Reliability of the chemical, metabolic, and molecular methods in discriminating aflatoxigenic from non-aflatoxigenic Aspergillus isolates

Peter Kipruto Ronoh; Faith Jebet Toroitich; Huxley Mae Makonde; Elijah Kipkorir Lelmen; Meshack Amos Obonyo

The Microbe (Sep 2024)

Reliability of the chemical, metabolic, and molecular methods in discriminating aflatoxigenic from non-aflatoxigenic Aspergillus isolates

Peter Kipruto Ronoh,
Faith Jebet Toroitich,
Huxley Mae Makonde,
Elijah Kipkorir Lelmen,
Meshack Amos Obonyo

Affiliations

Peter Kipruto Ronoh: Department of Biochemistry and Molecular Biology, Egerton University, Egerton, Nakuru County P.O. Box 536-20115, Kenya; Corresponding author.
Faith Jebet Toroitich: Department of Biological Sciences, Egerton University, Egerton, Nakuru County P.O. Box 536-20115, Kenya
Huxley Mae Makonde: Department of Pure and Applied Sciences, Technical University of Mombasa, Mombasa P.O Box 90420-80100, Kenya
Elijah Kipkorir Lelmen: Department of Biochemistry and Molecular Biology, Egerton University, Egerton, Nakuru County P.O. Box 536-20115, Kenya
Meshack Amos Obonyo: Department of Biochemistry and Molecular Biology, Egerton University, Egerton, Nakuru County P.O. Box 536-20115, Kenya; Mycotoxin Research Laboratory, Egerton University, P.O. Box 536, Egerton, Nakuru County 20115, Kenya; Corresponding author at: Department of Biochemistry and Molecular Biology, Egerton University, Egerton, Nakuru County P.O. Box 536-20115, Kenya.

Journal volume & issue: Vol. 4
p. 100115

Abstract

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Aflatoxins, potent carcinogens produced by Aspergillus species (A. flavus and A. parasiticus), are primarily consumed through dietary sources. Aflatoxin management using non-aflatoxigenic Aspergillus to outcompete their aflatoxigenic congeneric to achieve low residual toxin levels is a promising biological control (BC) field intervention. A prerequisite for the BC program is the accurate delineation of aflatoxigenic fungi from their non-aflatoxigenic relatives. In this study, we use three methods: Chemical (Dichlorvos-ammonia), Metabolic (ELISA coupled live cultures), and Molecular (10 aflatoxin biosynthetic genes) to determine the aflatoxigenicity of Aspergillus spp. previously collected from Eastern Kenya, an aflatoxin hotspot. Thirty-six different Aspergillus isolates were identified and studied microscopically from a total of 314 fungal cultures. The chemical method reported 21 aflatoxigenic and 15 non-aflatoxigenic isolates, while the metabolic technique distinguished 20 aflatoxigenic and 16 non-aflatoxigenic isolates. A large proportion (97.22 %) of the isolates harboured the aflR, aflO, and aflM genes, while 91.67 % of the isolates possessed the aflS gene. All isolates (100 %) harboured the aflD, aflQ, aflP, and aflK genes. ELISA-coupled live cultures positively correlated with Dichlorvos-ammonia (p > 0.01), only differing in one sample, indicating a strong concurrence between the two methods at segregating toxigenic A. flavus isolates. Cluster analysis based on Multiple Correspondence revealed that the non-aflatoxigenic group exhibited similar characteristics correlating with the absence of aflR, aflS, aflI, and aflO genes. These findings indicate the reliability of the Chemical and Metabolic methods and can function as confirmatory assays to complement the molecular detection approach in determining aflatoxigenicity among Aspergillus spp.

Published in The Microbe

ISSN: 2950-1946 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Science: Microbiology
Website: https://www.sciencedirect.com/journal/the-microbe

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