Search results for "Aspergillus niger"
showing 10 items of 41 documents
Synthesis of Isomaltooligosaccharides by Saccharomyces cerevisiae Cells Expressing Aspergillus niger α‑Glucosidase
2017
The α-glucosidase encoded by the aglA gene of Aspergillus niger is a secreted enzyme belonging to family 31 of glycoside hydrolases. This enzyme has a retaining mechanism of action and displays transglycosylating activity that makes it amenable to be used for the synthesis of isomaltooligosaccharides (IMOs). We have expressed the aglA gene in Saccharomyces cerevisiae under control of a galactose-inducible promoter. Recombinant yeast cells expressing the aglA gene produced extracellular α-glucosidase activity about half of which appeared cell bound whereas the other half was released into the culture medium. With maltose as the substrate, panose is the main transglycosylation product after 8…
Multiplex Detection of Aspergillus Species
2016
Multiplex real-time polymerase chain reaction (PCR) provides a fast and accurate DNA-based tool for the simultaneous amplification of more than one target sequence in a single reaction. Here a duplex real-time PCR assay is described for the simultaneous detection of Aspergillus carbonarius and members of the Aspergillus niger aggregate, which are the main responsible species for ochratoxin A (OTA) contamination in grapes. This single tube reaction targets the beta-ketosynthase and the acyl transferase domains of the polyketide synthase of A. carbonarius and the A. niger aggregate, respectively.Besides, a rapid and efficient fungi DNA extraction procedure is described suitable to be applied …
Biopreservation potential of lactic acid bacteria from Andean fermented food of vegetal origin
2017
Abstract Microbial fermentations have long represented a way of natural biopreservation of raw materials, which frequently originated new food products. Among them, traditionally fermented products still manufactured by native populations all around the world are source of lactic acid bacteria (LAB) strains with high biotechnological potential. LAB are food grade microorganisms and therefore a good alternative to chemicals to be applied in food preservation. A total of 130 LAB isolates recovered from “chicha” and “tocosh”, traditional fermented Andean products of vegetal origin, were screened for antimicrobial activities against spoiler fungi Meyerozyma guilliermondii CECT 1021 (synonym Pic…
Evaluation of the antioxidant/antimicrobial performance of Posidonia oceanica in comparison with three commercial natural extracts and as a treatment…
2017
Abstract This research aimed at extending the choice of natural antimicrobials/antioxidants for food applications. Four plant extracts, Posidonia oceanica (PO), Green Tea (GT), Grape seeds (GS) and Grape skin (GK), were analyzed to determine their total phenolic content, antioxidant activity and in vitro antimicrobial performance. PO extract showed the highest total phenolic content (711 mg gallic acid/g extract) and antifungal activity against Aspergillus niger and Penicillium chrysogenum . The highest antioxidant (3.81 mg/L EC 50 ) and antibacterial activities (bactericidal against Gram positives and bacteriostatic against Gram negatives) were found for GT extract. The best performing ext…
Analyzing chemical changes in verdigris pictorial specimens upon bacteria and fungi biodeterioration using voltammetry of microparticles
2017
[EN] It is reported the application of the voltammetry of microparticles (VMP), complemented with attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and field emission scanning electron microscopy (FESEM) techniques, to monitor the deterioration of verdigris pictorial specimens under the action of different biological agents. This methodology would be of application for identifying the type of biological agent causing deterioration of paintings, which is an important problem affecting cultural heritage. The analysis of biodeterioration processes is complicated by the fact that the action of microorganisms can affect both pigment and binding media. The deteriorat…
Solid-State Fermentations of the Genus Aspergillus
1994
For the majority of filamentous fungal species, solid-state media are the natural life media. Growth can occur on the surface or within the whole substrate, depending on the porosity. Industrial solid-state fermentations have been developed largely in traditional food industries such as cheese, Oriental fermentations, fermented vegetables, meat, and other products, and in modern biotechnological industries such as antibiotics and enzymes. At the industrial scale, the latter fermentations allow for a decrease in the drying costs of the final products.
Synthesis, structure, properties and antimicrobial activity of para trifluoromethyl phenylboronic derivatives
2021
The [2-formyl-4-(trifluoromethyl)phenyl]boronic acid as well as its benzoxaborole and bis(benzoxaborole) derivatives were obtained and their properties studied. The 2-formyl compound displays an unusual structure in the crystalline state, with a significant twist of the boronic group, whereas in DMSO solution it tautomerizes with formation of a cyclic isomer. All the studied compounds exhibit relatively high acidity as well as a reasonable antimicrobial activity. Docking studies showed interactions of all the investigated compounds with the binding pocket of Candida albicans LeuRS. High activity against Bacillus cereus was determined for the 2-formyl compound as well as for the novel bis(be…
Development of a rapid and highly sensitive biochemical method for the measurement of fungal spore viability. An alternative to the CFU method
2001
Abstract 1 A biochemical method, based on dehydrogenase activity (DHA) measurement, has been developed as an alternative to colony forming unit (CFU) enumeration, for assessing the viability of fungal spores. In viable cells, a tetrazolium salt (MTT) is reduced to a coloured formazan (MTTf) by cellular dehydrogenase enzymes. From the colorimetric assay developed by Mosmann for mammalian cells, the procedure has been adapted and optimised using P. digitatum spores as a model. Propan-2-ol has been selected as the best solvent to extract the MTTf from the spores. The sensitivity of the method has been considerably increased by determining the optimal conditions of incubation for the MTT reduct…
Synthesis and antimicrobial screening of tetra Schiff bases of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene
2014
Abstract In the present study, novel tetra Schiff bases were synthesized by condensation of 1,2,4,5-tetra (5-amino-1,3,4-thiadiazole-2-yl)benzene with different aromatic aldehydes. The chemical structures were confirmed by means of IR, 1 H NMR, 13 C NMR, and elemental analysis. All compounds were screened for antibacterial ( Staphylococcus aureus ATCC-9144, Staphylococcus epidermidis ATCC-155, Micrococcus luteus ATCC-4698, Bacillus cereus ATCC-11778, Escherichia coli ATCC-25922, and Pseudomonas aeruginosa ATCC-2853) and antifungal ( Aspergillus niger ATCC-9029 and Aspergillus fumigatus ATCC-46645) activities by paper disc diffusion technique. The minimum inhibitory concentrations (MICs) of …
Resistance of Conifer Needle Polyolefin Composites (CNPCs) Against Biodecomposition Caused by Fungi
2017
This study describes the resistance of composites filled with conifer needles to biodecomposition processes caused by a single strain of Aspergillus niger as well as by a consortium of microorganisms present in the compost substrates (forest or spent mushroom composts). The impact of various types of conifer needles on the growth of A. niger was studied to determine whether the filler can show the fungistatic effect. The changes in chemical composition of the composites surfaces were examined using attenuated total reflectance Fourier transform infrared spectroscopy (FTIR/ATR). The results showed that the fungistatic effects of conifer needles polyolefin composites (CNPCs) were associated w…