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1

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

2

Cryptic Sexuality in Aspergillus parasiticus and A. flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ascomycetous fungi of the genus Aspergillus comprise a wide variety of species of biotechnological importance (e.g. A. sojae, A. oryzae, A. niger) as well as pathogens and toxin producers (e.g. A. flavus, A. parasiticus, A. fumigatus, A. nidulans). With the exception of A. nidulans, which is a homot...

3

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

Microsoft Academic Search

Aspergillus nomius is described and represents a new aflatoxigenic species phenotypically similar to A. flavus. Strains examined were isolated from insects and agricultural commodities. Separation from A. flavus is based on the presence of indeterminate sclerotia and a lower growth temperature. Comparisons of DNA relatedness show A. nomius to have only relatively recently evolved from A. flavus and A. tamarii.

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

1987-01-01

4

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

5

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

Microsoft Academic Search

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

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

2001-01-01

6

IDENTIFICATION, CHARACTERIZATION AND ANTI-FUNGAL ACTVITIES OF SILK PROTEINS IN ASPERGILLUS FLAVUS  

E-print Network

IDENTIFICATION, CHARACTERIZATION AND ANTI-FUNGAL ACTVITIES OF SILK PROTEINS IN ASPERGILLUS FLAVUS 2006 #12;IDENTIFICATION, CHARACTERIZATION AND ANTI-FUNGAL ACTVITIES OF SILK PROTEINS IN ASPERGILLUS: IDENTIFICATION, CHARACTERIZATION AND ANTIFUNGAL ACTIVITIES OF SILK PROTEINS IN ASPERGILLUS FLAVUS RESISTANT

Ray, David

7

[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

8

Preharvest aflatoxin in maize genotypes under inoculation with Aspergillus flavus  

E-print Network

conducted through inoculation with a highly concentrated solution of Aspergillus flavus FR: Link spores, a naturally occurring fungus which infects maize and produces a toxic metabolite (aflatoxin) to humans and animals consuming the grain. No commercial...

Mayfield, Kerry L.

2009-05-15

9

The maize rachis affects Aspergillus flavus movement during ear development  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus expressing green fluorescent protein (GFP) was used to follow infection in ears of maize hybrids resistant and susceptible to the fungus. Developing ears were needle-inoculated with GFP-transformed A. flavus 20 days after silk emergence, and GFP fluorescence in the pith was evalu...

10

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

11

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

Microsoft Academic Search

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

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

2000-01-01

12

Evidence of aneuploidy modulating aflatoxigenicity in Aspergillus flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus is a well-known pathogen of many important agricultural commodities and is a major producer of aflatoxins, which are carcinogenic polyketides that pose a serious health risk to humans and animals. Aflatoxin contamination in peanut exports worldwide accounts for as much as $450 mi...

13

POPULATION OF ASPERGILLUS FLAVUS ON PISTACHIO BUDS AND FLOWERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus Link is an economically important fungus which produces carcinogenic compounds known as aflatoxins in agricultural crops such as corn, peanuts, cotton and tree nuts. The fungus has no known sexual stage; consequently, most studies on its genetic variability have been evaluated m...

14

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...

15

Sexual reproduction in Aspergillus flavus and A. parasiticus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus and A. parasiticus are potent producers of carcinogenic and hepatotoxic aflatoxins, polyketide-derived secondary metabolites that contaminate a wide variety of agricultural crops. Strains with opposite mating-type genes MAT1-1 and MAT1-2 within each species were crossed in an att...

16

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...

17

Lipids in Aspergillus flavus-maize interaction  

PubMed Central

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

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

2014-01-01

18

Potential involvement of Aspergillus flavus Link laccases in peanut invasion at low water potential  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus (Link) accumulates aflatoxins in peanuts, mainly affecting immature kernels during drought. Peanut invasion by A. flavus induces synthesis of phytoalexins, mostly stilbenoids, as a plant defense mechanism. Fungal laccases are often related to pathogenicity, and among other subst...

19

Aspergillus Flavus Keratitis after Deep Anterior Lamellar Keratoplasty  

PubMed Central

Purpose To report the clinical, microbiologic, confocal scan and histopathologic features of Aspergillus flavus keratitis which developed immediately after deep anterior lamellar keratoplasty (DALK). Case Report A 28-year-old woman underwent DALK using the big-bubble technique for keratoconus. The operation was uneventful, yielding a bare Descemet’s membrane (DM) followed by transplantation of a corneal graft devoid of DM and endothelium. Four days after keratoplasty, mild infiltrates were noticed in the inferonasal margin of the graft, which rapidly progressed to involve the adjacent recipient cornea. Confocal scan findings suggested filamentous fungal keratitis, leading to initiation of topical and systemic antifungal medications followed by immediate replacement of the graft. Histopathologic examination disclosed keratitis caused by a filamentous fungus, which was determined by microbiologic cultures to be Aspergillus flavus. Early diagnosis and appropriate management resulted in complete recovery from this potentially devastating infection. Conclusion Aspergillus Flavus can cause graft ulcers immediately after DALK. Confocal scan proved to be a valuable tool for early diagnosis and prompt intervention to control this otherwise devastating infection. PMID:23275826

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

2012-01-01

20

Genetic variability of Aspergillus flavus isolates from a Mississippi corn field  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fungus Aspergillus flavus represents a major threat to food safety and food security on a worldwide scale. Corn, peanuts, cotton, rice and edible nuts, can be colonized by A. flavus strains that produce carcinogenic aflatoxins. A biological strategy for control of toxigenic A. flavus starins inv...

21

?????????????????????????????????????????????????????????? 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

22

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

NASA Astrophysics Data System (ADS)

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

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

2011-05-01

23

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

24

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

25

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

26

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

27

Effect of corn and peanut cultivation on soil populations of Aspergillus flavus and A. parasiticus in southwestern Georgia.  

PubMed Central

The effect of corn and peanut cultivation on the proportion of Aspergillus flavus to A. parasiticus in soil was examined. Soil populations were monitored in three fields during three different years in southwestern Georgia. Each field was planted in both peanuts and corn, and soil was sampled within plots for each crop. A. flavus and A. parasiticus were present in similar proportions in plots from all fields at the beginning of the growing season. A. terreus, A. niger, and A. fumigatus were the other dominant aspergilli in soil. Fields A and B did not show drought stress in peanut or corn plants, and soil populations of A. flavus and A. parasiticus remained stable during the course of the year. In field C, drought stress in corn plants with associated A. flavus infection and aflatoxin contamination greatly increased soil populations of A. flavus relative to A. parasiticus upon dispersal of corn debris to the soil surface by a combine harvester. Colonization of organic debris after it has been added to the soil may maintain soil populations of A. parasiticus despite lower crop infection. PMID:7618858

Horn, B W; Greene, R L; Dorner, J W

1995-01-01

28

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

29

Evaluation of intraspecific competition (Aspergillus flavus Link) and aflatoxin formation in suspended disc culture and preharvest maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

The abilities of non-aflatoxin producing strains of Aspergillus flavus NRRL 32354; 18543; 21882; 21368 as well as domesticated koji strains Aspergillus oryzae (syn. A. flavus var. oryzae) NRRL 451; 1911; 5592; 6271; 30038 to interfere with aflatoxin formation by A. flavus NRRL 3357; 32355 were exami...

30

Flocculation behavior and mechanism of bioflocculant produced by Aspergillus flavus.  

PubMed

In this study, the flocculation behavior and mechanism of a cation-independent bioflocculant IH-7 produced by Aspergillus flavus were investigated. Results showed 91.6% was the lowest flocculating rate recorded by IH-7 (0.5 mg L(-1)) at pH range 4-8. Moreover, IH-7 showed better flocculation performance than polyaluminum chloride (PAC) at a wide range of flocculant concentration (0.06-25 mg L(-1)), temperature (5-45 °C) and salinity (10-60% w/w). The current study found that cation addition did not significantly enhance the flocculating rate and IH-7 is a positively charged bioflocculant. These findings suggest that charge neutralization is the main flocculation mechanism of IH-7 bioflocculant. IH-7 was significantly used to flocculate different types of suspended solids such as activated carbons, kaolin clays, soil solids and yeast cells. PMID:25560664

Aljuboori, Ahmad H Rajab; Idris, Azni; Al-Joubory, Hamid Hussain Rijab; Uemura, Yoshimitsu; Ibn Abubakar, B S U

2015-03-01

31

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

32

40 CFR 180.1254 - Aspergillus flavus NRRL 21882; exemption from the requirement of a tolerance.  

Code of Federal Regulations, 2012 CFR

...the requirement of a tolerance is established for residues of Aspergillus flavus NRRL 21882 on corn, field, forage; corn, field, grain; corn, field, stover; corn, field, aspirated grain fractions; corn, sweet, kernel plus cob...

2012-07-01

33

Influence of plant host species on intraspecific competition during infection by Aspergillus flavus  

E-print Network

of aflatoxin contamination. Host factors should be considered when designing and implementing aflatoxin management strategies including biocontrol with atoxigenic strains. Keywords: aflatoxin, Aspergillus flavus, cottonseed, intraspecific competition, maize Introduction Aflatoxins, highly carcinogenic secondary

Cotty, Peter J.

34

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...

35

Volatile profiles of toxigenic and non-toxigenic Aspergillus flavus using SPME for solid phase extraction  

Technology Transfer Automated Retrieval System (TEKTRAN)

Toxigenic and atoxigenic strains of Aspergillus flavus were grown on potato dextrose agar (PDA) and wetted sterile, cracked corn for 21 and 14 days, respectively. Volatile compounds produced by A. flavus, as well as those present in the PDA controls and sterile cracked corn, were collected using sol...

36

Cryptic speciation and recombination in the aflatoxin-producing fungus Aspergillus flavus  

Microsoft Academic Search

Aspergillus flavus, like approximately one- third of ascomycete fungi, is thought to be cosmopolitan and clonal because it has uniform asexual morphology. A. flavus produces af latoxin on nuts, grains, and cotton, and assump- tions about its life history are being used to develop strategies for its biological control. We tested the assumptions of clonality and conspecificity in a sample

DAVID M. GEISER; J OHN I. PITT; JOHN W. TAYLOR

1998-01-01

37

STABILITY OF MODIFIED ASPERGILLUS FLAVUS COMMUNITIES: NEED FOR AREA-WIDE  

E-print Network

of Agriculture New Orleans, LA Abstract Aspergillus flavus, the causal agent of aflatoxin contamination belonging to different vegetative compatibility groups may produce widely different quantities of aflatoxins. Some naturally occurring isolates of A. flavus produce no aflatoxins. Some of these atoxigenic strains

Cotty, Peter J.

38

Methods to sample air borne propagules of Aspergillus flavus C.H. Bock1,2,  

E-print Network

viable conidia of A. flavus under controlled environment conditions, but not in the field, although-dispersed propagules of Aspergillus flavus can infect and colonize many agricultural products, including cottonseed. To help reduce the risk of toxin entering the food chain, aflatoxin content is strictly regulated by law

Cotty, Peter J.

39

EVALUATION OF INTRASPECIFIC COMPETITION (ASPERGILLUS FLAVUS LINK) AND AFLATOXIN FORMATION IN SUSPENDED DISC CULTURE  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ability of two non-aflatoxin producing strains of Aspergillus flavus (NRRL 32354; NRRL 29269) to interfere with aflatoxin production by A. flavus NRRL 32355 was examined using a replacement series with the suspended disc culture method (R.A. Norton, 1995). Individual glass fiber discs, affixed ...

40

EST Profiling for Elucidation of Molecular Regulation of Aflatoxin bBiosynthesis in Aspergillus flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxins are toxic and carcinogenic polyketide metabolites produced by fungal species, including Aspergillus flavus and A. parasiticus. Many internal and external factors, such as nutrition and environment, affect aflatoxin biosynthesis. A. flavus EST has been carried out and a microarray has be...

41

Formation of Aspergillus flavus sclerotia on corn grown under different drought stress conditions  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus is a major producer of carcinogenic aflatoxins worldwide in corn, peanuts, tree nuts, cottonseed, spices and other crops. Many countries have strict limits on the amount of aflatoxins permitted in human commodities and animal feed. Sclerotia produced by A. flavus serve several f...

42

Characterization of an Aspergillus flavus alkaline protease and its role in the infection of maize kernels  

Technology Transfer Automated Retrieval System (TEKTRAN)

A 33 kDa protein present in Aspergillus flavus infected maize embryo tissue was identified as a fungal alkaline protease (ALP). This protein became one of the major extracellular proteins of A. flavus in potato dextrose broth medium cultural filtrate after 3 days, but was expressed at low levels or ...

43

Aspergillus flavus Genomic Data Mining Provides Clues for Its Use in Producing Biobased Products  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus is notorious for its ability to produce aflatoxins. It is also an opportunistic pathogen that infects plants, animals and human beings. The ability to survive in the natural environment, living on plant tissues (leaves or stalks), live or dead insects make A. flavus a ubiquitous...

44

Characterization and Population Analysis of the Mating-Type Genes in Aspergillus flavus and A. parasiticus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxins (AF) are acutely toxic and carcinogenic polyketides produced by several Aspergillus species. A. flavus and A. parasiticus are the most common agents of AF contamination of crops. Previously, we sequenced 21 intergenic regions in the aflatoxin gene cluster for 43 isolates of A. flavus and ...

45

Structural assessment of peanut cultivars for pod resistance to Aspergillus flavus  

E-print Network

STRUCTURAL ASSESSMENT OF PEANUT CULTIVARS FOR POD RESISTANCE TO ASPERGILLUS FLAVUS A Thesis by RUSSELYN DEE HENSON Submitted to the Office of Graduate Studies of Texas ARM University in partial fulfillment of the requirements for the degree... of Committee) Olin . Smith (Member) Ruth A. Taber (Member) . c )i~i ~) (, g. le j'(ZP'( I John S. Calahan (Member) eal Van Alfen (Department Head) May 1991 ABSTRACT Structural Assessment of Peanut Cultivars for Pod Resistance to Aspergillus flavus...

Henson, Russelyn Dee

2012-06-07

46

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

47

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

48

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

49

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

50

RNA interference reduces aflatoxin accumulation by Aspergillus flavus in peanut seeds  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxins are among the most powerful carcinogens in nature. They are produced by the fungal pathogen Aspergillus flavus Link and other Aspergillus species. Aflatoxins accumulate in many crops, including rice, wheat, oats, pecans, pistachios, soybean, cassava, almonds, peanuts, beans, corn and cot...

51

NsdC and NsdD affect Aspergillus flavus morphogenesis and aflatoxin production  

Technology Transfer Automated Retrieval System (TEKTRAN)

The transcription factors NsdC and NsdD have been shown to be necessary for sexual development in Aspergillus nidulans. Herein we examine the role of these proteins in development and aflatoxin production of the agriculturally important, aflatoxin-producing fungus, Aspergillus flavus. We found tha...

52

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

53

[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

54

Interactions in solution and crystallization of Aspergillus flavus urate oxidase  

NASA Astrophysics Data System (ADS)

Interparticle interactions of urate oxidase from Aspergillus flavus have been studied by small-angle X-ray scattering to determine crystallization conditions. This enzyme is a homotetramer with a total molecular weight of 128 kDa. It is a slightly basic protein (pI between 7.5 and 8). The interaction potentials have been studied as a function of the main thermodynamic and chemical parameters: temperature, protein concentration, pH, salt nature and concentration, addition of polyols. In 10 mM sodium carbonate at pH 10.5, the interactions are slightly repulsive and become less repulsive with a pH closer to pI. With the addition of carbonate, the protein loses its tetrameric structure for a dimeric one; with formate, the tetrameric structure remains stable. We also studied the effect of polyethylene glycols as it had been done with high molecular weight proteins. With the addition of PEG 8 K, the interactions became less repulsive and even turned attractive with the addition of both PEG 8 K and salt. Protein crystals of urate oxidase were observed in slightly repulsive conditions (second virial coefficient A2 about +10 -5 mol ml g -2 instead of -2 to -8×10 -4 mol ml g -2 for low molecular weight proteins).

Bonneté, F.; Vivarès, D.; Robert, Ch.; Colloc'h, N.

2001-11-01

55

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

56

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

57

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

58

Managing and monitoring of Aspergillus flavus in corn using bioplastic-based formulations  

Microsoft Academic Search

In this study, we evaluated the feasibility of bioplastic-based formulations for delivering a non-aflatoxigenic strain of Aspergillus flavus and for monitoring Aspergilli with the final objective of controlling aflatoxin contamination in corn. Field application of inoculated bioplastic granules showed a rapid shift in the composition of soil A. flavus population, with a significant decrease in relative abundance of indigenous aflatoxigenic isolates.

Cesare Accinelli; Mariangela Mencarelli; M. Ludovica Saccà; Alberto Vicari; Hamed K. Abbas

59

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

60

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

61

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

62

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

63

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

64

HYPERSPECTRAL IMAGERY FOR OBSERVING SPECTRAL SIGNATURE CHANGE IN ASPERGILLUS FLAVUS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxin contaminated corn is dangerous for domestic animals when used as feed and cause liver cancer when consumed by human beings. Therefore, the ability to detect A. flavus and its toxic metabolite, aflatoxin, is important. The objective of this study is to measure A. flavus growth using hyper...

65

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

66

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

Microsoft Academic Search

Forty-seven isolates of Aspergillus parasiticus were analyzed for production of aflatoxins B1, B2, G1, G2, and cyclopiazonic acid. None produced cyclopiazonic acid, whereas 46 of 47 produced aflatoxins B1 and G1. These data are related to previous studies pertaining to A. flavus and illustrate species validity from a biochemical standpoint.

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

1984-01-01

67

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

68

Bisulfite sequencing reveals that Aspergillus flavus holds a hollow in DNA methylation.  

PubMed

Aspergillus flavus first gained scientific attention for its production of aflatoxin. The underlying regulation of aflatoxin biosynthesis has been serving as a theoretical model for biosynthesis of other microbial secondary metabolites. Nevertheless, for several decades, the DNA methylation status, one of the important epigenomic modifications involved in gene regulation, in A. flavus remains to be controversial. Here, we applied bisulfite sequencing in conjunction with a biological replicate strategy to investigate the DNA methylation profiling of A. flavus genome. Both the bisulfite sequencing data and the methylome comparisons with other fungi confirm that the DNA methylation level of this fungus is negligible. Further investigation into the DNA methyltransferase of Aspergillus uncovers its close relationship with RID-like enzymes as well as its divergence with the methyltransferase of species with validated DNA methylation. The lack of repeat contents of the A. flavus' genome and the high RIP-index of the small amount of remanent repeat potentially support our speculation that DNA methylation may be absent in A. flavus or that it may possess de novo DNA methylation which occurs very transiently during the obscure sexual stage of this fungal species. This work contributes to our understanding on the DNA methylation status of A. flavus, as well as reinforces our views on the DNA methylation in fungal species. In addition, our strategy of applying bisulfite sequencing to DNA methylation detection in species with low DNA methylation may serve as a reference for later scientific investigations in other hypomethylated species. PMID:22276181

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

2012-01-01

69

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

PubMed Central

Aspergillus flavus first gained scientific attention for its production of aflatoxin. The underlying regulation of aflatoxin biosynthesis has been serving as a theoretical model for biosynthesis of other microbial secondary metabolites. Nevertheless, for several decades, the DNA methylation status, one of the important epigenomic modifications involved in gene regulation, in A. flavus remains to be controversial. Here, we applied bisulfite sequencing in conjunction with a biological replicate strategy to investigate the DNA methylation profiling of A. flavus genome. Both the bisulfite sequencing data and the methylome comparisons with other fungi confirm that the DNA methylation level of this fungus is negligible. Further investigation into the DNA methyltransferase of Aspergillus uncovers its close relationship with RID-like enzymes as well as its divergence with the methyltransferase of species with validated DNA methylation. The lack of repeat contents of the A. flavus' genome and the high RIP-index of the small amount of remanent repeat potentially support our speculation that DNA methylation may be absent in A. flavus or that it may possess de novo DNA methylation which occurs very transiently during the obscure sexual stage of this fungal species. This work contributes to our understanding on the DNA methylation status of A. flavus, as well as reinforces our views on the DNA methylation in fungal species. In addition, our strategy of applying bisulfite sequencing to DNA methylation detection in species with low DNA methylation may serve as a reference for later scientific investigations in other hypomethylated species. PMID:22276181

Wang, Cheng-Cheng; Huang, Shu-Jia; Luo, Yan-Feng; Sun, Ji-Hua; Zhou, Jian-Xiang; Yan, Shu-Jing; He, Jian-Guo; Wang, Jun; He, Zhu-Mei

2012-01-01

70

MINI-REVIEW Aspergillus flavus hydrolases: their roles in pathogenesis  

E-print Network

agricultural importance because it produces the potent mycotoxin aflatoxin B1. When A. flavus infects, spices, and figs, with contamination being most common in warm production areas. A mycotoxin risk

Cotty, Peter J.

71

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.

72

948 Plant Disease / Vol. 98 No. 7 Evaluation of the Atoxigenic Aspergillus flavus Strain AF36  

E-print Network

in Pistachio Orchards Mark A. Doster, Department of Plant Pathology, University of California, Davis of the atoxigenic Aspergillus flavus strain AF36 in pistachio orchards. Plant Dis. 98:948-956. The atoxigenic strain fields to reduce aflatoxin contamination, was applied in research pistachio orchards from 2002 to 2005

Cotty, Peter J.

73

EFFECT OF SOYBEAN LIPOXYGENASE ON VOLATILE GENERATION AND INHIBITION OF ASPERGILLUS FLAVUS MYCELIAL GROWTH  

Technology Transfer Automated Retrieval System (TEKTRAN)

Volatiles generated from LOX-normal and LOX-deficient soybean (Glycine max) varieties with and without added lipase inhibited Aspergillus flavus mycelial growth and aflatoxin production. Soybean volatiles were analyzed using a solid phase microextraction (SPME) method combined with gas chromatograp...

74

Crop rotation and soil temperature influence the community structure of Aspergillus flavus in soil  

E-print Network

s t r a c t Aspergillus flavus, the most important cause of aflatoxin contamination, has two major morphotypes commonly termed `S' and `L' strains. Strain S isolates, on average, produce more aflatoxins than aflatoxin severity, and that periods of increased soil temperature drive selection of the highly toxigenic

Cotty, Peter J.

75

1366 Plant Disease / Vol. 88 No. 121366 Aspergillus flavus in Soils and Corncobs in South Texas  

E-print Network

: Implications for Management of Aflatoxins in Corn­Cotton Rotations Ramon Jaime-Garcia and Peter J. Cotty and Microbiology, University of Arizona, Tucson 85721 Aspergillus flavus is the main causal agent of aflatoxin contamination in several agricultural products, including cottonseed and corn (2,11,15,22). Aflatoxins are toxic

Cotty, Peter J.

76

DEVELOPMENTS IN THE USE OF ATOXIGENIC STRAINS OF ASPERGILLUS FLAVUS TO  

E-print Network

270 DEVELOPMENTS IN THE USE OF ATOXIGENIC STRAINS OF ASPERGILLUS FLAVUS TO PREVENT AFLATOXIN aflatoxin contamination of cottonseed in field plot experiments. This has stimulated interest in large scale aflatoxin levels differ over the cotton belt. In Arizona, losses due to aflatoxin contamination havebeen

Cotty, Peter J.

77

212 Plant Disease / Vol. 95 No. 2 Identification of Atoxigenic Aspergillus flavus Isolates to Reduce Aflatoxin  

E-print Network

to Reduce Aflatoxin Contamination of Maize in Kenya C. Probst, The University of Arizona, School of Plant aflatoxin con- tamination of maize in Kenya. Plant Dis. 95:212-218. Aspergillus flavus has two morphotypes, the S strain and the L strain, that differ in aflatoxin-producing ability and other characteristics. Fun- gal

Cotty, Peter J.

78

Intraspecific competition during infection by Aspergillus flavus is influenced by plant host species  

Technology Transfer Automated Retrieval System (TEKTRAN)

Communities of Aspergillus flavus are composed of diverse genotypes that collectively influence incidence and severity of crop aflatoxin contamination. Isolates vary in competitive ability on maize, but empirical data on the extent to which host-specific influences determine outcomes of competition ...

79

INHIBITORY EFFECT OF ESSENTIAL OILS ON THE GROWTH OF Aspergillus flavus  

Microsoft Academic Search

The effects of 16 essential oils from aromatic plants were tested for their inhibitory effect on Aspergillus flavus IMI 242684 on PDA. The results showed that the essential oil of white wood (Melaleuca cajeputi) gave the highest inhibition followed by the essential oils of cinnamon (Cinnamomum cassia) and lavender (Lavandula officinalis), respectively. Furthermore, the inhibitory effects of these three essential

Dusanee Thanaboripat; Yaowapa Suvathi; Prapaporn Srilohasin; Saowalak Sripakdee

80

Hyperspectral image classification and development of fluorescence index for single corn kernels infected with Aspergillus flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxins are toxic secondary metabolites predominantly produced by the fungi Aspergillus flavus and A. parasiticus. Aflatoxin contaminated corn is toxic to domestic animals when ingested in feed and is a known carcinogen associated with liver and lung cancer in humans. Consequently, aflatoxin leve...

81

SCLEROTIAL PRODUCTION IN ASPERGILLUS FLAVUS VARIES WITH TEMPERATURE AND NITROGEN SOURCE  

Technology Transfer Automated Retrieval System (TEKTRAN)

Twenty strains of Aspergillus flavus from the culture collection of the Southern Regional Research Laboratory, New Orleans, LA, were grown on defined and complex media at 25 degrees C and 37 degrees C for one week. Colonies were screened for sclerotial production, as well as other colony characters...

82

Ear Rot, Aflatoxin Accumulation, and Fungal Biomass in Maize after Inoculation with Aspergillus flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxin, a toxin produced by the fungus Aspergillus flavus Link:Fries, occurs naturally in maize (Zea mays L.). Aflatoxin is a potent human carcinogen and is toxic to livestock, pets, and wildlife. When contaminated with aflatoxin, the value of maize grain is markedly reduced. Eight germplasm l...

83

Application of biotechnology towards the enhancement of maize resistance to aflatoxin contamination by Aspergillus flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Contamination of maize with aflatoxins by the fungi Aspergillus flavus and A. parasiticus poses serious health hazards to humans and animals worldwide. This important fact and the regulations instituted in many countries to control the occurrence of aflatoxins in foods and feed have stimulated rese...

84

Peanut resistant gene expression in response to Aspergillus flavus infection during seed germination  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus produces potent mutagenic and carcinogenic polyketide-derived secondary metabolites known as aflatoxins. Development of host-plant resistance in peanut and other crops would be a cost-effective and practical approach to eliminate the serious problem of aflatoxin contamination due...

85

Time Course Study of Substrate Utilization by Aspergillus flavus in Medium Simulating Corn (Zea mays) Kernels  

E-print Network

Utilization of the three major corn reserve materials, starch, triglycerides (refined corn oil), and zein kernels changed little over the first 18 h. Subsequently, hydrolysis of both starch and triglycerides such as starch or triglycerides. KEYWORDS: Aflatoxin; Aspergillus flavus; corn lipids; cornstarch; Zea mays; zein

Cotty, Peter J.

86

Comparison of Inoculation Methods for Evaluating Maize for Resistance to Aspergillus flavus Infection and Aflatoxin Accumulation  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxin, the most potent carcinogen found in nature, is produced by the fungus Aspergillus flavus. Aflatoxin occurs naturally in maize, Zea mays L. Growing maize hybrids with genetic resistance to aflatoxin contamination is generally considered a highly desirable way to reduce losses to aflatoxin....

87

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

88

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

89

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

90

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

91

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

92

PHENOTYPIC VARIATION WITHIN THE S STRAIN OF ASPERGILLUS FLAVUS  

E-print Network

for radial growth, and sclerotia, spore, aflatoxin, and pectinase production. Slow and fast biotypes were types produced similar quantities of aflatoxin B1 in vitro (>200,000 ng/g). Plate assays indicated document divergence within the S strain isolates of A. flavus. Introduction Aflatoxin contamination

Cotty, Peter J.

93

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

94

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

95

Aspergillus flavus endophthalmitis after penetrating keratoplasty combined with cataract phacoemulsification and IOL implantation.  

PubMed

To report the clinical findings and management of a case of Aspergillus flavus endophthalmitis following penetrating keratoplasty (PKP) and combined cataract extraction. Clinical cornea appearance was evaluated by slit-lamp examination. Ocular ultrasonography was performed to evaluate the anterior chamber and vitreous cavity. The cornea was scraped. The corneal-scleral donor rim and media were cultured. The diagnosis of A. flavus infection was made. The patient received fortified antifungal drops (voriconazole 1 % solution) plus systemic voriconazole 400 mg/die. A second corneal transplant was performed, and the anterior chamber was cleaned and washed with a solution of voriconazole 1 %. At the end of follow-up, CDVA was 20/20 and slit-lamp examination showed a clear cornea graft. This case illustrates a severe A. flavus endophthalmitis after PKP and demonstrates the possibilities of visual function restoration. Furthermore, this case describes the different sources of fungal infection after PKP and the different clinical appearances. PMID:25488017

Spadea, Leopoldo; Abbouda, Alessandro; Abicca, Irene; Paroli, Maria Pia

2014-12-01

96

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

97

Aspergillus flavus dose–response curves to selected natural and synthetic antimicrobials  

Microsoft Academic Search

The effects of selected concentrations of antimicrobials from natural (vanillin, thymol, eugenol, carvacrol or citral) or synthetic (potassium sorbate or sodium benzoate) origin on Aspergillus flavus lag time inoculated in laboratory media formulated at water activity (aw) 0.99 and pH 4.5 or 3.5, were evaluated. Time to detect a colony with a diameter >0.5 mm was determined. Mold response was

Aurelio López-Malo; Stella M Alzamora; Enrique Palou

2002-01-01

98

Aspergillus flavus growth in the presence of chemical preservatives and naturally occurring antimicrobial compounds  

Microsoft Academic Search

The combined effects of water activity ([aw] 0.99 or 0.95), pH (4.5 or 3.5) and antimicrobial agent (potassium sorbate, sodium benzoate, sodium bisulfite, carvacrol, citral, eugenol, thymol, or vanillin) concentration (0, 100, 200 up to 1800 ppm) on the growth of Aspergillus flavus were evaluated in potato dextrose agar (PDA).Mold spore germination time and radial growth rates (RGR) were significantly

Aurelio López-Malo; Stella Maris Alzamora; Enrique Palou

2005-01-01

99

Investigations on the Antifungal Effect of Nerol against Aspergillus flavus Causing Food Spoilage  

PubMed Central

The antifungal efficacy of nerol (NEL) has been proved against Aspergillus flavus by using in vitro and in vivo tests. The mycelial growth of A. flavus was completely inhibited at concentrations of 0.8??L/mL and 0.1??L/mL NEL in the air at contact and vapor conditions, respectively. The NEL also had an evident inhibitory effect on spore germination in A. flavus along with NEL concentration as well as time-dependent kinetic inhibition. The NEL presented noticeable inhibition on dry mycelium weight and synthesis of aflatoxin B1 (AFB1) by A. flavus, totally restraining AFB1 production at 0.6??L/mL. In real food system, the efficacy of the NEL on resistance to decay development in cherry tomatoes was investigated in vivo by exposing inoculated and control fruit groups to NEL vapor at different concentration. NEL vapors at 0.1??L/mL air concentration significantly reduced artificially contaminated A. flavus and a broad spectrum of fungal microbiota. Results obtained from presented study showed that the NEL had a great antifungal activity and could be considered as a benefit and safe tool to control food spoilage. PMID:24453813

Tian, Jun; Zeng, Xiaobin; Zeng, Hong; Feng, Zhaozhong; Miao, Xiangmin; Peng, Xue

2013-01-01

100

Survival of Aspergillus flavus and Fusarium moniliforme in high-moisture corn stored under modified atmospheres.  

PubMed

Freshly harvested high-moisture corn with 29.4% moisture and corn remoistened to 19.6% moisture were inoculated with Aspergillus flavus Link ex Fr. and stored for 4 weeks at about 27 C in air (0.03% CO2, 21% O2, and 78% N2) and three modified atmospheres: (i) 99.7% N2 and 0.3% O2; (ii) 61.7% CO2, 8.7% O2, and 29.6% N2; and (iii) 13.5% CO2, 0.5% O2, and 84.8% N2. Kernel infections by A. flavus, Fusarium moniliforme (Sheld.) Snyd. et Hans., and other fungi were monitored weekly. The modified-atmosphere treatments delayed deterioration by A. flavus and F. moniliforme, but their growth was not completely stopped. A. flavus survived better in the remoistened than in the freshly harvested corn. F. moniliforme survived in both. A. flavus and F. moniliforme were the dominant fungi in corn removed from the modified atmospheres and exposed to normal air for 1 week. PMID:811165

Wilson, D M; Huang, L H; Jay, E

1975-10-01

101

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

PubMed

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

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

2012-01-01

102

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

PubMed

Neutralized electrolyzed oxidizing water (NEW) and acidic electrolyzed oxidizing water (AcEW) are electrolyzed oxidizing waters (EOW) that have significantly different fungicidal efficiencies against Aspergillus flavus (A. flavus) (The actuation durations of no survival population to NEW and AcEW were 90s and 120s, respectively.), even when used at the same available chlorine concentration (30ppm). It has been verified by our previous research. This study hypothesized that this difference did not originate from the structure of water but based on the OH radical (OH). It was proved by the UV spectroscopy, (17)O-NMR spectroscopy and electron spin resonance analysis. NEW contains more OH compared with AcEW in the same available chlorine concentration level. The OH that exists in NEW and AcEW was found to have an important fungicidal factor that destroys the cellular structures of the A. flavus conidia. It also damages the cellular normal function of A. flavus conidia that brought about K+ and Mg2+ leakages. The levels of OH that exist in NEW and AcEW could be the important reason that leads to significant fungicidal efficiencies against A. flavus. PMID:19926156

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

2010-01-31

103

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

PubMed Central

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

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

2012-01-01

104

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

105

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

106

Aspergillus flavus biomass in maize estimated by quantitative real-time polymerase chain reaction is strongly correlated with aflatoxin concentration  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus causes Aspergillus ear rot of maize and produces aflatoxins. There are published assertions that resistance to aflatoxin accumulation and pathogen colonization are distinct traits in maize. However, the levels of colonization are difficult to characterize for a pathogen such as ...

107

Improved protocols for functional analysis in the pathogenic fungus Aspergillus flavus  

PubMed Central

Background An available whole genome sequence for Aspergillus flavus provides the opportunity to characterize factors involved in pathogenicity and to elucidate the regulatory networks involved in aflatoxin biosynthesis. Functional analysis of genes within the genome is greatly facilitated by the ability to disrupt or mis-express target genes and then evaluate their result on the phenotype of the fungus. Large-scale functional analysis requires an efficient genetic transformation system and the ability to readily select transformants with altered expression, and usually requires generation of double (or multi) gene deletion strains or the use of prototrophic strains. However, dominant selectable markers, an efficient transformation system and an efficient screening system for transformants in A. flavus are absent. Results The efficiency of the genetic transformation system for A. flavus based on uracil auxotrophy was improved. In addition, A. flavus was shown to be sensitive to the antibiotic, phleomycin. Transformation of A. flavus with the ble gene for resistance to phleomycin resulted in stable transformants when selected on 100 ?g/ml phleomycin. We also compared the phleomycin system with one based on complementation for uracil auxotrophy which was confirmed by uracil and 5-fluoroorotic acid selection and via transformation with the pyr4 gene from Neurospora crassa and pyrG gene from A. nidulans in A. flavus NRRL 3357. A transformation protocol using pyr4 as a selectable marker resulted in site specific disruption of a target gene. A rapid and convenient colony PCR method for screening genetically altered transformants was also developed in this study. Conclusion We employed phleomycin resistance as a new positive selectable marker for genetic transformation of A. flavus. The experiments outlined herein constitute the first report of the use of the antibiotic phleomycin for transformation of A. flavus. Further, we demonstrated that this transformation protocol could be used for directed gene disruption in A. flavus. The significance of this is twofold. First, it allows strains to be transformed without having to generate an auxotrophic mutation, which is time consuming and may result in undesirable mutations. Second, this protocol allows for double gene knockouts when used in conjunction with existing strains with auxotrophic mutations. To further facilitate functional analysis in this strain we developed a colony PCR-based method that is a rapid and convenient method for screening genetically altered transformants. This work will be of interest to those working on molecular biology of aflatoxin metabolism in A. flavus, especially for functional analysis using gene deletion and gene expression. PMID:18039373

He, Zhu-Mei; Price, Michael S; OBrian, Gregory R; Georgianna, D Ryan; Payne, Gary A

2007-01-01

108

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

109

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

110

Cryptic Sexuality Influences Aflatoxigenicity in Aspergillus parasiticus and A. flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

Ascomycetous fungi of the genus Aspergillus comprise a wide variety of species of biotechnological importance as well as pathogens and toxin producers. Recent studies report A. fumigatus to be heterothallic and possibly undergoing sexual reproduction. We therefore investigated whether compatible mat...

111

Aspergillus Flavus Endocarditis of the Native Mitral Valve in a Bone Marrow Transplant Patient  

PubMed Central

Patient: Male, 36 Final Diagnosis: Aspergillus flavus endocarditis Symptoms: Malaise • fatigue and dyspnea Medication: — Clinical Procedure: Mitral vale replacemnet Specialty: Cardiology Objective: Rare disease Background: Infective endocarditis due to Aspergillus species is an uncommon infection with a high mortality rate. It mostly occurs after the implantation of prosthetic heart valves. Parenteral nutrition, immunosuppression, broad-spectrum antibiotic regimens, and illegal intravenous drug use are the risk factors for developing infection. Case Report: We report a case of Aspergillus flavus native mitral valve endocarditis in a patient who had allogeneic stem cell transplantation in the past due to myelodysplastic syndrome. Conclusions: Although it is rare and there is limited experience available with the diagnosis and treatment, early recognition and therapeutic intervention with systemic antifungal therapy and aggressive surgical intervention are critical to prevent further complications that may eventually lead to death. In addition, better novel diagnostic tools are needed to facilitate more accurate identification of patients with invasive Aspergillus and to permit earlier initiation of antifungal treatment. PMID:25603977

Demir, Tolga; Ergenoglu, Mehmet Umit; Ekinci, Abdurrahman; Tanrikulu, Nursen; Sahin, Mazlum; Demirsoy, Ergun

2015-01-01

112

Aspergillus flavus endocarditis of the native mitral valve in a bone marrow transplant patient.  

PubMed

Background Infective endocarditis due to Aspergillus species is an uncommon infection with a high mortality rate. It mostly occurs after the implantation of prosthetic heart valves. Parenteral nutrition, immunosuppression, broad-spectrum antibiotic regimens, and illegal intravenous drug use are the risk factors for developing infection. Case Report We report a case of Aspergillus flavus native mitral valve endocarditis in a patient who had allogeneic stem cell transplantation in the past due to myelodysplastic syndrome. Conclusions Although it is rare and there is limited experience available with the diagnosis and treatment, early recognition and therapeutic intervention with systemic antifungal therapy and aggressive surgical intervention are critical to prevent further complications that may eventually lead to death. In addition, better novel diagnostic tools are needed to facilitate more accurate identification of patients with invasive Aspergillus and to permit earlier initiation of antifungal treatment. PMID:25603977

Demir, Tolga; Ergenoglu, Mehmet Umit; Ekinci, Abdurrahman; Tanrikulu, Nursen; Sahin, Mazlum; Demirsoy, Ergun

2015-01-01

113

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

114

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

PubMed Central

Aspergillus oryzae and A. flavus are important species in industrial biotechnology and food safety and have been some of the first aspergilli to be fully genome sequenced. Bioinformatic analysis has revealed 99.5% gene homology between the two species pointing towards a large coherence in the secondary metabolite production. In this study we report on the first comparison of secondary metabolite production between the full genome sequenced strains of A. oryzae (RIB40) and A. flavus (NRRL 3357). Surprisingly, the overall chemical profiles of the two strains were mostly very different across 15 growth conditions. Contrary to previous studies we found the aflatrem precursor 13-desoxypaxilline to be a major metabolite from A. oryzae under certain growth conditions. For the first time, we additionally report A. oryzae to produce parasiticolide A and two new analogues hereof, along with four new alkaloids related to the A. flavus metabolites ditryptophenalines and miyakamides. Generally the secondary metabolite capability of A. oryzae presents several novel end products likely to result from the domestication process from A. flavus. PMID:24957367

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

2012-01-01

115

Inactivation of Aspergillus flavus in drinking water after treatment with UV irradiation followed by chlorination.  

PubMed

The disinfection process for inactivating microorganisms at drinking water treatment plants is aimed for safety of drinking water for humans from a microorganism, such as bacteria, viruses, algae, fungi by using chlorination, ozonation, UV irradiation, etc. In the present study, a combination of two disinfectants, UV irradiation followed by chlorination, was evaluated for inactivating Aspergillus flavus under low contact time and low dosage of UV irradiation. The results indicated an inverse correlation between the inactivation of A. flavus by using UV irradiation only or chlorination alone. By using UV radiation, the 2 log10 control of A. flavus was achieved after 30 s of irradiation, while chlorination was observed to be more effective than UV, where the 2 log was achieved at chlorine concentration of 0.5, 1, 2 and 3 mg/l, in contact time of 60, 5, 1 and 1 min, respectively. However, combined use (UV irradiation followed by chlorination) was more effective than using either UV or chlorination alone; 5 s UV irradiation followed by chlorination produced 4 log10 reduction of A. flavus at chlorine concentrations of 2 and 3 mg/l under a contact time of 15 min. The results indicated that efficiency of UV irradiation improves when followed by chlorination at low concentrations. PMID:23831798

Al-Gabr, Hamid Mohammad; Zheng, Tianling; Yu, Xin

2013-10-01

116

RNA-Seq-Based Transcriptome Analysis of Aflatoxigenic Aspergillus flavus in Response to Water Activity.  

PubMed

Aspergillus flavus is one of the most important producers of carcinogenic aflatoxins in crops, and the effect of water activity (aw) on growth and aflatoxin production of A. flavus has been previously studied. Here we found the strains under 0.93 aw exhibited decreased conidiation and aflatoxin biosynthesis compared to that under 0.99 aw. When RNA-Seq was used to delineate gene expression profile under different water activities, 23,320 non-redundant unigenes, with an average length of 1297 bp, were yielded. By database comparisons, 19,838 unigenes were matched well (e-value < 10-5) with known gene sequences, and another 6767 novel unigenes were obtained by comparison to the current genome annotation of A. flavus. Based on the RPKM equation, 5362 differentially expressed unigenes (with |log2Ratio| ? 1) were identified between 0.99 aw and 0.93 aw treatments, including 3156 up-regulated and 2206 down-regulated unigenes, suggesting that A. flavus underwent an extensive transcriptome response during water activity variation. Furthermore, we found that the expression of 16 aflatoxin producing-related genes decreased obviously when water activity decreased, and the expression of 11 development-related genes increased after 0.99 aw treatment. Our data corroborate a model where water activity affects aflatoxin biosynthesis through increasing the expression of aflatoxin producing-related genes and regulating development-related genes. PMID:25421810

Zhang, Feng; Guo, Zhenni; Zhong, Hong; Wang, Sen; Yang, Weiqiang; Liu, Yongfeng; Wang, Shihua

2014-01-01

117

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...

118

Antimicrobial effects of ionizing radiation on artificially and naturally contaminated cacao beans. [Aspergillus flavus; Penicillium citrinum  

SciTech Connect

With an initial microbial level of ca. 10/sup 7/ microorganisms per g of Ivory Coast cacao beans, 5 kGy of gamma radiation from a Co/sup 60/ source under an atmosphere of air reduced the microflora per g by 2.49 and 3.03 logs at temperatures of 35 and 50/sup 0/C, respectively. Bahia cacao beans were artificially contaminated with dried spores of Aspergillus flavus and Penicillium citrinum, giving initial fungal levels of 1.9 x 10/sup 4/ and 1.4 x 10/sup 3/ spores per g of whole Bahia cacao beans, respectively. The average D/sub 10/ values for A. flavus and P. citrinum spores on Bahia cacao beans were 0.66 and 0.88 kGy, respectively. 12 references.

Restaino, L.; Myron, J.J.J.; Lenovich, L.M.; Bills, S.; Tscherneff, K.

1984-04-01

119

Aspergillus flavus infection induces transcriptional and physical changes in developing maize kernels.  

PubMed

Maize kernels are susceptible to infection by the opportunistic pathogen Aspergillus flavus. Infection results in reduction of grain quality and contamination of kernels with the highly carcinogenic mycotoxin, aflatoxin. To understanding host response to infection by the fungus, transcription of approximately 9000 maize genes were monitored during the host-pathogen interaction with a custom designed Affymetrix GeneChip® DNA array. More than 4000 maize genes were found differentially expressed at a FDR of 0.05. This included the up regulation of defense related genes and signaling pathways. Transcriptional changes also were observed in primary metabolism genes. Starch biosynthetic genes were down regulated during infection, while genes encoding maize hydrolytic enzymes, presumably involved in the degradation of host reserves, were up regulated. These data indicate that infection of the maize kernel by A. flavus induced metabolic changes in the kernel, including the production of a defense response, as well as a disruption in kernel development. PMID:25132833

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

2014-01-01

120

Aspergillus flavus infection induces transcriptional and physical changes in developing maize kernels  

PubMed Central

Maize kernels are susceptible to infection by the opportunistic pathogen Aspergillus flavus. Infection results in reduction of grain quality and contamination of kernels with the highly carcinogenic mycotoxin, aflatoxin. To understanding host response to infection by the fungus, transcription of approximately 9000 maize genes were monitored during the host-pathogen interaction with a custom designed Affymetrix GeneChip® DNA array. More than 4000 maize genes were found differentially expressed at a FDR of 0.05. This included the up regulation of defense related genes and signaling pathways. Transcriptional changes also were observed in primary metabolism genes. Starch biosynthetic genes were down regulated during infection, while genes encoding maize hydrolytic enzymes, presumably involved in the degradation of host reserves, were up regulated. These data indicate that infection of the maize kernel by A. flavus induced metabolic changes in the kernel, including the production of a defense response, as well as a disruption in kernel development. PMID:25132833

Dolezal, Andrea L.; Shu, Xiaomei; OBrian, Gregory R.; Nielsen, Dahlia M.; Woloshuk, Charles P.; Boston, Rebecca S.; Payne, Gary A.

2014-01-01

121

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

122

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

123

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

124

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

125

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

126

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

127

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

128

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

129

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

130

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

131

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

PubMed Central

Aspergillus flavus has received much attention owing to its severe impact on agriculture and fermented products induced by aflatoxin. Sclerotia morphogenesis is an important process related to A. flavus reproduction and aflatoxin biosynthesis. In order to obtain an extensive transcriptome profile of A. flavus and provide a comprehensive understanding of these physiological processes, the isolated mRNA of A. flavus CA43 cultures was subjected to high-throughput strand-specific RNA sequencing (ssRNA-seq). Our ssRNA-seq data profiled widespread transcription across the A. flavus genome, quantified vast transcripts (73% of total genes) and annotated precise transcript structures, including untranslated regions, upstream open reading frames (ORFs), alternative splicing variants and novel transcripts. We propose natural antisense transcripts in A. flavus might regulate gene expression mainly on the post-transcriptional level. This regulation might be relevant to tune biological processes such as aflatoxin biosynthesis and sclerotia development. Gene Ontology annotation of differentially expressed genes between the mycelia and sclerotia cultures indicated sclerotia development was related closely to A. flavus reproduction. Additionally, we have established the transcriptional profile of aflatoxin biosynthesis and its regulation model. We identified potential genes linking sclerotia development and aflatoxin biosynthesis. These genes could be used as targets for controlled regulation of aflatoxigenic strains of A. flavus. PMID:24849659

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

2014-01-01

132

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

133

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

134

Environmental influences on maize-Aspergillus flavus interactions and aflatoxin production  

PubMed Central

Since the early 1960s, the fungal pathogen Aspergillus flavus (Link ex Fr.) has been the focus of intensive research due to the production of carcinogenic and highly toxic secondary metabolites collectively known as aflatoxins following pre-harvest colonization of crops. Given this recurrent problem and the occurrence of a severe aflatoxin outbreak in maize (Zea mays L.), particularly in the Southeast U.S. in the 1977 growing season, a significant research effort has been put forth to determine the nature of the interaction occurring between aflatoxin production, A. flavus, environment and its various hosts before harvest. Many studies have investigated this interaction at the genetic, transcript, and protein levels, and in terms of fungal biology at either pre- or post-harvest time points. Later experiments have indicated that the interaction and overall resistance phenotype of the host is a quantitative trait with a relatively low heritability. In addition, a high degree of environmental interaction has been noted, particularly with sources of abiotic stress for either the host or the fungus such as drought or heat stresses. Here, we review the history of research into this complex interaction and propose future directions for elucidating the relationship between resistance and susceptibility to A. flavus colonization, abiotic stress, and its relationship to oxidative stress in which aflatoxin production may function as a form of antioxidant protection to the producing fungus. PMID:24550905

Fountain, Jake C.; Scully, Brian T.; Ni, Xinzhi; Kemerait, Robert C.; Lee, Robert D.; Chen, Zhi-Yuan; Guo, Baozhu

2014-01-01

135

Antifungal Activity of a Liposomal Itraconazole Formulation in Experimental Aspergillus flavus Keratitis with Endophthalmitis.  

PubMed

The aim of this study was to assess the efficacy of topical application of a liposomal formulation of itraconazole for the treatment of experimental keratitis with endophthalmitis caused by Aspergillus flavus. The liposomes were obtained by the lipid film hydration method followed by sonication. Adult female Wistar rats (weighing 200-220 g) were immunosuppressed by intraperitoneal injection of 150 mg/kg of cyclophosphamide 3 days before infection by exposure to the fungus A. flavus (10(7) spores/ml). Forty-eight hours later, the animals were treated with the liposomal formulation. For comparison, one group of animals (n = 6) was treated with the same drug not encapsulated. At the end of the experiment, the animals were evaluated for clinical signs and number of colony forming units (CFU/g), along with direct microscopic examination. The results indicated that the liposomal formulation of itraconazole has better antifungal activity than the unencapsulated drug in the treatment of fungal keratitis with endophthalmitis caused experimentally by A. flavus in Wistar rats. PMID:25431088

Leal, André Ferraz Goiana; Leite, Melyna Chaves; Medeiros, Caroline Sanuzi Quirino; Cavalcanti, Isabella Macário Ferro; Wanderley, Almir Gonçalves; Santos Magalhães, Nereide Stela; Neves, Rejane Pereira

2014-11-28

136

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

137

Buckwheat achenes antioxidant profile modulates Aspergillus flavus growth and aflatoxin production.  

PubMed

Buckwheat (Fagopyrum spp.) is a "pseudo-cereal" of great interest in the production of healthy foods since its flour, derived from achenes, is enriched with bioactive compounds and, due to the absence of gluten, may be used in composition of celiac diets. Amongst buckwheat species, F. tataricum achenes possess a larger amount of the antioxidant flavenol rutin than the common buckwheat F. esculentum. Ongoing climate change may favor plant susceptibility to the attack by pathogenic, often mycotoxigenic, fungi with consequent increase of mycotoxins in previously unexploited feeds and foodstuffs. In particular, Aspergillus flavus, under suitable environmental conditions such as those currently occurring in Italy, may produce aflatoxin B1 (AFB1), the most carcinogenic compound of fungal origin which is classified by IARC as Category 1. In this study, the viable achenes of two buckwheat species, F. tataricum (var. Golden) and F. esculentum (var. Aelita) were inoculated with an AFB1-producing A. flavus NRRL 3357 to analyze their relative performances against fungal invasion and toxin contamination. Notably, we sought the existence of a correlation between the amount of tocols/flavonols in the achenes of buckwheat, infected and non-infected with A. flavus, and to analyze the ability of the pathogen to grow and produce toxin during achene infection. Results suggest that achenes of F. tataricum, the best producer of antioxidant compounds in this study, are less susceptible to A. flavus infection and consequently, but not proportionally, to mycotoxin contamination compared with F. esculentum. Moreover, rutin-derived quercetin appears to be more efficient in inhibiting aflatoxin biosynthesis than the parent compound. PMID:25108759

Chitarrini, G; Nobili, C; Pinzari, F; Antonini, A; De Rossi, P; Del Fiore, A; Procacci, S; Tolaini, V; Scala, V; Scarpari, M; Reverberi, M

2014-10-17

138

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

139

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

140

Development of a GFP-Expressing Aspergillus flavus Strain to Study Fungal Invasion, Colonization, and Resistance in Cottonseed  

Technology Transfer Automated Retrieval System (TEKTRAN)

Cotton bolls were inoculated with a green fluorescent protein (GFP)-expressing Aspergillus flavus (strain 70) to monitor fungal growth, mode of entry, colonization of cottonseeds and production of aflatoxins. The GFP strain and the wild type did not differ significantly in pathogen aggressiveness a...

141

8ioconlrol Sci~flCt! and Technology (1995) 5. 175-184 Formulating Atoxigenic Aspergillus flavus for Field  

E-print Network

of Aspergillus ftavus in alginate pellets for seeding into agricultural fields in Qrder to reduce aflatoxin A. flavus strains 10 furrow-irrigated cotton in desert environments, where aflatoxin contamination & Stoloff, 1983). Since then, methods to detect and prevent or 0958-31571951fr20175-10 (11995 Journals

Cotty, Peter J.

142

EFFECT OF EAR BAGGING SYSTEMS ON ASPERGILLUS FLAVUS KERNEL INFECTION AND AFLATOXIN CONTAMINATION OF CORN HYBRIDS GROWN IN THE FIELD  

Technology Transfer Automated Retrieval System (TEKTRAN)

Field studies were conducted for 4 years in Mississippi to determine the effect of various ear bagging systems on Aspergillus flavus kernel infection and aflatoxin production in developing ears of corn hybrids. Each year, three corn hybrids were grown on Myatt loam (low water-holding capacity) and a...

143

Characterization of a maize association mapping panel for new sources of Aspergillus flavus and aflatoxin accumulation resistance  

Technology Transfer Automated Retrieval System (TEKTRAN)

Maize (Zea mays L.) susceptibility to ear rot and aflatoxin accumulation by Aspergillus flavus (Link:Fr) causes significant economic and human health damage worldwide. Although host plant resistance is an ideal solution to the problem, no commercial varieties display sufficient levels of resistance ...

144

Comparison of the side-needle and knife techniques for inducing Aspergillus flavus infection and aflatoxin accumulation in corn hybrids  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aflatoxin in corn grain is a problem in many areas of the world. Any combination of environmentally stressful or agronomically unfavorable conditions can increase the likelihood of Aspergillus flavus infection and production of aflatoxin in the corn grain. In the absence of a consistent natural A....

145

Inhibition of Aspergillus flavus on agar media and brown rice cereal bars using cold atmospheric plasma treatment.  

PubMed

This study aimed to optimize the operating parameters of cold atmospheric plasma treatment to inhibit the growth of Aspergillus flavus on agar media and brown rice cereal bars. The effects of argon plasma jet treatment on the growth of A. flavus on malt extract agar (MEA) at powers of 20 W and 40 W with exposure times at 5, 15 and 25 min were studied using response surface methodology (RSM) with a central composite face-centered (CCF) design. Multiple regression analysis indicated that plasma treatment at 40 W for 25 min is most effective for inhibiting growth of A. flavus on the agar medium. On brown rice cereal bars, plasma powered at 40 W for 20 min was capable of giving protection against A. flavus growth for up to 20 days under storage conditions of 25°C and 100% RH. These results demonstrated the potential of cold atmospheric plasma jet treatment to control mold growth on various food products. PMID:23279819

Suhem, Kitiya; Matan, Narumol; Nisoa, Mudtorlep; Matan, Nirundorn

2013-02-01

146

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

147

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

148

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

149

The Inhibitory Effects of Curcuma longa L. Essential Oil and Curcumin on Aspergillus flavus Link Growth and Morphology  

PubMed Central

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

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

2013-01-01

150

In vitro comparative analysis of monocrotophos degrading potential of Aspergillus flavus, Fusarium pallidoroseum and Macrophomina sp.  

PubMed

Fungal degradation is emerging as a new powerful tool for the removal of potent neurotoxin pesticide, monocrotophos. Therefore, the present study is aimed at comparative characterization of monocrotophos degrading ability of three different fungal strains. Fungal strains were isolated from local agricultural soil by enrichment culture method, screened by gradient culture and identified as Aspergillus flavus, Fusarium pallidoroseum and Macrophomina sp. Growth kinetics revealed a direct positive influence of monocrotophos on the viability of fungal isolates. Fungal degradation was studied in phosphorus free liquid culture medium supplemented with 150 mg L(-1) concentration of monocrotophos for a period of 15 days under optimized culture conditions. Degradation of MCP followed first order kinetics with kdeg of 0.007, 0.002 and 0.005 day(-1) and half life (t1/2) of 4.21, 12.64 and 6.32 days for A. flavus, F. pallidoroseum and Macrophomina sp. respectively. To the best of our knowledge, it is the first report signifying the potential of monocrotophos degradation by Fusarium and Macrophomina sp. The results were further confirmed by HPTLC and FTIR which indicates disappearance of monocrotophos by hydrolytic cleavage of vinyl phosphate bond. Degradation of monocrotophos by fungal isolates was accompanied by the release of extracellular alkaline phosphatases, inorganic phosphates and ammonia. The overall comparative analysis followed the order of A. flavus > Macrophomina sp. > F. pallidoroseum. Therefore, it could be concluded from the study that these three different fungal strains could be effectively used as a potential candidate for the removal of monocrotophos from contaminated sites. PMID:24179090

Jain, Rachna; Garg, Veena; Yadav, Deepak

2014-06-01

151

Extracellular biosynthesis and characterization of silver nanoparticles using Aspergillus flavus NJP08: A mechanism perspective  

NASA Astrophysics Data System (ADS)

The present study demonstrates an eco-friendly and low cost protocol for synthesis of silver nanoparticles using the cell-free filtrate of Aspergillus flavus NJP08 when supplied with aqueous silver (Ag+) ions. Identification of the fungal isolate was based on nuclear ribosomal DNA internal transcribed spacer (ITS) identities. Transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) revealed the formation of spherical metallic silver nanoparticles. The average particle size calculated using Dynamic Light Scattering measurements (DLS) was found to be 17 +/- 5.9 nm. UV-Visible and Fourier transform infrared (FTIR) spectroscopy confirmed the presence of extracellular proteins. SDS-PAGE profiles of the extracellular proteins showed the presence of two intense bands of 32 and 35 kDa, responsible for the synthesis and stability of silver nanoparticles, respectively. A probable mechanism behind the biosynthesis is discussed, which leads to the possibility of using the present protocol in future ``nano-factories''.

Jain, Navin; Bhargava, Arpit; Majumdar, Sonali; Tarafdar, J. C.; Panwar, Jitendra

2011-02-01

152

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

153

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

154

Global Survey of Canonical Aspergillus flavus G Protein-Coupled Receptors  

PubMed Central

ABSTRACT G protein-coupled receptors (GPCRs) are transmembrane receptors that relay signals from the external environment inside the cell, allowing an organism to adapt to its surroundings. They are known to detect a vast array of ligands, including sugars, amino acids, pheromone peptides, nitrogen sources, oxylipins, and light. Despite their prevalence in fungal genomes, very little is known about the functions of filamentous fungal GPCRs. Here we present the first full-genome assessment of fungal GPCRs through characterization of null mutants of all 15 GPCRs encoded by the aflatoxin-producing fungus Aspergillus flavus. All strains were assessed for growth, development, ability to produce aflatoxin, and response to carbon sources, nitrogen sources, stress agents, and lipids. Most GPCR mutants were aberrant in one or more response processes, possibly indicative of cross talk in downstream signaling pathways. Interestingly, the biological defects of the mutants did not correspond with assignment to established GPCR classes; this is likely due to the paucity of data for characterized fungal GPCRs. Many of the GPCR transcripts were differentially regulated under various conditions as well. The data presented here provide an extensive overview of the full set of GPCRs encoded by A. flavus and provide a framework for analysis in other fungal species. PMID:25316696

Affeldt, Katharyn J.; Carrig, Joseph; Amare, Meareg

2014-01-01

155

Phytochemical inhibition of aflatoxigenicity in Aspergillus flavus by constituents of walnut (Juglans regia).  

PubMed

Tulare walnut, a cultivar highly resistant to aflatoxin formation, was investigated for endogenous phytochemical constituents capable of inhibiting aflatoxigenesis in Aspergillus flavus. The activity, located entirely in the pellicle (seed coat), was extractable to various degrees with polar solvents, although some activity remained unextractable, indicating that the bioactivity resided in a complex of hydrolyzable tannins. These tannins can be hydrolyzed by a fungal tannase present in A. flavus, yielding gallic acid and ellagic acid, testing of which showed that only gallic acid had potent inhibitory activity toward aflatoxin biosynthesis. Comparison of the gallic and ellagic acid content in the pellicle of Tulare and Chico cultivars, over the 2002 and 2003 growing seasons, showed that the gallic acid content increased rapidly with maturation of the nut and was 1.5-2 times higher in Tulare than in Chico. Gallic acid content in the pellicle at maturity of a series of commercial English walnut cultivars, and two black walnut species, was determined as an indicator of potential for inhibition of aflatoxigenesis. Regulation of gallic acid levels in the hydrolyzable tannins of walnuts by conventional breeding or genetic manipulation has the potential to provide new cultivars with high resistance to aflatoxigenesis. PMID:15053524

Mahoney, Noreen; Molyneux, Russell J

2004-04-01

156

ROLE OF COMPETITION AND ADVERSE CULTURE CONDITIONS IN PREVENTING THE LOSS OF A AFLATOXIN PRODUCTION BY ASPERGILLUS FLAVUS DURING SERIAL TRANSFERS  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus is genetically unstable when repeatedly transferred in culture. Serial transfers often result in loss of aflatoxin production and in associated morphological changes such as reduced sporulation, proliferation of aerial hyphae and an inability to produce sclerotia. However, degene...

157

Aspergillus flavus genetic diversity of corn fields treated with non-toxigenic strain afla-guard in the southern U.S  

Technology Transfer Automated Retrieval System (TEKTRAN)

Aspergillus flavus genetic diversity of corn fields treated with the non-toxigenic strain Afla-Guard (NRRL 21882) was determined for 384 A. flavus isolates from 14 locations within 6 states in the southern U.S. ELISA test has determined low levels of toxigenic strains (only 91 positive). Nearly hal...

158

Inhibition of Aspergillus flavus growth and detoxification of aflatoxin B 1 by the medicinal plant zimmu ( Allium sativum L. ×  Allium cepa L.)  

Microsoft Academic Search

Aflatoxins are carcinogenic, teratogenic and immunosuppressive secondary metabolites produced by Aspergillus flavus and Aspergillus parasiticus. Aflatoxin contamination of peanut is one of the most important constraints to peanut production worldwide. In order to develop\\u000a an eco-friendly method of prevention of A. flavus infection and aflatoxin contamination in peanut, aqueous extracts obtained from leaves of 30 medicinal plants belonging to\\u000a different

R. Sandosskumar; M. Karthikeyan; S. Mathiyazhagan; M. Mohankumar; G. Chandrasekar; R. Velazhahan

2007-01-01

159

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

160

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

161

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

162

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

163

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

PubMed Central

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

Ehrlich, Kenneth C.; Mack, Brian M.

2014-01-01

164

A volatile relationship: profiling an inter-kingdom dialogue between two plant pathogens, Ralstonia Solanacearum and Aspergillus Flavus.  

PubMed

Microbes in the rhizosphere have a suite of extracellular compounds, both primary and secondary, that communicate with other organisms in their immediate environment. Here, we describe a two-way volatile interaction between two widespread and economically important soil-borne pathogens of peanut, Aspergillus flavus and Ralstonia solanacearum, a fungus and bacterium, respectively. In response to A. flavus volatiles, R. solanacearum reduced production of the major virulence factor extracellular polysaccharide (EPS). In parallel, A. flavus responded to R. solanacearum volatiles by reducing conidia production, both on plates and on peanut seeds and by increasing aflatoxin production on peanut. Volatile profiling of these organisms using solid-phase micro-extraction gas chromatography mass spectroscopy (SPME-GCMS) provided a first glimpse at the compounds that may drive these interactions. PMID:24801606

Spraker, Joseph E; Jewell, Kelsea; Roze, Ludmila V; Scherf, Jacob; Ndagano, Dora; Beaudry, Randolph; Linz, John E; Allen, Caitilyn; Keller, Nancy P

2014-05-01

165

Use of a granular bioplastic formulation for carrying conidia of a non-aflatoxigenic strain of Aspergillus flavus  

Microsoft Academic Search

Previous research demonstrated that aflatoxin contamination in corn is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillus flavus strain NRRL 30797. To facilitate field applications of this biocontrol isolate, a series of laboratory studies were conducted on the reliability and efficiency of replacing wheat grains with the novel bioplastic formulation Mater-Bi® to serve as a carrier

Cesare Accinelli; M. Ludovica Saccà; Hamed K. Abbas; Robert M. Zablotowicz; Jeffery R. Wilkinson

2009-01-01

166

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

167

Distinct Roles for VeA and LaeA in Development and Pathogenesis of Aspergillus flavus?  

PubMed Central

Aspergillus flavus, a mycotoxigenic filamentous fungus, colonizes several important agricultural crops, such as maize and peanuts. Two proteins, VeA and LaeA, known to form a nuclear complex in Aspergillus nidulans have been found to positively regulate developmental processes in several Aspergillus species. Here, an examination of near-isogenic A. flavus mutants differing in copy number of veA and laeA alleles (0, 1, or at least 2 each) revealed critical roles for VeA and LaeA in A. flavus development and seed colonization. In contrast to the wild type, both null mutants were unable to metabolize host cell lipid reserves and were inhibited by oleic acid in growth assays. The copy number of LaeA but not VeA appeared critical for a density-dependent sclerotial-to-conidial shift, since the multicopy laeA (MClaeA) strain produced relatively constant sclerotial numbers with increasing population size rather than showing the decrease in sclerotia seen in both the wild-type and MCveA strains. The MCveA-laeA strain yielded an intermediate phenotype. This study revealed unique roles of VeA and LaeA in seed pathogenesis and fungal biology, distinct from their cooperative regulatory functions in aflatoxin and sclerotial development. PMID:19411623

Amaike, Saori; Keller, Nancy P.

2009-01-01

168

Development and evaluation of ITS- and aflP-based LAMP assays for rapid detection of Aspergillus flavus in food samples.  

PubMed

Aspergillus flavus is a common filamentous fungus that produces aflatoxins and presents a major threat to agriculture and human health. Previous studies focused mainly on the detection of A. flavus or aflatoxin separately. Here, we developed internal transcribed spacer (ITS)- and aflP-based rapid detection of A. flavus in food samples using the loop-mediated isothermal amplification (LAMP) method. The ITS1-5.8S-ITS2 rDNA region of A. flavus and the aflatoxin-encoding gene aflP were used as target regions. The detection limits of A. flavus and aflP were 10 fg and 1 pg pure DNA, respectively, which allows aflatoxin-contaminated samples to be differentiated from infected samples and reduces false-negative or false-positive results. For specificity testing, DNA extracted from 7 A. flavus, 5 different Aspergillus spp., and 21 other fungi were used, and our results showed that A. flavus strains are detected by ITS-based detection and aflatoxigenic A. flavus strains are detected by aflP-based detection. Furthermore, the ITS- and aflP-based LAMP assays were used for detection analysis of DNA from food samples artificially and naturally contaminated with A. flavus. Our results showed that the detection rate of A. flavus based on the multi-ITS-based LAMP detection is 100% and that the aflatoxigenic strains in all A. flavus are detected by the aflP-based LAMP assay. The LAMP protocol described in our study represents a rapid and highly specific and sensitive diagnostic method for A. flavus detection, which can be used as a diagnostic tool that simplifies A. flavus monitoring and guarantees the quality and safety of foods. PMID:25126831

Liu, Peiqing; Li, Benjin; Yin, Rongmei; Weng, Qiyong; Chen, Qinghe

2014-09-01

169

Inhibition of aflatoxin metabolism and growth of Aspergillus flavus in liquid culture by a DNA methylation inhibitor.  

PubMed

Aflatoxins (AFs) are a group of highly oxygenated polyketidese-derived toxins mainly produced by Aspergillus flavus and A. parasiticus, whose biosynthesis mechanisms are extremely sophisticated. Methylation is known as the major form of epigenetic regulation, which is correlated with gene expression. As the DNA methylation inhibitor 5-azacytidine (5-AC) blocks AF production, we studied AFB1 metabolism and morphological changes of A. flavus by treatment with 5-AC in liquid culture. The results show that 5-AC caused a decrease in AF production and concurrent changes in morphology. In addition, we isolated a non-aflatoxigenic mutant of A. flavus, showing a significant reduction in pigment production, after 5-AC treatment. This mutant showed significant reduction in the expression of genes in the AF biosynthesis pathway, and conidia formation. Furthermore, as AF biosynthesis and oxidative stress are intimately related events, we assessed the viability of A. flavus to oxidative stress after treatment with 5-AC, which showed that the mutant was more sensitive to the strong oxidant hydrogen peroxide. We found that the non-aflatoxigenic mutant showed a decrease in reactive oxygen species (ROS) and metabolites indicative of oxidative stress, which may be caused by the disruption of the defence system against excessive ROS formation after 5-AC treatment. These data indicate that 5-AC, as an inactivator of DNA methyltransferase, plays a very important role in AFB1 metabolism and the development of A. flavus, which might provide an effective strategy to pre- or post-harvest control of AFs. PMID:25312249

Yang, Kunlong; Zhuang, Zhenhong; Zhang, Feng; Song, Fengqin; Zhong, Hong; Ran, Fanlei; Yu, Song; Xu, Gaopo; Lan, Faxiu; Wang, Shihua

2014-10-31

170

Tissue specific gene expression in maize seeds during colonization by Aspergillus flavus and Fusarium verticillioides.  

PubMed

Aspergillus flavus and Fusarium verticillioides are fungal pathogens that colonize maize kernels and produce the harmful mycotoxins aflatoxin and fumonisin, respectively. Management practice based on potential host resistance to reduce contamination by these mycotoxins has proven difficult, resulting in the need for a better understanding of the infection process by these fungi and the response of maize seeds to infection. In this study, we followed colonization of seeds by histological methods and transcriptional changes of two maize defense-related genes in specific seed tissues by RNA in situ hybridization. Maize kernels were inoculated with either A. flavus or F. verticillioides 21-22 days after pollination and harvested at 4, 12, 24, 48, 72, 96, and 120 hours post inoculation. The fungi colonized all tissues of the maize seed, but differed in their interactions with aleurone and germ tissues. RNA in situ hybridization showed the induction of the maize pathogenesis-related protein, maize seed (PRms) gene in the aleurone and scutellum upon infection by either fungus. Transcripts of the maize sucrose synthase encoding gene, shrunken-1 (Sh1), were observed in the embryo of non-infected kernels, but induced upon infection by each fungus in the aleurone and scutellum. By comparing histological and RNA in situ hybridization results from adjacent serial sections, we found transcripts of these two genes accumulated in tissue prior to arrival of the advancing pathogens in the seeds. Knowledge of the patterns of colonization and tissue-specific gene expression in response to these fungi will be helpful in developing resistance. PMID:25469958

Shu, Xiaomei; Livingston, David P; Franks, Robert G; Boston, Rebecca S; Woloshuk, Charles P; Payne, Gary A

2014-12-01

171

[Study of immunological activity of Aspergillus flavus Link. II. Immunogenicity, antigenic properties and evaluation of cross reactions of Aspergillus flavus antibodies with Aspergillus fumigatus antigens].  

PubMed

The aim of this study was to determine immunogenic and antigenic properties of tested strain. Chemically characterised AEM and APP antigens were used for immunisation of laboratory animals. Immunogenic, antigenic and multideterminant character of tested preparations was shown by immunodiffusion technique. It was found that AEM and its two fractions AS and API share common immunodeterminant what requires additional studies on their further separation. Using techniques described in this study no antigenic relationship was found between tested A. flavus strain and antigens derived from A. fumigatus and A. candidus. Multideterminant character of AEM and APP was confirmed by rockett immunoelectrophoresis, defining 6 different immunodeterminants for APP and 9-10 determinants for AEM, showing by the method used as separate precipitation arcs. In this study a fused rockett immunoelectrophoresis was highly appreciated as an usefull technique for investigation of fungal antigens. The results obtained require further confirmation by testing human sera. They indicate that it would be usefull to apply other antigens than derived from A. fumigatus and A. candidus for clinical diagnostic of Aspergillosis and related diseases. PMID:2128103

Bi?, W A

1990-01-01

172

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

173

Characterization of Expressed Sequence Tag-Derived Simple Sequence Repeat Markers for Aspergillus flavus: Emphasis on Variability of Isolates from the Southern United States  

Technology Transfer Automated Retrieval System (TEKTRAN)

Simple Sequence Repeat (SSR) markers were developed from Aspergillus flavus expressed sequence tag (EST) database to conduct an analysis of genetic relationships of Aspergillus isolates from numerous host species and geographical regions, but primarily from the United States. Twenty-nine primers wer...

174

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

175

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

176

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

177

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

178

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

179

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

180

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

181

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

182

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

183

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

184

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

185

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

186

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

187

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

188

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.

189

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

190

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

191

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

192

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

193

Reduction of Aflatoxin in Pistachio Through Biological Control of Aspergillus flavus  

Technology Transfer Automated Retrieval System (TEKTRAN)

A retrotransposon, AFLAV (A. flavus retrotransposon), has been recently characterized in A. flavus. Complete DNA sequence of 7784 bp containing the AFLAV has been submitted to GenBank (accession number AY485785). Multicopies of this transposon are dispersed in the chromosomes of A. flavus. PCR pr...

194

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

PubMed Central

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

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

2014-01-01

195

Synthesis, characterization and antifungal activity of quaternary derivatives of chitosan on Aspergillus flavus.  

PubMed

Two series of new chitosan derivatives were synthesized by reaction of deacetylated chitosan (CH) with propyl (CH-Propyl) and pentyl (CH-Pentyl) trimethylammonium bromides to obtain derivatives with increasing degrees of substitution (DS). The derivatives were characterized by (1)H NMR and potentiometric titration techniques and their antifungal activities on the mycelial growth of Aspergillus flavus were investigated in vitro. The antifungal activities increase with DS and the more substituted derivatives of both series, CH-Propyl and CH-Pentyl, exhibited antifungal activities respectively three and six times higher than those obtained with commercial and deacetylated chitosan. The minimum inhibitory concentrations (MIC) were evaluated at 24, 48 and 72 h by varying the polymer concentration from 0.5 to 16 g/L and the results showed that the quaternary derivatives inhibited the fungus growth at polymer concentrations four times lower than that obtained with deacetylated chitosan (CH). The chitosans modified with pentyltrimethylammonium bromide exhibited higher activity and results are discussed taking into account the degree of substitution (DS). PMID:22819383

de Oliveira Pedro, Rafael; Takaki, Mirelle; Gorayeb, Teresa Cristina Castilho; Del Bianchi, Vanildo Luiz; Thomeo, João Cláudio; Tiera, Marcio José; de Oliveira Tiera, Vera Aparecida

2013-01-15

196

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

PubMed Central

Aspergillus flavus differentiates to produce asexual dispersing spores (conidia) or overwintering survival structures called sclerotia. Results described here show that these two processes are oppositely regulated by density-dependent mechanisms and that increasing the cell density (from 101 to 107 cells/plate) results in the lowest numbers of sclerotial and the highest numbers of conidial. Extract from spent medium of low-cell-density cultures induced a high-sclerotium-number phenotype, whereas high-cell-density extract increased conidiation. Density-dependent development is also modified by changes in lipid availability. Exogenous linoleic acid increased sclerotial production at intermediate cell densities (104 and 105 cells/plate), whereas oleic and linolenic acids inhibited sclerotium formation. Deletion of Aflox encoding a lipoxygenase (LOX) greatly diminished density-dependent development of both sclerotia and conidia, resulting in an overall increase in the number of sclerotia and a decrease in the number of conidia at high cell densities (>105 cells/plate). Aflox mutants showed decreased linoleic acid LOX activity. Taken together, these results suggest that there is a quorum-sensing mechanism in which a factor(s) produced in dense cultures, perhaps a LOX-derived metabolite, activates conidium formation, while a factor(s) produced in low-density cultures stimulates sclerotium formation. PMID:18658287

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

2008-01-01

197

Expression, purification and characterization of a feruloyl esterase A from Aspergillus flavus.  

PubMed

Feruloyl esterases are key enzymes involved in the complete hydrolysis of hemicellulose. In the present study, the encoding sequence of putative feruloyl esterase A (AfFaeA) was cloned from genomic DNA from Aspergillus flavus and expressed in Pichia pastoris. The purified recombinant AfFaeA had apparent relative molecular mass of about 40,000 and had an optimum pH of 6.0, although it was stable at pH values ranging from 4.5 to 8.0. The optimum temperature for AfFaeA was 58°C. AfFaeA had hydrolytic activity toward methyl caffeate, methyl p-coumarate, methyl ferulate and methyl sinapate. Substrate specificity profiling of AfFaeA demostrated it is a type-A feruloyl esterase. The good performance of AfFaeA to release ferulic acid from steam exploded corn stalk in concert with Geobacillus stearothermophilus xylanase mutant indicated it is a promising biocatalyst for biomass degradation. PMID:23981381

Zhang, Shuai-Bing; Zhai, Huan-Chen; Wang, Le; Yu, Guang-Hai

2013-11-01

198

Misidentification of Aspergillus nomius and Aspergillus tamarii as Aspergillus flavus: Characterization by Internal Transcribed Spacer, ?-Tubulin, and Calmodulin Gene Sequencing, Metabolic Fingerprinting, and Matrix-Assisted Laser Desorption Ionization–Time of Flight Mass Spectrometry  

PubMed Central

Aspergillus nomius and Aspergillus tamarii are Aspergillus species that phenotypically resemble Aspergillus flavus. In the last decade, a number of case reports have identified A. nomius and A. tamarii as causes of human infections. In this study, using an internal transcribed spacer, ?-tubulin, and calmodulin gene sequencing, only 8 of 11 clinical isolates reported as A. flavus in our clinical microbiology laboratory by phenotypic methods were identified as A. flavus. The other three isolates were A. nomius (n = 2) or A. tamarii (n = 1). The results corresponded with those of metabolic fingerprinting, in which the A. flavus, A. nomius, and A. tamarii strains were separated into three clusters based on ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC MS) analysis. The first two patients with A. nomius infections had invasive aspergillosis and chronic cavitary and fibrosing pulmonary and pleural aspergillosis, respectively, whereas the third patient had A. tamarii colonization of the airway. Identification of the 11 clinical isolates and three reference strains by matrix-assisted laser desorption ionization–time of flight mass spectrometry (MALDI-TOF MS) showed that only six of the nine strains of A. flavus were identified correctly. None of the strains of A. nomius and A. tamarii was correctly identified. ?-Tubulin or the calmodulin gene should be the gene target of choice for identifying A. flavus, A. nomius, and A. tamarii. To improve the usefulness of MALDI-TOF MS, the number of strains for each species in MALDI-TOF MS databases should be expanded to cover intraspecies variability. PMID:24452174

Tam, Emily W. T.; Chen, Jonathan H. K.; Lau, Eunice C. L.; Ngan, Antonio H. Y.; Fung, Kitty S. C.; Lee, Kim-Chung; Lam, Ching-Wan; Yuen, Kwok-Yung

2014-01-01

199

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

200

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

201

In vitro activity of isavuconazole against 208 Aspergillus flavus isolates in comparison with 7 other antifungal agents: assessment according to the methodology of the European Committee on Antimicrobial Susceptibility Testing  

Microsoft Academic Search

Aspergillus flavus is the second most common species causing invasive aspergillosis after A. fumigatus. In certain countries like India, Sudan, and Saudi Arabia, A. flavus is most frequently isolated from patients with fungal rhinosinusitis and endophthalmitis. A. flavus exhibit an increased resistance to antifungal agents compared to A. fumigatus. We determined the in vitro activity of isavuconazole, voriconazole, posaconazole, itraconazole,

Shivaprakash M. Rudramurthy; Arunaloke Chakrabarti; Erik Geertsen; Johan W. Mouton; Jacques F. Meis

2011-01-01

202

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

203

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

204

Absence of the aflatoxin biosynthesis gene, norA, allows accumulation of deoxyaflatoxin B1 in Aspergillus flavus cultures  

PubMed Central

Biosynthesis of the highly toxic and carcinogenic aflatoxins in select Aspergillus species from the common intermediate O-methylsterigmatocystin (OMST) has been postulated to require only the cytochrome P450 monooxygenase, OrdA (AflQ). We now provide evidence that the aryl alcohol dehydrogenase NorA (AflE) encoded by the aflatoxin biosynthetic gene cluster in A. flavus affects the accumulation of aflatoxins in the final steps of aflatoxin biosynthesis. Mutants with inactive norA produced reduced quantities of aflatoxin B1 (AFB1), but elevated quantities of a new metabolite, deoxyAFB1. To explain this result, we suggest that, in the absence of NorA, the AFB1 reduction product, aflatoxicol, is produced and is readily dehydrated to deoxyAFB1 in the acidic medium, enabling us to observe this otherwise minor toxin produced in wild-type A. flavus. PMID:20158523

Ehrlich, Kenneth C.; Chang, Perng-Kuang; Scharfenstein, Lester L.; Cary, Jeffrey W.; Crawford, Jason M.; Townsend, Craig A.

2010-01-01

205

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

206

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

207

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

208

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

209

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

210

Identification of Aspergillus Species Using Internal Transcribed Spacer Regions 1 and 2  

Microsoft Academic Search

Aspergillus species are the most frequent cause of invasive mold infections in immunocompromised patients. Although over 180 species are found within the genus, 3 species, Aspergillus flavus, A. fumigatus, and A. terreus, account for most cases of invasive aspergillosis (IA), with A. nidulans, A. niger, and A. ustus being rare causes of IA. The ability to distinguish between the various

TRAVIS HENRY; PETER C. IWEN; STEVEN H. HINRICHS

2000-01-01

211

Comparison of immunodiffusion and enzyme linked immunosorbent assay for antibodies to four Aspergillus species  

Microsoft Academic Search

Antigenic extracts were prepared from Aspergillus fumigatus, A niger, A flavus and A terreus for use in enzyme linked immunosorbent assay (ELISA) and immunodiffusion (ID) tests for Aspergillus antibodies to determine whether the use of antigenic extracts from species other than A fumigatus increased the sensitivity of the ELISA. ELISA titres correlated well with positive ID tests. Patient titres by

J H Froudist; G B Harnett; R McAleer

1989-01-01

212

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

213

EVALUATION OF A BIOPESTICIDE, PICHIA ANOMALA WRL-076 TO CONTROL ASPERGILLUS FLAVUS IN A COMMERCIAL ORCHARD  

Technology Transfer Automated Retrieval System (TEKTRAN)

Existing literatures indicate that wounds in plant tissues provide the entry to A. flavus. By mechanically wounding pistachio nut-fruits, sufficient number of nut-fruits conducive to A. flavus and fungal infection are generated. The wounded nut-fruits are easily recognized for sampling. Two experim...

214

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

215

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

216

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

217

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

218

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

219

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

220

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

221

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

222

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

223

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

224

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

225

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

226

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

227

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

228

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

229

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

230

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

231

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

232

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

233

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

234

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

235

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

236

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

237

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

238

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

239

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

240

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

241

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

242

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

243

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

244

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

245

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

246

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

247

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

248

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

249

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

250

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

251

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

252

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

253

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

254

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

255

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

256

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

257

Use of a granular bioplastic formulation for carrying conidia of a non-aflatoxigenic strain of Aspergillus flavus.  

PubMed

Previous research demonstrated that aflatoxin contamination in corn is reduced by field application of wheat grains pre-inoculated with the non-aflatoxigenic Aspergillus flavus strain NRRL 30797. To facilitate field applications of this biocontrol isolate, a series of laboratory studies were conducted on the reliability and efficiency of replacing wheat grains with the novel bioplastic formulation Mater-Bi to serve as a carrier matrix to formulate this fungus. Mater-Bi granules were inoculated with a conidial suspension of NRRL 30797 to achieve a final cell density of approximately log 7 conidia/granule. Incubation of 20-g soil samples receiving a single Mater-Bi granule for 60-days resulted in log 4.2-5.3 propagules of A. flavus/g soil in microbiologically active and sterilized soil, respectively. Increasing the number of granules had no effect on the degree of soil colonization by the biocontrol fungus. In addition to the maintenance of rapid vegetative growth and colonization of soil samples, the bioplastic formulation was highly stable, indicating that Mater-Bi is a suitable substitute for biocontrol applications of A. flavus NRRL 30797. PMID:19349167

Accinelli, Cesare; Saccà, M Ludovica; Abbas, Hamed K; Zablotowicz, Robert M; Wilkinson, Jeffery R

2009-09-01

258

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

259

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

260

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

E-print Network

Accepted 6 January 2012 Available online 12 January 2012 Keywords: Aspergillus flavus Aflatoxin Biocontrol Cyclopiazonic acid Gene cluster Contamination of corn, cotton, peanuts and tree nuts by aflatoxins is a severe aflatoxins and cyclopiazonic acid (CPA) and is currently being tested in corn-growing fields in Mississippi

Cotty, Peter J.

261

A public platform for the verification of the phenotypic effect of candidate genes for resistance to aflatoxin accumulation and Aspergillus flavus infection in maize  

Technology Transfer Automated Retrieval System (TEKTRAN)

A public candidate gene testing pipeline for resistance to aflatoxin accumulation or Aspergillus flavus infection in maize is presented here. The pipeline consists of steps for identifying, testing, and verifying the association of any maize gene sequence with resistance under field conditions. Reso...

262

75 FR 9596 - Notice of Filing of a Pesticide Petition for Residues of a Aspergillus flavus AF36 on Corn Food...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Notice of Filing of a Pesticide Petition for Residues of a Aspergillus flavus...modification of regulations for residues of a pesticide chemical in or on various...in 40 CFR part 180 for residues of a pesticide chemical in or on...

2010-03-03

263

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

264

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

265

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

266

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

267

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

268

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

269

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

270

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

271

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

272

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

PubMed

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

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

2014-07-01

273

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

PubMed

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

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

2014-06-01

274

Utilization of waste fruit-peels to inhibit aflatoxins synthesis by Aspergillus flavus: a biotreatment of rice for safer storage.  

PubMed

Antifungal activity in lemon and pomegranate peels was considerable against Aspergillus flavus, higher in pomegranate (DIZ 37mm; MIC 135?g/mL). Powdered peels (5, 10, 20% w/w) were mixed in inoculated rice. The inhibitory effect on fungal-growth and production of aflatoxins by A. flavus was investigated at storage conditions - temperature (25, 30°C) and moisture (18%, 21%) for 9months. The maximum total aflatoxins accumulated at 30°C, 21% moisture and at 25°C, 18% moisture were 265.09 and 163.45ng/g, respectively in control. Addition of pomegranate-peels inhibited aflatoxins production to 100% during four month-storage of rice at 25°C and 18% moisture, while lemon-peels showed similar inhibitory effect for 3months at same conditions. However a linear correlation was observed in aflatoxins level with temperature and moisture. Studies showed that both fruit-wastes are potent preventer of aflatoxin production in rice, useful for a safer and longer storage of rice. PMID:25270080

Naseer, R; Sultana, Bushra; Khan, M Z; Naseer, D; Nigam, Poonam

2014-11-01

275

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

PubMed

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

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

2011-12-01

276

Removal of aflatoxin B1 and inhibition of Aspergillus flavus growth by the use of Lactobacillus plantarum on olives.  

PubMed

Olives can be contaminated with a wide variety of molds (Aspergillus and/or Penicillium) that can be occurring naturally on fresh and processed olives and could support mycotoxin production. The aim of this work was to investigate aflatoxin B1 (AFB1) production by fungi and its bioaccumulation in olives during storage and to study the impact of the application of Lactobacillus plantarum on the inhibition of mold development and production of AFB1. Two different treatments were applied: (i) olives with natural microflora and (ii) olives inoculated with Aspergillus flavus after elimination of natural microflora. AFB1 has been extracted from olives and quantitated by high-performance liquid chromatography using a fluorescence detector. Results showed the absence of this metabolite in the olives for the season 2008 to 2009. In 2009 to 2010, AFB1 was detected at the level of 11 ?g/kg. The application of L. plantarum during the storage of olives favors the reduction of the level of AFB1 to 5.9 ?g/kg correlated with a decrease in the amount of molds (86.3%). The images obtained by environmental scanning electron microscopy showed that L. plantarum was able to adhere to the olive surface and probably produce a biofilm that inhibits the multiplication of yeast and fungi by oxygen competition. Results showed an increase of antioxidant activity and amount of total phenolic compounds of olives, respectively, by 24 and 8.6%. In many olives contaminated with A. flavus, AFB1 was present at an initial level of 5.15 ?g/kg and increased to 6.55 ?g/kg after 8 days of storage. The biological detoxification of AFB1 in olives by L. plantarum is confirmed by the reduction of the level of AFB1 to 2.12 ?g/kg on day 0 and its absence after 4 days of storage. PMID:25285494

Kachouri, Faten; Ksontini, Hamida; Hamdi, Moktar

2014-10-01

277

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

278

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

279

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

280

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

281

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

282

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

PubMed Central

Aspergillus ?avus and Aspergillus parasiticus are important pathogens of cotton, corn, peanuts and other oil-seed crops, producing toxins both in the field and during storage. We have designed three siRNA sequences (Nor-Ia, Nor-Ib, Nor-Ic) to target the mRNA sequence of the aflD gene to examine the potential for using RNA silencing technology to control aflatoxin production. Thus, the effect of siRNAs targeting of two key genes in the aflatoxin biosynthetic pathway, aflD (structural) and aflR (regulatory gene) and on aflatoxin B1 (AFB1), and aflatoxin G1 (AFG1) production was examined. The study showed that Nor-Ib gave a significant decrease in aflD mRNA, aflR mRNA abundance, and AFB1 production (98, 97 and 97% when compared to the controls) in A. flavus NRRL3357, respectively. Reduction in aflD and aflR mRNA abundance and AFB1 production increased with concentration of siRNA tested. There was a significant inhibition in aflD and AFB1 production by A. flavus EGP9 and AFG1 production by A. parasiticus NRRL 13005. However, there was no significant decrease in AFG1 production by A. parasiticus SSWT 2999. Changes in AFB1 production in relation to mRNA levels of aflD showed a good correlation (R = 0.88; P = 0.00001); changes in aflR mRNA level in relation to mRNA level of aflD also showed good correlation (R = 0.82; P = 0.0001). The correlations between changes in aflR and aflD gene expression suggests a strong relationship between these structural and regulatory genes, and that aflD could be used as a target gene to develop efficient means for aflatoxin control using RNA silencing technology. PMID:22069731

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

2011-01-01

283

Plant Disease / August 1997 911 Spatial and Temporal Patterns of Aspergillus flavus Strain Composition  

E-print Network

of trout liver cancer (18). The cause was subsequently found to be aflatoxins produced by A. flavus (12). Cottonseed is a preferred feed for dairy cows and, with the demonstration that aflatoxins were passed from feed to milk, aflatoxin content of cottonseed became regulated closely. An aflatoxin content greater

Cotty, Peter J.

284

EVALUATION OF A BIOPESTICIDE, PICHIA ANOMALA TO CONTROL ASPERGILLUS FLAVUS FOR REDUCING AFLATOXIN IN PISTACHIO  

Technology Transfer Automated Retrieval System (TEKTRAN)

Existing literatures indicate that wounds in plant tissues provide the entry to A. flavus. Two experiments were conducted in a commercial orchard in the summer of 2005. Nut-fruits of pistachio were individually wounded with a dissecting needle. Four treatments were applied. Nut clusters were spraye...

285

Transcriptional Profiles Uncover Aspergillus flavus-Induced Resistance in Maize Kernels  

PubMed Central

Aflatoxin contamination caused by the opportunistic pathogen A. flavus is a major concern in maize production prior to harvest and through storage. Previous studies have highlighted the constitutive production of proteins involved in maize kernel resistance against A. flavus’ infection. However, little is known about induced resistance nor about defense gene expression and regulation in kernels. In this study, maize oligonucleotide arrays and a pair of closely-related maize lines varying in aflatoxin accumulation were used to reveal the gene expression network in imbibed mature kernels in response to A. flavus’ challenge. Inoculated kernels were incubated 72 h via the laboratory-based Kernel Screening Assay (KSA), which highlights kernel responses to fungal challenge. Gene expression profiling detected 6955 genes in resistant and 6565 genes in susceptible controls; 214 genes induced in resistant and 2159 genes induced in susceptible inoculated kernels. Defense related and regulation related genes were identified in both treatments. Comparisons between the resistant and susceptible lines indicate differences in the gene expression network which may enhance our understanding of the maize-A. flavus interaction. PMID:22069739

Luo, Meng; Brown, Robert L.; Chen, Zhi-Yuan; Menkir, Abebe; Yu, Jiujiang; Bhatnagar, Deepak

2011-01-01

286

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

287

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

288

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

289

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

290

Aspergillus flavus AF36 Biopesticides Registration Action Document Final July 03, 2003  

E-print Network

AGENCY OFFICE OF PESTICIDE PROGRAMS BIOPESTICIDES AND POLLUTION PREVENTION DIVISION #12;Aspergillus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 3. Dietary Exposure and Risk Characterization . . . . . . . . . . . . . . . . . . . . . . 20 4. Occupational and Residential Exposure and Risk Characterization . . . 21 5. Drinking Water Exposure and Risk

Cotty, Peter J.

291

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

292

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

293

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

294

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

295

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

296

[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

297

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

298

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

299

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

300

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

301

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

302

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

303

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

304

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

305

Development of toxigenic Aspergillus flavus and A. parasiticus on kernels of native pecan [ Carya illinoensis (Wangenh) K. Koch] genotypes under different water activities  

Microsoft Academic Search

Susceptibility of kernels of 11 pecan [Carya illinoensis (Wangenh) K. Koch] genotypes to infection by Aspergillus flavus Link (strain 7757-3) and A. parasiticus Speare (strain CI 13-3) at 0.86, 0.90 and 0.97 water activity (Aw) was evaluated. For each genotype, Aw, and fungal species, five pecan kernels were inoculated with a spore suspension and incubated at 22–24°C; the test was

M. E Vázquez-Barrios; R Mart??nez-Peniche; E Fernández-Escart??n

2001-01-01

306

Efficacy of aqueous garlic extract on growth, aflatoxin B1 production, and cyto-morphological aberrations of Aspergillus flavus, causing human ophthalmic infection: topical treatment of A. flavus keratitis  

PubMed Central

By using agar well diffusion assay, antifungal activity of aqueous extract prepared from Egyptian garlic (Allium sativum L.) was evaluated in vitro against two strains of Aspergillus flavus (OC1 and OC10) causing human ocular infection. The recorded minimum inhibitory concentration (MIC) for growth inhibition of both strains was 3.60 mg/ml. Aqueous garlic extract (AGE) was used in successive in vivo tests as an attempt to cure rabbit’s fungal keratitis caused by A. flavus OC1. Findings showed that diluted preparation of AGE was effective topical antifungal agent and succeeded to cure severe A. flavus keratitis in a time course less than 10 days without any observable side effects. Microscopic examination showed that AGE induced deleterious cyto-morphological aberrations in A. flavus target cells. AGE applied to Czapek’s broth via contact method was more effective on growth, spores and aflatoxin B1 production than AGE applied to the same broth at the same concentration via fumigation method. PMID:24031964

Ismaiel, Ahmed A.; Rabie, Gamal H.; Kenawey, Saied E.M.; Abd EL-Aal, Marwa A.

2012-01-01

307

VeA Is Associated with the Response to Oxidative Stress in the Aflatoxin Producer Aspergillus flavus  

PubMed Central

Survival of fungal species depends on the ability of these organisms to respond to environmental stresses. Osmotic stress or high levels of reactive oxygen species (ROS) can cause stress in fungi resulting in growth inhibition. Both eukaryotic and prokaryotic cells have developed numerous mechanisms to counteract and survive the stress in the presence of ROS. In many fungi, the HOG signaling pathway is crucial for the oxidative stress response as well as for osmotic stress response. This study revealed that while the osmotic stress response is only slightly affected by the master regulator veA, this gene, also known to control morphological development and secondary metabolism in numerous fungal species, has a profound effect on the oxidative stress response in the aflatoxin-producing fungus Aspergillus flavus. We found that the expression of A. flavus homolog genes involved in the HOG signaling pathway is regulated by veA. Deletion of veA resulted in a reduction in transcription levels of oxidative stress response genes after exposure to hydrogen peroxide. Furthermore, analyses of the effect of VeA on the promoters of cat1 and trxB indicate that the presence of VeA alters DNA-protein complex formation. This is particularly notable in the cat1 promoter, where the absence of VeA results in abnormally stronger complex formation with reduced cat1 expression and more sensitivity to ROS in a veA deletion mutant, suggesting that VeA might prevent binding of negative transcription regulators to the cat1 promoter. Our study also revealed that veA positively influences the expression of the transcription factor gene atfB and that normal formation of DNA-protein complexes in the cat1 promoter is dependent on AtfB. PMID:24951443

Baidya, Sachin; Duran, Rocio M.; Lohmar, Jessica M.; Harris-Coward, Pamela Y.; Cary, Jeffrey W.; Hong, Sung-Yong; Roze, Ludmila V.; Linz, John E.

2014-01-01

308

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

309

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

310

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

311

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

312

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

313

[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

314

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

315

The Breeding of a Pigment Mutant Strain of Steroid Hydroxylation Aspergillus Flavus by Low Energy Ion Implantation  

NASA Astrophysics Data System (ADS)

In the process of the fermentation of steroid C11?-hydroxylgenation strain Aspergillus flavus AF-ANo208, a red pigment is derived, which will affect the isolation and purification of the target product. Low energy ion beam implantation is a new tool for breeding excellent mutant strains. In this study, the ion beam implantation experiments were performed by infusing two different ions: argon ion (Ar+) and nitrogen ion (N+). The results showed that the optimal ion implantation was N+ with an optimum dose of 2.08 × 1015 ions/cm2, with which the mutant strain AF-ANm16 that produced no red pigment was obtained. The strain had high genetic stability and kept the strong capacity of C11?-hydroxylgenation, which could be utilized in industrial fermentation. The differences between the original strain and the mutant strain at a molecular level were analyzed by randomly amplified polymorphic DNA (RAPD). The results indicated that the frequency of variation was 7.00%, which would establish the basis of application investigation into the breeding of pigment mutant strains by low energy ion implantation.

Ye, Hui; Ma, Jingming; Feng, Chun; Cheng, Ying; Zhu, Suwen; Cheng, Beijiu

2009-02-01

316

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

PubMed Central

Background Aflatoxins (AFs) are potent carcinogenic compounds produced by several Aspergillus species, which pose serious threats to human health. As sugar is a preferred carbohydrate source for AF production, we examined the possibility of using sugar analogs to inhibit AF biosynthesis. Results We showed that although D-glucal cannot be utilized by A. flavus as the sole carbohydrate source, it inhibited AF biosynthesis and promoted kojic acid production without affecting mycelial growth when applied to a glucose-containing medium. The inhibition occurred before the production of the first stable intermediate, norsolorinic acid, suggesting a complete inhibition of the AF biosynthetic pathway. Further studies showed that exogenous D-glucal in culture led to reduced accumulation of tricarboxylic acid (TCA) cycle intermediates and reduced glucose consumption, indicating that glycolysis is inhibited. Expression analyses revealed that D-glucal suppressed the expression of AF biosynthetic genes but promoted the expression of kojic acid biosynthetic genes. Conclusions D-glucal as a non-metabolizable glucose analog inhibits the AF biosynthesis pathway by suppressing the expression of AF biosynthetic genes. The inhibition may occur either directly through interfering with glycolysis, or indirectly through reduced oxidative stresses from kojic acid biosynthesis. PMID:24742119

2014-01-01

317

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

318

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

319

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

320

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

321

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

322

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

323

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

324

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

325

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

326

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

327

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

328

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

329

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

330

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.

331

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

332

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

333

Correlation and classification of single kernel fluorescence hyperspectral data with aflatoxin concentration in corn kernels inoculated with Aspergillus flavus spores.  

PubMed

The objective of this study was to examine the relationship between fluorescence emissions of corn kernels inoculated with Aspergillus flavus and aflatoxin contamination levels within the kernels. Aflatoxin contamination in corn has been a long-standing problem plaguing the grain industry with potentially devastating consequences to corn growers. In this study, aflatoxin-contaminated corn kernels were produced through artificial inoculation of corn ears in the field with toxigenic A. flavus spores. The kernel fluorescence emission data were taken with a fluorescence hyperspectral imaging system when corn kernels were excited with ultraviolet light. Raw fluorescence image data were preprocessed and regions of interest in each image were created for all kernels. The regions of interest were used to extract spectral signatures and statistical information. The aflatoxin contamination level of single corn kernels was then chemically measured using affinity column chromatography. A fluorescence peak shift phenomenon was noted among different groups of kernels with different aflatoxin contamination levels. The fluorescence peak shift was found to move more toward the longer wavelength in the blue region for the highly contaminated kernels and toward the shorter wavelengths for the clean kernels. Highly contaminated kernels were also found to have a lower fluorescence peak magnitude compared with the less contaminated kernels. It was also noted that a general negative correlation exists between measured aflatoxin and the fluorescence image bands in the blue and green regions. The correlation coefficients of determination, r(2), was 0.72 for the multiple linear regression model. The multivariate analysis of variance found that the fluorescence means of four aflatoxin groups, <1, 1-20, 20-100, and >or=100 ng g(-1) (parts per billion), were significantly different from each other at the 0.01 level of alpha. Classification accuracy under a two-class schema ranged from 0.84 to 0.91 when a threshold of either 20 or 100 ng g(-1) was used. Overall, the results indicate that fluorescence hyperspectral imaging may be applicable in estimating aflatoxin content in individual corn kernels. PMID:20221935

Yao, H; Hruska, Z; Kincaid, R; Brown, R; Cleveland, T; Bhatnagar, D

2010-05-01

334

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

335

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

336

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

337

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

338

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

339

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

340

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

341

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

342

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

343

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

344

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

345

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

346

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

347

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

Microsoft Academic Search

In separate treatments, a spore suspension ofA. flavus (control), an aqueous leaf extract of the subtropical neem tree plus a spore suspension ofA. flavus, or an aqueous neem leaf extract followed by anA. flavus spore suspension were injected 48 hr later onto the surfaces of locks of developing cotton bolls (30-day post anthesis).\\u000a Thirteen days after the treatments, the seeds

Hampden J. Zeringue; Deepak Bhatnagar

1990-01-01

348

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

349

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

350

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

351

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

352

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

353

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

354

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

355

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

356

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

357

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

PubMed

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

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

2014-05-01

358

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

359

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

360

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

361

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

362

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

363

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

364

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

365

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

366

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

367

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

368

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

369

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

370

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

371

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

372

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

373

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

374

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

375

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

376

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

377

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

378

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

379

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

380

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

381

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

382

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

383

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

384

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

385

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

386

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

387

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

388

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

389

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

390

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

391

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

392

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

393

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

394

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

395

Co-inoculation of aflatoxigenic and non-aflatoxigenic strains of Aspergillus flavus to study fungal invasion, colonization, and competition in maize kernels  

PubMed Central

A currently utilized pre-harvest biocontrol method involves field inoculations with non-aflatoxigenic Aspergillus flavus strains, a tactic shown to strategically suppress native aflatoxin-producing strains and effectively decrease aflatoxin contamination in corn. The present in situ study focuses on tracking the invasion and colonization of an aflatoxigenic A. flavus strain (AF70), labeled with green fluorescent protein (GFP), in the presence of a non-aflatoxigenic A. flavus biocontrol strain (AF36), to better understand the competitive interaction between these two strains in seed tissue of corn (Zea mays). Corn kernels that had been co-inoculated with GFP-labeled AF70 and wild-type AF36 were cross-sectioned and observed under UV and blue light to determine the outcome of competition between these strains. After imaging, all kernels were analyzed for aflatoxin levels. There appeared to be a population difference between the co-inoculated AF70-GFP+AF36 and the individual AF70-GFP tests, both visually and with pixel count analysis. The GFP allowed us to observe that AF70-GFP inside the kernels was suppressed up to 82% when co-inoculated with AF36 indicating that AF36 inhibited progression of AF70-GFP. This was in agreement with images taken of whole kernels where AF36 exhibited a more robust external growth compared to AF70-GFP. The suppressed growth of AF70-GFP was reflected in a corresponding (upto 73%) suppression in aflatoxin levels. Our results indicate that the decrease in aflatoxin production correlated with population depression of the aflatoxigenic fungus by the biocontrol strain supporting the theory of competitive exclusion through robust propagation and fast colonization by the non-aflatoxigenic fungus. PMID:24734028

Hruska, Zuzana; Rajasekaran, Kanniah; Yao, Haibo; Kincaid, Russell; Darlington, Dawn; Brown, Robert L.; Bhatnagar, Deepak; Cleveland, Thomas E.

2014-01-01

396

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

397

Production of Alkaline Protease by a New Aspergillus flavus Isolate under Solid-Substrate Fermentation Conditions for Use as a Depilation Agent  

PubMed Central

The production of alkaline protease by an Aspergillus flavus strain isolated in our laboratory by solid-substrate fermentation for use as a depilation agent and the influence of various factors on enzyme production are reported. The optimum conditions for maximum production were a growth temperature of 32°C, 63% substrate moisture, and a growth period of 48 h. Enrichment with corn steep liquor or Casitone increased productivity. Scaling-up experiments indicated that flask-scale results could be reproduced at 1 and 30 kg of substrate. The enzyme preparation exhibited maximum activity at both pH 7.5 and pH 9.5. The use of this enzyme as a depilation agent was confirmed by experiments in a tannery. PMID:16348437

Malathi, S.; Chakraborty, R.

1991-01-01

398

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

399

Physico-chemical study for zinc removal and recovery onto native/chemically modified Aspergillus flavus NA9 from industrial effluent.  

PubMed

Zinc biosorption characteristic of locally isolated Aspergillus flavus NA9 were examined as a function of pH, temperature, pulp density, contact time and initial metal ion concentration. The maximum zinc uptake was found to be 287.8 ± 11.1 mg g(-1) with initial metal concentration 600 mg L(-1) at initial pH 5.0 and temperature 30 °C. The equilibrium data gave good fits to Freundlich and Florry models with correlation coefficient value of 0.98. The contribution of the functional groups and lipids to zinc biosorption as identified by chemical pretreatment was in the order: carboxylic acids > hydroxyl > amines > lipids. The mechanism of biosorption was also studied using Fourier transform infrared (FTIR) spectrometry, scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX). The biosorbent was regenerated using 0.01 M HCl with 83.3% elution efficiency and was reused for five sorption-desorption cycles with 23.5% loss in biosorption capacity. The order of co-cations showing increased inhibitions of zinc uptake by A. flavus NA9 was Pb > Cu > Mn > Ni. The biosorption assays conducted with actual paint industry effluents revealed efficiency of 88.7% for Zn (II) removal by candidate biomass. PMID:23764574

Aftab, Kiran; Akhtar, Kalsoom; Jabbar, Abdul; Bukhari, Iftikhar H; Noreen, Razia

2013-09-01

400

Efficacy of the combined application of chitosan and Locust Bean Gum with different citrus essential oils to control postharvest spoilage caused by Aspergillus flavus in dates.  

PubMed

This study reports the efficacy of the combined application of chitosan (CH) and Locust Bean Gum (LBG) in combination with different citrus essential oils (EOs) to inhibit Aspergillus flavus in vitro and on artificially infected dates for a storage period of 12 days. The effect of these treatments on the fruits' sensory characteristics was evaluated to verify the complete absence of off-odours and off-flavours. Bergamot EO was the most effective in reducing mycelial growth, followed by bitter orange EO. Both bergamot and bitter orange oils significantly reduced conidial germination and a complete inhibition was obtained at concentrations higher than 2%. The mixtures based on CH-2% (v/v) bergamot EO or CH-2% (v/v) bitter orange EO proved to be the most effective coatings to reduce conidial germination resulting in an 87-90% inhibition compared with the control. In fruit decay assays coatings based on CH incorporating citrus oils were able to reduce fungal decay in the range of 52-62% at day 12. The study results and the complete absence of off-flavours and off-odours demonstrate the potential of CH coatings carrying citrus EOs at sub-inhibitory concentrations to control postharvest growth of A. flavus in dates. PMID:24291176

Aloui, Hajer; Khwaldia, Khaoula; Licciardello, Fabio; Mazzaglia, Agata; Muratore, Giuseppe; Hamdi, Moktar; Restuccia, Cristina

2014-01-17

401

Effect of Equisetum arvense and Stevia rebaudiana extracts on growth and mycotoxin production by Aspergillus flavus and Fusarium verticillioides in maize seeds as affected by water activity.  

PubMed

Cereals are a very important part of the human and animal diets. However, agricultural products can be contaminated by moulds and their mycotoxins. Plant extracts, particularly those of Equisetum arvense and Stevia rebaudiana have been reported previously to contain antioxidant compounds which may have antifungal properties. In this study, E. arvense and S. rebaudiana extracts were tested for their control of mycotoxigenic fungi in maize. The extracts were tested separately and as a mixture for their effect on growth of Aspergillus flavus and Fusarium verticillioides. Extracts were added to unsterilised inoculated maize at different water activity (a(w)) levels (0.85-0.95). Moulds were inoculated and incubated for 30 days. Results confirmed that the extract of E. arvense and a mixture 1:1 of Equisetum-Stevia may be effective for the inhibition of both growth of A. flavus and aflatoxin production at high water activity levels (pre-harvest conditions). In general, growth of the F. verticillioides was reduced by the use of plant extracts, especially at 0.95 a(w). However, fumonisin presence was not significantly affected. E. arvense and S. rebaudiana extracts could be developed as an alternative treatment to control aflatoxigenic mycobiota in moist maize. PMID:22104120

Garcia, Daiana; Ramos, Antonio J; Sanchis, Vicente; Marín, Sonia

2012-02-01

402

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

403

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

404

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

405

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

406

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

407

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

408

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

409

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

410

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

411

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

412

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

413

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

414

Application of loop-mediated isothermal amplification assays for direct identification of pure cultures of Aspergillus flavus, A. nomius, and A. caelatus and for their rapid detection in shelled Brazil nuts.  

PubMed

Brazil nuts have a high nutritional content and are a very important trade commodity for some Latin American countries. Aflatoxins are carcinogenic fungal secondary metabolites. In Brazil nuts they are produced predominantly by Aspergillus (A.) nomius and A. flavus. In the present study we applied and evaluated two sets of primers previously published for the specific detection of the two species using loop-mediated isothermal amplification (LAMP) technology. Moreover, a primer set specific for A. caelatus as a frequently occurring non-aflatoxigenic member of Aspergillus section Flavi in Brazil nuts was newly developed. LAMP assays were combined with a simplified DNA release method and used for rapid identification of pure cultures and rapid detection of A. nomius and A. flavus from samples of shelled Brazil nuts. An analysis of pure cultures of 68 isolates representing the major Aspergillus species occurring on Brazil nuts showed that the three LAMP assays had individual accuracies of 61.5%, 84.4%, and 93.3% for A. flavus, A. nomius, and A. caelatus, respectively when morphological identification was used as a reference. The detection limits for conidia added directly to the individual LAMP reactions were found to be 10? conidia per reaction with the primer set ID9 for A. nomius and 10? conidia per reaction with the primer set ID58 for A. flavus. Sensitivity was increased to 10¹ and 10² conidia per reaction for A. nomius and A. flavus, respectively, when sample preparation included a spore disruption step. The results of LAMP assays obtained during the analysis of 32 Brazil nut samples from different regions of Brazil and from different steps in the production process of the commodity were compared with results obtained from mycological analysis and aflatoxin analysis of corresponding samples. Compared with mycological analysis of the samples, the Negative Predictive Values of LAMP assays were 42.1% and 12.5% while the Positive Predictive Values were 61.5% and 66.7% for A. nomius and A. flavus, respectively. When LAMP results were compared with the presence of aflatoxins in corresponding samples, the Negative Predictive Values were 22.2% and 44.4% and the Positive Predictive Values were 52.2% and 78.3% for aflatoxins produced by A. nomius and A. flavus, respectively. The LAMP assays described in this study have been demonstrated to be a specific, sensitive and easy to use tool for the survey of Brazil nuts for contaminations with potential aflatoxin-producing A. nomius and A. flavus in low tech environments where resources may be limited. PMID:24361827

Luo, Jie; Taniwaki, Marta H; Iamanaka, Beatriz T; Vogel, Rudi F; Niessen, Ludwig

2014-02-17

415

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

416

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

417

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

418

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

419

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

420

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

421

Regional differences in production of aflatoxin B1 and cyclopiazonic acid by soil isolates of aspergillus flavus along a transect within the United States.  

PubMed

Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in regions where peanuts are not commonly grown. The A. flavus isolates were identified as members of either the L strain (n = 774), which produces sclerotia that are >400 micrometer in diameter, or the S strain (n = 309), which produces numerous small sclerotia that are <400 micrometer in diameter. The S-strain isolates generally produced high levels of aflatoxin B1, whereas the L-strain isolates were more variable in aflatoxin production; variation in cyclopiazonic acid production also was greater in the L strain than in the S strain. There was a positive correlation between aflatoxin B1 production and cyclopiazonic acid production in both strains, although 12% of the L-strain isolates produced only cyclopiazonic acid. Significant differences in production of aflatoxin B1 and cyclopiazonic acid by the L-strain isolates were detected among regions. In the western half of Texas and the peanut-growing region of Georgia and Alabama, 62 to 94% of the isolates produced >10 microgram of aflatoxin B1 per ml. The percentages of isolates producing >10 microgram of aflatoxin B1 per ml ranged from 0 to 52% in the remaining regions of the transect; other isolates were often nonaflatoxigenic. A total of 53 of the 126 L-strain isolates that did not produce aflatoxin B1 or cyclopiazonic acid were placed in 17 vegetative compatibility groups. Several of these groups contained isolates from widely separated regions of the transect. PMID:10103234

Horn, B W; Dorner, J W

1999-04-01

422

Regional Differences in Production of Aflatoxin B1 and Cyclopiazonic Acid by Soil Isolates of Aspergillus flavus along a Transect within the United States  

PubMed Central

Soil isolates of Aspergillus flavus from a transect extending from eastern New Mexico through Georgia to eastern Virginia were examined for production of aflatoxin B1 and cyclopiazonic acid in a liquid medium. Peanut fields from major peanut-growing regions (western Texas; central Texas; Georgia and Alabama; and Virginia and North Carolina) were sampled, and fields with other crops were sampled in regions where peanuts are not commonly grown. The A. flavus isolates were identified as members of either the L strain (n = 774), which produces sclerotia that are >400 ?m in diameter, or the S strain (n = 309), which produces numerous small sclerotia that are <400 ?m in diameter. The S-strain isolates generally produced high levels of aflatoxin B1, whereas the L-strain isolates were more variable in aflatoxin production; variation in cyclopiazonic acid production also was greater in the L strain than in the S strain. There was a positive correlation between aflatoxin B1 production and cyclopiazonic acid production in both strains, although 12% of the L-strain isolates produced only cyclopiazonic acid. Significant differences in production of aflatoxin B1 and cyclopiazonic acid by the L-strain isolates were detected among regions. In the western half of Texas and the peanut-growing region of Georgia and Alabama, 62 to 94% of the isolates produced >10 ?g of aflatoxin B1 per ml. The percentages of isolates producing >10 ?g of aflatoxin B1 per ml ranged from 0 to 52% in the remaining regions of the transect; other isolates were often nonaflatoxigenic. A total of 53 of the 126 L-strain isolates that did not produce aflatoxin B1 or cyclopiazonic acid were placed in 17 vegetative compatibility groups. Several of these groups contained isolates from widely separated regions of the transect. PMID:10103234

Horn, B. W.; Dorner, J. W.

1999-01-01

423

Natural Control of Corn Postharvest Fungi Aspergillus flavus and Penicillium sp. Using Essential Oils from Plants Grown in Argentina.  

PubMed

The objective in this study was to evaluate the antifungal activity of essential oils from native and commercial aromatic plants grown in Argentina against corn postharvest fungi and to link the essential oil bioactivity with lipid oxidation and morphological changes in fungus cell membrane. Essential oil (EO) of oregano variety Mendocino (OMen), Cordobes (OCor), and Compacto (OCom), mint variety Inglesa (Mi), and Pehaujo (Mp), Suico (Sui); rosemary (Ro), and Aguaribay (Ag) were tested in vitro against 4 corn fungi: A. flavus (CCC116-83 and BXC01), P. oxalicum (083296), and P. minioluteum (BXC03). The minimum fungicidal concentration (MFC) and the minimum inhibitory concentration (MIC) were determined. The chemical profiles of the EOs were analyzed by GC-MS. Lipid oxidation in cell membrane of fungi was determined by hydroperoxides and related with essential oil antifungal activity. The major compounds were Thymol in OCor (18.66%), Omen (12.18%), and OCom (9.44%); menthol in Mi and Mp; verbenone in Sui; dehydroxy-isocalamendiol in Ag; and eucaliptol in Ro. OCor, Omen, and OCom showed the best antifungal activity. No antifungal activity was observed in Ag and Ro EO. The hydroperoxide value depended on the fungi (P < 0.001) and the antimicrobial agent (P < 0.001).Membrane lipids were oxidized by Sui EO in A. flavus BXC01 and A. flavus CCC116-83 (0.021 and 0.027 meqO2 /kg, respectively). The results suggest that the EOs of OCor, OMen, OCom, Mi, Mp, and Sui grown in Argentina can be used as natural alternatives to control fungi that produce mycotoxin in maize. PMID:25376651

Camiletti, Boris X; Asensio, Claudia M; Pecci, María de la Paz Giménez; Lucini, Enrique I

2014-12-01

424

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

425

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

426

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

427

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

428

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

429

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

430

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

431

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

432

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

433

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

434

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

435

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.

436

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

437

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

438

Influence of kernel size on the presence of Aspergillus flavus, aflatoxin content and moisture content in Dominican Republic grown peanuts  

E-print Network

(13). Christensen et al. (14), report d that in wheat the range between 14 and 15% mois- ture content, a dilference of less than one per cent made a great difference in the growth of A. restrictus. hopez and Christensen (36) stated that A. flavus... is dif- ficult. Christensen (15) speculated that moisture content. 13 may vary from seed Lo . ', cod in a supposedly uni . rm lot of grain, which may explain why in a given lot . ;f g;ain with an average moisture content nearr Cne lower (:!! , L t...

Herrera-Perez, Teodoro

1969-01-01

439

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

440

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

441

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

442

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

443

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

444

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

445

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

446

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

447

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

448

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

449

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 a