Showing papers on "Aspergillus niger published in 2013"

Aspergillus luchuensis, an industrially important black aspergillus in east asia

Abstract: Aspergilli known as black- and white-koji molds which are used for awamori, shochu, makgeolli and other food and beverage fermentations, are reported in the literature as A. luchuensis, A. awamori, A. kawachii, or A. acidus. In order to elucidate the taxonomic position of these species, available ex-type cultures were compared based on morphology and molecular characters. A. luchuensis, A. kawachii and A. acidus showed the same banding patterns in RAPD, and the three species had the same rDNA-ITS, b-tubulin and calmodulin sequences and these differed from those of the closely related A. niger and A. tubingensis. Morphologically, the three species are not significantly different from each other or from A. niger and A. tubingensis. It is concluded that A. luchuensis, A. kawachii and A. acidus are the same species, and A. luchuensis is selected as the correct name based on priority. Strains of A. awamori which are stored in National Research Institute of Brewing in Japan, represent A. niger (n=14) and A. luchuensis (n=6). The neotype of A. awamori (CBS 557.65= NRRL 4948) does not originate from awamori fermentation and it is shown to be identical with the unknown taxon Aspergillus welwitschiae. Extrolite analysis of strains of A. luchuensis showed that they do not produce mycotoxins and therefore can be considered safe for food and beverage fermentations. A. luchuensis is also frequently isolated from meju and nuruk in Korea and Puerh tea in China and the species is probably common in the fermentation environment of East Asia. A re-description of A. luchuensis is provided because the incomplete data in the original literature.

Biochemistry of microbial itaconic acid production

Abstract: Itaconic acid is an unsatured dicarbonic acid which has a high potential as a biochemical building block, because it can be used as a monomer for the production of a plethora of products including resins, plastics, paints and synthetic fibers. Some Aspergillus species, like A. itaconicus and A. terreus, show the ability to synthesize this organic acid and A. terreus can secrete significant amounts to the media (> 80 g/L). However, compared with the citric acid production process (titers > 200 g/L) the achieved titers are still low and the overall process is expensive because purified substrates are required for optimal productivity. Itaconate is formed by the enzymatic activity of a cis-aconitate decarboxylase (CadA) encoded by the cadA gene in A. terreus. Cloning of the cadA gene into the citric acid producing fungus A. niger showed that it is possible to produce itaconic acid also in a different host organism. This review will describe the current status and recent advances in the understanding of the molecular processes leading to the biotechnological production of itaconic acid.

Antifungal activity of volatile organic compounds from Streptomyces alboflavus TD-1.

Abstract: Streptomyces sp. TD-1 was identified as Streptomyces alboflavus based on its morphological characteristics, physiological properties, and 16S rDNA gene sequence analysis. The antifungal activity of the volatile-producing S. alboflavus TD-1 was investigated. Results showed that volatiles generated by S. alboflavus TD-1 inhibited storage fungi Fusarium moniliforme Sheldon, Aspergillus flavus, Aspergillus ochraceus, Aspergillus niger, and Penicillum citrinum in vitro. GC/MS analysis revealed that 27 kinds of volatile organic compounds were identified from the volatiles of S. alboflavus TD-1 mycelia, among which the most abundant compound was 2-methylisoborneol. Dimethyl disulfide was proved to have antifungal activity against F. moniliforme by fumigation in vitro.

The capability of endophytic fungi for production of hemicellulases and related enzymes

Abstract: There is an imperative necessity for alternative sources of energy able to reduce the world dependence of fossil oil One of the most successful options is ethanol obtained mainly from sugarcane and corn fermentation The foremost residue from sugarcane industry is the bagasse, a rich lignocellulosic raw material uses for the production of ethanol second generation (2G) New cellulolytic and hemicellulytic enzymes are needed, in order to optimize the degradation of bagasse and production of ethanol 2G The ability to produce hemicellulases and related enzymes, suitable for lignocellulosic biomass deconstruction, was explored using 110 endophytic fungi and 9 fungi isolated from spoiled books in Brazil Two initial selections were performed, one employing the esculin gel diffusion assay, and the other by culturing on agar plate media with beechwood xylan and liquor from the hydrothermal pretreatment of sugar cane bagasse A total of 56 isolates were then grown at 29°C on steam-exploded delignified sugar cane bagasse (DEB) plus soybean bran (SB) (3:1), with measurement of the xylanase, pectinase, β-glucosidase, CMCase, and FPase activities Twelve strains were selected, and their enzyme extracts were assessed using different substrates Finally, the best six strains were grown under xylan and pectin, and several glycohydrolases activities were also assessed These strains were identified morphologically and by sequencing the internal transcribed spacer (ITS) regions and the partial β-tubulin gene (BT2) The best six strains were identified as Aspergillus niger DR02, Trichoderma atroviride DR17 and DR19, Alternaria sp DR45, Annulohypoxylon stigyum DR47 and Talaromyces wortmannii DR49 These strains produced glycohydrolases with different profiles, and production was highly influenced by the carbon sources in the media The selected endophytic fungi Aspergillus niger DR02, Trichoderma atroviride DR17 and DR19, Alternaria sp DR45, Annulohypoxylon stigyum DR47 and Talaromyces wortmannii DR49 are excellent producers of hydrolytic enzymes to be used as part of blends to decompose sugarcane biomass at industrial level

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

Abstract: 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 .S imilarly toA. 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.

A comparative study of hydrolysis and transglycosylation activities of fungal β-glucosidases

Abstract: β-glucosidases (BGs) from Aspergillus fumigatus, Aspergillus niger, Aspergillus oryzae, Magnaporthe grisea, Neurospora crassa, and Penicillium brasilianum were purified to homogeneity, and investigated for their (simultaneous) hydrolytic and transglycosylation activity in samples with high concentrations of either cellobiose or glucose. The rate of the hydrolytic process (which converts one cellobiose to two glucose molecules) shows a maximum around 10–15 mM cellobiose and decreases with further increase in the concentration of substrate. At the highest investigated concentration (100 mM cellobiose), the hydrolytic activity for the different enzymes ranged from 10% to 55% of the maximum value. This decline in hydrolysis was essentially compensated by increased transglycosylation (which converts two cellobiose to one glucose and one trisaccharide). Hence, it was concluded that the hydrolytic slowdown at high substrate concentrations solely relies on an increased flow through the transglycosylation pathway and not an inhibition that delays the catalytic cycle. Transglycosylation was also detected at high product (glucose) concentrations, but in this case, it was not a major cause for the slowdown in hydrolysis. The experimental data was modeled to obtain kinetic parameters for both hydrolysis and transglycosylation. These parameters were subsequently used in calculations that quantified the negative effects on BG activity of respectively transglycosylation and product inhibition. The kinetic parameters and the mathematical method presented here allow estimation of these effects, and we suggest that this may be useful for the evaluation of BGs for industrial use.

Use of pectinases produced by a new strain of Aspergillus niger for the enzymatic treatment of apple and blueberry juice

Abstract: In this work, pectinases-producing filamentous fungi were isolated with the aim of using their enzymes in the clarification of apple and blueberry juices. The experimental extract enzyme EE obtained in solid-state process with a strain identified as belonging to the species Aspergillus niger and designated LB23 was used for treating juices and compared with two commercial enzyme preparations: Pectinex ® Clear (PC) for apple juice, and Pectinex ® BE Color (PB) for blueberry juice. After the enzymatic treatment, the treated juices were evaluated with respect to parameters such as viscosity, turbidity, and degree of clarification, as well as antioxidant capacity, and total phenolic compound content. Considering all comparison criteria, the experimental preparation EE showed results statistically similar or superior to those obtained with the commercial enzyme preparations.

Six novel constitutive promoters for metabolic engineering of Aspergillus niger

Abstract: Genetic tools for the fine-tuning of gene expression levels are a prerequisite for rational strain optimization through metabolic engineering. While Aspergillus niger is an industrially important fungus, widely used for production of organic acids and heterologous proteins, the available genetic tool box for this organism is still rather limited. Here, we characterize six novel constitutive promoters of A. niger providing different expression levels. The selection of the promoters was based on published transcription data of A. niger. The promoter strength was determined with the β-glucuronidase (gusA) reporter gene of Escherichia coli. The six promoters covered a GUS activity range of two to three orders of magnitude depending on the strain background. In order to demonstrate the power of the newly characterized promoters for metabolic engineering, they were used for heterologous expression of the cis-aconitate decarboxylase (cad1) gene of Aspergillus terreus, allowing the production of the building block chemical itaconic acid with A. niger. The CAD activity, dependent on the choice of promoter, showed a positive correlation with the specific productivity of itaconic acid. Product titers from the detection limit to up to 570 mg/L proved that the set of constitutive promoters is a powerful tool for the fine-tuning of metabolic pathways for the improvement of industrial production processes.

In Vitro Activity of a New Oral Glucan Synthase Inhibitor (MK-3118) Tested Against Aspergillus spp. by CLSI and EUCAST Broth Microdilution Methods

Abstract: MK-3118, a glucan synthase inhibitor derived from enfumafungin, and comparator agents were tested against 71 Aspergillus spp., including itraconazole-resistant strains (MIC, ≥4 μg/ml), using CLSI and EUCAST reference broth microdilution methods. The CLSI 90% minimum effective concentration (MEC 90 )/MIC 90 values (μg/ml) for MK-3118, amphotericin B, and caspofungin, respectively, were as follows: 0.12, 2, and 0.03 for Aspergillus flavus species complex (SC); 0.25, 2, and 0.06 for Aspergillus fumigatus SC; 0.12, 2, and 0.06 for Aspergillus terreus SC; and 0.06, 1, and 0.03 for Aspergillus niger SC. Essential agreement between the values found by CLSI and EUCAST (±2 log 2 dilution steps) was 94.3%. MK-3118 was determined to be a potent agent regardless of the in vitro method applied, with excellent activity against contemporary wild-type and itraconazole-resistant strains of Aspergillus spp.

Reduced by-product formation and modified oxygen availability improve itaconic acid production in Aspergillus niger

Abstract: Aspergillus niger has an extraordinary potential to produce organic acids as proven by its application in industrial citric acid production. Previously, it was shown that expression of the cis-aconitate decarboxylase gene (cadA) from Aspergillus terreus converted A. niger into an itaconic acid producer (Li et al., Fungal Genet Bio 48: 602-611, 2011). After some initial steps in production optimization in the previous research (Li et al., BMC biotechnol 12: 57, 2012), this research aims at modifying host strains and fermentation conditions to further improve itaconic acid production. Expression of two previously identified A. terreus genes encoding putative organic acid transporters (mttA, mfsA) increased itaconic acid production in an A. niger cis-aconitate decarboxylase expressing strain. Surprisingly, the production did not increase further when both transporters were expressed together. Meanwhile, oxalic acid was accumulated as a by-product in the culture of mfsA transformants. In order to further increase itaconic acid production and eliminate by-product formation, the non-acidifying strain D15#26 and the oxaloacetate acetylhydrolase (oahA) deletion strain AB 1.13 ΔoahA #76 have been analyzed for itaconic acid production. Whereas cadA expression in AB 1.13 ΔoahA #76 resulted in higher itaconic acid production than strain CAD 10.1, this was not the case in strain D15#26. As expected, oxalic acid production was eliminated in both strains. In a further attempt to increase itaconic acid levels, an improved basal citric acid-producing strain, N201, was used for cadA expression. A selected transformant (N201CAD) produced more itaconic acid than strain CAD 10.1, derived from A. niger strain AB1.13. Subsequently, we have focused on the influence of dissolved oxygen (D.O.) on itaconic acid production. Interestingly, reduced D.O. levels (10-25 %) increased itaconic acid production using strain N201 CAD. Similar results were obtained in strain AB 1.13 CAD + HBD2.5 (HBD 2.5) which overexpressed a fungal hemoglobin domain. Our results showed that overexpression of the hemoglobin domain increased itaconic acid production in A. niger at lower D.O. levels. Evidently, the lower levels of D.O. have a positive influence on itaconic acid production in A. niger strains.Chemicals/CAS: itaconic acid, 97-65-4; oxygen, 7782-44-7; Oxygen, 7782-44-7; Succinates; itaconic acid, 97-65-4

Multicomponent synthesis of dihydropyrano[2,3-c]pyrazoles catalyzed by lipase from Aspergillus niger

Abstract: Lipase from Aspergillus niger (ANL) was found to be an extremely effective catalyst for four-component synthesis of dihydropyrano[2,3- c ]pyrazoles from a stoichiometric mixture of ethyl acetoacetate, hydrazine hydrate, aldehyde/ketone, and malononitrile in ethanol. The lipase ANL showed a broad range of enzymatic promiscuity toward various aromatic and aliphatic aldehydes as well as ketones. Use of environmentally benign biocatalyst, reusability of the catalyst, room temperature reaction conditions, no hazardous solvent, and excellent yields are some of the important features of this protocol.

Isolation and characterization of a proteinaceous antifungal compound from Lactobacillus plantarum YML007 and its application as a food preservative

Abstract: UNLABELLED Korean kimchi is known for its myriad of lactic acid bacteria (LAB) with diverse bioactive compounds. This study was undertaken to isolate an efficient antifungal LAB strain among the isolated kimchi LABs. One thousand and four hundred LABs isolated from different kimchi samples were initially screened against Aspergillus niger. The strain exhibiting the highest antifungal activity was identified as Lactobacillus plantarum YML007 by 16S rRNA sequencing and biochemical assays using API 50 CHL kit. Lact. plantarum YML007 was further screened against Aspergillus oryzae, Aspergillus flavus, Fusarium oxysporum and other pathogenic bacteria. The morphological changes during the inhibition were assessed by scanning electron microscopy. Preliminary studies on the antifungal compound demonstrated its proteinaceous nature with a molecular weight of 1256·617 Da, analysed by matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF). The biopreservative activity of Lact. plantarum YML007 was evaluated using dried soybeans. Spores of A. niger were observed in the negative control after 15 days of incubation. However, fungal growth was not observed in the soybeans treated with fivefold concentrated cell-free supernatant of Lact. plantarum YML007. The broad activity of Lact. plantarum YML007 against various food spoilage moulds and bacteria suggests its scope as a food preservative. SIGNIFICANCE AND IMPACT OF THE STUDY After screening 1400 kimchi bacterial isolates, strain Lactobacillus plantarum YML007 was selected with strong antifungal activity against various foodborne pathogens. From the preliminary studies, it was found that the bioactive compound is a low molecular weight novel protein of 1256·617 Da. Biopreservative potential of Lact. plantarum YML007 was demonstrated on soybean grains, and the results point out YML007 as a potent biopreservative having broad antimicrobial activity against various foodborne pathogens.

Screening of biocatalysts for transformation of sucrose to fructooligosaccharides

Abstract: Twenty microorganisms comprising of sixteen molds, two yeasts and two bacteria were evaluated for their ability to produce fructosyltransferase (FTase) and generate fructooligosaccharides (FOS) from sucrose. FTase production by these microorganisms was studied over a period of 120 h on medium containing 20% (w/v) sucrose as the sole carbon source. High FTase levels (35–31 U/ml) were observed in culture filtrates of Aspergillus flavus , Aspergillus niger , Aspergillus terreus and Penicillium islandicum . Higher concentrations of FOS were generated from 50% (w/v) sucrose using culture filtrates of A. flavus NFCCI 2364 (63.40%, w/w), A. niger SI 19 (54.94%, w/w), A. flavus NFCCI 2785 (44.61%, w/w), P. islandicum MTCC 4926 (43.56%, w/w), A. terreus NFCCI 2347 (24.17%, w/w) and Fusarium solani NFCCI 2315 (15.25%, w/w). Kestose, nystose and 1-fructofuranosyl nystose were the predominant oligosaccharides as revealed by HPLC analysis.

Immobilization of inulinase from Aspergillus niger NCIM 945 on chitosan and its application in continuous inulin hydrolysis

Abstract: Crude inulinase from Aspergillus niger (A. niger) NCIM 945 was immobilized on chitosan beads using a two-step covalent immobilization approach. Immobilization conditions were optimized to achieve 86% immobilization efficiency with 83 inulinase activity units/g of wet support. At lower pH values (pH 2.5 and 3) the relative activity of the immobilized enzyme was higher than the free enzyme. Also, thermal stability increased considerably at 50 and 60 °C after immobilization on chitosan beads. The Km values of free and immobilized inulinase were 0.25 and 0.21 mM, respectively and Vmax values were close to 0.2 μM/min/mL. In a continuous packed bed column 5% w/v inulin was completely hydrolyzed at optimized conditions of flow rate (0.1 mL/min) and incubation temperature (60 °C). This resulted in volumetric productivity of 68 g/L/h. This simple and efficient covalent immobilization approach has a potential for continuous inulin hydrolysis.

Fungal rock phosphate solubilization using sugarcane bagasse

Abstract: The effects of different doses of rock phosphate (RP), sucrose, and (NH4)2SO4 on the solubilization of RP from Araxa and Catalao (Brazil) by Aspergillus niger, Penicillium canescens, Eupenicillium ludwigii, and Penicillium islandicum were evaluated in a solid-state fermentation (SSF) system with sugarcane bagasse. The factors evaluated were combined following a 23 + 1 factorial design to determine their optimum concentrations. The fitted response surfaces showed that higher doses of RP promoted higher phosphorus (P) solubilization. The addition of sucrose did not have effects on P solubilization in most treatments due to the presence of soluble sugars in the bagasse. Except for A. niger, all the fungi required high (NH4)2SO4 doses to achieve the highest level of P solubilization. Inversely, addition of (NH4)2SO4 was inhibitory to P solubilization by A. niger. Among the fungi tested, A. niger stood out, showing the highest solubilization capacity and for not requiring sucrose or (NH4)2SO4 supplementation. An additional experiment with A. niger showed that the content of soluble P can be increased by adding higher RP doses in the medium. However, P yield decreases with increasing RP doses. In this experiment, the maximal P yield (approximately 60 %) was achieved with the lower RP dose (3 g L−1). Our results show that SSF can be used to obtain a low cost biofertilizer rich in P combining RP, sugarcane bagasse, and A. niger. Moreover, sugarcane bagasse is a suitable substrate for SSF aiming at RP solubilization, since this residue can supply the C and N necessary for the metabolism of A. niger within a range that favors RP solubilization.