Tremorgenic indole metabolites and aflatoxins in sclerotia of Aspergillus flavus: an evolutionary perspective

1982 ◽  
Vol 60 (5) ◽  
pp. 525-528 ◽  
Author(s):  
Donald T. Wicklow ◽  
Richard J. Cole
Keyword(s):  
Aspergillus Flavus ◽  
Culture Medium ◽  
Cyclopiazonic Acid ◽  
Petri Dish ◽  
Potato Dextrose Agar ◽  
Evolutionary Perspective ◽  
Toxic Compounds ◽  
Defense Systems ◽  
Selective Forces ◽  
First Time

Isolates of Aspergillus flavus Link from both cool and warm latitudes were cultured on potato dextrose agar containing yeast extract to identify sclerotia-producing strains. Chloroform–MeOH extracts of sclerotia were analyzed for the presence of aflatoxins and major indole metabolites (e.g., cyclopiazonic acid, aflatrem, and dihydroxyaflavinine). Aflatoxin is reported from sclerotia of A. flavus for the first time. Cyclopiazonic acid was detected primarily in sclerotia of isolates from warmer latitudes. Aflatrem and dihydroxyaflavinine were detected in sclerotia from 85% of the strains examined. These metabolites are associated with the sclerotial stage of the life cycle, because neither were detected in extracts of the culture medium and mycelium of Petri dish cultures from which all the sclerotia were removed. Geographic variation and intrafungal allocation of these toxic compounds in A. flavus are examined from the evolutionary ecologist's perspective of selective forces shaping the chemical defense systems of fungi.

scholarly journals Characterization of Argentinian Endemic Aspergillus flavus Isolates and Their Potential Use as Biocontrol Agents for Mycotoxins in Maize

2018 ◽  
Vol 108 (7) ◽  
pp. 818-828 ◽  
Author(s):  
Boris X. Camiletti ◽  
Juan Moral ◽  
Claudia M. Asensio ◽  
Ada Karina Torrico ◽  
Enrique I. Lucini ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Cyclopiazonic Acid ◽  
Fungal Species ◽  
Biocontrol Agents ◽  
Vegetative Compatibility Groups ◽  
Quality Properties ◽  
Control Approach ◽  
Liquid Culture Medium ◽  
Maize Kernels ◽  
First Time

Maize (Zea mays L.) is a highly valuable crop in Argentina, frequently contaminated with the mycotoxins produced by Aspergillus flavus. Biocontrol products formulated with atoxigenic (nontoxic) strains of this fungal species are well known as an effective method to reduce this contamination. In the present study, 83 A. flavus isolates from two maize regions of Argentina were characterized and evaluated for their ability to produce or lack of producing mycotoxins in order to select atoxigenic strains to be used as potential biocontrol agents (BCA). All of the isolates were tested for aflatoxin and cyclopiazonic acid (CPA) production in maize kernels and a liquid culture medium. Genetic diversity of the nonaflatoxigenic isolates was evaluated by analysis of vegetative compatibility groups (VCG) and confirmation of deletions in the aflatoxin biosynthesis cluster. Eight atoxigenic isolates were compared for their ability to reduce aflatoxin and CPA contamination in maize kernels in coinoculation tests. The A. flavus population was composed of 32% aflatoxin and CPA producers and 52% CPA producers, and 16% was determined as atoxigenic. All of the aflatoxin producer isolates also produced CPA. Aflatoxin and CPA production was significantly higher in maize kernels than in liquid medium. The 57 nonaflatoxigenic strains formed six VCG, with AM1 and AM5 being the dominant groups, with a frequency of 58 and 35%, respectively. In coinoculation experiments, all of the atoxigenic strains reduced aflatoxin from 54 to 83% and CPA from 60 to 97%. Members of group AM1 showed a greater aflatoxin reduction than members of AM5 (72 versus 66%) but no differences were detected in CPA production. Here, we described for the first time atoxigenic isolates of A. flavus that show promise to be used as BCA in maize crops in Argentina. This innovating biological control approach should be considered, developed further, and used by the maize industry to preserve the quality properties and food safety of maize kernels in Argentina.

Modelling the colonisation of maize by toxigenic and non-toxigenic Aspergillus flavus strains: implications for biological control

2008 ◽  
Vol 1 (3) ◽  
pp. 333-340 ◽  
Author(s):  
H. Abbas ◽  
R. Zablotowicz ◽  
H. Bruns
Keyword(s):  
Biological Control ◽  
Aspergillus Flavus ◽  
Growth Parameters ◽  
Biological Control Agent ◽  
Cyclopiazonic Acid ◽  
Aflatoxin Contamination ◽  
Tween 20 ◽  
Lag Phase ◽  
Gompertz Equation ◽  
Aflatoxin Accumulation

To successfully exploit biological control it is desirable to understand how the introduced agent colonises the host and interferes with establishment of the pest. This study assessed field colonisation of maize by Aspergillus flavus strains as biological control agents to reduce aflatoxin contamination. Maize (corn, Zea mays L.) ears were inoculated with A. flavus using a pin-bar technique in 2004 and 2005. Non-aflatoxigenic strains K49 (NRRL 30797) & CT3 (NRRL 30798) and toxigenic F3W4 (NRRL 30798) were compared against a carrier control (0.2% aqueous Tween 20). Ten ears were sampled over 12 to 20 days, visually assessed, and curves fit to a three compartment Gompertz equation or other best appropriate regressions. Aflatoxin was determined by HPLC and cyclopiazonic acid (CPA) by LC/MS. The Gompertz model describes growth parameters, e.g. growth constant, lag phase and maximum colonisation characterised patterns of maize colonisation for most inoculated treatments. Aflatoxin accumulation in maize inoculated with F3W4 was about 35,000 ng/g in 2004 and 2005, with kinetics of aflatoxin accumulation in 2005 well described by the Gompertz equation. Less than 200 ng/g was observed in maize inoculated with strains CT3 & K49 and accumulation was described by a linear or logistic model. Maize inoculated with strains CT3 and F3W4 accumulated a maximum of 220 and 169 µg/kg CPA, respectively, compared to 22 and 0.2 µg/kg in the control and K49 inoculated, respectively. This technique can be used to elucidate colonisation potential of non-toxigenic A. flavus in maize in relation to biological control of aflatoxin. The greatest reduction of aflatoxin and CPA in maize inoculated with strain K49 and Gompertz parameters on colonisation indicates its superiority to CT3 as a biological control agent. The dynamics of maize colonisation by A. flavus strains and subsequent mycotoxin accumulation generated by using the pin-bar technique has implications for characterising the competence of biocontrol strains for reducing aflatoxin contamination.

scholarly journals Streptomyces roseolus, A Promising Biocontrol Agent Against Aspergillus flavus, the Main Aflatoxin B1 Producer

Toxins ◽  
2018 ◽  
Vol 10 (11) ◽  
pp. 442 ◽  
Author(s):  
Isaura Caceres ◽  
Selma Snini ◽  
Olivier Puel ◽  
Florence Mathieu
Keyword(s):  
Aspergillus Flavus ◽  
Aflatoxin B1 ◽  
Biocontrol Agent ◽  
Cyclopiazonic Acid ◽  
Over Expression ◽  
Expression Of Genes ◽  
B1 Gene ◽  
Genes Encoding ◽  
Molecular Mechanism Of Action ◽  
Potential Use

Crop contamination by aflatoxin B1 is a current problem in tropical and subtropical regions. In the future, this contamination risk may be expanded to European countries due to climate change. The development of alternative strategies to prevent mycotoxin contamination that further contribute to the substitution of phytopharmaceutical products are thus needed. For this, a promising method resides in the use of biocontrol agents. Several actinobacteria strains have demonstrated to effectively reduce the aflatoxin B1 concentration. Nevertheless, the molecular mechanism of action by which these biological agents reduce the mycotoxin concentration has not been determined. The aim of the present study was to test the potential use of Streptomyces roseolus as a biocontrol agent against aflatoxin B1 contamination. Co-cultures with Aspergillus flavus were conducted, and the molecular fungal response was investigated through analyzing the q-PCR expression of 65 genes encoding relevant fungal functions. Moreover, kojic and cyclopiazonic acid concentrations, as well as morphological fungal changes were also analyzed. The results demonstrated that reduced concentrations of aflatoxin B1 and kojic acid were respectively correlated with the down-regulation of the aflatoxin B1 gene cluster and kojR gene expression. Moreover, a fungal hypersporulated phenotype and a general over-expression of genes involved in fungal development were observed in the co-culture condition.

scholarly journals An engraved surface induces weak adherence and high proliferation of nonadherent cells and microorganisms during culture

BioTechniques ◽  
2020 ◽  
Vol 69 (2) ◽  
pp. 113-125
Author(s):  
Sunil Thomas
Keyword(s):  
16S Rrna ◽  
Culture Medium ◽  
Petri Dish ◽  
Adherent Cells ◽  
Plastic Dish ◽  
Nonadherent Cells

When cells are cultured in a Petri dish, the adherent cells attach to the bottom of the dish; whereas, the nonadherent cells float in the culture medium. It was observed that nonadherent cells could be induced to adherent-like cells when cultured in an engraved plastic dish (biosimulator). The adherence of these cells to the engraved surface could be prevented with inhibitors specific for adhesion. It was also observed that culturing microorganisms of the environment in a biosimulator induced weak adhesion and high proliferation. Analysis of the microbiome using 16S rRNA profiling demonstrated that the biosimulator was more efficient in inducing proliferation of several phyla of microorganisms compared with culture by conventional techniques.

scholarly journals The T788G Mutation in thecyp51CGene Confers Voriconazole Resistance in Aspergillus flavus Causing Aspergillosis

2012 ◽  
Vol 56 (5) ◽  
pp. 2598-2603 ◽  
Author(s):  
Wei Liu ◽  
Yi Sun ◽  
Wei Chen ◽  
Weixia Liu ◽  
Zhe Wan ◽  
...  
Keyword(s):  
Aspergillus Flavus ◽  
Resistant Strain ◽  
Antifungal Susceptibility ◽  
Gene Replacement ◽  
Content Type ◽  
Replacement Method ◽  
First Choice ◽  
The One ◽  
A Site ◽  
First Time

ABSTRACTWith voriconazole (VRC) being approved as the first choice in treating invasive aspergillosis (IA) and its increasing use in treatment, a VRC-resistant strain ofAspergillus flavus, the second leading cause of IA afterAspergillus fumigatus, has emerged. The VRC-resistant strain ofA. flavuswas isolated for the first time from the surgical lung specimen of an IA patient with no response to VRC therapy. In order to ascertain the mechanism of VRC resistance, the azole target enzyme genes in this strain ofA. flavuswere cloned and sequenced, and 4 mutations generating amino acid residue substitutions were found in thecyp51Cgene. To further determine the role of this mutated gene for VRC resistance inA. flavus, anAgrobacterium tumefaciens-mediated gene replacement approach was applied. Consequently, the mutatedcyp51Cgene from thisA. flavusstrain was proven to confer the VRC resistance. Finally, to discern the one out of the four mutations in thecyp51Cgene that is responsible for contributing to VRC resistance, a site-directed gene mutagenesis procedure combined with a gene replacement method was performed. As a result, the T788G missense mutation in thecyp51Cgene was identified as responsible for VRC resistance inA. flavus. These findings indicated that the detection of this mutation inA. flavuscould serve as an indicator for physicians to avoid the use of VRC during IA treatment. Further comprehensive surveillance for antifungal susceptibility, as well as intensive study on the mechanism of azole resistance inA. flavuscausing IA, would be required to fully understand this mechanism.

scholarly journals Growth Inhibition of Cocoa Pod Rot Fungus Phytophthora palmivora byPseudomonas fluorescence and Bacillus subtilis bacteria

2013 ◽  
Vol 29 (2) ◽  
Author(s):  
Sakti Widyanta Pratama ◽  
Sri Sukamto ◽  
Lis Nur Asyiah ◽  
Yeni Vida Ervina
Keyword(s):  
Bacillus Subtilis ◽  
Fungal Growth ◽  
Petri Dish ◽  
Phytophthora Palmivora ◽  
Fungal Treatment ◽  
Pure Cultures ◽  
Black Pod ◽  
Black Pod Disease ◽  
First Time ◽  
Important Disease

Black pod disease caused by Phytophthora palmivorafungus is one of the important diseases on cocoa crop. Pod rot is the most important disease because it may cause loss of cocoa pod. Until now, the fungal pathogen of cocoa black pod disease is still a crucial problem and there is no fungicide that is really effective against the disease. One alternative to control the cocoa black pod disease is by using biological agents as biofungicide, including utilizing Pseudomonas fluorescenceand Bacillus subtilis bacteria. The research was done by isolation of P. palmivora from infected pods of Kaliwining Experimental Station to obtain pure cultures of fungus and by multiplication of P. fluorescence and B. subtilis. Antagonist test was performed by inoculating P. palmivora into a petri dish in a distance of 3 cm from the edge. P. fluorescenceand B. Subtilis were inoculated into petridishes in three days after the fungal treatment. Control was inoculated with isolate of P. palmivora only. Fungal growth was measured everyday by measuring radius of fungal colonies first time 24 hours after inoculation. Growth of Phytophthora palmivora in the two treatmens were used to calculate the percentage of inhibition. The results of this study indicated that P. fluorescence and B. subtiliswere able to inhibit fungal growth of P. palmivora. Both bacterial antagonists had the same effectiveness in inhibiting the growth of P. palmivora fungus based on the percentage of inhibition and effectiveness criteria. Based on the results of translucent zones indicated that B. subtiliswas more powerfull in inhibiting growth of P. Palmivora compared to P. fluorescence. Key words: Black pod disease of cocoa, biological control, Phytophthora palmivora, Pseudomonas fluorescence, Bacillus subtilis

scholarly journals Keanekaragaman Kapang Patogen dan Non Patogen pada Imago, Kokon, dan Larva Instar Keenam Ulat Sutera Liar Attacus atlas (Lepidoptera: Saturniidae)

2019 ◽  
Vol 37 (2) ◽  
pp. 232
Author(s):  
Agustin Indrawati ◽  
Damiana Rita Ekastuti ◽  
Erdina Pangestika ◽  
Reinilda Alwina
Keyword(s):  
Aspergillus Fumigatus ◽  
Fusarium Oxysporum ◽  
Aspergillus Flavus ◽  
Microscopic Observation ◽  
Potato Dextrose Agar ◽  
Aspergillus Versicolor ◽  
Wild Silkworm ◽  
Opportunistic Pathogenic

Attacus atlas is one of several mould species in Indonesia known as kupu-kupu gajah. Information about variety of mould is rarely known. The purpose of this research was to obtain data about variety of pathogenic or non pathogenic mould at imago,cocoon, and sixth larvae phase of wild silkworm A. atlas. Mould was isolated from cocoon, integument, alimentary duct and reproduction duct of imago, trachea, midgut and hindgut, also haemolymph of larvae. Isolated mould was cultured on potato dextrose agar. Isolated mould from cocoon and imago was identified by macroscopic and microscopic observation. The results showed that there were two kind of moulds from cocoon which were Fusarium oxysporum  and Aspergillus flavus. There were four kind of moulds from imago A. atlas which were Aspergillus flavus, Aspergillus versicolor, Aspergillus fumigatus, Fusarium dimerum, and Aspergillus sp.There were three kind of moulds from sixth larvae which were Aspergillus fumigatus, Aspergillus flavus, and Fusarium dimerum. The mould which has opportunistic pathogenic for Attacus atlas were Fusarium oxysporum, Aspergillus  flavus, Aspergillus fumigatus and Fusarium dimerum.

scholarly journals Impact of environmental factors on growth and satratoxin G production by strains of Stachybotrys chartarum

2012 ◽  
Vol 5 (1) ◽  
pp. 37-43 ◽  
Author(s):  
S. Frazer ◽  
J. Pestka ◽  
J. Kim ◽  
A. Medina ◽  
D. Aldred ◽  
...  
Keyword(s):  
Environmental Factors ◽  
Water Availability ◽  
Indoor Environment ◽  
Potato Dextrose Agar ◽  
Enzyme Linked Immunosorbent Assay ◽  
Stachybotrys Chartarum ◽  
Data Sets ◽  
Elisa Method ◽  
Contour Maps ◽  
First Time

The black mould Stachybotrys chartarum and its mycotoxins have been linked to damp building-associated illnesses. The objective of this study was to determine the effects of water availability (water activity, aw) and temperature on growth and production of satratoxin G (SG) by a macrocyclic trichothecene-producing strain (IBT 7711) and non-producing strain (IBT 1495) of S. chartarum. Growth studies were carried out on potato dextrose agar modified with glycerol to 0.995-0.92 aw at 10-37 °C. Growth extension was measured and the cultures were extracted after 10 days and a competitive enzyme-linked immunosorbent assay (ELISA) method used to quantify the SG content. Growth was optimal at 25 to 30 °C at 0.995 aw, but this was modified to 0.98 aw at 30 °C for both strains (1.4-1.6 mm/day, respectively). The ELISA method revealed that, in contrast to growth, SG production was maximal at 20 °C with highest production at 0.98 aw (approximately 250 μg/g mycelia). When water was freely available (0.995 aw), SG was maximally produced at 15 °C and decreased as temperature was increased. Interestingly, the strain classified as a non-toxigenic produced very low amounts of SG (<1.6 μg/g mycelia) that were maximal at 25 °C and 0.98 aw. Contour maps for growth and SG production were developed from these data sets. These data have shown, for the first time, that growth and SG production profiles are very different in relation to key environmental conditions in the indoor environment. This will be very useful in practically determining the risk from exposure to S. chartarum and its toxins in the built environment.

Lowering the inhibition of sugarcane vinasse as a culture medium for oleaginous fungi through oxidative pre‐treatment aiming at the degradation of toxic compounds

2020 ◽  
Vol 95 (11) ◽  
pp. 2943-2950
Author(s):  
Cristiano E Rodrigues Reis ◽  
Ana KF Carvalho ◽  
Heitor BS Bento ◽  
Thiago M Alves ◽  
Heizir F Castro
Keyword(s):  
Culture Medium ◽  
Toxic Compounds ◽  
Oleaginous Fungi ◽  
Pre Treatment ◽  
Sugarcane Vinasse

A morphological, enzymatic and metabolic approach to elucidate apoptotic-like cell death in fungi exposed to h- and α-molybdenum trioxide nanoparticles

Nanoscale ◽  
2018 ◽  
Vol 10 (44) ◽  
pp. 20702-20716 ◽  
Author(s):  
Clemencia Chaves-Lopez ◽  
Hang N. Nguyen ◽  
Rodrigo C. Oliveira ◽  
Enrico T. Nadres ◽  
Antonello Paparella ◽  
...  
Keyword(s):  
Cell Death ◽  
Aspergillus Niger ◽  
Aspergillus Flavus ◽  
Molybdenum Trioxide ◽  
Fungal Strains ◽  
First Time

The present study compares for the first time the effects of h-MoO3and α-MoO3against two fungal strains:Aspergillus nigerandAspergillus flavus.

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