A reappraisal of fungi producing aflatoxins

2009 ◽  
Vol 2 (3) ◽  
pp. 263-277 ◽  
Author(s):  
J. Varga ◽  
J. Frisvad ◽  
R. Samson
Keyword(s):  
Secondary Metabolites ◽  
Biosynthetic Pathway ◽  
Aflatoxin Production ◽  
Aspergillus Species ◽  
Aflatoxin Biosynthesis ◽  
Aspergillus Section Flavi ◽  
Naturally Occurring ◽  
Aflatoxin B ◽  
Aspergillus Section

Aflatoxins are decaketide-derived secondary metabolites which are produced by a complex biosynthetic pathway. Aflatoxins are among the economically most important mycotoxins. Aflatoxin B1 exhibits hepatocarcinogenic and hepatotoxic properties, and is frequently referred to as the most potent naturally occurring carcinogen. Acute aflatoxicosis epidemics occur in several parts of Asia and Africa leading to the death of several hundred people. Aflatoxin production has incorrectly been claimed for a long list of Aspergillus species and also for species assigned to other fungal genera. Recent data indicate that aflatoxins are produced by 13 species assigned to three sections of the genus Aspergillus: section Flavi (A. flavus, A. pseudotamarii, A. parasiticus, A. nomius, A. bombycis, A. parvisclerotigenus, A. minisclerotigenes, A. arachidicola), section Nidulantes (Emericella astellata, E. venezuelensis, E. olivicola) and section Ochraceorosei (A. ochraceoroseus, A. rambellii). Several species claimed to produce aflatoxins have been synonymised with other aflatoxin producers, including A. toxicarius (=A. parasiticus), A. flavus var. columnaris (=A. flavus) or A. zhaoqingensis (=A. nomius). Compounds with related structures include sterigmatocystin, an intermediate of aflatoxin biosynthesis produced by several Aspergilli and species assigned to other genera, and dothistromin produced by a range of non-Aspergillus species. In this review, we wish to give an overview of aflatoxin production including the list of species incorrectly identified as aflatoxin producers, and provide short descriptions of the 'true' aflatoxin producing species.

Quantitative Detection of Aflatoxin and Species Identification of Aspergillus section Flavi Isolates from Peanuts using Molecular Approaches

2020 ◽  
Author(s):  
I. Lavkor
Keyword(s):  
Sequence Data ◽  
Aflatoxin Production ◽  
Quantitative Detection ◽  
Aflatoxin Biosynthesis ◽  
Chain Reactions ◽  
Polymerase Chain Reactions ◽  
Dna Sequence Data ◽  
Aspergillus Section Flavi ◽  
Molecular Approaches ◽  
Aspergillus Section

Totally, 50 Aspergillus section Flavi were identified isolates having aflatoxin biosynthesis genes on peanut by molecular method and aflatoxin production. Primer pair (IGS-F/R) recognized the aflatoxin biosynthesis gene (aflJ-aflR) targeting the intergenic region (IGS) on DNA was amplified by polymerase chain reactions (PCR). The PCR product were restricted by BglII enzyme within Restriction Fragment Length Polymorphism (RFLP) and obtained from 33 (66%) Aspergillus flavus was cleaved into three band sizes of 362, 210 and 102 bp. However, BglII enzyme generated two band sizes of 363 and 311 bp for 17 (34%) Aspergillus parasiticus. An investigation examined DNA sequence data to characterize these isolates and describe the species. Phylogenetic analysis showed that A. flavus and A. parasiticus have been identified in different groups. All the A. flavus and A. parasiticus isolates produced aflatoxins. The present study provides a new method on molecular characterization of A. section Flavi in Turkey.

scholarly journals Molecular Characterisation of Aflatoxigenic and Non-Aflatoxigenic Strains of Aspergillus Section Flavi Isolated from Imported Peanuts along the Supply Chain in Malaysia

Toxins ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 501 ◽  
Author(s):  
Mahror Norlia ◽  
Selamat Jinap ◽  
Mahmud Ab Rashid Nor-Khaizura ◽  
Son Radu ◽  
Cheow Keat Chin ◽  
...  
Keyword(s):  
Aflatoxin Production ◽  
Storage Conditions ◽  
Aflatoxin Contamination ◽  
Aflatoxin Biosynthesis ◽  
Asian Countries ◽  
Aspergillus Section Flavi ◽  
Aflatoxigenic Fungi ◽  
Tropical Weather ◽  
Southeast Asian Countries ◽  
Aspergillus Section

Peanuts are widely consumed in many local dishes in southeast Asian countries, especially in Malaysia which is one of the major peanut-importing countries in this region. Therefore, Aspergillus spp. and aflatoxin contamination in peanuts during storage are becoming major concerns due to the tropical weather in this region that favours the growth of aflatoxigenic fungi. The present study thus aimed to molecularly identify and characterise the Aspergillus section Flavi isolated from imported peanuts in Malaysia. The internal transcribed spacer (ITS) and β-tubulin sequences were used to confirm the species and determine the phylogenetic relationship among the isolates, while aflatoxin biosynthesis genes (aflR, aflP (omtA), aflD (nor-1), aflM (ver-1), and pksA) were targeted in a multiplex PCR to determine the toxigenic potential. A total of 76 and one isolates were confirmed as A. flavus and A. tamarii, respectively. The Maximum Likelihood (ML) phylogenetic tree resolved the species into two different clades in which all A. flavus (both aflatoxigenic and non-aflatoxigenic) were grouped in the same clade and A. tamarii was grouped in a different clade. The aflatoxin biosynthesis genes were detected in all aflatoxigenic A. flavus while the non-aflatoxigenic A. flavus failed to amplify at least one of the genes. The results indicated that both aflatoxigenic and non-aflatoxigenic A. flavus could survive in imported peanuts and, thus, appropriate storage conditions preferably with low temperature should be considered to avoid the re-emergence of aflatoxigenic A. flavus and the subsequent aflatoxin production in peanuts during storage.

Phenotypic differentiation of species from Aspergillus section Flavi on neutral red desiccated coconut agar

2014 ◽  
Vol 7 (3) ◽  
pp. 335-344 ◽  
Author(s):  
C.N. Ezekiel ◽  
M.C. Adetunji ◽  
O.O. Atanda ◽  
J.C. Frisvad ◽  
J. Houbraken ◽  
...  
Keyword(s):  
Morphological Differentiation ◽  
Aflatoxin Production ◽  
Neutral Red ◽  
Rapid Identification ◽  
Phenotypic Traits ◽  
Phenotypic Differentiation ◽  
Aspergillus Section Flavi ◽  
Aflatoxin B ◽  
The Relationship ◽  
Aspergillus Section

In order to facilitate easy and rapid identification of aflatoxin-producing Aspergillus species, the phenotypic traits of Aspergillus section Flavi isolates were examined on neutral red desiccated coconut agar (NRDCA). Phenotype variations in colony morphology and the relationship between colour/intensity of fluorescence and aflatoxin production were assessed. The isolates included 10 Aspergillus minisclerotigenes strains, 11 non-aflatoxigenic Aspergillus flavus L strains, 29 aflatoxigenic A. flavus L strains and 20 strains each of Aspergillus parasiticus and Aspergillus parvisclerotigenus. The NRDCA medium supported morphological differentiation of the four species based on colony features, conidia type and colour. In particular, the two very closely related minisclerotial species, A. minisclerotigenes and A. parvisclerotigenus, were clearly differentiated by their colony colour on NRDCA. All toxigenic isolates produced aflatoxins in the culture medium in varying quantities. Plates of aflatoxigenic A. flavus L strains fluoresced bluish purple/lavender around the colony on the obverse and pastel blue on the reverse side due to aflatoxin B production while those of A. minisclerotigenes, A. parasiticus and A. parvisclerotigenus fluoresced with a light blue or light turquoise ring around the colony on the obverse and light sky blue or cadet blue on the reverse side depending on the amount of aflatoxin B and G produced. The colour of fluorescence significantly correlated (r=0.95, P=0.001) with the type(s) of aflatoxins produced by the isolates. In addition, the concentration of aflatoxins significantly (r=0.92; P=0.001) influenced the intensity of fluorescence in the aflatoxin-producing species. NRDCA can therefore be used for the rapid identification of Aspergillus section Flavi species based on colonial characteristics, and grouping of species into B and B+G aflatoxin producers within 5 days thus obviating the need for chemical analysis of the culture.

Prevalence of Aspergillus species on selected Colombian animal feedstuffs and ability of Aspergillus section Flavi to produce aflatoxins

2009 ◽  
Vol 2 (1) ◽  
pp. 31-34 ◽  
Author(s):  
G. Diaz ◽  
M. Lozano ◽  
A. Acuña
Keyword(s):  
Liquid Chromatography ◽  
Cottonseed Meal ◽  
Sunflower Seed ◽  
Seed Meal ◽  
Aspergillus Section Flavi ◽  
Wheat Middlings ◽  
Highperformance Liquid Chromatography ◽  
Animal Feedstuffs ◽  
Aflatoxin B ◽  
Aspergillus Section

A total of 57 samples of feedstuffs commonly used for animal nutrition in Colombia (maize, soybean, sorghum, cottonseed meal, sunflower seed meal, wheat middlings and rice) were analysed for Aspergillus contamination. Aspergillus fungi were identified at species level and their ability to produce aflatoxins was determined by highperformance liquid chromatography. A total of 31 of the feedstuffs analysed (54.4%) were found to contain Aspergillus spp. The most contaminated substrate was maize (100%) followed by cottonseed meal (80%), sorghum (60%) and wheat middlings (60%). Soybean showed lower levels of contamination (10%). No Aspergillus spp. could be isolated from rice or sunflower seed meal. Total Aspergillus strains isolated were 50, with 28 belonging to section Flavi (56%), 17 to section Nigri (34%), 4 to section Circumdati (8%) and 1 to section Fumigati (2%). Among section Flavi, 17 isolates were identified as A. flavus, seven as A. parasiticus, two as A. oryzae and two as A. tamarii. Production of aflatoxins by Aspergillus section Flavi was screened by liquid chromatography. About three quarters of the A. flavus strains (76.5%) produced aflatoxin B1 (0.2 to 240.4 µg/g) and aflatoxin B2 (0.2 to 1.6 µg/g), while all A. parasiticus strains produced the four naturally occurring aflatoxins (aflatoxin B1 from 0.6 to 83.5 µg/g, aflatoxin B2 from 0.3 to 4.8 µg/g, aflatoxin G1 from 0.4 to 19.3 µg/g and aflatoxin G2 from 0.1 to 1.0 µg/g). This is the first study demonstrating the presence of highly toxigenic Aspergillus fungi in Colombian animal feedstuffs.

Natural maize phytochemicals for control of maize mycoflora and aflatoxigenic fungi

2009 ◽  
Vol 2 (3) ◽  
pp. 305-312 ◽  
Author(s):  
A. Nesci ◽  
S. Marín ◽  
M. Etcheverry ◽  
V. Sanchis
Keyword(s):  
Ferulic Acid ◽  
Incubation Period ◽  
Cinnamic Acid ◽  
Inhibitory Effect ◽  
Aspergillus Section Flavi ◽  
Aflatoxigenic Fungi ◽  
Incubation Periods ◽  
Maize Grain ◽  
Aflatoxin B ◽  
Aspergillus Section

This research was undertaken to evaluate the effects of the natural phytochemicals trans-cinnamic acid (CA) alone at concentrations of 20 and 25 mM, ferulic acid (FA) at concentration of 30 mM and two mixtures, CA-FA (20+30 mM) and CA-FA (25+30 mM) on natural maize mycoflora, Aspergillus section Flavi population and aflatoxin B1 production. These studies were carried out in maize grain in relation to a water activity of 0.99, 0.97 and 0.94. CA at 25 mM and the mixture CA-FA (25+30 mM) were the most effective treatments at inhibiting natural maize mycoflora at all aw assayed after 11 and 35 days of incubation at 25 °C. In general, 20 mM CA caused complete inhibition of Aspergillus section Flavi population at all aw values tested during all incubation period without an additional inoculum. 20 mM CA and 25 mM CA showed the major inhibitory effect on aflatoxin B1 accumulation of control and Aspergillus section Flavi additionally inoculated during all incubation periods. The data showed that CA and FA could be considered as effective fungitoxicants for natural maize mycoflora and aflatoxigenic fungi in the aw range 0.99 to 0.94. The information obtained shows promise for controlling aflatoxigenic fungi in stored maize.

scholarly journals Aflatoxin B and G contamination in imported peanuts and Aspergillus section Flavi of the causing fungi

2008 ◽  
Vol 58 (2) ◽  
pp. 107-114 ◽  
Author(s):  
Kiyoshi OKANO ◽  
Tsuneyoshi TOMITA ◽  
Yuko KUMEDA ◽  
Keiko MATSUMARU ◽  
Masakatsu ICHINOE
Keyword(s):  
Aspergillus Section Flavi ◽  
Aflatoxin B ◽  
Aspergillus Section

scholarly journals Distribution of Aspergillus Section Flavi among Field Soils from the Four Agroecological Zones of the Republic of Bénin, West Africa

Plant Disease ◽  
2002 ◽  
Vol 86 (4) ◽  
pp. 434-439 ◽  
Author(s):  
K. F. Cardwell ◽  
P. J. Cotty
Keyword(s):  
Cropping Systems ◽  
Fermentation Medium ◽  
Soil Samples ◽  
Aspergillus Section Flavi ◽  
The North ◽  
Agroecological Zones ◽  
Republic Of Benin ◽  
The Republic ◽  
Aflatoxin B ◽  
Aspergillus Section

Certain members of Aspergillus section Flavi produce carcinogenic and immunotoxic metabo-lites called aflatoxins. These fungi perennate in soils and infect maize grain in the field and in storage. The distribution of Aspergillus section Flavi across the four different agroecologies of Bénin Republic was determined. The four agroecological zones range from humid equatorial tropics in the south to the dry savanna near the Sahara desert in the north. Soil samples collected in 1994 to 1996 from 44 different maize fields in Bénin were assayed over 3 years (88 samples total) for fungi in Aspergillus section Flavi. All soils tested contained A. flavus. Isolates (1,454 total) were collected by dilution plate from the soils and existed in populations ranging from <10 to >200 CFU/g of soil. CFU counts did not differ from year to year or change significantly with cropping systems within a zone, but differed significantly among zones. Incidence of A. flavus strain isolations varied from south to north, with greater number of CFU of L strain isolates in southern latitudes and higher numbers of CFU of S strain isolates found in the north. The L strain isolates occurred in 81 of 88 samples, whereas S strain isolates were in only 41 of 88 soil samples. Of 96 L strain isolates tested, 44% produced aflatoxins. Only B toxins were produced, and toxigenic isolates averaged over 100 μg of aflatoxin B1 per 70 ml of fermentation medium (~1.4 ppm). All S strain isolates produced both B and G aflatoxins, averaging over 557 μg of aflatoxin B1 per 70 ml (8 ppm) and 197 μg of aflatoxin G1 per 70 ml of fermentation me- dium (2.8 ppm). A. parasiticus and A. tamarii were present in less than 10% of the fields and were not associated with any particular agroecological zone.

scholarly journals γ-Butyrolactones from Aspergillus Species: Structures, Biosynthesis, and Biological Activities

2017 ◽  
Vol 12 (5) ◽  
pp. 1934578X1701200 ◽  
Author(s):  
Sabrin R. M. Ibrahim ◽  
Gamal A. Mohamed ◽  
Amgad I.M. Khedr
Keyword(s):  
Secondary Metabolites ◽  
Biological Activities ◽  
Rich Source ◽  
Aspergillus Species ◽  
Aromatic Rings ◽  
Naturally Occurring ◽  
Fungal Secondary Metabolites

Recently, numerous metabolites possessing uncommon structures and potent bioactivity have been isolated from strains of fungi collected from diverse environments. The genus Aspergillus is known as a rich source of γ-butyrolactones. These are a group of fungal secondary metabolites, consisting of a five-membered lactone bearing two aromatic rings, which shows a great variety of biological activities. This review summarizes the research on the biosynthesis, source, and biological activities of the naturally occurring γ-butyrolactones that have been isolated from Aspergillus species published over the last decades. More than 75 compounds are described and 65 references are cited.

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