scholarly journals Minimizing Ochratoxin A Contamination through the Use of Actinobacteria and Their Active Molecules

Toxins ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 296
Author(s):  
Ixchel Campos-Avelar ◽  
Alexandre Colas de la Noue ◽  
Noel Durand ◽  
Blandine Fay ◽  
Véronique Martinez ◽  
...  
Keyword(s):  
Ochratoxin A ◽  
Fungal Pathogens ◽  
Fungal Growth ◽  
Dual Culture ◽  
Specific Production ◽  
Penicillium Verrucosum ◽  
Subsequent Degradation ◽  
Food Commodities ◽  
Detoxification Mechanisms

Ochratoxin A (OTA) is a secondary metabolite produced by fungal pathogens such as Penicillium verrucosum, which develops in food commodities during storage such as cereals, grapes, and coffee. It represents public health concerns due to its genotoxicity, carcinogenicity, and teratogenicity. The objective of this study was to evaluate the ability of actinobacteria and their metabolites to degrade OTA and/or to decrease its production. Sixty strains of actinobacteria were tested for their ability to prevent OTA formation by in vitro dual culture assays or with cell free extracts (CFEs). In dual culture, 17 strains strongly inhibited fungal growth, although it was generally associated with an increase in OTA specific production. Seventeen strains inhibited OTA specific production up to 4% of the control. Eleven actinobacteria CFEs reduced OTA specific production up to 62% of the control, while no substantial growth inhibition was observed except for two strains up to 72% of the control. Thirty-three strains were able to degrade OTA almost completely in liquid medium whereas only five were able to decrease it on solid medium, and two of them reduced OTA to an undetectable amount. Our results suggest that OTA decrease could be related to different strategies of degradation/metabolization by actinobacteria, through enzyme activities and secretion of secondary metabolites interfering with the OTA biosynthetic pathway. CFEs appeared to be ineffective at degrading OTA, raising interesting questions about the detoxification mechanisms. Common degradation by-products (e.g., OTα or L-β-phenylalanine) were searched by HPLC-MS/MS, however, none of them were found, which implies a different mechanism of detoxification and/or a subsequent degradation into unknown products.

scholarly journals Aspergillus flavus Growth Inhibition and Aflatoxin B1 Decontamination by Streptomyces Isolates and Their Metabolites

Toxins ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 340
Author(s):  
Ixchel Campos-Avelar ◽  
Alexandre Colas de la Noue ◽  
Noël Durand ◽  
Guillaume Cazals ◽  
Véronique Martinez ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Fungal Growth ◽  
Dual Culture ◽  
Bacterial Cells ◽  
Specific Production ◽  
Penicillium Verrucosum ◽  
Streptomyces Spp ◽  
Residual Toxicity ◽  
Promising Source

Aflatoxin B1 is a potent carcinogen produced by Aspergillus flavus, mainly during grain storage. As pre-harvest methods are insufficient to avoid mycotoxin presence during storage, diverse curative techniques are being investigated for the inhibition of fungal growth and aflatoxin detoxification. Streptomyces spp. represent an alternative as they are a promising source of detoxifying enzymes. Fifty-nine Streptomyces isolates and a Streptomyces griseoviridis strain from the commercial product Mycostop®, evaluated against Penicillium verrucosum and ochratoxin A during previous work, were screened for their ability to inhibit Aspergillus flavus growth and decrease the aflatoxin amount. The activities of bacterial cells and cell-free extracts (CFEs) from liquid cultures were also evaluated. Fifty-eight isolates were able to inhibit fungal growth during dual culture assays, with a maximal reduction going down to 13% of the control. Aflatoxin-specific production was decreased by all isolates to at least 54% of the control. CFEs were less effective in decreasing fungal growth (down to 40% and 55% for unheated and heated CFEs, respectively) and aflatoxin-specific production, with a few CFEs causing an overproduction of mycotoxins. Nearly all Streptomyces isolates were able to degrade AFB1 when growing in solid and liquid media. A total degradation of AFB1 was achieved by Mycostop® on solid medium, as well as an almost complete degradation by IX20 in liquid medium (6% of the control). CFE maximal degradation went down to 37% of the control for isolate IX09. The search for degradation by-products indicated the presence of a few unknown molecules. The evaluation of residual toxicity of the tested isolates by the SOS chromotest indicated a detoxification of at least 68% of AFB1’s genotoxicity.

scholarly journals Trichoderma asperellum T76-14 Released Volatile Organic Compounds against Postharvest Fruit Rot in Muskmelons (Cucumis melo) Caused by Fusarium incarnatum

2021 ◽  
Vol 7 (1) ◽  
pp. 46
Author(s):  
Warin Intana ◽  
Suchawadee Kheawleng ◽  
Anurag Sunpapao
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Cucumis Melo ◽  
Fungal Growth ◽  
Fruit Rot ◽  
Postharvest Disease ◽  
Dual Culture ◽  
Trichoderma Asperellum ◽  
Volatile Organic

Postharvest fruit rot caused by Fusarium incarnatum is a destructive postharvest disease of muskmelon (Cucumis melo). Biocontrol by antagonistic microorganisms is considered an alternative to synthetic fungicide application. The aim of this study was to investigate the mechanisms of action involved in the biocontrol of postharvest fruit rot in muskmelons by Trichoderma species. Seven Trichoderma spp. isolates were selected for in vitro testing against F. incarnatum in potato dextrose agar (PDA) by dual culture assay. In other relevant works, Trichoderma asperellum T76-14 showed a significantly higher percentage of inhibition (81%) than other isolates. Through the sealed plate method, volatile organic compounds (VOCs) emitted from T. asperellum T76-14 proved effective at inhibiting the fungal growth of F. incarnatum by 62.5%. Solid-phase microextraction GC/MS analysis revealed several VOCs emitted from T. asperellum T76-14, whereas the dominant compound was tentatively identified as phenylethyl alcohol (PEA). We have tested commercial volatile (PEA) against in vitro growth of F. incarnatum; the result showed PEA at a concentration of 1.5 mg mL−1 suppressed fungal growth with 56% inhibition. Both VOCs and PEA caused abnormal changes in the fungal mycelia. In vivo testing showed that the lesion size of muskmelons exposed to VOCs from T. asperellum T76-14 was significantly smaller than that of the control. Muskmelons exposed to VOCs from T. asperellum T76-14 showed no fruit rot after incubation at seven days compared to fruit rot in the control. This study demonstrated the ability of T. asperellum T76-14 to produce volatile antifungal compounds, showing that it can be a major mechanism involved in and responsible for the successful inhibition of F. incarnatum and control of postharvest fruit rot in muskmelons.

scholarly journals In-Vitro Application of a Qatari Burkholderia cepacia strain (QBC03) in the Biocontrol of Mycotoxigenic Fungi and in the Reduction of Ochratoxin A biosynthesis by Aspergillus carbonarius

Toxins ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 700 ◽  
Author(s):  
Randa Zeidan ◽  
Zahoor Ul-Hassan ◽  
Roda Al-Thani ◽  
Quirico Migheli ◽  
Samir Jaoua
Keyword(s):  
Antifungal Activity ◽  
Ochratoxin A ◽  
Burkholderia Cepacia ◽  
Culture Supernatant ◽  
Animal Health ◽  
Aspergillus Carbonarius ◽  
Penicillium Verrucosum ◽  
Wide Range ◽  
Mycotoxigenic Fungi

Mycotoxins are secondary metabolites produced by certain filamentous fungi, causing human and animal health issues upon the ingestion of contaminated food and feed. Among the safest approaches to the control of mycotoxigenic fungi and mycotoxin detoxification is the application of microbial biocontrol agents. Burkholderia cepacia is known for producing metabolites active against a broad number of pathogenic fungi. In this study, the antifungal potential of a Qatari strain of Burkholderia cepacia (QBC03) was explored. QBC03 exhibited antifungal activity against a wide range of mycotoxigenic, as well as phytopathogenic, fungal genera and species. The QBC03 culture supernatant significantly inhibited the growth of Aspergillus carbonarius, Fusarium culmorum and Penicillium verrucosum in PDA medium, as well as A. carbonarius and P. verrucosum biomass in PDB medium. The QBC03 culture supernatant was found to dramatically reduce the synthesis of ochratoxin A (OTA) by A. carbonarius, in addition to inducing mycelia malformation. The antifungal activity of QBC03’s culture extract was retained following thermal treatment at 100 °C for 30 min. The findings of the present study advocate that QBC03 is a suitable biocontrol agent against toxigenic fungi, due to the inhibitory activity of its thermostable metabolites.

scholarly journals In vitro interactions between primycin and different statins in their effects against some clinically important fungi

2010 ◽  
Vol 59 (2) ◽  
pp. 200-205 ◽  
Author(s):  
Ildikó Nyilasi ◽  
Sándor Kocsubé ◽  
Miklós Pesti ◽  
Gyöngyi Lukács ◽  
Tamás Papp ◽  
...  
Keyword(s):  
Fungal Pathogens ◽  
Rhizopus Oryzae ◽  
Fungal Growth ◽  
Pathogenic Fungi ◽  
Titration Method ◽  
Antifungal Activities ◽  
Opportunistic Pathogenic ◽  
The Given ◽  
In Vitro Interactions

The in vitro antifungal activities of primycin (PN) and various statins against some opportunistic pathogenic fungi were investigated. PN completely inhibited the growth of Candida albicans (MIC 64 μg ml−1) and Candida glabrata (MIC 32 μg ml−1), and was very effective against Paecilomyces variotii (MIC 2 μg ml−1), but had little effect on Aspergillus fumigatus, Aspergillus flavus or Rhizopus oryzae (MICs >64 μg ml−1). The fungi exhibited different degrees of sensitivity to the statins; fluvastatin (FLV) and simvastatin (SIM) exerted potent antifungal activities against a wide variety of clinically important fungal pathogens. Atorvastatin, rosuvastatin and lovastatin (LOV) had a slight effect against all fungal isolates tested, whereas pravastatin was completely ineffective. The in vitro interactions between PN and the different statins were investigated using a standard chequerboard titration method. When PN was combined with FLV, LOV or SIM, both synergistic and additive effects were observed. The extent of inhibition was higher when these compounds were applied together, and the concentrations of PN and the given statin needed to block fungal growth completely could be decreased by several dilution steps. Similar interactions were observed when the variability of the within-species sensitivities was investigated.

Current Importance of Ochratoxin A–Producing Aspergillus spp.

2001 ◽  
Vol 64 (6) ◽  
pp. 903-906 ◽  
Author(s):  
M. L. ABARCA ◽  
F. ACCENSI ◽  
M. R. BRAGULAT ◽  
F. J. CABAÑES
Keyword(s):  
Ochratoxin A ◽  
Animal Health ◽  
Grape Juice ◽  
Poultry Meat ◽  
Aspergillus Ochraceus ◽  
Aspergillus Carbonarius ◽  
Penicillium Verrucosum ◽  
Closely Related Species ◽  
High Incidence ◽  
Food Commodities

Ochratoxin A (OA) is receiving attention worldwide because of the hazard it poses to human and animal health. OA contamination of commodities, such as cereals or pork and poultry meat, is well recognized. Nevertheless, there is an increasing number of articles reporting OA contamination in other food commodities, such as coffee, beer, wine, grape juice, and milk, in the last few years. This continuous and increasing exposure to OA that humans experience is reflected in the high incidence of OA in both human blood and milk in several countries. OA was believed to be produced only by Aspergillus ochraceus and closely related species of section Circumdati and by Penicillium verrucosum; however, in the genus Aspergillus, the production of OA has been recently reported by species outside the section Circumdati. Thus, it has been clearly established as a metabolite of different species of the section Nigri, such as Aspergillus niger and Aspergillus carbonarius. OA production ability by Aspergillus spp. is more widespread than previously thought; therefore, there is the possibility that unexpected species can be new sources of this mycotoxin in their natural substrates.

scholarly journals Effect of Trichoderma sp. on Anthracnose Disease of Stored Chilli

2018 ◽  
Vol 8 (2) ◽  
pp. 90-102
Author(s):  
Zee Kar Yan ◽  
Vu Thanh Tu Anh
Keyword(s):  
Fungal Growth ◽  
Pathogen Resistance ◽  
Raw Material ◽  
Small Lesion ◽  
Dual Culture ◽  
Anthracnose Disease ◽  
Colletotrichum Capsici ◽  
Trichoderma Sp

Chilli is commonly used as spice in Malaysian culinary, principal ingredients in paste (sambal) and as the raw material in sauce industry. Anthracnose disease caused by Colletotrichum capsici is one of the major causes of economic loss to chilli production especially in Asia. Even a small lesion on chilli might affect the quality, thus the market value of the chilli. Disease symptoms caused by C. capsici include brown, circular and sunken lesion with concentric rings of black acervuli. Chemicals have been used to treat the chilli but they might cause environmental pollution, affect human health and lead to pathogen resistance to the chemicals. Therefore, an alternative method to chemical control is required. In this study, C. capsici was isolated from a naturally infected chilli fruit (Capsicum frutescens), and a species of Trichoderma was isolated from the rhizosphere of grasses. Pure cultures of both fungi were established then used in antagonism studies in in vitro and in vivo. Dual culture of pathogens and Trichoderma sp. indicated that Trichoderma sp. competed with C. capsici for space and nutrients, caused the loss of turgidity of the fungal hyphae, and reduced the fungal growth by producing volatile metabolites. Trichoderma sp. decreased disease severity on chilli artificially inoculated fruits up to 64% when Trichoderma mycelial plug was used and 55% when culture filtrate was applied. Field trials are recommended to examine the antagonism of Trichoderma sp. in real production conditions. Keywords: Anthracnose, biological control, Colletotrichum capsici, Trichoderma sp.

scholarly journals Quantitative Microplate-Based Growth Assay for Determination of Antifungal Susceptibility of Histoplasma capsulatum Yeasts

2015 ◽  
Vol 53 (10) ◽  
pp. 3286-3295 ◽  
Author(s):  
Kristie D. Goughenour ◽  
Joan-Miquel Balada-Llasat ◽  
Chad A. Rappleye
Keyword(s):  
Fungal Pathogens ◽  
Histoplasma Capsulatum ◽  
Dynamic Range ◽  
Antifungal Susceptibility ◽  
Fungal Growth ◽  
Invasive Fungal Disease ◽  
Phylogenetic Groups ◽  
Morphological Form ◽  
Content Type

Standardized methodologies for determining the antifungal susceptibility of fungal pathogens is central to the clinical management of invasive fungal disease. Yeast-form fungi can be tested using broth macrodilution and microdilution assays. Reference procedures exist forCandidaspecies andCryptococcusyeasts; however, no standardized methods have been developed for testing the antifungal susceptibility of yeast forms of the dimorphic systemic fungal pathogens. For the dimorphic fungal pathogenHistoplasma capsulatum, susceptibility to echinocandins differs for the yeast and the filamentous forms, which highlights the need to employHistoplasmayeasts, not hyphae, in antifungal susceptibility tests. To address this, we developed and optimized methodology for the 96-well microtiter plate-based measurement ofHistoplasmayeast growthin vitro. Using optical density, the assay is quantitative for fungal growth with a dynamic range greater than 30-fold. Concentration and assay reaction time parameters were also optimized for colorimetric (MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] reduction) and fluorescent (resazurin reduction) indicators of fungal vitality. We employed this microtiter-based assay to determine the antifungal susceptibility patterns of multiple clinical isolates ofHistoplasmarepresenting different phylogenetic groups. This methodology fulfills a critical need for the ability to monitor the effectiveness of antifungals onHistoplasmayeasts, the morphological form present in mammalian hosts and, thus, the form most relevant to disease.

scholarly journals Trichoderma species as Biocontrol Agent against Soil Borne Fungal Pathogens

2017 ◽  
Vol 5 (1) ◽  
pp. 39-45 ◽  
Author(s):  
Srijana Bastakoti ◽  
Shiva Belbase ◽  
Shrinkhala Manandhar ◽  
Charu Arjyal
Keyword(s):  
Rhizoctonia Solani ◽  
Fusarium Solani ◽  
Fungal Pathogens ◽  
Plant Pathogens ◽  
Biocontrol Agent ◽  
Sclerotium Rolfsii ◽  
Dual Culture ◽  
Trichoderma Species ◽  
Biocontrol Efficacy

Soil borne pathogenic fungi are of major concern in agriculture which significantly decreases the plant yield. Chemically controlled plant imposes environmental threats potentially dangerous to humans as well as other animals. Thus, application of biological methods in plant disease control is more effective alternative technique. This study was carried out to isolate Trichoderma species from soil sample and to assess its in vitro biocontrol efficacy against fungal pathogens viz. Sclerotium rolfsii, Sclerotionia sclerotiorum, Fusarium solani and Rhizoctonia solani. Biocontrol efficacy testing of isolates against different fungal pathogens was performed by dual culture technique.In this study, 5 different Trichoderma species were isolated from 26 various soil samples and were tested against four fungal soil-borne pathogens. Inhibition percentage of radial growth of Sclerotium rolfsii by three of the Trichoderma isolates was found to be 100%; about 62% and 68% of maximum inhibition was observed against Rhizoctonia solani and Fusarium solani respectively whereas Sclerotionia sclerotiorum was inhibited maximum up to 23%. This in vitro study revealed that although Trichoderma species plays an important role in controlling all type of soil borne fungal plant pathogens, however, isolates as biocontrol agent against Sclerotium rolfsii was found to be more efficient in comparison to other pathogens.Nepal Journal of Biotechnology. Dec. 2017 Vol. 5, No. 1: 39-49

Effect of five fungicides on growth and ochratoxin A production by two Aspergillus carbonarius and Aspergillus niger isolated from Moroccan grapes

2014 ◽  
Vol 4 (3) ◽  
pp. 118-126
Author(s):  
Souad Zouhair ◽  
Souad Qjidaa Qjidaa ◽  
Atar Selouane ◽  
Driss Bouya ◽  
Cony Decock ◽  
...  
Keyword(s):  
Growth Rate ◽  
Ochratoxin A ◽  
Fungal Growth ◽  
Inhibitory Effect ◽  
Aspergillus Carbonarius ◽  
Total Inhibition ◽  
Germination And Growth ◽  
Dose Dependent Increase ◽  
Dose Dependent

Five fungicides azoxystrobin (ortiva), benomyl (benlate), hexaconazole (hexa), pyrimethanil (scala) and thiabendazole (tectocal) were tested sepa-rately in vitro for their ability to inhibit the growth of two ochratoxigenic strains of A. niger and A. carbonarius previously isolated from grapes. All fungicides effectively reduced the growth rate of A. carbonarius and A. niger from 34 to 100% at the recommended dose (RD). Thiabendazole caused total inhibition of spore germination and growth of the two strains, regardless of the doses assayed. Benomyl completely inhibited growth of A. niger whereas for A. carbonarius, concentrations above 0.02xRD were required to prevent the growth. The inhibitory effect of hexaconazole, azoxystrobin and pyrime-thanil was dose-dependent. At sub-lethal concentrations of three fungicides, a dose-dependent increase in in ochratoxin A biosynthesis by two strains was observed. The use of fungicide should be checked for its ability to inhibit fungal growth as well as for their effect in terms of mycotoxins biosynthesis.

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