substantial reduction of spore production on CM. It also delayed spore germination in the liquid cultures of both CM and PDA media, but led to a significant accumulation of red pigment on both CM and liquid modified minimal medium (MM) supplemented with yeast extract. The relative abundance of 55 proteins of the total 190 proteins identified in the secretome was significantly different as a result of alg3 gene deletion. Comparison of a Trichoderma reesei cellobiohydrolase (Cel7A) heterologously expressed in A. niger parental and ?alg3 strains showed that the recombinant Cel7A expressed in the mutant background was smaller in size than that from the parental strains. This study suggests that ALG3 is critical for growth and development, pigment production, and protein secretion in A. niger. Functional analysis of recombinant Cel7A with aberrant glycosylation demonstrates the feasibility of this alternative approach to evaluate the role of N-linked glycosylation in glycoprotein secretion and function.

Dai, Ziyu; Aryal, Uma K.; Shukla, Anil K.; Qian, Weijun; Smith, Richard D.; Magnuson, Jon K.; Adney, William S.; Beckham, Gregg T.; Brunecky, Roman; Himmel, Michael E.; Decker, Stephen R.; Ju, Xiaohui; Zhang, Xiao; Baker, Scott E.

2013-09-25

359

Role of ozone in UV-C disinfection, demonstrated by comparison between wild-type and mutant conidia of Aspergillus niger.  

PubMed

This study aimed to investigate the tolerance of a melanized wild-type strain of Aspergillus niger (CON1) and its light-colored mutant (MUT1) to UV-C light and the concomitantly generated ozone. Treatments were segregated into four groups based on whether UV irradiation was used and the presence or absence of ozone: (-UV, -O3), (-UV, +O3), (+UV, -O3) and (+UV, +O3). The survival of CON1 and MUT1 conidia under +UV decreased as the exposure time increased, with CON1 showing greater resistance to UV irradiation than MUT1. Ozone induced CON1 conidium inactivation only under conditions of UV radiation exposure. While, the inactivation effect of ozone on MUT1 was always detectable regardless of the presence of UV irradiation. Furthermore, the CON1 conidial suspension showed lower UV light transmission than MUT1 when examined at the same concentration. Compared with the pigment in MUT1, the melanin in CON1 exhibited more potent radical-scavenging activity and stronger UV absorbance. These results suggested that melanin protected A. niger against UV disinfection via UV screening and free radical scavenging. The process by which UV-C disinfection induces a continual decrease in conidial survival suggests that UV irradiation and ozone exert a synergistic fungicidal effect on A. niger prior to reaching a plateau. PMID:24283963

Liu, Jing; Zhou, Lin; Chen, Ji-Hong; Mao, Wang; Li, Wen-Jian; Hu, Wei; Wang, Shu-Yang; Wang, Chun-Ming

2014-01-01

360

In Vitro Activity of the Echinocandin Antifungal Agent LY303,366 in Comparison with Itraconazole and Amphotericin B against Aspergillus spp  

Microsoft Academic Search

LY303,366 (LY) is a novel derivative of the echinocandin class of antifungal agents. The in vitro activities of LY, itraconazole (ITZ), and amphotericin B (AMB) were assessed against 60 Aspergillus isolates, including 35 isolates of A. fumigatus, eight isolates of A. terreus, eight isolates of A. flavus, eight isolates of A. niger and one isolate of A. nidulans. Four A.

KAREN L. OAKLEY; CAROLINE B. MOORE; DAVID W. DENNING

1998-01-01

361

Morphological development of Aspergillus niger in submerged citric acid fermentation as a function of the spore inoculum level. Application of neural network and cluster analysis for characterization of mycelial morphology  

Microsoft Academic Search

BACKGROUND: Although the citric acid fermentation by Aspergillus niger is one of the most important industrial microbial processes and various aspects of the fermentation appear in a very large number of publications since the 1950s, the effect of the spore inoculum level on fungal morphology is a rather neglected area. The aim of the presented investigations was to quantify the

Maria Papagianni; Michael Mattey

2006-01-01

362

Computerized study of interactions among factors and their optimization through response surface methodology for the production of tannin acyl hydrolase by Aspergillus niger PKL 104 under solid state fermentation  

Microsoft Academic Search

Optimization of five parameters (initial moisture, initial pH, incubation temperature, inoculum ratio and fermentation period), as per central composite rotable design falling under the response surface methodology, was attempted in a total of 32 experimental sets, after fitting the experimental data to the polynomial model of a suitable degree, for tannin acyl hydrolase production by Aspergillus niger PKL 104 in

P. K. Lekha; Nagin Chand; B. K. Lonsane

1994-01-01

363

NON-TOXIGENIC ASPERGILLUS FLAVUS ISOLATES FOR REDUCING AFLATOXIN IN MISSISSIPPI DELTA CORN  

Technology Transfer Automated Retrieval System (TEKTRAN)

The potential for two non-toxigenic isolates of Aspergillus flavus CT3 and K49 isolated from the Mississippi Delta to reduce aflatoxin contamination of corn was assessed in a field study. These two isolates exhibited comparable growth and aggressiveness as the toxigenic A. flavus isolate F3W4. The...

364

Selection and Identification of Fungi Isolated from Sugarcane Bagasse and their Application for Phenanthrene Removal from Soil  

Microsoft Academic Search

This work investigated the identification and selection of fungi isolated from sugarcane bagasse and their application for phenanthrene (Phe) removal from soil. Fungi were identified by PCR amplification of ITS regions as Aspergillus terrus, Aspergillus fumigatus and Aspergillus niger, Penicillium glabrum and Cladosporium cladosporioides. A primary selection of fungi was accomplished in plate, considering Phe tolerance of every strain in

D. V. CORTÉS-ESPINOSA; F. J. FERNÁNDEZ-PERRINO; A. ARANA-CUENCA; F. ESPARZA-GARCÍA; O. LOERA; R. RODRÍGUEZ-VÁZQUEZ

2006-01-01

365

Molecular Typing of Environmental and Patient Isolates of Aspergillus fumigatus from Various Hospital Settings  

Microsoft Academic Search

Fingerprinting of more than 700 clinical and environmental isolates of Aspergillus fumigatus from four differential hospital settings was undertaken with a dispersed repeated DNA sequence. The analysis of the environmental isolates showed that the airborne A. fumigatus population is extremely diverse, with 85% of the strains being represented as a single genotype isolated once. The remaining 15% of the strains

VALERIE CHAZALET; JEAN-PAUL DEBEAUPUIS; JACQUELINE SARFATI; JACQUES LORTHOLARY; PATRICIA RIBAUD; PRAMOD SHAH; MURIEL CORNET; HOANG VU THIEN; ELIANE GLUCKMAN; GILLES BRUCKER; JEAN-PAUL LATGE

1998-01-01

366

Cloning and functional expression of the mitochondrial alternative oxidase gene (aox1) of Aspergillus niger in Lactococcus lactis and its induction by oxidizing conditions.  

PubMed

Lactococcus lactis is a widely used food bacterium mainly known for its fermentation metabolism. An important, and for long time overlooked, trait of this species is its ability to perform respiratory metabolism in the presence of heme and under aerobic conditions. There is no evidence however for the presence of an alternative respiration pathway and AOX activity. In this study, a cDNA fragment encoding the mitochondrial alternative oxidase, the enzyme responsible for alternative respiration, from a citric acid producing Aspergillus niger strain was cloned and expressed in L. lactis as a host strain. Expression of aox1 conferred on this organism cyanide-resistant and salicylhydroxamate-sensitive growth. Bioreactor cultures under fully aerobic conditions of the transformed L. lactis showed that the alternative respiratory pathway operates and improves significantly the microorganism's response to oxidizing stress conditions as it enhances biomass production, suppresses lactate formation, and leads to accumulation of large amounts of nisin. PMID:22133435

Papagianni, Maria; Avramidis, Nicholaos

2012-01-01

367

Discovery and Characterization of a Silent Gene Cluster that Produces Azaphilones from Aspergillus niger ATCC 1015 Reveal a Hydroxylation-Mediated Pyran-Ring Formation  

PubMed Central

SUMMARY Azaphilones are a class of fungal metabolites characterized by a highly oxygenated pyrano-quinone bicyclic core and exhibits a broad range of bioactivities. While widespread among various fungi, their biosynthesis has not been thoroughly elucidated. By activation of a silent (aza) gene cluster in Aspergillus niger ATCC 1015, we have discovered six new azaphilone compounds, azanigerones A-F (1, 3-7). Transcriptional analysis and deletion of a key polyketide synthase (PKS) gene further confirmed the involvement of the aza gene cluster. The biosynthetic pathway was shown to involve the convergent actions of a highly-reducing and a non-reducing PKSs. Most significantly, in vitro reaction of a key flavin-dependent monooxygenase encoded in the cluster with an early benzaldehyde intermediate revealed its roles in hydroxylation and pyran-ring formation to afford the characteristic bicylic core shared by azaphilones. PMID:22921072

Zabala, Angelica O.; Xu, Wei; Chooi, Yit-Heng; Tang, Yi

2012-01-01

368

Biodegradation of Low-Density Polyethylene (LDPE) by Mixed Culture of Lysinibacillus xylanilyticus and Aspergillus niger in Soil  

PubMed Central

In this study, two strains of Aspergillus sp. and Lysinibacillus sp. with remarkable abilities to degrade low-density polyethylene (LDPE) were isolated from landfill soils in Tehran using enrichment culture and screening procedures. The biodegradation process was performed for 126 days in soil using UV- and non-UV-irradiated pure LDPE films without pro-oxidant additives in the presence and absence of mixed cultures of selected microorganisms. The process was monitored by measuring the microbial population, the biomass carbon, pH and respiration in the soil, and the mechanical properties of the films. The carbon dioxide measurements in the soil showed that the biodegradation in the un-inoculated treatments were slow and were about 7.6% and 8.6% of the mineralisation measured for the non-UV-irradiated and UV-irradiated LDPE, respectively, after 126 days. In contrast, in the presence of the selected microorganisms, biodegradation was much more efficient and the percentages of biodegradation were 29.5% and 15.8% for the UV-irradiated and non-UV-irradiated films, respectively. The percentage decrease in the carbonyl index was higher for the UV-irradiated LDPE when the biodegradation was performed in soil inoculated with the selected microorganisms. The percentage elongation of the films decreased during the biodegradation process. The Fourier transform infra-red (FT-IR), x-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to determine structural, morphological and surface changes on polyethylene. These analyses showed that the selected microorganisms could modify and colonise both types of polyethylene. This study also confirmed the ability of these isolates to utilise virgin polyethylene without pro-oxidant additives and oxidation pretreatment, as the carbon source. PMID:24086254

Esmaeili, Atefeh; Pourbabaee, Ahmad Ali; Alikhani, Hossein Ali; Shabani, Farzin; Esmaeili, Ensieh

2013-01-01

369

Comparative sequence analysis of citrate synthase and 18S ribosomal DNA from a wild and mutant strains of Aspergillus niger with various fungi  

PubMed Central

A mutation was induced in Aspergillus niger wild strain using ethidium bromide resulting in enhanced expression of citric acid by three folds and 112.42 mg/mL citric acid was produced under optimum conditions with 121.84 mg/mL of sugar utilization. Dendograms of 18S rDNA and citrate synthase from different fungi including sample strains were made to assess homology among different fungi and to study the correlation of citrate synthase gene with evolution of fungi. Subsequent comparative sequence analysis revealed strangeness between the citrate synthase and 18S rDNA phylogenetic trees. Furthermore, the citrate synthase movement suggests that the use of traditional marker molecule of 18S rDNA gives misleading information about the evolution of citrate synthase in different fungi as it has shown that citrate synthase gene transferred independently among different fungi having no evolutionary relationships. Random amplified polymorphic DNA (RAPD-PCR) analysis was also employed to study genetic variation between wild and mutant strains of A. niger and only 71.43% similarity was found between both the genomes. Keeping in view the importance of citric acid as a necessary constituent of various food preparations, synthetic biodegradable detergents and pharmaceuticals the enhanced production of citric acid by mutant derivative might provide significant boost in commercial scale viability of this useful product. Abbreviations CS - Citrate synthase, CA - Citric acid, RAPD - Random amplified polymorphic DNA, TAF - Total amplified fragments, PAF - Polymorphic amplified fragments, CAF - Common amplified fragments. PMID:24516318

Mustafa, Ghulam; Tahir, Aisha; Asgher, Muhammad; Rahman, Mehboob-ur; Jamil, Amer

2014-01-01

370

Control of pellet morphology of filamentous fungi in fluidized bed bioreactors by means of a pulsing flow. Application to Aspergillus niger and Phanerochaete chrysosporium.  

PubMed

The application of a pulsing flow to fluidized-bed bioreactors in order to control pellet morphology of filamentous fungi was investigated. The operation at an optimum pulsation frequency allowed two effects: a narrower pellet size distribution which improves fluidization quality, and an enhanced production of citric acid by Aspergillus niger and manganese peroxidase by Phanerochaete chrysosporium. In the case of A. niger, the pellet diameter corresponding to the pulsed system operated at 0.35 s-1 was kept between 3.3 +/- 0.1 mm after 22 days of operation; however, in the nonpulsed bioreactor which was operative for only 11 days, pellets with a diameter of 6.7 +/- 0.3 mm were produced. Similar results were obtained in the case of P. chrysosporium, since with a pulsing frequency of 0.0625 s-1, a pellet diameter of 2.1 +/- 0.4 mm after 34 days of operation was maintained. On the contrary, the system without pulsation presented great conglomerates of mycelia with an average diameter of 3 cm surrounded by free pellets with a diameter distribution of 2.75 +/- 0.5 mm. The nonpulsed bioreactor was only operative for 14 days. Both citric acid and manganese peroxidase production attained higher values and were maintained longer in the pulsed bioreactor. PMID:8987486

Moreira, M T; Sanromán, A; Feijoo, G; Lema, J M

1996-09-01

371

Aspergillus niger lipase: Heterologous expression in Pichia pastoris, molecular modeling prediction and the importance of the hinge domains at both sides of the lid domain to interfacial activation.  

PubMed

Aspergillus niger lipase (ANL) is an important biocatalyst in the food processing industry. However, there is no report of its detailed three-dimensional structure because of difficulties in crystallization. In this article, based on experimental data and bioinformational analysis results, the structural features of ANL were simulated. Firstly, two recombinant ANLs expressed in Pichia pastoris were purified to homogeneity and their corresponding secondary structure compositions were determined by circular dichroism spectra. Secondly, the primary structure, the secondary structure and the three-dimensional structure of ANL were modeled by comparison with homologous lipases with known three-dimensional structures using the BioEdit software, lipase engineering database (http://www.led.uni-stuttgart.de/), PSIPRED server and SwissModel server. The predicted molecular structure of ANL presented typical features of the alpha/beta hydrolase fold including positioning of the putative catalytic triad residues and the GXSXG signature motif. Comparison of the predicted three-dimensional structure of ANL with the X-ray three-dimensional structure of A. niger feruloyl esterase showed that the functional difference of interfacial activation between lipase and esterase was concerned with the difference in position of the lid. Our three-dimensional model of ANL helps to modify lipase structure by protein engineering, which will further expand the scope of application of ANL. PMID:19248178

Shu, Zhengyu; Duan, Mojie; Yang, Jiangke; Xu, Li; Yan, Yunjun

2009-01-01

372

Characterization of the starvation-induced chitinase CfcA and ?-1,3-glucanase AgnB of Aspergillus niger.  

PubMed

The common saprophyte Aspergillus niger may experience carbon starvation in nature as well as during industrial fermentations. Starvation survival strategies, such as conidiation or the formation of exploratory hyphae, require energy and building blocks, which may be supplied by autolysis. Glycoside hydrolases are key effectors of autolytic degradation of fungal cell walls, but knowledge on their identity and functionality is still limited. We recently identified agnB and cfcA as two genes encoding carbohydrate-active enzymes that had notably increased transcription during carbon starvation in A. niger. Here, we report the biochemical and functional characterization of these enzymes. AgnB is an ?-1,3-glucanase that releases glucose from ?-1,3-glucan substrates with a minimum degree of polymerization of 4. CfcA is a chitinase that releases dimers from the nonreducing end of chitin. These enzymes thus attack polymers that are found in the fungal cell wall and may have a role in autolytic fungal cell wall degradation in A. niger. Indeed, cell wall degradation during carbon starvation was reduced in the double deletion mutant ?cfcA ?agnB compared to the wild-type strain. Furthermore, the cell walls of the carbon-starved mycelium of the mutant contained a higher fraction of chitin or chitosan. The function of at least one of these enzymes, CfcA, therefore appears to be in the recycling of cell wall carbohydrates under carbon limiting conditions. CfcA thus may be a candidate effector for on demand cell lysis, which could be employed in industrial processes for recovery of intracellular products. PMID:25219534

van Munster, Jolanda M; Dobruchowska, Justyna M; Veloo, Ruud; Dijkhuizen, Lubbert; van der Maarel, Marc J E C

2014-09-16

373

Aflaquinolones A-G: Secondary metabolites from marine and fungicolous isolates of Aspergillus spp.  

Technology Transfer Automated Retrieval System (TEKTRAN)

Seven new compounds (aflaquinolones A-G; 1-7) containing dihydroquinolin-2-one and terpenoid units have been isolated from two different fungal sources. Two of these metabolites (1 and 2) were obtained from a Hawaiian fungicolous isolate of Aspergillus sp. (section Flavipedes; MYC-2048=NRRL 58570), ...

374

ENZYMATIC DEHAIRING OF CATTLE HIDE WITH AN ALKALINE PROTEASE ISOLATED FROM ASPERGILLUS TAMARII  

Technology Transfer Automated Retrieval System (TEKTRAN)

An alkaline protease isolated from Aspergillus tamarii shows promise as a dehairing agent for use in the tannery. Standard dehairing conditions established for the protease isolated from Streptomyces griseus proved to be unsatisfactory for the alkaline protease. We optimized the dehairing conditio...

375

Microsatellite (STRAf) Genotyping Cannot Differentiate between Invasive and Colonizing Aspergillus fumigatus Isolates.  

PubMed

We studied whether short tandem repeats of Aspergillus fumigatus (STRAf) can differentiate between invasive and colonizing genotypes of A. fumigatus. Of the 395 genotypes detected (n = 1,373 isolates), 50 were clusters and 24 (6% of all genotypes) involved the patients with invasive aspergillosis and those colonized with A. fumigatus, indicating that genotyping cannot discriminate between invasive and colonizing isolates. PMID:25411179

Escribano, Pilar; Peláez, Teresa; Bouza, Emilio; Guinea, Jesús

2015-02-01

376

Use of Plackett-Burman design for rapid screening of several nitrogen sources, growth\\/product promoters, minerals and enzyme inducers for the production of alpha-galactosidase by Aspergillus niger MRSS 234 in solid state fermentation system  

Microsoft Academic Search

Five sources of nitrogen, six minerals, six enzyme inducers and one each of growth as well as product promotors were screened by Plackett-Burman design, consisting of a total of 20 experiments for the above 19 sources\\/categories of medium ingredients, for their effect on the production of alpha-galactosidase by Aspergillus niger MRSS 234 in solid state fermentation system. The enzyme production

M. R. S. Srinivas; Nagin Chand; B. K. Lonsane

1994-01-01

377

Biodiversity and ITS-RFLP Characterisation of Aspergillus Section Nigri Isolates in Grapes from Four Traditional Grape-Producing Areas in Greece  

PubMed Central

A study on the occurrence of Aspergillus section Nigri species on grapes from four traditional grape-producing areas in Greece during the 2011/2012 vintage, and their capability to produce OTA was conducted. One hundred and twenty-eight black aspergilli isolates were characterised at the species level initially by the use of morphological criteria in accordance with appropriate keys, followed by molecular characterisation performed with Polymerase Chain Reaction–Restriction Fragment Length Polymorphism (PCR-RFLP) of the 5.8 ribosomal RNA gene Internal Transcribed Spacer region (5.8 rRNA ITS). Restriction enzyme digestion of the ITS amplicons using the HhaI, HinfI and RsaI, endonucleases distinguished eleven different patterns of restriction fragment length polymorphism (RFLP), four for each of the HhaI and RsaI digests and three for HinfI. From a total number of 128 individual isolates, 124 were classified into four Aspergillus species corresponding to A. carbonarius, A. tubingensis, A. japonicus and A. ibericus, and the remaining 4 were classified as members of the A. niger aggregate. A. carbonarius and A. tubingensis being the main representative species were equally counted, with higher geographical representation of the former in southern and the latter in northern regions, respectively. All isolates were tested for their ochratoxigenic potential by use of High Performance Liquid Chromatography (HPLC) and Enzyme Linked Immuno Sorbent Assay (ELISA), resulting in significant interspecies differences in OTA production. PMID:24710283

Kizis, Dimosthenis; Natskoulis, Pantelis; Nychas, George-John E.; Panagou, Efstathios Z.

2014-01-01

378

In vitro synergistic efficacy of combination of amphotericin B with Myrtus communis essential oil against clinical isolates of Candida albicans  

Microsoft Academic Search

In this study, we evaluated the antifungal activity of the essential oil from Myrtus communis (myrtle) leaves against Candida albicans (eight clinical isolates and one ATCC type strains) and different species of Aspergillus sp (A. niger, A. parasiticus, six isolates of Aspergillus flavus) using broth micro dilution assay. In addition, we evaluated the synergistic effect between the essential oil and

M. Mahboubi; F. Ghazian Bidgoli

2010-01-01

379

Evaluation of the potential of Aspergillus niger species for the bioconversion of L-phenylalanine into 2-phenylethanol  

Microsoft Academic Search

Aspergillusniger was explored, for the first time, for the production of 2-phenylethanol (a rose-like aroma) using L-phenylalanine as precursor. Among the strains screened, A. niger CMICC 298302 was shown to produce, in a culture medium containing 6 g L-phenylalanine l-1 and 60 g glucose l-1, 1375 mg 2-phenylethanol l-1 with a productivity of 153 mg l-1 day-1 and a molar

Anne Lomascolo; Laurence Lesage-Meessen; Mireille Haon; David Navarro; Claudine Antona; Craig Faulds; Asther Marcel

2001-01-01

380

Development of cost-effective media to increase the economic potential for larger-scale bioproduction of natural food additives by Lactobacillus rhamnosus , Debaryomyces hansenii , and Aspergillus niger.  

PubMed

Yeast extract (YE) is the most common nitrogen source in a variety of bioprocesses in spite of the high cost. Therefore, the use of YE in culture media is one of the major technical hurdles to be overcome for the development of low-cost fermentation routes, making the search for alternative-cheaper nitrogen sources particularly desired. The aim of the current study is to develop cost-effective media based on corn steep liquor (CSL) and locally available vinasses in order to increase the economic potential for larger-scale bioproduction. Three microorganisms were evaluated: Lactobacillus rhamnosus , Debaryomyces hansenii , and Aspergillus niger . The amino acid profile and protein concentration was relevant for the xylitol and citric acid production by D. hansenii and A. niger , respectively. Metals also played an important role for citric acid production, meanwhile, D. hansenii showed a strong dependence with the initial amount of Mg(2+). Under the best conditions, 28.8 g lactic acid/L (Q(LA) = 0.800 g/L.h, Y(LA/S) = 0.95 g/g), 35.3 g xylitol/L (Q(xylitol) = 0.380 g/L.h, Y(xylitol/S) = 0.69 g/g), and 13.9 g citric acid/L (Q(CA) = 0.146 g/L.h, Y(CA/S) = 0.63 g/g) were obtained. The economic efficiency (E(p/euro)) parameter identify vinasses as a lower cost and more effective nutrient source in comparison to CSL. PMID:19821581

Salgado, José Manuel; Rodríguez, Noelia; Cortés, Sandra; Domínguez, José Manuel

2009-11-11

381

Systems Approaches to Predict the Functions of Glycoside Hydrolases during the Life Cycle of Aspergillus niger Using Developmental Mutants ?brlA and ?flbA  

PubMed Central

Background The filamentous fungus Aspergillus niger encounters carbon starvation in nature as well as during industrial fermentations. In response, regulatory networks initiate and control autolysis and sporulation. Carbohydrate-active enzymes play an important role in these processes, for example by modifying cell walls during spore cell wall biogenesis or in cell wall degradation connected to autolysis. Results In this study, we used developmental mutants (?flbA and ?brlA) which are characterized by an aconidial phenotype when grown on a plate, but also in bioreactor-controlled submerged cultivations during carbon starvation. By comparing the transcriptomes, proteomes, enzyme activities and the fungal cell wall compositions of a wild type A. niger strain and these developmental mutants during carbon starvation, a global overview of the function of carbohydrate-active enzymes is provided. Seven genes encoding carbohydrate-active enzymes, including cfcA, were expressed during starvation in all strains; they may encode enzymes involved in cell wall recycling. Genes expressed in the wild-type during starvation, but not in the developmental mutants are likely involved in conidiogenesis. Eighteen of such genes were identified, including characterized sporulation-specific chitinases and An15g02350, member of the recently identified carbohydrate-active enzyme family AA11. Eight of the eighteen genes were also expressed, independent of FlbA or BrlA, in vegetative mycelium, indicating that they also have a role during vegetative growth. The ?flbA strain had a reduced specific growth rate, an increased chitin content of the cell wall and specific expression of genes that are induced in response to cell wall stress, indicating that integrity of the cell wall of strain ?flbA is reduced. Conclusion The combination of the developmental mutants ?flbA and ?brlA resulted in the identification of enzymes involved in cell wall recycling and sporulation-specific cell wall modification, which contributes to understanding cell wall remodeling mechanisms during development. PMID:25629352

van Munster, Jolanda M.; Nitsche, Benjamin M.; Akeroyd, Michiel; Dijkhuizen, Lubbert; van der Maarel, Marc J. E. C.; Ram, Arthur F. J.

2015-01-01

382

d-Xylose Concentration-Dependent Hydrolase Expression Profiles and the Function of CreA and XlnR in Aspergillus niger  

PubMed Central

Aspergillus niger is an important organism for the production of industrial enzymes such as hemicellulases and pectinases. The xylan-backbone monomer, d-xylose, is an inducing substance for the coordinate expression of a large number of polysaccharide-degrading enzymes. In this study, the responses of 22 genes to low (1 mM) and high (50 mM) d-xylose concentrations were investigated. These 22 genes encode enzymes that function as xylan backbone-degrading enzymes, accessory enzymes, cellulose-degrading enzymes, or enzymes involved in the pentose catabolic pathway in A. niger. Notably, genes encoding enzymes that have a similar function (e.g., xylan backbone degradation) respond in a similar manner to different concentrations of d-xylose. Although low d-xylose concentrations provoke the greatest change in transcript levels, in particular, for hemicellulase-encoding genes, transcript formation in the presence of high concentrations of d-xylose was also observed. Interestingly, a high d-xylose concentration is favorable for certain groups of genes. Furthermore, the repressing influence of CreA on the transcription and transcript levels of a subset of these genes was observed regardless of whether a low or high concentration of d-xylose was used. Interestingly, the decrease in transcript levels of certain genes on high d-xylose concentrations is not reflected by the transcript level of their activator, XlnR. Regardless of the d-xylose concentration applied and whether CreA was functional, xlnR was constitutively expressed at a low level. PMID:22344641

Mach-Aigner, Astrid R.; Omony, Jimmy; Jovanovic, Birgit; van Boxtel, Anton J. B.

2012-01-01

383

The Transcriptional Repressor TupA in Aspergillus niger Is Involved in Controlling Gene Expression Related to Cell Wall Biosynthesis, Development, and Nitrogen Source Availability  

PubMed Central

The Tup1-Cyc8 (Ssn6) complex is a well characterized and conserved general transcriptional repressor complex in eukaryotic cells. Here, we report the identification of the Tup1 (TupA) homolog in the filamentous fungus Aspergillus niger in a genetic screen for mutants with a constitutive expression of the agsA gene. The agsA gene encodes a putative alpha-glucan synthase, which is induced in response to cell wall stress in A. niger. Apart from the constitutive expression of agsA, the selected mutant was also found to produce an unknown pigment at high temperatures. Complementation analysis with a genomic library showed that the tupA gene could complement the phenotypes of the mutant. Screening of a collection of 240 mutants with constitutive expression of agsA identified sixteen additional pigment-secreting mutants, which were all mutated in the tupA gene. The phenotypes of the tupA mutants were very similar to the phenotypes of a tupA deletion strain. Further analysis of the tupA-17 mutant and the ?tupA mutant revealed that TupA is also required for normal growth and morphogenesis. The production of the pigment at 37°C is nitrogen source-dependent and repressed by ammonium. Genome-wide expression analysis of the tupA mutant during exponential growth revealed derepression of a large group of diverse genes, including genes related to development and cell wall biosynthesis, and also protease-encoding genes that are normally repressed by ammonium. Comparison of the transcriptome of up-regulated genes in the tupA mutant showed limited overlap with the transcriptome of caspofungin-induced cell wall stress-related genes, suggesting that TupA is not a general suppressor of cell wall stress-induced genes. We propose that TupA is an important repressor of genes related to development and nitrogen metabolism. PMID:24205111

Schachtschabel, Doreen; Arentshorst, Mark; Nitsche, Benjamin M.; Morris, Sam; Nielsen, Kristian F.; van den Hondel, Cees A. M. J. J.; Klis, Frans M.; Ram, Arthur F. J.

2013-01-01

384

Substrate Utilization by Aspergillus flavus in Inoculated Whole Corn Kernels and Isolated Tissues  

E-print Network

Substrate Utilization by Aspergillus flavus in Inoculated Whole Corn Kernels and Isolated Tissues, University of Arizona, P.O. Box 210036, Tucson, Arizona 85721 Utilization of the major corn (Zea mays carbon substrates followed by triglycerides. When invading nonwounded corn kernels, the fungus

Cotty, Peter J.

385

A Potent Nonpeptide Cholecystokinin Antagonist Selective for Peripheral Tissues Isolated from Aspergillus alliaceus  

Microsoft Academic Search

A new, competitive, nonpeptide cholecystokinin (CCK) antagonist, asperlicin, was isolated from the fungus Aspergillus alliaceus. The compound has 300 to 400 times the affinity for pancreatic, ileal, and gallbladder CCK receptors than proglumide, a standard agent of this class. Moreover, asperlicin is highly selective for peripheral CCK receptors relative to brain CCK and gastrin receptors. Since asperlicin also exhibits long-lasting

Raymond S. L. Chang; Victor J. Lotti; Richard L. Monaghan; Jerome Birnbaum; Edward O. Stapley; Michael A. Goetz; Georg Albers-Schonberg; Arthur A. Patchett; Jerrold M. Liesch; Otto D. Hensens; James P. Springer

1985-01-01

386

Enzymatic Dehairing of Cattlehide with an Alkaline Protease Isolated from Aspergillus tamarii  

Technology Transfer Automated Retrieval System (TEKTRAN)

An enzymatic dehairing protocol based on the alkaline serine protease isolated from Aspergillus tamarii required 16h, and we observed concomitant grain damage. The use of sodium dodecyl sulfate as a pretreatment to remove the lipids from the hide allowed a shortening of the dehairing time to 6 h wi...

387

Antimicrobial Susceptibility of Fusarium, Aspergillus, and Other Filamentous Fungi Isolated From Keratitis  

Microsoft Academic Search

Results: The 90 isolates included 41 Aspergillus spe- cies, 38 Fusarium species, and 11 others. The triazoles and caspofungin had the lowest MICs against Aspergil- lus species; voriconazole, amphotericin B, and posacona- zole had the lowest MICs against Fusarium species, and none of theFusarium species were inhibited by itracona- zole or caspofungin. Amphotericin B had significantly lower MICs compared with

Prajna Lalitha; Brett L. Shapiro; Muthiah Srinivasan; Namperumalsamy Venkatesh Prajna; Nisha R. Acharya; Annette W. Fothergill; Jazmin Ruiz; Jaya D. Chidambaram; Kathryn J. Maxey; Kevin C. Hong; Stephen D. McLeod; Thomas M. Lietman

388

Aspergillus, Penicillium and Talaromyces isolated from house dust samples collected around the world  

E-print Network

of a worldwide survey of the indoor mycobiota, dust was collected from nine countries. Analyses of dust samplesAspergillus, Penicillium and Talaromyces isolated from house dust samples collected around serve as alternative identification markers. Key words: Environmental metagenomics, Indoor moulds

Amend, Anthony S.

389

Penicillium parvulum and Penicillium georgiense sp. nov. Isolated from the Conidial Heads of Aspergillus Species  

Technology Transfer Automated Retrieval System (TEKTRAN)

Two new Penicillium species were isolated from peanut-field soils in Georgia. The species were particularly noted because they sporulated on the conidial heads of Aspergillus species. Phenotypic descriptions were prepared using standard media. ITS and lsu-rDNA sequences were made from the new spe...

390

Aflaquinolones A–G: Secondary Metabolites from Marine and Fungicolous Isolates of Aspergillus Spp.†  

PubMed Central

Seven new compounds (aflaquinolones A – G; 1 – 7) containing dihydroquinolin-2-one and terpenoid units have been isolated from two different fungal sources. Two of these metabolites (1 and 2) were obtained from a Hawaiian fungicolous isolate of Aspergillus sp. (section Flavipedes; MYC-2048 = NRRL 58570), while the others were obtained from a marine Aspergillus isolate (SF-5044) collected in Korea. The structures of these compounds were determined mainly by analysis of NMR and MS data. Relative and absolute configurations were assigned on the basis of NOESY data and 1H NMR J-values, comparison of calculated and experimental ECD spectra, and analysis of a Mosher’s ester derivative of 2. Several known compounds, including alantrypinone, aspochalasins I and J, methyl-3,4,5-trimethoxy-2((2-((3-pyridinylcarbonyl)amino) benzoyl)amino) benzoate, and trans-dehydrocurvularin were also encountered in the extract of the Hawaiian isolate. PMID:22295903

Neff, Scott A.; Lee, Sang Un; Asami, Yukihiro; Ahn, Jong Seog; Oh, Hyuncheol; Baltrusaitis, Jonas; Gloer, James B.; Wicklow, Donald T.

2012-01-01

391

Aspergillus, Penicillium and Talaromyces isolated from house dust samples collected around the world.  

PubMed

As part of a worldwide survey of the indoor mycobiota, dust was collected from nine countries. Analyses of dust samples included the culture-dependent dilution-to-extinction method and the culture-independent 454-pyrosequencing. Of the 7?904 isolates, 2?717 isolates were identified as belonging to Aspergillus, Penicillium and Talaromyces. The aim of this study was to identify isolates to species level and describe the new species found. Secondly, we wanted to create a reliable reference sequence database to be used for next-generation sequencing projects. Isolates represented 59 Aspergillus species, including eight undescribed species, 49 Penicillium species of which seven were undescribed and 18 Talaromyces species including three described here as new. In total, 568 ITS barcodes were generated, and 391 ?-tubulin and 507 calmodulin sequences, which serve as alternative identification markers. PMID:25492981

Visagie, C M; Hirooka, Y; Tanney, J B; Whitfield, E; Mwange, K; Meijer, M; Amend, A S; Seifert, K A; Samson, R A

2014-06-01

392

Reliable and simple detection of ochratoxin and fumonisin production in black Aspergillus.  

PubMed

To date, edible fungi such as black Aspergillus (Aspergillus niger aggregates) have been considered as safe. However, it has recently been reported that some strains have a mycotoxin biosynthetic capability, and this capability must be evaluated to determine the safety of edible fungi. In this study, we assessed the ability of mycotoxin production in A. niger aggregates isolated from various Korean foods using multiplex PCR and high-performance liquid chromatography (HPLC) analyses. Multiplex PCR and HPLC analyses of 32 A. niger aggregates showed that ochratoxin and fumonisin were produced only by strains exhibiting positive PCR patterns with ochratoxin and fumonisin biosynthesis genes. However, several strains did not produce mycotoxins, even though they contained mycotoxin biosynthesis genes. Using multiplex PCR pattern and HPLC analyses, we selected Aspergillus strains that do not produce mycotoxins, which will contribute to the development of safer fermented foods. PMID:24680080

Kim, Nam Yeun; Lee, Inhyung; Ji, Geun Eog

2014-04-01

393

Molecular characterization of Aspergillus infections in an Iranian educational hospital using RAPD-PCR method  

PubMed Central

Objective(s): The nosocomial infections by Aspergillus species are associated with constructions and increased dust loads in hospital indoors. Our main object was to find the environmental sources of Aspergillus species causing hospital acquired infections. Materials and Methods: The clinical and environmental samplings were performed during 18 months from spring 2010 to summer 2011 in Imam educational hospital, Urmia, Iran. A morphological diagnosis was performed including microscopic characterization of isolated aspergillus from cultured specimens and polymerase chain reaction - restriction fragment length polymorphism (PCR-RFLP) for the identification in the level of species. Random amplified polymorphic DNA - PCR RAPD-PCR using random primers for rDNA gene was performed to compare Aspergillus isolates of clinical cases with the relevant environmental sources. Results: Use of RAPD method resulted various differential patterns, so that some Aspergillus isolates from the clinical and hospital indoor were completely matched (matched pairs) and some other Aspergillus isolates were not matched. In the case of matched pairs, Aspergillus niger and A. flavus isolated from broncoalveolar lavage and sinus discharge were relevant to those of air conditioner and walls surfaces, respectively. Conclusion: The hospital sources for the Aspergillus clinical isolates included air condition and walls. RAPD-PCR analysis can play a trivial role to find the hospital sources of Aspergillus clinical isolates.

Diba, Kambiz; Makhdoomi, Khadijeh; Mirhendi, Hossein

2014-01-01

394

Effect of Terminalia catappa Fruit Meal Fermented by Aspergillus niger as Replacement of Maize on Growth Performance, Nutrient Digestibility, and Serum Biochemical Profile of Broiler Chickens  

PubMed Central

A feeding experiment was conducted to investigate the effect of fermented Terminalia catappa fruit meal (FTCM) with Aspergillus niger as replacement for maize on broiler growth performance, nutrient digestibility, and serum biochemical constituents. Dietary maize was replaced by FTCM at 0, 20, 40, 60, or 80%. One hundred and eighty one-day-old Shaver broiler chicks were randomly allocated to the five dietary treatments, three replicate groups of twelve chicks each for a 42-day period. There was no significant difference (P > .05) in the feed intake, weight gain, and feed; gain ratio between the broilers fed on 40% FTCM diet and the control group. The apparent digestibilities of nitrogen, crude fibre, and fat decreased significantly in broilers fed higher levels (>40%) of FTCM replacement diets compared with the control or lower FTCM diets. Serum concentrations of total protein, albumin, and globulin were decreased (P < .05) on 80% FTCM fed broilers. Serum cholesterol, creatinine, and glucose were not significantly (P > .05) altered among treatments. The activities of aspartate and alanine aminotransferases and alkaline phosphatase were significantly (P < .05) increased with higher FTCM replacement. The results indicate that FTCM could replace up to 40% of dietary maize in the diets of broiler chickens without adverse effect on growth performance or serum constituents. PMID:21350670

Apata, David Friday

2011-01-01

395

Tamarind seed powder and palm kernel cake: two novel agro residues for the production of tannase under solid state fermentation by Aspergillus niger ATCC 16620.  

PubMed

Palm kernel cake (PKC), the residue obtained after extraction of palm oil from oil palm seeds and tamarind seed powder (TSP) obtained after removing the fruit pulp from tamarind fruit pod were tested for the production of tannase under solid-state fermentation (SSF) using Aspergillus niger ATCC 16620. The fungal strain was grown on the substrates without any pretreatment. In PKC medium, a maximum enzyme yield of 13.03 IU/g dry substrate (gds) was obtained when SSF was carried out at 30 degrees C, 53.5% initial substrate moisture, 33 x 10(9) spores/5 g substrate inoculum size and 5% tannic acid as additional carbon source after 96 h of fermentation. In TSP medium, maximum tannase yield of 6.44 IU/gds was obtained at 30 degrees C, 65.75% initial substrate moisture, 11 x 10(9) spores/5 g substrate inoculum, 1% glycerol as additional carbon source and 1% potassium nitrate as additional nitrogen source after 120 h of fermentation. Results from the study are promising for the economic utilization and value addition of these important agro residues, which are abundantly available in many tropical and subtropical countries. PMID:15734308

Sabu, A; Pandey, A; Daud, M Jaafar; Szakacs, G

2005-07-01

396

Effect of C/N ratio and media optimization through response surface methodology on simultaneous productions of intra- and extracellular inulinase and invertase from Aspergillus niger ATCC 20611.  

PubMed

The study is to identify the extraction of intracellular inulinase (exo- and endoinulinase) and invertase as well as optimization medium composition for maximum productions of intra- and extracellular enzymes from Aspergillus niger ATCC 20611. From two different methods for extraction of intracellular enzymes, ultrasonic method was found more effective. Response surface methodology (RSM) with a five-variable and three-level central composite design (CCD) was employed to optimize the medium composition. The effect of five main reaction parameters including sucrose, yeast extract, NaNO?, Zn?², and Triton X-100 on the production of enzymes was analyzed. A modified quadratic model was fitted to the data with a coefficient of determination (R²) more than 0.90 for all responses. The intra-extracellular inulinase and invertase productions increased in the range from 16 to 8.4 times in the optimized medium (10% (w/v) sucrose, 2.5% (w/v) yeast extract, 2% (w/v) NaNO?, 1.5?mM (v/v) Zn?², and 1% (v/v) Triton X-100) by RSM and from around 1.2 to 1.3 times greater than in the medium optimized by one-factor-at-a-time, respectively. The results of bioprocesses optimization can be useful in the scale-up fermentation and food industry. PMID:24151605

Dinarvand, Mojdeh; Rezaee, Malahat; Masomian, Malihe; Jazayeri, Seyed Davoud; Zareian, Mohsen; Abbasi, Sahar; Ariff, Arbakariya B

2013-01-01

397

Use of the chemiluminescent probe lucigenin to monitor the production of the superoxide anion radical in a recombinant Aspergillus niger (B1-D).  

PubMed

Direct detection of intracellular superoxide anion radical (O(2)(.-)) production is of critical importance for investigating the responses of filamentous fungi to oxidative stress in bioprocesses. The purpose of this study is to establish a reliable method to monitor the O(2)(.-) production within pellets of Aspergillus niger. Addition of pure oxygen and the redox cycling agent paraquat to fungal pellet suspensions resulted in a considerable increase in lucigenin-derived chemiluminescence (LDCL). In the presence of exogenous superoxide dismutase (SOD), the LDCL of a disrupted cell solution was inhibited. In contrast, with addition of diethyldithiocarbamate and sodium azide, respectively, the inhibitors of Cu, Zn-SOD and Mn-SOD, an increased LDCL was observed. Further, as a probe, lucigenin can be absorbed and accumulated in fungal pellet within a few minutes. Various pretreatments of the bioreactor sample for the measurement of LDCL, were also investigated in the present study, and the use of intact pellets was adopted here rather than disrupting cells because the latter treatment led to difficulties in LDCL measurement. These results show that lucigenin may be used as a convenient chemiluminescent probe to monitor intracellular production of O(2)(.-) in filamentous fungi, and thus to follow changes in the level of this stressor within fungi PMID:11536143

Bai, Z; Harvey, L M; McNeil, B

2001-10-20

398

Production of an endoinulinase from Aspergillus niger AUMC 9375, by solid state fermentation of agricultural wastes, with purification and characterization of the free and immobilized enzyme.  

PubMed

Two different substrates, sunflower (Helianthus annuus L.) tubers and lettuce (Lactuca sativa) roots, were tested. Using a mixture of both wastes resulted in higher production of endoinulinase than either waste alone. Also, ten fungal species grown on these substrates as inexpensive, carbon sources were screened for the best production of endoinulinase activities. Of these, Aspergillus niger AUMC 9375 was the most productive, when grown on the mixture using a 6:1 w/w ratio of sun flower: lettuce, and yielded the highest levels of inulinase at 50% moisture, 30°C, pH 5.0, with seven days of incubation, and with yeast extract as the best nitrogen source. Inulinase was purified to homogeneity by ion-exchange chromatography and gel-filtration giving a 51.11 fold purification. The mixture of sunflower tubers and lettuce roots has potential to be an effective and economical substrate for inulinase production. Inulinase was successfully immobilized with an immobilization yield of 71.28%. After incubation for 2 h at 60°C, the free enzyme activity decreased markedly to 10%, whereas that of the immobilized form decreased only to 87%. A reusability test demonstrated the durability of the immobilized inulinase for 10 cycles and in addition, that it could be stored for 32 days at 4°C. These results indicate that this inulinase, in the immobilized form, is a potential candidate for large-scale production of high purity fructose syrups. PMID:24810318

Housseiny, Manal M

2014-05-01

399

Effect of C/N Ratio and Media Optimization through Response Surface Methodology on Simultaneous Productions of Intra- and Extracellular Inulinase and Invertase from Aspergillus niger ATCC 20611  

PubMed Central

The study is to identify the extraction of intracellular inulinase (exo- and endoinulinase) and invertase as well as optimization medium composition for maximum productions of intra- and extracellular enzymes from Aspergillus niger ATCC 20611. From two different methods for extraction of intracellular enzymes, ultrasonic method was found more effective. Response surface methodology (RSM) with a five-variable and three-level central composite design (CCD) was employed to optimize the medium composition. The effect of five main reaction parameters including sucrose, yeast extract, NaNO3, Zn+2, and Triton X-100 on the production of enzymes was analyzed. A modified quadratic model was fitted to the data with a coefficient of determination (R2) more than 0.90 for all responses. The intra-extracellular inulinase and invertase productions increased in the range from 16 to 8.4 times in the optimized medium (10% (w/v) sucrose, 2.5% (w/v) yeast extract, 2% (w/v) NaNO3, 1.5?mM (v/v) Zn+2, and 1% (v/v) Triton X-100) by RSM and from around 1.2 to 1.3 times greater than in the medium optimized by one-factor-at-a-time, respectively. The results of bioprocesses optimization can be useful in the scale-up fermentation and food industry. PMID:24151605

Dinarvand, Mojdeh; Rezaee, Malahat; Masomian, Malihe; Jazayeri, Seyed Davoud; Zareian, Mohsen; Abbasi, Sahar; Ariff, Arbakariya B.

2013-01-01

400

Analysis of Metal Bioleaching from Thermal Power Plant Fly Ash by Aspergillus niger 34770 Culture Supernatant and Reduction of Phytotoxicity During the Process.  

PubMed

Aspergillus niger culture supernatant is used for bioleaching process. Before starting bioleaching process, fly ash was washed with distilled water. This removed 100 % sodium, 47 % (±0.45) boron, 38.07 % (±0.12) calcium, 29.89 % (±0.78) magnesium, and 11.8 % (±0.05) potassium. The pH was reduced from 10.5 to 8.5 after water washing. During bioleaching process, around 100 % metal removal was achieved in 4 h for all metals except chromium 93 % (±1.18), nickel 83 % (±0.32), arsenic 78 % (±0.52), and lead 70 % (±0.20). The process parameters including temperature, shaking speed, and solid/liquid ratio were optimized for bioleaching process. Experiments were conducted to evaluate effect of fly ash on growth of mung bean (Vigna radiata). At 20 g/100 ml fly ash concentration no germination of V. radiata seeds was observed. With an increasing concentration of untreated fly ash, a gradual decrease in root/shoot length was observed. After bioleaching process 78 % (±0.19) germination of V. radiata was observed with 20 g/100 ml fly ash. This study will help to develop an efficient process to remove the toxic metals from fly ash. PMID:25349087

Jadhav, Umesh U; Hocheng, Hong

2015-01-01

401

Effects of elevated dissolved CO2 levels on batch and continuous cultures of Aspergillus niger A60: an evaluation of experimental methods.  

PubMed Central

The effects of elevated levels of dissolved carbon dioxide (dCO2), produced by gassing with CO2-enriched gas mixtures, upon an industrial strain of Aspergillus niger (strain A60) producing citrate and gluconate were quantitatively assessed. Particular attention was paid to the reliability and accuracy of the steam-sterilizable dCO2 probe, especially in the presence of high concentrations of potentially interfering acidic species. The response of the organism to elevated dCO2 levels was assessed by using both batch and chemostat cultures, and the sensitivity of the organism in different growth phases (lag, exponential, and stationary) was examined. Chemostat cultures showed markedly less inhibition (in terms of biomass and organic acid synthesis) than did batch cultures. Studies in batch culture indicated that lag-phase cultures were especially sensitive to elevated dCO2 levels. Overall, the results of this study indicate that previous experimental methods used to examine dCO2 effects in submerged cultures (continuous CO2-enriched gassing of batch cultures from time zero) have been inappropriate and have led to systematic overestimation of the inhibitory effects of dCO2 on mycelial organisms. PMID:9361401

McIntyre, M; McNeil, B

1997-01-01

402

Impact of assay conditions on activity estimate and kinetics comparison of Aspergillus niger PhyA and Escherichia coli AppA2 phytases.  

PubMed

Aspergillus niger PhyA and Escherichia coli AppA2 are increasingly used in animal feed for phosphorus nutrition and environmental protection. The objective of this study was to determine the impacts of assay conditions on activity estimates of these two phytases and to compare their biochemical characteristics at a pH similar to the stomach environment. The activities of the unpurified AppA2 were more variable than those of PhyA with three commonly used phytase activity assays. The variations associated with AppA2 were accounted for by buffer, pH, and the inclusion of Triton X-100 and BSA by approximately one-third each. At the commonly observed stomach pH of 3.5, the purified AppA2 had a lower affinity to phytate (a higher K(m)), but greater V(max), k(cat), and k(cat)/K(m) than those of PhyA. In summary, differences between AppA2 and PhyA in responses to activity assay conditions and in inherent kinetic properties should be considered in interpreting their feeding efficacy. PMID:19530713

Weaver, Jeremy D; Ullah, Abul H J; Sethumadhavan, Kandan; Mullaney, Edward J; Lei, Xin Gen

2009-06-24

403

Effects of High Pressure Homogenization on the Activity, Stability, Kinetics and Three-Dimensional Conformation of a Glucose Oxidase Produced by Aspergillus niger  

PubMed Central

High pressure homogenization (HPH) is a non-thermal method, which has been employed to change the activity and stability of biotechnologically relevant enzymes. This work investigated how HPH affects the structural and functional characteristics of a glucose oxidase (GO) from Aspergillus niger. The enzyme was homogenized at 75 and 150 MPa and the effects were evaluated with respect to the enzyme activity, stability, kinetic parameters and molecular structure. The enzyme showed a pH-dependent response to the HPH treatment, with reduction or maintenance of activity at pH 4.5–6.0 and a remarkable activity increase (30–300%) at pH 6.5 in all tested temperatures (15, 50 and 75°C). The enzyme thermal tolerance was reduced due to HPH treatment and the storage for 24 h at high temperatures (50 and 75°C) also caused a reduction of activity. Interestingly, at lower temperatures (15°C) the activity levels were slightly higher than that observed for native enzyme or at least maintained. These effects of HPH treatment on function and stability of GO were further investigated by spectroscopic methods. Both fluorescence and circular dichroism revealed conformational changes in the molecular structure of the enzyme that might be associated with the distinct functional and stability behavior of GO. PMID:25061935

Tribst, Alline Artigiani Lima; Cota, Júnio; Murakami, Mario Tyago; Cristianini, Marcelo

2014-01-01

404

The efficacy of disinfectants on abattoirs’ Candida albicans isolates in Niger Delta region  

PubMed Central

This study was conducted to evaluate the antimicrobial activities of common disinfectants- these are (parachlorometaxylenol) dettol, savlon purit and jik (sodium hypochlorite) on  Candida albicans isolated from displaying and cutting tables in five different abattoirs in Port Harcourt (Niger Delta region); the abattoirs include Trans Amadi, Agip, Woji, Rumuokoro, and Rumuodara. This research was carried out between January 2005 and June 2006. Swab samples were collected from abattoirs cutting tables with sterile swab sticks and immediately transferred and cultured in the laboratory on a selective medium Sabouraud Dextrose Agar (SDA). The disinfectants’ concentrations were prepared at 10%, 20%, 40%, and 70%, in triplicates and the mean values calculated. 0.5 Mc Farland turbidity method of standardization and Agar diffusion method were used for disinfectants testing of the isolates. Statistical analysis of the data showed no significant difference in the effectiveness of these disinfectants at (p<0.05). In conclusion, this study has shown that savlon and dettol were the most potent antimicrobial agents at 10% concentration on  Candida albicans isolates when compared with purit and jik in this study, hence they are good sanitizing agents to be applied on the abattoirs cutting tables, before meat products can be displayed for sale. PMID:24358834

Olorode, Oluwayemisi A

2012-01-01

405

ANTíGENOS NATIVOS DE ASPERGILLUS FUMIGATUS CON UTILIDAD PARA EL INMUNODIAGNÓSTICO DE ASPERGILOMA  

Microsoft Academic Search

In order to evaluate the usefulness of native antigens of autochthonous strains of Aspergillus fumigatus for immunodiagnosis of aspergilloma, We was conducted a study using two strains of this fungus, isolated from patients with aspergilloma (533 and 554), which were confronted with commercial control serum of A. fumigatus, A. flavus, A. niger, Candida, Coccidioides, Histoplasma and Paracoccidioides by immunodiffusion test,

José Casquero; Elizabeth Sánchez

2009-01-01

406

Comparison of species composition and fumonisin production in Aspergillus section Nigri populations in maize kernels from USA and Italy.  

PubMed

Fumonisin contamination of maize is considered a serious problem in most maize-growing regions of the world, due to the widespread occurrence of these mycotoxins and their association with toxicosis in livestock and humans. Fumonisins are produced primarily by species of Fusarium that are common in maize grain, but also by some species of Aspergillus sect. Nigri, which can also occur on maize kernels as opportunistic pathogens. Understanding the origin of fumonisin contamination in maize is a key component in developing effective management strategies. Although some fungi in Aspergillus sect. Nigri are known to produce fumonisins, little is known about the species which are common in maize and whether they make a measurable contribution to fumonisin contamination of maize grain. In this work, we evaluated populations of Aspergillus sect. Nigri isolated from maize in USA and Italy, focusing on analysis of housekeeping genes, the fum8 gene and in vitro capability of producing fumonisins. DNA sequencing was used to identify Aspergillus strains belonging to sect. Nigri, in order to compare species composition between the two populations, which might influence specific mycotoxicological risks. Combined beta-tubulin/calmodulin sequences were used to genetically characterize 300 strains (199 from Italy and 101 from USA) which grouped into 4 clades: Aspergillus welwitschiae (syn. Aspergillus awamori, 14.7%), Aspergillus tubingensis (37.0%) and Aspergillus niger group 1 (6.7%) and group 2 (41.3%). Only one strain was identified as Aspergillus carbonarius. Species composition differed between the two populations; A. niger predominated among the USA isolates (69%), but comprised a smaller percentage (38%) of Italian isolates. Conversely, A. tubingensis and A. welwitschiae occurred at higher frequencies in the Italian population (42% and 20%, respectively) than in the USA population (27% and 5%). The evaluation of FB2 production on CY20S agar revealed 118 FB2 producing and 84 non-producing strains distributed among the clades: A. welwitschiae, A. niger group 1 and A. niger group 2, confirming the potential of Aspergillus sect. Nigri species to contribute to total fumonisin contamination of maize. A higher percentage of A. niger isolates (72.0%) produced FB2 compared to A. welwitschiae (36.6%). The percentage of FB2-producing A. niger strains was similar in the USA and Italian populations; however, the predominance of A. niger in the USA population suggests a higher potential for fumonisin production. Some strains with fum8 present in the genome did not produce FB2in vitro, confirming the ineffectiveness of fum8 presence as a predictor of FB2 production. PMID:25087207

Susca, Antonia; Moretti, Antonio; Stea, Gaetano; Villani, Alessandra; Haidukowski, Miriam; Logrieco, Antonio; Munkvold, Gary

2014-10-01

407

Mapping the structural requirements of inducers and substrates for decarboxylation of weak acid preservatives by the food spoilage mould Aspergillus niger.  

PubMed

Moulds are able to cause spoilage in preserved foods through degradation of the preservatives using the Pad-decarboxylation system. This causes, for example, decarboxylation of the preservative sorbic acid to 1,3-pentadiene, a volatile compound with a kerosene-like odour. Neither the natural role of this system nor the range of potential substrates has yet been reported. The Pad-decarboxylation system, encoded by a gene cluster in germinating spores of the mould Aspergillus niger, involves activity by two decarboxylases, PadA1 and OhbA1, and a regulator, SdrA, acting pleiotropically on sorbic acid and cinnamic acid. The structural features of compounds important for the induction of Pad-decarboxylation at both transcriptional and functionality levels were investigated by rtPCR and GCMS. Sorbic and cinnamic acids served as transcriptional inducers but ferulic, coumaric and hexanoic acids did not. 2,3,4,5,6-Pentafluorocinnamic acid was a substrate for the enzyme but had no inducer function; it was used to distinguish induction and competence for decarboxylation in combination with the analogue chemicals. The structural requirements for the substrates of the Pad-decarboxylation system were probed using a variety of sorbic and cinnamic acid analogues. High decarboxylation activity, ~100% conversion of 1mM substrates, required a mono-carboxylic acid with an alkenyl double bond in the trans (E)-configuration at position C2, further unsaturation at C4, and an overall molecular length between 6.5Å and 9Å. Polar groups on the phenyl ring of cinnamic acid abolished activity (no conversion). Furthermore, several compounds were shown to block Pad-decarboxylation. These compounds, primarily aldehyde analogues of active substrates, may serve to reduce food spoilage by moulds such as A. niger. The possible ecological role of Pad-decarboxylation of spore self-inhibitors is unlikely and the most probable role for Pad-decarboxylation is to remove cinnamic acid-type inhibitors from plant material and allow uninhibited germination and growth of mould spores. PMID:22726726

Stratford, Malcolm; Plumridge, Andrew; Pleasants, Mike W; Novodvorska, Michaela; Baker-Glenn, Charles A G; Pattenden, Gerald; Archer, David B

2012-07-16

408

Impact of alg3 gene deletion on growth, development, pigment production, protein secretion, and functions of recombinant Trichoderma reesei cellobiohydrolases in Aspergillus niger.  

PubMed

Dolichyl-P-Man:Man(5)GlcNAc(2)-PP-dolichyl ?-1,3-mannosyltransferase (also known as "asparagine-linked glycosylation 3", or ALG3) is involved in early N-linked glycan synthesis and thus is essential for formation of N-linked protein glycosylation. In this study, we examined the effects of alg3 gene deletion (alg3?) on growth, development, pigment production, protein secretion and recombinant Trichoderma reesei cellobiohydrolase (rCel7A) expressed in Aspergillus niger. The alg3? delayed spore germination in liquid cultures of complete medium (CM), potato dextrose (PD), minimal medium (MM) and CM with addition of cAMP (CM+cAMP), and resulted in significant reduction of hyphal growth on CM, potato dextrose agar (PDA), and CM+cAMP and spore production on CM. The alg3? also led to a significant accumulation of red pigment on both liquid and solid CM cultures. The relative abundances of 54 of the total 215 proteins identified in the secretome were significantly altered as a result of alg3?, 63% of which were secreted at higher levels in alg3? strain than the parent. The rCel7A expressed in the alg3? mutant was smaller in size than that expressed in both wild-type and parental strains, but still larger than T. reesei Cel7A. The circular dichroism (CD)-melt scans indicated that change in glycosylation of rCel7A does not appear to impact the secondary structure or folding. Enzyme assays of Cel7A and rCel7A on nanocrystalline cellulose and bleached kraft pulp demonstrated that the rCel7As have improved activities on hydrolyzing the nanocrystalline cellulose. Overall, the results suggest that alg3 is critical for growth, sporulation, pigment production, and protein secretion in A. niger, and demonstrate the feasibility of this alternative approach to evaluate the roles of N-linked glycosylation in glycoprotein secretion and function. PMID:24076077

Dai, Ziyu; Aryal, Uma K; Shukla, Anil; Qian, Wei-Jun; Smith, Richard D; Magnuson, Jon K; Adney, William S; Beckham, Gregg T; Brunecky, Roman; Himmel, Michael E; Decker, Stephen R; Ju, Xiaohui; Zhang, Xiao; Baker, Scott E

2013-12-01

409

Utilization of palm kernel cake for production of beta-mannanase by Aspergillus niger FTCC 5003 in solid substrate fermentation using an aerated column bioreactor.  

PubMed

The production of beta-mannanase from palm kernel cake (PKC) as a substrate in solid substrate fermentation (SSF) was studied using a laboratory column bioreactor. The simultaneous effects of three independent variables, namely incubation temperature, initial moisture content of substrate and airflow rate, on beta-mannanase production were evaluated by response surface methodology (RSM) on the basis of a central composite face-centered (CCF) design. Eighteen trials were conducted in which Aspergillus niger FTCC 5003 was cultivated on PKC in an aerated column bioreactor for seven days under SSF process. The highest level of beta-mannanase (2117.89 U/g) was obtained when SSF process was performed at incubation temperature, initial moisture level and aeration rate of 32.5 degrees C, 60% and 0.5 l/min, respectively. Statistical analysis revealed that the quadratic terms of incubation temperature and initial moisture content had significant effects on the production of beta-mannanase (P < 0.01). A similar analysis also demonstrated that the linear effect of initial moisture level and an interaction effect between the initial moisture content and aeration rate significantly influenced the production of beta-mannanase (P < 0.01). The statistical model suggested that the optimal conditions for attaining the highest level of beta-mannanase were incubation temperature of 32 degrees C, initial moisture level of 59% and aeration rate of 0.5 l/min. A beta-mannanase yield of 2231.26 U/g was obtained when SSF process was carried out under the optimal conditions described above. PMID:19937085

Abdeshahian, Peyman; Samat, Noraini; Hamid, Aidil Abdul; Yusoff, Wan Mohtar Wan

2010-01-01

410

[The isolation and evaluation of Aspergillus fumigatus antigens].  

PubMed

Antigens from three strains of Aspergillus fumigatus (354, 356, and JIG) and an antiserum against the mixing of these antigens have been produced, and evaluated immunochemically. The antigens were obtained through a modified Coleman & Kaufman technique (culture filtrate concentrated by acetone). Analysis by the immunodiffusion test (ID) against homologous serum has yielded 100% sensitivity (with the studied sera). Concerning heterologous sera we found reactivity with a serum of a patient of candidiasis and another with histoplasmosis. The same result was obtained with a reference antigen in immunodiffusion, showing similar standards of response. Titration of the antiserum by ID and counterimmunoelectrophoresis showed a title of 1:32, and by complement fixation (micro-technique) a title of 1:128. Using immunoelectrophoresis (IEF), the produced antiserum yielded 8 lines of precipitation (5 in the anodic pole and 3 in the cathodic one). In SDS-PAGE at 12.5% the antigen has presented a rather complex electrophoretic profile (26 proteic subunits with a molecular weight ranging from 18 a > 100 kDa). Immunogenicity of the antigen was observed in all fractions of SDS-PAGE when the immunoblotting against the antiserum was carried out. PMID:1342095

Lirio, V de S; de Assis, C M; Cano, M I; Lacaz, C da S

1992-01-01

411

Aspergillus 6V4, a Strain Isolated from Manipueira, Produces High Amylases Levels by Using Wheat Bran as a Substrate  

PubMed Central

The aim of this study was screening fungi strains, isolated from manipueira (a liquid subproduct obtained from the flour production of Manihot esculenta), for amylases production and investigating production of these enzymes by the strain Aspergillus 6V4. The fungi isolated from manipueira belonged to Ascomycota phylum. The strain Aspergillus 6V4 was the best amylase producer in the screening assay of starch hydrolysis in petri dishes (ASHPD) and in the assay in submerged fermentation (ASbF). The strain Aspergillus 6V4 produced high amylase levels (335?UI/L) using wheat bran infusion as the exclusive substrate and the supplementation of this substrate with peptone decreased the production of this enzyme. The moisture content of 70% was the best condition for the production of Aspergillus 6V4 amylases (385?IU/g) in solid state fermentation (SSF). PMID:24724017

Celestino, Jessyca dos Reis; Duarte, Ana Caroline; Silva, Cláudia Maria de Melo; Sena, Hellen Holanda; Ferreira, Maria do Perpétuo Socorro Borges Carriço; Mallmann, Neila Hiraishi; Lima, Natacha Pinheiro Costa; Tavares, Chanderlei de Castro; de Souza, Rodrigo Otávio Silva; Souza, Érica Simplício; Souza, João Vicente Braga

2014-01-01

412

Aspergillus 6V4, a Strain Isolated from Manipueira, Produces High Amylases Levels by Using Wheat Bran as a Substrate.  

PubMed

The aim of this study was screening fungi strains, isolated from manipueira (a liquid subproduct obtained from the flour production of Manihot esculenta), for amylases production and investigating production of these enzymes by the strain Aspergillus 6V4. The fungi isolated from manipueira belonged to Ascomycota phylum. The strain Aspergillus 6V4 was the best amylase producer in the screening assay of starch hydrolysis in petri dishes (ASHPD) and in the assay in submerged fermentation (ASbF). The strain Aspergillus 6V4 produced high amylase levels (335?UI/L) using wheat bran infusion as the exclusive substrate and the supplementation of this substrate with peptone decreased the production of this enzyme. The moisture content of 70% was the best condition for the production of Aspergillus 6V4 amylases (385?IU/g) in solid state fermentation (SSF). PMID:24724017

Celestino, Jessyca Dos Reis; Duarte, Ana Caroline; Silva, Cláudia Maria de Melo; Sena, Hellen Holanda; Ferreira, Maria do Perpétuo Socorro Borges Carriço; Mallmann, Neila Hiraishi; Lima, Natacha Pinheiro Costa; Tavares, Chanderlei de Castro; de Souza, Rodrigo Otávio Silva; Souza, Erica Simplício; Souza, João Vicente Braga

2014-01-01

413

The influence of Aspergillus niger transcription factors AraR and XlnR in the gene expression during growth in D-xylose, L-arabinose and steam-exploded sugarcane bagasse.  

PubMed

The interest in the conversion of plant biomass to renewable fuels such as bioethanol has led to an increased investigation into the processes regulating biomass saccharification. The filamentous fungus Aspergillus niger is an important microorganism capable of producing a wide variety of plant biomass degrading enzymes. In A. niger the transcriptional activator XlnR and its close homolog, AraR, controls the main (hemi-)cellulolytic system responsible for plant polysaccharide degradation. Sugarcane is used worldwide as a feedstock for sugar and ethanol production, while the lignocellulosic residual bagasse can be used in different industrial applications, including ethanol production. The use of pentose sugars from hemicelluloses represents an opportunity to further increase production efficiencies. In the present study, we describe a global gene expression analysis of A. niger XlnR- and AraR-deficient mutant strains, grown on a D-xylose/L-arabinose monosaccharide mixture and steam-exploded sugarcane bagasse. Different gene sets of CAZy enzymes and sugar transporters were shown to be individually or dually regulated by XlnR and AraR, with XlnR appearing to be the major regulator on complex polysaccharides. Our study contributes to understanding of the complex regulatory mechanisms responsible for plant polysaccharide-degrading gene expression, and opens new possibilities for the engineering of fungi able to produce more efficient enzymatic cocktails to be used in biofuel production. PMID:23892063

de Souza, Wagner Rodrigo; Maitan-Alfenas, Gabriela Piccolo; de Gouvêa, Paula Fagundes; Brown, Neil Andrew; Savoldi, Marcela; Battaglia, Evy; Goldman, Maria Helena S; de Vries, Ronald P; Goldman, Gustavo Henrique

2013-11-01

414

Antifungal Activity of Lactic Acid Bacteria Isolated from Kimchi Against Aspergillus fumigatus  

PubMed Central

More than 120 isolates of lactic acid bacteria obtained from Kimchi was screened for antifungal activity against Aspergillus fumigatus. Approximately 10% of the isolates showed inhibitory activity and only 4.16% (five isolates) exhibited strong activity against the indicator fungus A. fumigatus. The five isolates showed a wide rang of antifungal activity against A. flavus, Fusarium moniliforme, Penicillium commune, and Rhizopus oryzae. They were identified by 16S rDNA sequencing as Lactobacillus cruvatus, L. lactis subsp. lactis, L. casei, L. pentosus, and L. sakei. The effect of Lactobacillus on mycelial growth and fungal biomass as well as its ability to produce toxic compounds were determined. The results indicate that the three species, Lactobacillus casei, L. lactis subsp. lactis, and L. pentosus, are active against A. fumigatus. PMID:24049503

2005-01-01

415

Isolate-Dependent Growth, Virulence, and Cell Wall Composition in the Human Pathogen Aspergillus fumigatus  

PubMed Central

The ubiquitous fungal pathogen Aspergillus fumigatus is a mediator of allergic sensitization and invasive disease in susceptible individuals. The significant genetic and phenotypic variability between and among clinical and environmental isolates are important considerations in host-pathogen studies of A. fumigatus-mediated disease. We observed decreased radial growth, rate of germination, and ability to establish colony growth in a single environmental isolate of A. fumigatus, Af5517, when compared to other clinical and environmental isolates. Af5517 also exhibited increased hyphal diameter and cell wall ?-glucan and chitin content, with chitin most significantly increased. Morbidity, mortality, lung fungal burden, and tissue pathology were decreased in neutropenic Af5517-infected mice when compared to the clinical isolate Af293. Our results support previous findings that suggest a correlation between in vitro growth rates and in vivo virulence, and we propose that changes in cell wall composition may contribute to this phenotype. PMID:24945802

Amarsaikhan, Nansalmaa; O’Dea, Evan M.; Tsoggerel, Angar; Owegi, Henry; Gillenwater, Jordan; Templeton, Steven P.

2014-01-01

416

In-depth analysis of the Aspergillus niger glucoamylase (glaA) promoter performance using high-throughput screening and controlled bioreactor cultivation techniques.  

PubMed

An in-depth characterization of the Aspergillus niger glucoamylase (glaA) promoter performance was carried out on defined medium employing multi-well high-throughput screening as well as controlled batch and fed-batch bioreactor culture techniques with GFP as a fluorescent reporter protein. A variety of metabolizable carbon substrates and non-metabolizable analogs were screened with regard to their effect on the glaA expression system. The results clearly demonstrate that only starch and its hydrolytic products, including glucose, act as inducers. However, induction of the glaA expression system through the monosaccharide glucose is significantly lower compared to starch and the higher molecular weight starch degradation products. All other 26 carbon substrates tested do not induce, or even, as in the case of the easily metabolizable monosaccharide xylose, repress glaA-promoter controlled gene expression in the presence of the inducing disaccharide maltose with an increase of repression strength by increasing xylose concentrations. The complex effect of glucose on glaA-promoter controlled expression was also analyzed using non-metabolizable glucose analogs, namely 5-thio-glucose and 2-deoxyglucose, which were identified as novel and potent inducers of the glaA expression system. The results show that the induction strength depends on the inducer concentration with a maximum at defined concentrations and lower induction or even repression at concentrations above. Moreover, controlled fed-batch cultivations using a high maltose feed rate with concomitant extracellular accumulation of glucose resulted in lower levels of the reporter protein compared to cultures with a low-maltose feed rate without extracellular glucose accumulation, thus supporting the conclusion that increasing the glucose concentration beyond a critical point reduces the induction strength or may even cause repression. This way, the speed of polymer hydrolysis, glucose uptake and intracellular breakdown can be fine-tuned for optimal fungal growth and the metabolic burden for glucoamylase synthesis can be limited adequately in response to nutrient availability. PMID:18501461

Ganzlin, Markus; Rinas, Ursula

2008-06-30

417

Diversity of Aspergillus oryzae genotypes (RFLP) isolated from traditional soy sauce production within Malaysia and Southeast Asia  

Technology Transfer Automated Retrieval System (TEKTRAN)

DNA fingerprinting was performed on 64 strains of Aspergillus oryzae and one strain of A. sojae isolated from soysauce factories within Malaysia and Southeast Asia that use primitive traditional methods in producing 'tamari type' Cantonese soy sauce. PstI digests of total genomic DNA from each isol...

418

Comparison of cultural and analytical methods for determination of aflatoxin production by Mississippi Delta Aspergillus isolates.  

PubMed

This study compared cultural and analytical methods for detecting aflatoxin production by Aspergillus species. Aspergillus isolates were obtained from various Mississippi Delta crops (corn, peanut, rice, cotton) and soils. Most of the isolates (99%) were A. flavus and the remainder comprised A. parasiticus and A. nomius. The following three cultural methods were evaluated on potato dextrose agar: fluorescence (FL) on beta-cyclodextrin-containing media (CD), yellow pigment (YP) formation in mycelium and medium, and color change after ammonium hydroxide vapor exposure (AV). Aflatoxins in culture extracts were confirmed by thin-layer chromatography (TLC) and quantified by enzyme-linked immunosorbent assay (ELISA). Of the 517 isolates, 314 produced greater than 20 ng/g of total aflatoxin based on ELISA, and 180 produced greater than 10 000 ng/g of aflatoxin in the medium. Almost all the toxigenic isolates (97%) were confirmed by TLC as producers. Of the toxigenic isolates, as determined by ELISA, 93%, 73%, and 70% gave positive FL, YP, and AV responses, respectively. Of the 203 isolates producing less than 20 ng/g of aflatoxin, 20%, 6%, and 0% of respective FL, YP, and AV methods gave false-positive responses. The 9% false-positive results from TLC fall within this range. This study showed good agreement among all tested cultural methods. However, these cultural techniques did not detect aflatoxin in all cultures that were found to produce aflatoxins by ELISA, LC/MS, and TLC. The best results were obtained when the AV color change and CD fluorescence methods were used together, yielding an overall success rate comparable to TLC but without the need for chemical extraction and the time and expense of TLC. PMID:15105886

Abbas, Hamed K; Zablotowicz, R M; Weaver, M A; Horn, B W; Xie, W; Shier, W T

2004-03-01

419

Isolation of Aspergillus spp. from the respiratory tract in critically ill patients: risk factors, clinical presentation and outcome  

PubMed Central

Introduction Our aims were to assess risk factors, clinical features, management and outcomes in critically ill patients in whom Aspergillus spp. were isolated from respiratory secretions, using a database from a study designed to assess fungal infections. Methods A multicentre prospective study was conducted over a 9-month period in 73 intensive care units (ICUs) and included patients with an ICU stay longer than 7 days. Tracheal aspirate and urine samples, and oropharyngeal and gastric swabs were collected and cultured each week. On admission to the ICU and at the initiation of antifungal therapy, the severity of illness was evaluated using the Acute Physiology and Chronic Health Evaluation II score. Retrospectively, isolation of Aspergillus spp. was considered to reflect colonization if the patient did not fulfil criteria for pneumonia, and infection if the patient met criteria for pulmonary infection and if the clinician in charge considered the isolation to be clinically valuable. Risk factors, antifungal use and duration of therapy were noted. Results Out of a total of 1756 patients, Aspergillus spp. were recovered in 36. Treatment with steroids (odds ratio = 4.5) and chronic obstructive pulmonary disease (odds ratio = 2.9) were significantly associated with Aspergillus spp. isolation in multivariate analysis. In 14 patients isolation of Aspergillus spp. was interpreted as colonization, in 20 it was interpreted as invasive aspergillosis, and two cases were not classified. The mortality rates were 50% in the colonization group and 80% in the invasive infection group. Autopsy was performed in five patients with clinically suspected infection and confirmed the diagnosis in all of these cases. Conclusion In critically ill patients, treatment should be considered if features of pulmonary infection are present and Aspergillus spp. are isolated from respiratory secretions. PMID:15987390

Garnacho-Montero, José; Amaya-Villar, Rosario; Ortiz-Leyba, Carlos; León, Cristóbal; Álvarez-Lerma, Francisco; Nolla-Salas, Juan; Iruretagoyena, José R; Barcenilla, Fernando

2005-01-01

420

Occurrence of toxigenic Aspergillus spp. and aflatoxins in selected food commodities of Asian origin sourced in the West of Scotland.  

PubMed

The occurrence of Aspergillus moulds and aflatoxins in 12 commercially-available dried foods of Asian origin were examined. All food samples, except green beans and three types of dried fruit, contained multiple genera of moulds of which Aspergillus (55%) was the most frequently detected. Penicillium (15%), Rhizopus (11%), Mucor (3%), Monascus (1%), Eurotium (1%) and unidentified (14%) were also observed. The occurrence of aflatoxigenic moulds, however, did not correspond with the occurrence of aflatoxins in foods. Aflatoxigenic Aspergillus spp. (39 isolates) were recovered from long grain rice, fragrant rice, peanuts, black beans and black pepper. The predominant Aspergillus species was A. parasiticus (61%) while Aspergillus oryzae (3%), Aspergillus utus (5%), Aspergillus niger (5%), Aspergillus ochraceus (3%) and unidentified (23%) were also observed. Long grain rice, fragrant rice, peanuts, black beans and black pepper were positive for Aspergillus but contained undetectable aflatoxins. In contrast, Jasmine brown rice and crushed chilli contained 14.7 and 11.4?g/kg of total aflatoxins, respectively, in the absence of Aspergillus so aflatoxigenic Aspergillus was present at some stage of food production. The results from this study emphasise the need for stricter control measures in reducing occurrence of aflatoxins in foods for export and domestic use. PMID:23416649

Ruadrew, Sayan; Craft, John; Aidoo, Kofi

2013-05-01

421

Sequence determination of a quadripartite dsRNA virus isolated from Aspergillus foetidus.  

PubMed

Virus infection of Aspergillus foetidus was documented over 40 years ago and was one of the first mycovirus infections described in a filamentous fungus. The virus, named Aspergillus foetidus virus (AfV), contains at least two types of icosahedral particles, called AfV-fast (-F) and AfV-slow (-S) virions, based on their relative electrophoretic mobilities. Here, we report the complete nucleotide sequence of the AfV-F genome isolated from virions purified from the prototype isolate of the fungus. The AfV-F double-stranded (ds) RNA genome is tetra-segmented, and the plus strands of each of the four segments, but not the minus strands, are polyadenylated. The organisation and sequences of the four AfV-F dsRNAs are similar to those described for Alternaria alternata virus 1, which we propose is a member of an emerging mycovirus genus ("Alternavirus") and family ("Alternaviridae"), which also includes AfV-F. PMID:22760661

Kozlakidis, Zisis; Herrero, Noemi; Ozkan, Selin; Kanhayuwa, Lakkhana; Jamal, Atif; Bhatti, Muhammad F; Coutts, Robert H A

2013-01-01

422

Aspergillus citrinoterreus, a New Species of Section Terrei Isolated from Samples of Patients with Nonhematological Predisposing Conditions.  

PubMed

The use of molecular identification techniques has revealed an increasing number of new species within Aspergillus section Terrei. We phenotyped a set of 26 clinical isolates that showed genetic differences from Aspergillus terreus sensu stricto by analyzing sequences from PCR-amplified ?-tubulin and calmodulin genes and the internal transcribed spacer region. Since the isolates were phylogenetically and morphologically different from all of the members of Aspergillus section Terrei, they are described here as a new species, Aspergillus citrinoterreus, so named because it produces a diffusible yellowish pigment in agar. A. citrinoterreus isolates were significantly more susceptible to itraconazole, voriconazole, and posaconazole than A. terreus sensu stricto isolates were; in contrast, the amphotericin B MICs for both species were high. A. citrinoterreus was found in clinical samples from patients with proven or probable invasive aspergillosis and colonized patients, none of whom had hematological malignancies as predisposing conditions. However, they did have other underlying conditions such as chronic obstructive pulmonary disease, cirrhosis, and cancer or had received a solid organ transplants and presented not only with invasive pulmonary aspergillosis but also with mediastinitis. A. citrinoterreus isolates were detected for the first time in 2002. In all cases of invasive aspergillosis, A. citrinoterreus was found to be a copathogen, mostly with A. fumigatus. PMID:25502530

Guinea, Jesús; Sandoval-Denis, Marcelo; Escribano, Pilar; Peláez, Teresa; Guarro, Josep; Bouza, Emilio

2015-02-01

423

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. PMID:24986045

2014-01-01

424

Screening of tannin acyl hydrolase (E.C.3.1.1.20) producing tannery effluent fungal isolates using simple agar plate and SmF process  

Microsoft Academic Search

Industrially important tannase producing fungi were isolated from tannery effluent using simple agar plate method. The isolates were screened by submerged fermentation using auto-controlled bioreactor. The colony diameter on the solid surface media shows high correlation with quantitative production of tannase. The isolate Aspergillus niger shows maximum production of both extracellular and intracellular enzyme.

K. Murugan; S. Saravanababu; M. Arunachalam

2007-01-01

425