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Microorganisms Dec 2021Pathogenic fungi belonging to the genera , , , and are responsible for vines diseases that affect the growth, grapevine yield and organoleptic quality. Among...
Pathogenic fungi belonging to the genera , , , and are responsible for vines diseases that affect the growth, grapevine yield and organoleptic quality. Among innovative strategies for in-field plant disease control, one of the most promising is represented by biocontrol agents, including wild epiphytic yeast strains of grapevine berries. Twenty wild yeast, isolated and molecularly identified from three different Malaysian regions (Perlis, Perak and Pahang), were evaluated in a preliminary screening test on agar to select isolates with inhibition against On the basis of the results, nine yeasts belonging to genera , , , were selected and then tested against five grape berry pathogens: , , , and FE08.05 and GP8 and GM19 showed the highest effect on inhibiting mycelial growth, which ranged between 15.1 and 4.3 mm for the inhibition ring. The quantitative analysis of the volatile organic compound profiles highlighted the presence of isoamyl and phenylethyl alcohols and an overall higher presence of low-chain fatty acids and volatile ethyl esters. The results of this study suggest that antagonist yeasts, potentially effective for the biological control of pathogenic moulds, can be found among the epiphytic microbiota associated with grape berries.
PubMed: 34946182
DOI: 10.3390/microorganisms9122582 -
Studies in Mycology Jun 2014Aspergillus section Circumdati or the Aspergillus ochraceus group, includes species with rough walled stipes, biseriate conidial heads, yellow to ochre conidia and...
Aspergillus section Circumdati or the Aspergillus ochraceus group, includes species with rough walled stipes, biseriate conidial heads, yellow to ochre conidia and sclerotia that do not turn black. Several species are able to produce mycotoxins including ochratoxins, penicillic acids, and xanthomegnins. Some species also produce drug lead candidates such as the notoamides. A polyphasic approach was applied using morphological characters, extrolite data and partial calmodulin, β-tubulin and ITS sequences to examine the evolutionary relationships within this section. Based on this approach the section Circumdati is revised and 27 species are accepted, introducing seven new species: A. occultus, A. pallidofulvus, A. pulvericola, A. salwaensis, A. sesamicola, A. subramanianii and A. westlandensis. In addition we correctly apply the name A. fresenii (≡ A. sulphureus (nom. illeg.)). A guide for the identification of these 27 species is provided. These new species can be distinguished from others based on morphological characters, sequence data and extrolite profiles. The previously described A. onikii and A. petrakii were found to be conspecific with A. ochraceus, whilst A. flocculosus is tentatively synonymised with A. ochraceopetaliformis, despite extrolite differences between the two species. Based on the extrolite data, 13 species of section Circumdati produce large amounts of ochratoxin A: A. affinis, A. cretensis, A. fresenii, A. muricatus, A. occultus, A. ochraceopetaliformis (A. flocculosus), A. ochraceus, A. pseudoelegans, A. pulvericola, A. roseoglobulosus, A. sclerotiorum, A. steynii and A. westerdijkiae. Seven additional species produce ochratoxin A inconsistently and/or in trace amounts: A. melleus, A. ostianus, A. persii, A. salwaensis, A. sesamicola, A. subramanianii and A. westlandensis. The most important species regarding potential ochratoxin A contamination in agricultural products are A. ochraceus, A. steynii and A. westerdijkiae.
PubMed: 25492980
DOI: 10.1016/j.simyco.2014.07.001 -
Food Microbiology Dec 2011The present work was carried out to study the mycobiota of cocoa beans from farm to chocolate. Four hundred and ninety-four samples were analyzed at various stages of...
The present work was carried out to study the mycobiota of cocoa beans from farm to chocolate. Four hundred and ninety-four samples were analyzed at various stages of cocoa processing: (i) primary stage at the farm (fermentation, drying, and storage), (ii) secondary stage at processing (testa, nibs, liquor, butter, cake and powder) and (iii) the final chocolate product (dark, milk, white and powdered) collected from retail outlets. Direct plating or dilution plating on Dichloran 18% Glycerol agar were used for cocoa beans and processed product analyses, respectively. Fungi were isolated and identified using different keys of identification. The largest numbers and diversity of fungi were observed in the samples collected at the farm, especially during drying and storage. The species with the highest occurrence among samples were: Absidia corymbifera, Aspergillus sp. nov., A. flavus, Penicillium paneum and yeasts. A total of 1132 potentially toxigenic fungi were isolated from the following species or species groups: A. flavus, Aspergillus parasiticus, Aspergillus nomius, Aspergillus niger group, Aspergillus carbonarius and Aspergillus ochraceus group. The highest percentage of toxigenic fungi was found at the drying and storage stages. The industrial processing reduced the fungal contamination in all fractions and no fungi were found in the final chocolate products. The knowledge of which fungi are dominant at each processing stage of cocoa provides important data about their ecology. This understanding leads to a reduction in fungal spoilage and mycotoxin production in this product.
Topics: Cacao; Candy; Fermentation; Food Contamination; Food Handling; Fungi
PubMed: 21925035
DOI: 10.1016/j.fm.2011.08.005 -
Toxins Dec 2012The aim of this study was to select wine yeast strains as biocontrol agents against fungal contaminants responsible for the accumulation of ochratoxin A (OTA) in grape...
The aim of this study was to select wine yeast strains as biocontrol agents against fungal contaminants responsible for the accumulation of ochratoxin A (OTA) in grape and wine and to dissect the mechanism of OTA detoxification by a Saccharomyces cerevisiae strain (DISAABA1182), which had previously been reported to reduce OTA in a synthetic must. All of the yeast strains tested displayed an ability to inhibit the growth of Aspergillus carbonarius both in vivo and in vitro and addition of culture filtrates from the tested isolates led to complete inhibition of OTA production. S. cerevisiae DISAABA1182 was selected and further tested for its capacity to inhibit OTA production and pks (polyketide synthase) transcription in A. carbonarius and Aspergillus ochraceus in vitro. In order to dissect the mechanism of OTA detoxification, each of these two fungi was co-cultured with living yeast cells exposed to yeast crude or to autoclaved supernatant: S. cerevisiae DISAABA1182 was found to inhibit mycelial growth and OTA production in both Aspergilli when co-cultured in the OTA-inducing YES medium. Moreover, a decrease in pks transcription was observed in the presence of living cells of S. cerevisiae DISAABA1182 or its supernatant, while no effects were observed on transcription of either of the constitutively expressed calmodulin and β-tubulin genes. This suggests that transcriptional regulation of OTA biosynthetic genes takes place during the interaction between DISAABA1182 and OTA-producing Aspergilli.
Topics: Aspergillus; Biological Control Agents; Carcinogens; Kloeckera; Ochratoxins; Saccharomyces cerevisiae; Wine
PubMed: 23223175
DOI: 10.3390/toxins4121468 -
Journal of Microbiology and... Nov 2019biofilm, developed on an inert support, can produce tannase in Khanna medium containing 1.5% (w/v) tannic acid as the carbon source, at an initial pH of 5.0, for 72 h...
biofilm, developed on an inert support, can produce tannase in Khanna medium containing 1.5% (w/v) tannic acid as the carbon source, at an initial pH of 5.0, for 72 h at 28 °C. Addition of 0.1% yeast extract increased enzyme production. The enzyme in the crude filtrate exhibited the highest activity at 30 °C and pH 6.0. At 50 °C, the half-life was 60 min and 260 min at pH 6.0. In general, addition of detergents and surfactants did not affect tannase activity significantly. Tannase has potential applications in various biotechnological processes such as the production of propyl gallate and in the treatment of tannin-rich effluents. The content of tannins and total phenolic compounds in effluents from leather treatment was reduced by 56-83% and 47-64%, respectively, after 2 h of enzyme treatment. The content of tannins and total phenolic compounds in the sorghum flour treated for 120 h with tannase were reduced by 61% and 17%, respectively. Interestingly, the same biofilm was able to produce tannase for three sequential fermentative process. In conclusion, fungal biofilm is an interesting alternative to produce high levels of tannase with biotechnological potential to be applied in different industrial sectors.
Topics: Aspergillus ochraceus; Biofilms; Carboxylic Ester Hydrolases; Culture Media; Fermentation; Fungal Proteins; Hydrogen-Ion Concentration; Phenols; Propyl Gallate; Sorghum; Surface-Active Agents; Tannins; Temperature; Water Pollutants
PubMed: 31474100
DOI: 10.4014/jmb.1903.03060 -
Applied and Environmental Microbiology Feb 1996We studied the metabolic profile of ochratoxin A (OA) in rats and in a culture of OA-producing Aspergillus ochraceus. Ochratoxin alpha (O alpha), ochratoxin beta (O...
We studied the metabolic profile of ochratoxin A (OA) in rats and in a culture of OA-producing Aspergillus ochraceus. Ochratoxin alpha (O alpha), ochratoxin beta (O beta), 4-R-hydroxyochratoxin A (4-R-OH OA), 4-R-hydroxyochratoxin B (4-R-OH OB), and 10-hydroxyochratoxin A (10-OH OA) were isolated from a culture of A. ochraceus and structurally characterized by 1H nuclear magnetic resonance spectroscopy, mass spectrometry and high-pressure liquid chromatography. 4-R-OH OA and O alpha were consistently produced and were the dominant biotransformed metabolites in the fungal culture and in rats treated with OA and ochratoxin C (OC), while the formation of 10-OH OA was conditional in the fungal system. Green fluorescent biomacromolecules were isolated by detergent extraction of the fungal culture followed by cold-acetone precipitation and gel filtration. Acid hydrolysis of the fluorescent macromolecules resulted in the release of several ochratoxins, including O alpha (80%), OA (2%), and OC (5%), and other unidentified fluorescent compounds but not OB and O beta. Cross-reactivity studies of the natural macromolecule conjugates of OA with anti-OA polyclonal antibodies indicated that they were covalently linked to the macromolecules via a group other than the carboxyl group. These studies demonstrated that a fungus can produce some of the same metabolites of OA as the rat and that O alpha, OA, and OC may be covalently linked to fungal macromolecules.
Topics: Animals; Aspergillus ochraceus; Chromatography, High Pressure Liquid; Macromolecular Substances; Magnetic Resonance Spectroscopy; Mass Spectrometry; Molecular Structure; Ochratoxins; Rats; Rats, Sprague-Dawley
PubMed: 8593066
DOI: 10.1128/aem.62.2.648-655.1996 -
Metabolites Mar 2023Quorum sensing (QS) is a cellular strategy of communication between intra- and inter-specific microorganisms, characterized by the release of quorum sensing molecules...
Quorum sensing (QS) is a cellular strategy of communication between intra- and inter-specific microorganisms, characterized by the release of quorum sensing molecules (QSMs) that achieve coordination to adaptation to the environment. In , lipids carry population density-mediated stresses, and their oxidative metabolite oxylipins act as signaling to transmit information inside cells to regulate fungal development in a synchronized way. In this study, we investigated the regulation of density-dependent lipid metabolism in the toxigenic fungi by the oxidative lipid metabolomics in conjunction with transcriptomics. In addition to proven hydroxyoctadecadienoic acids (HODEs), prostaglandins (PGs) also appear to have the properties of QSM. As a class of signaling molecule, oxylipins regulate the fungal morphology, secondary metabolism, and host infection through the G protein signaling pathway. The results of combined omics lay a foundation for further verification of oxylipin function, which is expected to elucidate the complex adaptability mechanism in and realize fungal utilization and damage control.
PubMed: 37110150
DOI: 10.3390/metabo13040491 -
Mycology 2019Medicines developed from natural sources are a frequent target for the research and discovery of antimicrobial compounds. Discovering of penicillin in 1928 was a motive... (Review)
Review
Medicines developed from natural sources are a frequent target for the research and discovery of antimicrobial compounds. Discovering of penicillin in 1928 was a motive to explore of nature as a source of new antimicrobial agents. Fungi produce a diverse range of bioactive metabolites, making them rich source of different types of medicines. The purpose of this paper was to review studies on antibacterials from terrestrial published exclusively during 1942-2018, with emphasis on their antibacterial activities, structures, and mechanisms of action if present. According to the results from different studies in the world, large number of compounds and extracts showed different activities against different bacterial species, including Gram-positive and Gram-negative bacteria. The most prominent result was that of the compound CJ-17,665, isolated from , showing good activity against multi-drug resistant , which is well-recognised to be one of the most important current public health problem. These findings may motivate scientists to undertake a project that may result in the development of novel antibacterial drugs from terrestrial-derived spp., although further toxicity assays () must be performed before their application.
PubMed: 31632829
DOI: 10.1080/21501203.2019.1604576 -
Applied and Environmental Microbiology Mar 1976Spores from the toxigenic organism Aspergillus ochraceus NRRL-3174 were exposed to specific levels of gamma irradiation and then allowed to germinate on selected media.... (Comparative Study)
Comparative Study
Spores from the toxigenic organism Aspergillus ochraceus NRRL-3174 were exposed to specific levels of gamma irradiation and then allowed to germinate on selected media. Increases in ochratoxin A production by irradiated, compared to non-irradiated, spores were observed after inoculation of spores onto a cracked red wheat or into a synthetic liquid medium. Variations in daily ochratoxin production were also observed for control and irradiated spore-derived cultures developing on both media, with maximum toxin production varying from 7 to 11 days of incubation. The most notable increases in ochratoxin A production occurred from cultures developing from spores having been irradiated with 10, 25, or 50 krad. Exposures to 400 or 600 krad resulted in complete inhibition of spore germination and, consequently, no ochratoxin production. Of the two substrates used, wheat and synthetic, the quantities of ochratoxin A produced were significantly lower in the synthetic media than on the natural substrate. Higher and more rapid toxin production occurred from spores having been irradiated with 10, 25, 50, and 100 krad than occurred from the non-irradiated control spores when grown on synthetic media. Cultures derived from spores having been exposed to 10, 25, 50, and 100 krad produced significantly higher levels of ochratoxin A after 8 days of incubation on natural substrate than did the controls. Analysis of variance revealed that substrate, length of incubation, as well as irradiation levels all affected the time required to produce maximum levels of ochratoxin A.
Topics: Aspergillus; Cobalt Radioisotopes; Culture Media; Dose-Response Relationship, Radiation; Ochratoxins; Radiation Effects; Spores, Fungal; Triticum
PubMed: 938031
DOI: 10.1128/aem.31.3.349-353.1976 -
Scientific Reports Dec 2022The aim of the study was to investigate the biological activity and chemical composition of Satureja kitaibelii Wierzb. ex Heuff. LC-PDA/MS analyses for the aqueous...
The aim of the study was to investigate the biological activity and chemical composition of Satureja kitaibelii Wierzb. ex Heuff. LC-PDA/MS analyses for the aqueous extracts (A1-stem, leaves and flowers, A2-leaves and flowers) and ethyl-acetate extracts (E1-stem, leaves and flowers, E2-leaves and flowers) obtained by ultrasound-assisted extraction enabled the identification of thirty-four compounds. Quantitative analysis revealed that the aqueous extract obtained from leaves and flowers was the richest in total phenolic acids (65.36 mg/g) and flavonoids (21.17 mg/g). The total polyphenol content was the highest in the aqueous extract obtained from leaves and flowers (274 ± 2.4 mg Gallic Acid equivalents/g). The best antioxidant activity was observed for the same extract using the DPPH (SC50 20 ± 10 µg/mL), ABTS (2.834 ± 0.02 mg Ascorbic Acid/g), FRAP (1.922 ± 0.03 mmol Fe/mg), and total reducing power tests (16.4 ± 1.0 mg Ascorbic Acid/g). Both ethyl acetate extracts were the most active against strains of Bacillus cereus and Micrococcus flavus (MIC 1.70-1.99 mg/mL and 1.99-3.41 mg/mL, respectively). They were more efficient against Aspergillus ochraceus (MFC 0.86 mg/mL) and towards HeLa cell lines. All the obtained results implied the good potential of the investigated extracts to be used as effective preservatives and functional ingredients in food products and dietary supplements.
Topics: Humans; Satureja; HeLa Cells; Acetates; Ascorbic Acid
PubMed: 36481842
DOI: 10.1038/s41598-022-25668-3