Risk assessment of secondary metabolites produced by fungi in the genus Stemphylium

2021 ◽  
Author(s):  
Sara M Stricker ◽  
Bruce D. Gossen ◽  
Mary Ruth McDonald
Keyword(s):  
Secondary Metabolites ◽  
Health Agency ◽  
Toxin Production ◽  
Fungal Species ◽  
Health Concern ◽  
Regulatory Body ◽  
Vegetable Crops ◽  
Aromatic Polyketides ◽  
Detailed Assessment ◽  
Mammalian Toxicity

The fungal genus <i>Stemphylium</i> (phylum Ascomycota, teleomorph <i>Pleospora</i>) includes plant pathogenic, endophytic, and saprophytic species with worldwide distributions. <i>Stemphylium<i></i> spp. produce prodigious numbers of air-borne spores, so are a human health concern as allergens. Some species also produce secondary metabolites such as glucosides, ferric chelates, aromatic polyketides, and others that function as toxins that damage plants and other fungal species. Some of these compounds also exhibit a low level of mammalian toxicity. The high production of air-borne spores by this genus can result in a high incidence of human exposure. Concern about toxin production appears to be the reason that <i></i>S. vesicarium<i></i>, which is a pathogen of several vegetable crops, was classified in Canada as a potential risk of harm to humans for many years. A detailed assessment of the risk of exposure was provided to the relevant regulatory body, Public Health Agency of Canada. They determined that <i></i>Stemphylium<i></i> spp., in nature or under laboratory conditions, posed little to no risk to humans or animals, and the species was re-assigned as a basic (level 1) risk agent.

scholarly journals Phytotoxic Secondary Metabolites from Fungi

Toxins ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 261
Author(s):  
Dan Xu ◽  
Mengyao Xue ◽  
Zhen Shen ◽  
Xiaowei Jia ◽  
Xuwen Hou ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Phenolic Acids ◽  
Future Development ◽  
Fungal Species ◽  
Biochemical Reactions ◽  
Chemical Structures ◽  
Aromatic Polyketides ◽  
Naturally Occurring ◽  
Structure Activity ◽  
High Level

Fungal phytotoxic secondary metabolites are poisonous substances to plants produced by fungi through naturally occurring biochemical reactions. These metabolites exhibit a high level of diversity in their properties, such as structures, phytotoxic activities, and modes of toxicity. They are mainly isolated from phytopathogenic fungal species in the genera of Alternaria, Botrytis, Colletotrichum, Fusarium, Helminthosporium, and Phoma. Phytotoxins are either host specific or non-host specific phytotoxins. Up to now, at least 545 fungal phytotoxic secondary metabolites, including 207 polyketides, 46 phenols and phenolic acids, 135 terpenoids, 146 nitrogen-containing metabolites, and 11 others, have been reported. Among them, aromatic polyketides and sesquiterpenoids are the main phytotoxic compounds. This review summarizes their chemical structures, sources, and phytotoxic activities. We also discuss their phytotoxic mechanisms and structure–activity relationships to lay the foundation for the future development and application of these promising metabolites as herbicides.

scholarly journals Aeromonas detection and their toxins from drinking water from reservoirs and drinking fountains

2007 ◽  
Vol 6 (1) ◽  
pp. 117-123 ◽  
Author(s):  
Maria Tereza Pepe Razzolini ◽  
Marisa Di Bari ◽  
Petra Sanchez Sanchez ◽  
Maria Inês Zanoli Sato
Keyword(s):  
Drinking Water ◽  
Aquatic Ecosystems ◽  
Membrane Filtration ◽  
Biochemical Characterization ◽  
Toxin Production ◽  
Health Concern ◽  
Public Health Concern ◽  
Emerging Pathogen ◽  
Pathogenic Potential ◽  
Drinking Water Samples

Aeromonads are inhabitants of aquatic ecosystems and are described as being involved in intestinal disturbances and other infections. A total of 200 drinking water samples from domestic and public reservoirs and drinking fountains located in São Paulo (Brazil), were analyzed for the presence of Aeromonas. Samples were concentrated by membrane filtration and enriched in APW. ADA medium was used for Aeromonas isolation and colonies were confirmed by biochemical characterization. Strains isolated were tested for hemolysin and toxin production. Aeromonas was detected in 12 samples (6.0%). Aeromonas strains (96) were isolated and identified as: A. caviae (41.7%), A.hydrophila (15.7%), A.allosacharophila (10.4%), A. schubertii (1.0%) and Aeromonas spp. (31.2%).The results revealed that 70% of A. caviae, 66.7% of A. hydrophila, 80% of A. allosacharophila and 46.6% of Aeromonas spp. were hemolytic. The assay for checking production of toxins showed that 17.5% of A. caviae, 73.3% of A. hydrophila, 60% of A. allosacharophila, 100% of A. schubertii, and 33.3% of Aeromonas spp. were able to produce toxins. The results demonstrated the pathogenic potential of Aeromonas, indicating that the presence of this emerging pathogen in water systems is a public health concern.

scholarly journals Aflatoxin Biosynthesis and Genetic Regulation: A Review

Toxins ◽  
2020 ◽  
Vol 12 (3) ◽  
pp. 150 ◽  
Author(s):  
Isaura Caceres ◽  
Anthony Al Khoury ◽  
Rhoda El Khoury ◽  
Sophie Lorber ◽  
Isabelle P. Oswald ◽  
...  
Keyword(s):  
Genetic Regulation ◽  
Aflatoxin Production ◽  
Toxin Production ◽  
Molecular Study ◽  
Fungal Species ◽  
Molecular Techniques ◽  
Environmental Signals ◽  
Effective Strategies ◽  
Global Environmental ◽  
New Evidence

The study of fungal species evolved radically with the development of molecular techniques and produced new evidence to understand specific fungal mechanisms such as the production of toxic secondary metabolites. Taking advantage of these technologies to improve food safety, the molecular study of toxinogenic species can help elucidate the mechanisms underlying toxin production and enable the development of new effective strategies to control fungal toxicity. Numerous studies have been made on genes involved in aflatoxin B1 (AFB1) production, one of the most hazardous carcinogenic toxins for humans and animals. The current review presents the roles of these different genes and their possible impact on AFB1 production. We focus on the toxinogenic strains Aspergillus flavus and A. parasiticus, primary contaminants and major producers of AFB1 in crops. However, genetic reports on A. nidulans are also included because of the capacity of this fungus to produce sterigmatocystin, the penultimate stable metabolite during AFB1 production. The aim of this review is to provide a general overview of the AFB1 enzymatic biosynthesis pathway and its link with the genes belonging to the AFB1 cluster. It also aims to illustrate the role of global environmental factors on aflatoxin production and the recent data that demonstrate an interconnection between genes regulated by these environmental signals and aflatoxin biosynthetic pathway.

scholarly journals Neurotoxic effects in zebrafish embryos by valproic acid and nine of its analogues: the fish-mouse connection?

2020 ◽  
Author(s):  
Katharina Brotzmann ◽  
André Wolterbeek ◽  
Dinant Kroese ◽  
Thomas Braunbeck
Keyword(s):  
Valproic Acid ◽  
Predictive Power ◽  
In Vivo Studies ◽  
In Vivo Model ◽  
Zebrafish Embryos ◽  
Fish Embryo ◽  
Modes Of Action ◽  
Detailed Assessment ◽  
Mammalian Toxicity

Abstract Since teratogenicity testing in mammals is a particular challenge from an animal welfare perspective, there is a great need for the development of alternative test systems. In this context, the zebrafish (Danio rerio) embryo has received increasing attention as a non-protected embryonic vertebrate in vivo model. The predictive power of zebrafish embryos for general vertebrate teratogenicity strongly depends on the correlation between fish and mammals with respect to both overall general toxicity and more specific endpoints indicative of certain modes-of-action. The present study was designed to analyze the correlation between (1) effects of valproic acid and nine of its analogues in zebrafish embryos and (2) their known neurodevelopmental effects in mice. To this end, zebrafish embryos exposed for 120 h in an extended version of the acute fish embryo toxicity test (FET; OECD TG 236) were analyzed with respect to an extended list of sublethal endpoints. Particular care was given to endpoints putatively related to neurodevelopmental toxicity, namely jitter/tremor, deformation of sensory organs (eyes) and craniofacial deformation, which might correlate to neural tube defects caused by valproic acid in mammals. A standard evaluation of lethal (LC according to OECD TG 236) and sublethal toxicity (EC) merely indicated that four out of ten compounds tested in zebrafish correlate with positive results in mouse in vivo studies. A detailed assessment of more specific effects, however, namely, jitter/tremor, small eyes and craniofacial deformation, resulted in a correspondence of 75% with in vivo mouse data. A refinement of endpoint analysis from an integration of all observations into one LCx or ECx data (as foreseen by current ecotoxicology-driven OECD guidelines) to a differential evaluation of endpoints specific of selected modes-of-action thus increases significantly the predictive power of the zebrafish embryo model for mammalian teratogenicity. However, for some of the endpoints observed, e.g., scoliosis, lordosis, pectoral fin deformation and lack of movement, further experiments are required for the identification of underlying modes-of-action and an unambiguous interpretation of their predictive power for mammalian toxicity.

scholarly journals Comparative Transcriptome Analysis Shows Conserved Metabolic Regulation during Production of Secondary Metabolites in Filamentous Fungi

mSystems ◽  
2019 ◽  
Vol 4 (2) ◽  
Author(s):  
Jens Christian Nielsen ◽  
Sylvain Prigent ◽  
Sietske Grijseels ◽  
Mhairi Workman ◽  
Boyang Ji ◽  
...  
Keyword(s):  
Secondary Metabolites ◽  
Secondary Metabolism ◽  
Secondary Metabolite ◽  
Filamentous Fungi ◽  
Metabolic Regulation ◽  
Fungal Species ◽  
Efficient Production ◽  
Fungal Cell ◽  
Fungal Metabolism ◽  
Cell Factories

ABSTRACTFilamentous fungi possess great potential as sources of medicinal bioactive compounds, such as antibiotics, but efficient production is hampered by a limited understanding of how their metabolism is regulated. We investigated the metabolism of six secondary metabolite-producing fungi of thePenicilliumgenus during nutrient depletion in the stationary phase of batch fermentations and assessed conserved metabolic responses across species using genome-wide transcriptional profiling. A coexpression analysis revealed that expression of biosynthetic genes correlates with expression of genes associated with pathways responsible for the generation of precursor metabolites for secondary metabolism. Our results highlight the main metabolic routes for the supply of precursors for secondary metabolism and suggest that the regulation of fungal metabolism is tailored to meet the demands for secondary metabolite production. These findings can aid in identifying fungal species that are optimized for the production of specific secondary metabolites and in designing metabolic engineering strategies to develop high-yielding fungal cell factories for production of secondary metabolites.IMPORTANCESecondary metabolites are a major source of pharmaceuticals, especially antibiotics. However, the development of efficient processes of production of secondary metabolites has proved troublesome due to a limited understanding of the metabolic regulations governing secondary metabolism. By analyzing the conservation in gene expression across secondary metabolite-producing fungal species, we identified a metabolic signature that links primary and secondary metabolism and that demonstrates that fungal metabolism is tailored for the efficient production of secondary metabolites. The insight that we provide can be used to develop high-yielding fungal cell factories that are optimized for the production of specific secondary metabolites of pharmaceutical interest.

scholarly journals Phytotoxins, Elicitors and Other Secondary Metabolites from Phytopathogenic “Blackleg” Fungi: Structure, Phytotoxicity and Biosynthesis

2009 ◽  
Vol 4 (9) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
M. Soledade C. Pedras ◽  
Yang Yu
Keyword(s):  
Secondary Metabolites ◽  
Leptosphaeria Maculans ◽  
Culture Conditions ◽  
Fungal Species ◽  
Biosynthetic Studies

The metabolites produced by the fungal species Leptosphaeria maculans and L. biglobosa under different culture conditions, together with their phytotoxic activities are reviewed. In addition, the biosynthetic studies of blackleg metabolites carried out to date are described and suggestions for species reclassification are provided.

scholarly journals Stachybotriaceae on Cucurbits Demystified: Genetic Diversity and Pathogenicity of Ink Spot Pathogens

Plant Disease ◽  
2020 ◽  
Vol 104 (8) ◽  
pp. 2242-2251
Author(s):  
Gabriel Rennberger ◽  
Anthony P. Keinath
Keyword(s):  
South Carolina ◽  
Leaf Spot ◽  
Sequence Data ◽  
Spatial Scales ◽  
Fungal Species ◽  
Vegetable Crops ◽  
Tomato Plants ◽  
Predominant Species ◽  
The Family ◽  
The Common

Recently, the incidence of Myrothecium leaf spot, a foliar disease of watermelon, has increased in South Carolina. However, the identity of the fungal species responsible for outbreaks of this disease has not been determined. Sequence data from four partial gene regions were used to conduct Bayesian inference in order to identify 95 isolates of Stachybotriaceae. Isolates were collected in South Carolina between July 2015 and May 2018. In total, six species of Stachybotriaceae were identified on watermelon and two other cucurbits: Albifimbria verrucaria, Gregatothecium humicola, Paramyrothecium foliicola, P. humicola, Xenomyrothecium tongaense, and Xepicula leucotricha. Two species, G. humicola and P. foliicola, were the predominant species found. Within these two species, genetic differences within small spatial scales were detected. Five species (all except Xenomyrothecium tongaense) were tested in experiments to determine their pathogenicity and relative virulence on three hosts grown in rotation in South Carolina. Southern pea plants were less susceptible than watermelon and tomato plants, which were equally susceptible. This constitutes the first reliable report of pathogenicity of any of the five tested species of Stachybotriaceae on these three vegetable crops. Another important finding was that none of the isolates were identified as P. roridum, the species considered to be the only causal agent of Myrothecium leaf spot on cucurbits. We propose the common name “ink spot” for the foliar phase of diseases caused by genera within the family Stachybotriaceae. This name is descriptive and likely to be accepted by growers. To prevent further loss incurred by ink spot, watermelon and tomato crops should be monitored for this disease.

Vanadate inhibits the production and/or release of secondary metabolites without impairing growth in several fungal species

1996 ◽  
Vol 41 (6) ◽  
pp. 494-498 ◽  
Author(s):  
S. Cehulová ◽  
S. Kryštofová ◽  
V. Betina ◽  
L'. Varečka
Keyword(s):  
Secondary Metabolites ◽  
Fungal Species
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