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.

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.

scholarly journals Landscape resistance constrains hybridization across contact zones in a reproductively and morphologically polymorphic salamander

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Guillermo Velo-Antón ◽  
André Lourenço ◽  
Pedro Galán ◽  
Alfredo Nicieza ◽  
Pedro Tarroso
Keyword(s):  
Contact Zone ◽  
Environmental Heterogeneity ◽  
Evolutionary Dynamics ◽  
Morphological Differentiation ◽  
Phenotypic Traits ◽  
Hybrid Zones ◽  
Landscape Resistance ◽  
Phenotypic Differentiation ◽  
Contact Zones

AbstractExplicitly accounting for phenotypic differentiation together with environmental heterogeneity is crucial to understand the evolutionary dynamics in hybrid zones. Species showing intra-specific variation in phenotypic traits that meet across environmentally heterogeneous regions constitute excellent natural settings to study the role of phenotypic differentiation and environmental factors in shaping the spatial extent and patterns of admixture in hybrid zones. We studied three environmentally distinct contact zones where morphologically and reproductively divergent subspecies of Salamandra salamandra co-occur: the pueriparous S. s. bernardezi that is mostly parapatric to its three larviparous subspecies neighbours. We used a landscape genetics framework to: (i) characterise the spatial location and extent of each contact zone; (ii) assess patterns of introgression and hybridization between subspecies pairs; and (iii) examine the role of environmental heterogeneity in the evolutionary dynamics of hybrid zones. We found high levels of introgression between parity modes, and between distinct phenotypes, thus demonstrating the evolution to pueriparity alone or morphological differentiation do not lead to reproductive isolation between these highly divergent S. salamandra morphotypes. However, we detected substantial variation in patterns of hybridization across contact zones, being lower in the contact zone located on a topographically complex area. We highlight the importance of accounting for spatial environmental heterogeneity when studying evolutionary dynamics of hybrid zones.

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 Aflatoxin Contamination of Dried Insects and Fish in Zambia

2018 ◽  
Vol 81 (9) ◽  
pp. 1508-1518 ◽  
Author(s):  
PAUL W. KACHAPULULA ◽  
JULIET AKELLO ◽  
RANAJIT BANDYOPADHYAY ◽  
PETER J. COTTY
Keyword(s):  
Dietary Protein ◽  
Aflatoxin Production ◽  
Aflatoxin Contamination ◽  
Food Contaminants ◽  
Edible Insect ◽  
Aspergillus Section Flavi ◽  
Regulatory Limits ◽  
Data Gaps ◽  
Dried Fish ◽  
Aspergillus Section

ABSTRACT Dried insects and fish are important sources of income and dietary protein in Zambia. Some aflatoxin-producing fungi are entomopathogenic and also colonize insects and fish after harvest and processing. Aflatoxins are carcinogenic, immune-suppressing mycotoxins that are frequent food contaminants worldwide. Several species within Aspergillus section Flavi have been implicated as causal agents of aflatoxin contamination of crops in Africa. However, aflatoxin producers associated with dried fish and edible insects in Zambia remain unknown, and aflatoxin concentrations in these foods have been inadequately evaluated. The current study sought to address these data gaps to assess potential human vulnerability through the dried fish and edible insect routes of aflatoxin exposure. Caterpillars (n = 97), termites (n = 4), and dried fish (n = 66) sampled in 2016 and 2017 were assayed for aflatoxin by using lateral flow immunochromatography. Average aflatoxin concentrations exceeded regulatory limits for Zambia (10 μg/kg) in the moth Gynanisa maja (11 μg/kg), the moth Gonimbrasia zambesina (Walker) (12 μg/kg), and the termite Macrotermes falciger (Gerstacker) (24 μg/kg). When samples were subjected to simulated poor storage, aflatoxins increased (P &lt; 0.001) to unsafe levels in caterpillars (mean, 4,800 μg/kg) and fish (Oreochromis) (mean, 23 μg/kg). The L strain morphotype of A. flavus was the most common aflatoxin producer on dried fish (88% of Aspergillus section Flavi), termites (68%), and caterpillars (61%), with the exception of Gynanisa maja, for which A. parasiticus was the most common (44%). Dried fish and insects supported growth (mean, 1.3 × 109 CFU/g) and aflatoxin production (mean, 63,620 μg/kg) by previously characterized toxigenic Aspergillus section Flavi species, although the extent of growth and aflatoxigenicity depended on specific fungus-host combinations. The current study shows the need for proper storage and testing of dried insects and fish before consumption as measures to mitigate human exposure to aflatoxins through consumption in Zambia.

Fungal screening and aflatoxin production by Aspergillus section Flavi isolated from pre-harvest maize ears grown in two Argentine regions

2017 ◽  
Vol 92 ◽  
pp. 41-48 ◽  
Author(s):  
Boris X. Camiletti ◽  
Ada K. Torrico ◽  
M. Fernanda Maurino ◽  
Diego Cristos ◽  
Carina Magnoli ◽  
...  
Keyword(s):  
Aflatoxin Production ◽  
Aspergillus Section Flavi ◽  
Aspergillus Section
Sign in / Sign up

Export Citation Format

Share Document