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Open AccessArticle

Polyphasic Assessment of Aflatoxin Production Potential in Selected Aspergilli

1
Bacteriophage Therapy and Phage Bio-control Laboratory, Department of Microbiology, Faculty of Natural and Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2745, South Africa
2
Center for Animal Health Studies, Faculty of Natural and Agricultural Sciences, North-West University, Private Bag X2046, Mmabatho 2745, South Africa
*
Author to whom correspondence should be addressed.
Toxins 2019, 11(12), 692; https://doi.org/10.3390/toxins11120692
Received: 24 September 2019 / Revised: 10 November 2019 / Accepted: 15 November 2019 / Published: 26 November 2019
This study investigated the aflatoxin production potentials of selected fungi using a polyphasic approach. Internally transcribed spacer region of the fungi was amplified using the polymerase chain reaction. Forty-five Aspergillus strains were further assessed for aflatoxin production using the conventional methods such as growth on yeast extract sucrose, β-cyclodextrin neutral red desiccated coconut agar (β-CNRDCA); expression of the aflatoxin regulatory genes and the use of both thin-layer chromatography (TLC) and high-performance liquid chromatography (HPLC). A large proportion (82.22%) of the isolates harbored the Nor-1 gene while 55.56%, 68.89%, and 80% possessed the ver-1, omt-A, and aflR genes, respectively. All 100% the isolates harbored the aflJ gene. Twenty-three isolates were positive for aflatoxin production based on the yeast extract sucrose medium (YES) test; ammonium vapor test (51%), yellow pigment production (75.5%), and β-CNRDCA tests; and blue/green fluorescence (57.7%). Based on TLC detection 42.2% produced aflatoxins while in the HPLC, total aflatoxin (AFTOT) production concentrations ranged from 6.77–71,453 µg/g. Detectable aflatoxin B1 (AFB1) concentrations obtained from the HPLC ranged between 3.76 and 70,288 µg/g; 6.77 and 242.50 µg/g for aflatoxin B2 (AFB2); 1.87 and 745.30 µg/g for aflatoxin G1 (AFG1); and 1.67 and 768.52 µg/g for aflatoxin G2 (AFG2). AFTOT contamination levels were higher than European Union tolerable limits (4 µg/kg). The regression coefficient was one (R2 = 1) while significant differences exist in the aflatoxin concentrations of Aspergillus (p ≤ 0.05). This study reports the potentials of Aspergillus oryzae previously known as a non-aflatoxin producer to produce AFG1, AFG2, AFB1, and AFB2 toxins. Aspergillus species in feedlots of animals reared for food are capable of producing aflatoxins which could pose hazards to health. View Full-Text
Keywords: aflatoxin; Aspergilli; feedlots; PCR; fungi aflatoxin; Aspergilli; feedlots; PCR; fungi
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Akinola, S.A.; Ateba, C.N.; Mwanza, M. Polyphasic Assessment of Aflatoxin Production Potential in Selected Aspergilli. Toxins 2019, 11, 692.

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