Search results for "aspergillus"
showing 10 items of 221 documents
Cytotoxic secondary metabolites from the endophytic fungus Aspergillus versicolor KU258497
2018
Abstract Two new isocoumarin dimers (1 and 2) and one new dihydroquinolone derivative (3) were isolated from Aspergillus versicolor, an endophyte derived from leaves of the Egyptian water hyacinth Eichhornia crassipes (Pontederiaceae), together with ten other known metabolites. Chemical structures of the isolated metabolites were determined based on HRESIMS, extensive 1D and 2D NMR spectroscopy. The relative and absolute configurations of the new natural products were established by ROESY and electronic circular dichroism (ECD) spectroscopy, respectively. The axial chirality of the isocoumarin 7,7′-homodimers (1 and 2) was deduced by TDDFT-ECD calculations. All isolated compounds were asses…
Transcription of genes in the biosynthetic pathway for fumonisin mycotoxins is epigenetically and differentially regulated in the fungal maize pathog…
2012
ABSTRACT When the fungal pathogen Gibberella moniliformis (anamorph, Fusarium verticillioides ) colonizes maize and maize-based products, it produces class B fumonisin (FB) mycotoxins, which are a significant threat to human and animal health. FB biosynthetic enzymes and accessory proteins are encoded by a set of clustered and cotranscribed genes collectively named FUM, whose molecular regulation is beginning to be unraveled by researchers. FB accumulation correlates with the amount of transcripts from the key FUM genes, FUM1 , FUM21 , and FUM8 . In fungi in general, gene expression is often partially controlled at the chromatin level in secondary metabolism; when this is the case, the deac…
Transformation of Aspergillus parasiticus using autonomously replicating plasmids from Aspergillus nidulans.
1994
A genetic transformation system for the aflatoxin-producing fungus Aspergillus parasiticus using two autonomously replicating plasmids from A. nidulans (ARp1 and pDHG25) is reported. Transformation frequencies using the plasmid pDHG25 were from 5 x 10(2) to 2.5 x 10(4) transformants per 10(6) viable protoplasts and microgram DNA. The stability of the plasmids in the transformants was also studied. This transformation system offers a new opportunity to clone genes related to aflatoxin production using appropriate aflatoxin-defective mutants.
Identification of the mstE Gene Encoding a Glucose-inducible, Low Affinity Glucose Transporter in Aspergillus nidulans
2006
The mstE gene encoding a low affinity glucose transporter active during the germination of Aspergillus nidulans conidia on glucose medium has been identified. mstE expression also occurs in hyphae, is induced in the presence of other repressing carbon sources besides glucose, and is dependent on the function of the transcriptional repressor CreA. The expression of MstE and its subcellular distribution have been studied using a MstE-sGFP fusion protein. Concordant with data on mstE expression, MstE-sGFP is synthesized in the presence of repressing carbon sources, and fluorescence at the periphery of conidia and hyphae is consistent with MstE location in the plasma membrane. Deletion of mstE …
Comparison and improvement of the existing methods for the determination of aflatoxins in human serum by LC-MS/MS
2010
Aflatoxins are toxic metabolites of some Aspergillus flavus, A. parasiticus and A. nomius strains that occur in many foods and feeds. Aflatoxin B1 is the most abundant and toxic member of the family, and it is also the most potent hepatocarcinogen known. In order to estimate the potential human health risk of aflatoxin B1, it is useful to measure its blood concentration. In this work a rapid liquid chromatography coupled to mass spectrometry (LC-MS/MS) method for the simultaneous determination of aflatoxins B1, B2, G1 and G2 and its metabolites, aflatoxins M1 and M2 in human serum, is proposed. Small serum volumes have been used and the extracts have been obtained without any clean-up proce…
Determination of ochratoxin A in maize bread samples by LC with fluorescence detection.
2007
Ochratoxin A (OTA) is a secondary fungal metabolite produced by several moulds, mainly by Aspergillus ochraceus, A. carbonarius, A. niger and by Penicillium verrucosum. The present work shows the results of comparative studies using different procedures for the analysis of OTA in maize bread samples. The studied analytical methods involved extraction with different volumes of PBS/methanol, different extraction apparatus, and clean-up through immunoaffinity columns. The separation and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method for analysis of OTA in maize bread involved extraction with PBS:methanol (50:50), and …
Emergence of Aspergillus fumigatus azole resistance in azole-naïve patients with chronic obstructive pulmonary disease and their homes.
2017
Azole-resistant Aspergillus fumigatus (ARAF) has been reported in patients with chronic obstructive pulmonary disease (COPD) but has not been specifically assessed so far. Here, we evaluated ARAF prevalence in azole-naïve COPD patients and their homes, and assessed whether CYP51A mutations were similar in clinical and environmental reservoirs. Sixty respiratory samples from 41 COPD patients with acute exacerbation and environmental samples from 36 of these patient's homes were prospectively collected. A. fumigatus was detected in respiratory samples from 11 of 41 patients (27%) and in 15 of 36 domiciles (42%). Cyp51A sequencing and selection on itraconazole medium of clinical (n = 68) and e…
The overproduction of 2,4-DTBP accompanying to the lack of available form of phosphorus during the biodegradative utilization of aminophosphonates by…
2014
Although information about the ability of some filamentous fungi to biodegrade organophosphonates is available, the knowledge about accompanying changes in fungal metabolism is very limited. The aim of our study was to determine the utilization of the chosen, structurally diverse aminophosphonates by Aspergillus terreus (Thom), in the context of the behaviour of this fungus while growing in unfavourable conditions, namely the lack of easily available phosphates. We found that all the studied compounds were utilized by fungus as nutritive sources of phosphorus, however, their effect on the production of fungal biomass depended on their structure. We also observed an interesting change in the…
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…
Comparative analysis and antimicrobial action of some essential oils from plants
2021
In this research, essential oils (EOs) were extracted through steaming from aerial parts of three plants: basil (Ocinum basilicum L.), peppermint (Mentha piperita L.) and oregano (Origanum vulgare L.) form Sibiu County, Romania. The GC-MS analysis indicated that eugenol and apiol were the major compounds in the basil EO. Timol, ɣ-terpinene, and p-cymene were the major compounds in the volatile oil extracted from oregano and menthol and methone the main components in the peppermint EO. In the first 48 h of analysis, basil EO inhibition action was the highest against Salmonella anatum (48%), followed by Aspergillus niger (26%), Bacillus cereus (21%) and Saccharomyces cerevisiae (15%); this ac…