Isolation and identification of secondary metabolites of a strain ofAspergillus terreus,a common food contaminant

2-Hydroxy 3-methyl 1,4-benzoquinone 5,6 epoxide was identified as secondary metabolite of a strain ofAspergillus terreus, a common contaminant of animal feeds. In addition, the following compounds were also tentatively identified to be produced by this organism: 2-hYdroxy 3-methyl 1,4-benzoquinone; 2-methyl 1,4-benzoquinone 5,6-epoxide; naphthazarin epoxide; and 2-hydroxy 3-methyl 1,4-benzoquinone 5, 6-epoxide.     

Studies on the application of immobilization technique for the production of cyclosporin A by a local strain of Aspergillus terreus

The formation of cyclosporin A (Cy A) by immobilized spores and mycelia of Aspergillus terreus was investigated. Different carriers were tested as immobilizing carriers, whereby Ca-alginate was selected for further experimentation. The role of alginate concentration, biomass weight, pH value of the cultivation medium, repeated utilization of the immobilized fungus as well as the supplementation of different amino acid precursors were studied. Best Cy A outputs were attained with Ca-alginate 3% (w/v), mycelial weight 15% (w/v), pH 4.5 and four repeated cycles. Similarly, the Cy A productivity was markedly accelerated in the presence of L-valine and L-valine and L-leucine mixture.     

Production of glucoamylase by 2-deoxy-D-glucose resistant mutant ofAspergillus terreus 4

Summary A catabolite derepressed mutant of a glucoamylolytic strain ofAspergillus terreus 4 produced 1.8 times more glucoamylase than its parent; the crude enzyme preparation appreciably degraded raw starchy materials like wheat, rice, potato and barley.     

Extracellular proteinase spectrum ofAspergillus terreus grown on various substrates

The level of proteinase activity and the ratio of proteinases I and II, secreted byAspergillus terreus, a cellulase producer, was followed during its growth on media containing various carbon sources. Correlation was found between the level of proteinase secretion and the rate of change of the cellulase complex spectrum. The extracellular proteolytic system ofA. terreus was presented mainly by proteinase II (metalloproteinase) during cultivation under conditions favoring fast accumulation of low-molar mass cellulases. The results indicate that proteinase II could be responsible for the limited proteolysis of high-molar mass cellulases ofA. terreus into smaller enzymes of the cellulolytic complex, thus changing their substrate specificity.     

Response surface methodology for lovastatin production by Aspergillus terreus GD13 strain

A wild type Aspergillus terreus GD13 strain, chosen after extensive screening, was optimized for lovastatin production using statistical Box-Behnken design of experiments. The interactive effect of four process parameters, i.e. lactose and soybean meal, inoculum size (spore concentration) and age of the spore culture, on the production of lovastatin was evaluated employing response surface methodology (RSM). The model highlighted the positive effect of soybean meal concentration and inoculum level for achieving maximal level of lovastatin (1342 mg/l). The optimal fermentation conditions improved the lovastatin titre by 7.0-folds when compared to the titres obtained under unoptimized conditions.     

Some nutritional factors influencing mevinolin production byAspergillus terreus strain

Aspergillus terreus produces the hypocholesterolemic compound mevinolin. Its growth and mevinolin production were affected by the composition of the culture medium. Both were at a maximum with glucose (6%) as the sole carbon source and in the presence of a mixture of yeast extract and sodium nitrate as nitrogen source. Influence of the concentration of some inorganic salts are also discussed.     

Production of fumigaclavine B by a thermophilic strain ofAspergillus fumigatus

Summary From a culture filtrate (about 10 litres) ofAspergillus fumigatus no. 2–18, isolated from the soil samples collected in Bangkok as having high productivity of indole alkaloids, a main alkaloid (compound A) was isolated in crystalline form with the yield of 70 mg. Compound A had a m.p. 188–189°C, [] _D ²⁰ -106° (pyr.) and molecular formula C₁₆H₂₀ON₂. From these data and its MS and NMR spectra, compound A was shown to be identical with fumigaclavine B.

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Production de fumigaclavine B par une souche thermophile d'Aspergillus fumigatus

Résumé On a isolé un alcaloïde principal, le composé A, sous forme cristalline et avec un rendement de 70 mg à partir de 10 litres de filtrat de culture d'Aspergillusfumigatus sp. n 2–18, isolée d'échantillons de sol récoltés à Bangkok et connus comme ayant une haute productivité en alcaloïdes de nature indolique. Ce composé A a un point de fusion compris entre 188 et 189°C, un [] _D ²⁰ de 106° (pyr.) et la formule moléculaire C₁₆H₂₀ON₂., Sur base de ces données et de spectres SM et RMN, le composé A apparaît identique avec la fumigaclavine B.

     

Citric acid production from sugar cane molasses by 2-deoxyglucose-resistant mutant strain ofAspergillus niger

Citric acid production from sugar cane molasses byAspergillus niger NIAB 280 was studied in a batch cultivation process. A maximum of 90 g/L total sugar was utilized in citric acid production medium. From the parental strainA. niger, mutant strains showing resistance to 2-deoxyglucose in Vogal's medium containing molasses as a carbon source were induced by γ-irradiation. Among the new series of mutant strains, strain RP7 produced 120 g/L while the parental strain produced 80 g/L citric acid (1.5-fold improvement) from 150 g/L of molasses sugars. The period of citric acid production was shortened from 10 d for the wild-type strain to 6–7 d for the mutant strain. The efficiency of substrate uptake rate with respect to total volume substrate consumption rate,Q _s (g per L per h) and specific substrate consumption rate,q _s (g substrate per g cells per h) revealed that the mutant grew faster than its parent. This indicated that the selected mutant is insensitive to catabolite repression by higher concentrations of sugars for citric acid production. With respect to the product yield coefficient (Y _p/x), volume productivity (Q _p) and specific product yields (q _p), the mutant strain is significantly (p≤0.05) improved over the parental strain.     

Purification and characterization of pectinesterase produced by a strain ofAspergillus niger

After an 88-fold purification, pectinesterase produced by a strain ofAspergillus niger, isolated from rotten lemons, showed the following main characteristics: maximum activity at 45°C, pH 5; Km, with pectin as substrate, 1.01 mg/L; G^*, 4750 Cal/mol. Polygalacturonic acid and methanol acted as competitive and non-competitive inhibitors, respectively. The activity of the enzyme was impaired by MgCl₂ and stimulated by NaCl.     

Production of lovastatin by a wild strain of Aspergillus terreus

Of 68 Aspergillus terreus, three produced lovastatin with equivalent or better yield than strain ATCC 20542 originally described for lovastatin production. Medium optimization experiments with the best isolate (TUB F-514) indicated that lactose, rapeseed meal and KNO3 were the best carbon, organic nitrogen and inorganic nitrogen sources, respectively. In shake-flasks with optimized medium containing 4 % (w/v) lactose, 400 g lovastatin/ml was produced, with a yield of 10 mg/g lactose. In solid substrate fermentation on extracted sweet sorghum pulp supplemented with cheese whey 1500 g lovastatin/g dry weight was produced with a yield of 37.5 mg/g lactose. © Rapid Science Ltd. 1998     

Enhancing itaconic acid production by Aspergillus terreus

Aspergillus terreus is successfully used for industrial production of itaconic acid. The acid is formed from cis-aconitate, an intermediate of the tricarboxylic (TCA) cycle, by catalytic action of cis-aconitate decarboxylase. It could be assumed that strong anaplerotic reactions that replenish the pool of the TCA cycle intermediates would enhance the synthesis and excretion rate of itaconic acid. In the phylogenetic close relative Aspergillus niger, upregulated metabolic flux through glycolysis has been described that acted as a strong anaplerotic reaction. Deregulated glycolytic flux was caused by posttranslational modification of 6-phosphofructo-1-kinase (PFK1) that resulted in formation of a highly active, citrate inhibition-resistant shorter form of the enzyme. In order to avoid complex posttranslational modification, the native A. niger pfkA gene has been modified to encode for an active shorter PFK1 fragment. By the insertion of the modified A. niger pfkA genes into the A. terreus strain, increased specific productivities of itaconic acid and final yields were documented by transformants in respect to the parental strain. On the other hand, growth rate of all transformants remained suppressed which is due to the low initial pH value of the medium, one of the prerequisites for the accumulation of itaconic acid by A. terreus mycelium.     

Improved glucoamylase production by less unstable strains ofAspergillus awamori

Summary The NRRL 3112 strain ofAspergillus awamori showed spontaneous segregation and sector formation tentatively attributed to a chromosomal instability. Spontaneous segregants showing stablepro1 (proline) requirement were easily isolated and stablepro+ strains were not isolated at all. Derivatives showing lower frequency ofpro1 conidia produced significantly more glucoamylase than the parental strain.     

Enhanced production of (+)-terrein by Aspergillus terreus strain PF26 with epigenetic modifier suberoylanilide hydroxamic acid

New strategies for improving the fermentation yield of (+)-terrein which is a fungal metabolite with multiple bioactivities are very urgent. In this study, the effect of suberoylanilide hydroxamic acid, one kind of epigenetic modifier, on the biosynthesis of (+)-terrein by Aspergillus terreus strain PF26 isolated from the marine sponge Phakellia fusca was investigated. It was found that suberoylanilide hydroxamic acid exhibited a positive impact on (+)-terrein production, resulting from promoting the biosynthesis of 6-hydroxymellein, the precursor of (+)-terrein. Through optimization of feeding concentration and time of suberoylanilide hydroxamic acid, 5.58 g/L (+)-terrein could be obtained in shake flask cultivation, 29.5% higher than the control. Correspondingly, the fermentation of A. terreus strain PF26 in 7.5-L stirred bioreactor with feeding suberoylanilide hydroxamic acid (900 μM, day 4) yielded 9.07 g/L (+)-terrein, 77.1% higher than the control. These results showed that the epigenetic modifier-suberoylanilide hydroxamic acid could be utilized to enhance the production of (+)-terrein, which laid the foundation of massive production of (+)-terrein by fermentation.     

Itaconic acid production by immobilizedAspergillus terreus on sucrose medium

Summary The itaconic acid production by immobilizedAspergillus terreus TTK 200-5-3 mycelium was optimized in shake flask fermentations using statistical experimental design and empirical modelling. The maximum itaconic acid concentration was calculated to be 13.3 g/l in the investigated experimental area when initial sucrose concentration was 10%, ammonium nitrate concentration 0.275% and initial pH 3. The itaconic acid product concentration using immobilized mycelium was about double of that obtained with the free mycelium.     

Induction of glucoamylase production by non-starchy carbohydrates inAspergillus terreus

Glucoamylase production inAspergillus terreus was induced, in order, by glucose, cellobiose, sorbitol, sucrose, -methyl mannoside and -methyl glucoside. Optimal induction was at 38°C, pH 4.0 and with 8 mg glucose/ml. Cycloheximide at 10 g/ml completely inhibited induction indicatingde novo protein synthesis was involved in induction of glucoamylase.

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Résumé La production de gluco-amylase est induite chezAspergillus terreus, en ordre décroissant, par le glucose, le celloboise, le sorbitol, le sucrose, l'-methylmannoside et l'-methylglucoside. L'induction est optimum à 38°C, pH 4.0 et en présence de 8 mg de glucose parml. La cycloheximide à 10 g par ml inhibe complètement l'induction, ce qui implique use synthèse de protéinede novo dans l'induction de la gluco-amylase.

     

Regulation of the production of polygalacturonase by Aspergillus terreus

The synthesis of polygalacturonase (PG) (EC 3.2.1.15) by a strain of Aspergillus terreus was induced by polygalacturonic acid and repressed by glucose, galactose or fructose even in the presence of the inducer. The production of PG increased when the mycelium was washed free of glucose and incubated in a glucose-free medium containing the inducer, a fact that indicated the reversibility of the repression mechanism. When Actinomycin D and cycloheximide were added to the culture medium, the synthesis of PG ceased. PG synthesis increased 43% with the addition of methionine and 64% both with leucine and with tyrosine. Specific productivity with leucine was 210% higher than that of the control as against 149% with methionine and 70% with tyrosine. The results obtained suggest that PG synthesis is regulated by leucine.     

Itaconic acid production from wheat chaff by Aspergillus terreus

Biotechnologically produced itaconic acid is an important building block for the chemical industry and still based on pure carbon sources, detoxified molasses or starch hydrolysates. Changing these first generation feedstocks to alternative renewable resources of a second generation implies new challenges for the cultivation process of the industrial itaconic acid producer Aspergillus terreus, which is known to be very sensitive towards impurities. To select a suitable pretreatment method of a second generation feedstock, the influences of different hydrolysate components, like monosaccharides and sugar degradation products, were tested. Particular the impact of those components on itaconic acid yield, productivity, titer and morphology was investigated in detail. Wheat chaff was used as lignocellulosic biomass, which is an agricultural residue. An alkaline pretreatment method with sodium hydroxide at room temperature and a subsequent enzymatic saccharification at pH 4.8 at 50 °C with 10 FPU/g_Biomass Biogazyme 2x proved to be very suitable for a subsequent biotechnological production of itaconic acid. A purification by a cation exchanger of the wheat chaff hydrolysate resulted in a final titer of 27.7 g/L itaconic acid with a yield of 0.41 g/g_{total sugar}.     

Removal of heavy metals by an Aspergillus terreus strain immobilized in a polyurethane matrix

AIMS: The aim was to investigate the biosorption of chromium, nickel and iron from metallurgical effluents, produced by a steel foundry, using a strain of Aspergillus terreus immobilized in polyurethane foam. METHODS AND RESULTS: A. terreus UFMG-F01 was immobilized in polyurethane foam and subjected to biosorption tests with metallurgical effluents. Maximal metal uptake values of 164.5 mg g(-1) iron, 96.5 mg g(-1) chromium and 19.6 mg g(-1) nickel were attained in a culture medium containing 100% of effluent stream supplemented with 1% of glucose, after 6 d of incubation. CONCLUSIONS: Microbial populations in metal-polluted environments include fungi that have adapted to otherwise toxic concentrations of heavy metals and have become metal resistant. In this work, a strain of A. terreus was successfully used as a metal biosorbent for the treatment of metallurgical effluents. SIGNIFICANCE AND IMPACT OF THE STUDY: A. terreus UFMG-F01 was shown to have good biosorption properties with respect to heavy metals. The low cost and simplicity of this technique make its use ideal for the treatment of effluents from steel foundries.     

Operating conditions optimization for (+)-terrein production in a stirred bioreactor by Aspergillus terreus strain PF-26 from marine sponge Phakellia fusca

Terrein is a fungal metabolite with application values in the fields of medicine, cosmetology, and agriculture. However, mass production of single configuration terrein is still a big challenge. In this study, operating factors such as inoculation, agitation speed, aeration rate, pH control, and nutrient feeding were preliminarily optimized to improve the (+)-terrein production in the 5-L stirred bioreactor from the marine sponge-derived fungus Aspergillus terreus PF-26. Spore inoculation, low agitation speed, and aeration rate were proved to be suitable for A. terreus PF-26 to produce (+)-terrein in the stirred bioreactor. At 50?rpm agitation speed and 0.33?vvm aeration rate, 2.68?g/L (+)-terrein was achieved by feeding twofold concentrated maltose and glucose medium on the sixth day and controlling pH at 4.5 from the fourth day. This study lays foundation for the mass production of (+)-terrein by the marine filamentous A. terreus strain PF-26 in the stirred bioreactor.     

Citric acid production from beet molasses by cell recycle ofAspergillus niger

Summary Production of citric acid from beet molasses at a varying pH profile using cell recycle ofAspergillus niger was investigated. Best results in terms of citric acid concentration, yield, productivity and specific citric acid productivity were obtained with a substrate pH of 3.0.