Toxic Metabolite Produced by Aspergillus wentii

Mycelial extracts of an Aspergillus wentii strain grown on yeast-extract sucrose medium and initially isolated from country-cured ham were highly toxic when inoculated into chicken embryos or fed to mice. Moldy corn and rice were less toxic when fed to mice. Water extracts of moldy corn or rice or culture filtrates from yeast-extract sucrose medium were not toxic. Purification by thin-layer chromatography followed by crystallization yielded orange-red crystals that showed high toxicity and had a melting point of 285 to 286 C. Chloroform solutions of the crystals had absorption maxima at 270, 295, and 452 nm. The smallest amount of this component necessary to have zero hatchability of fertile eggs was 50 mug/egg.     

Starch Hydrolysis by Conidia of Aspergillus wentii

Soluble starch was hydrolyzed to glucose by conidia of Aspergillus wentii NRRL 2001. Peak yields of glucose were achieved in 3 days. A glucoamylase-like enzyme was assumed to be responsible since maltose was not detected during the conversion. Spore age, storage conditions, and temperature affected the level of glucose accumulated. Iodoacetate inhibited catabolism of the glucose formed and this inhibition increased product yield. Spores of other fungi also hydrolyzed starch but none accumulated glucose naturally as did A. wentii spores.     

Biotransformation of some steroids by Aspergillus wentii

First steroid biotransformations performed by Aspergillus wentii MRC 200316 are reported. Testosterone (1) yields 6beta-hydroxytestosterone (3) and 14alpha-hydroxytestosterone (4) while progesterone (2) yields 11alpha-hydroxyprogesterone (5).     

Antioxidant metabolites from marine alga-derived fungus Aspergillus wentii EN-48

Eight secondary metabolites (1–8) including a new seco-anthraquinone (wentiquinone C, 1) and a new benzamide derivative (methyl 4-(3,4-dihydroxybenzamido)butanoate, 2), as well as three other derivatives (4, 7, and 8) that were isolated from natural source for the first time, were characterized from the EtOAc extracts of the marine alga-derived endophytic fungus Aspergillus wentii EN-48. The structures of the isolated compounds were elucidated on the basis of 1D and 2D NMR experiments. Each of the isolated compounds was evaluated for α,α-diphenyl-picrylhydrazyl (DPPH) radical scavenging activity, and some of them showed potent activities with IC₅₀ values ranging from 5.2 to 99.4 μg/mL, compared to the positive control, butylated hydroxytoluene (BHT), with an IC₅₀ of 36.9 μg/mL.     

β - glucosidase production by Aspergillus wentii in stirred tank bioreactors

Summary Batch cultivation of Aspergillus wentii, Wehmer, Pt 2804 was carried out on Mandels and Reese (1957) medium containing 3% cellulose and 0.3% peptone at 30°C in 14 and 30 liter Bioreactors. Use of a 48 hours old inoculum (10% v/v), 0.5 vvm aeration at 400–800 rpm and maintenance of dissolved oxygen and pH above 50% saturation level and between 5.2 to 4.0 respectively, produced 10.58 g cells/lit and 61.9 IU/1/hr cellobiase productivity.     

Endoglucanase from the mixed culture of Trichoderma reesei and Aspergillus wentii

The level of α-mannanase in mixed fungal culture of Trichoderma reesei, D1-6, and Aspergillus wentii, Pt 2804, affects the extracellular activities of cellulase. The endoglucanase component of the cellulase system is a glycoprotein having mannose and other sugars and sugaramines in its glycan moiety. Its activity is inhibited by α-mannanase. The inactivation of endoglucanase by α-mannanase can be prevented by galactose.     

Sequential cold-sensitive mutations in Aspergillus fumigatus.

Mutants of thermotolerant fungus Aspergillus fumigatus I-21 (ATCC 32722) unable to grow at 37 degrees C were sought. Cold-sensitive mutants were enriched from progeny spores of gamma-irradiated conidia by two or more incubations at various nonpermissive temperatures alternating with filtrations through chessecloth. The approximate minimum, optimum, and maximum growth temperatures of the parent were 12, 40, and 50 degrees C, respectively. Mutants unable to grow at 37 degrees C were not successfully isolated directly from the wild type. A mutant unable to grow at 25 degrees C was isolated and mutations further increasing the cold sensitivity by increments of 3-5 degrees C were found to occur. Mutants completely unable to grow at 37 degrees C were obtained by five sequential mutations. All mutants grew as fast as the wild-type parent at 45 degrees C and higher. Each mutant produced revertants able to grow not only at the nonpermissive temperature used for its isolation but also at lower temperatures.     

Differences among the cell wall galactomannans from Aspergillus wentii and Chaetosartorya chrysella and that of Aspergillus fumigatus

The alkali extractable and water-soluble cell wall polysaccharides F1SS from Aspergillus wentii and Chaetosartorya chrysella have been studied by methylation analysis, 1D- and 2D-NMR, and MALDI-TOF analysis. Their structures are almost identical, corresponding to the following repeating unit: [--> 3)-beta-D-Gal f -(1 --> 5)-beta-D-Gal f-(1 -->]n --> mannan core. The structure of this galactofuranose side chain differs from that found in the pathogenic fungus Aspergillus fumigatus, in other Aspergillii and members of Trichocomaceae: [--> 5)-beta-D-Gal f-(1 -->]n --> mannan core. The mannan cores have also been investigated, and are constituted by a (1 --> 6)-alpha-mannan backbone, substituted at positions 2 by chains from 1 to 7 residues of (1 --> 2) linked alpha-mannopyranoses.     

Emodin, a Toxic Metabolite of Aspergillus wentii Isolated from Weevil-Damaged Chestnuts

A diarrheagenic toxin from culture extracts of Aspergillus wentii Wehmer isolated from weevil-damaged Chinese chestnuts was identified as emodin (2-methyl-4,5,7-trihydroxyanthraquinone). The orange-red, crystalline toxin (mp 255 to 257 C) showed ultraviolet absorption maxima in ethyl alcohol at 223, 250, 267, 290, and 442 nm, and infrared absorption maxima at 3,400 cm-1 (OH), 1,635, and 1,625 CM-1. Chemical shifts and coupling constants of the proton magnetic resonance spectra of the A. wentii toxin and of authentic emodin agreed. Mean lethal dose of emodin orally administered to 1-day-old DeKalb cockerels was 3.7 mg/kg.     

Differences among the cell wall galactomannans from Aspergillus wentii and Chaetosartorya chrysella and that of Aspergillus fumigatus

The alkali extractable and water-soluble cell wall polysaccharides F1SS from Aspergillus wentii and Chaetosartorya chrysella have been studied by methylation analysis, 1D- and 2D-NMR, and MALDI-TOF analysis. Their structures are almost identical, corresponding to the following repeating unit: [→ 3)-β-D-Galf-(1 → 5)-β-D-Galf-(1 →] _n → mannan core. The structure of this galactofuranose side chain differs from that found in the pathogenic fungus Aspergillus fumigatus, in other Aspergillii and members of Trichocomaceae: [→ 5)-β-D-Galf-(1 →] _n → mannan core. The mannan cores have also been investigated, and are constituted by a (1 → 6)-α-mannan backbone, substituted at positions 2 by chains from 1 to 7 residues of (1 → 2) linked α-mannopyranoses. Published in 2004. This revised version was published online in July 2006 with corrections to the Cover Date.     

Xanthone,benzophenone and bianthrone derivatives from the hypersaline lake-derived fungus Aspergillus wentii

Five new metabolites, including the xanthone derivative wentixanthone A (1), the benzophenone wentiphenone A (2), the diastereomeric mixtures of the bianthrones wentibianthrone A (3a, b) and wentibianthrone B (4a, b), as well as (10R,10′S)-wentibianthrone C (5a) and (10R,10′R)-wentibianthrone C (5b) were obtained from the fungus Aspergillus wentii, isolated from soil of the hypersaline lake El Hamra in Wadi El-Natrun, Egypt. The structures of the isolated compounds were established by one and two-dimensional NMR and MS spectroscopic analysis. The relative configuration of bianthrones (3–5) was elucidated by comparison of experimental and computed ¹H NMR chemical shifts. Results of biological assays are reported.     

Method To Estimate Growth of Trichoderma reesei and Aspergillus wentii in Mixed Culture on Cellulosic Substrates

A simple differential method based on measurement of an intracellular pigment of Aspergillus wentii was developed for estimation of the individual growths of two fungi, Trichoderma reesei and A. wentii, in mixed-culture fermentation of an insoluble cellulosic substrate.     

Frequency of spontaneous and induced recessive mutations in a diploid strain of Aspergillus nidulans

The spontaneous and UV-induced frequencies of recessive mutations have been studied in a diploid strain of Aspergillus nidulans, by the p-fluoro-phenylalanine (FPA) and 8-azaguanine (8-AZA) resistance tests, on their resting or germinating conidia.

Observed frequencies are in the order of magnitude of those expected, which have been calculated considering the observed mutation frequencies in the diploid strain as well as mitotic recombination frequencies.

We also review some papers which claim to have found higher rates of recessive mutations in mammalian cell lines; in some cases no really higher rates are evident and the authors' conclusions often rest on misinterpretation of their own data.