Molecular and Vegetative Compatibility Groups Characterization of <i>Aspergillus flavus</i> Isolates from Kenya

Alfred Mitema; Naser Aliye Feto; Alfred Mitema; Naser Aliye Feto

doi:10.3934/microbiol.2020015

AIMS Microbiology

2020, Volume 6, Issue 3: 231-249. doi: 10.3934/microbiol.2020015

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Research article

Molecular and Vegetative Compatibility Groups Characterization of Aspergillus flavus Isolates from Kenya

Alfred Mitema ^1,2,
Naser Aliye Feto ^{1
,
,}

1.
OMICS Research Group, Department of Biotechnology, Vaal University of Technology, Vanderbijlpark 1911, South Africa
2.
School of Biological Sciences, University of Nairobi, Nairobi, Kenya

Received: 21 April 2020 Accepted: 06 July 2020 Published: 31 July 2020

The genus Aspergillus contains diverse species and the identification is complicated. Vegetative compatibility groups (VCGs) and molecular mechanisms were deployed to study the species. The study was randomly conducted in four counties in Kenya based on the history of aflatoxicosis and maize cultivation. Thirty-seven Aspergillus flavus isolates from Nandi, Kisumu, Homa Bay and Makueni were characterized to determine their taxonomic status based on their VCGs and genotypes. A phylogenetic analysis of ITS1 and ITS2 sequences of the isolates investigated revealed ITS primers discriminating some of the A. flavus isolates as 100% sequence identity to the RefSeq. Nit mutants' complementation test revealed strong heterokaryon incompatibility between isolates of Nandi region (67%) and Makueni (33%). The trend based on VCGs and molecular findings showed high incidence of toxigenic A. flavus in Makueni, which could be the reason why the region frequently experiences chronic aflatoxicosis incidences over the last few decades as compared to other regions. Interestingly, we have discovered all S and L-morphotypes including the rare S/L-morphotypes, which implies that Kenya is home to all morphotypes of A. flavus. Thus, the analysis provides a deeper understanding of the taxonomic relationship between the A. flavus isolates and could help contextualise the data obtained for each isolate with respect to VCG genetic diversity and genotypes. Determining the primary causal agents of aflatoxin contamination is critical for predicting risk of contamination events and designing and implementing effective management strategies.
- Aspergillus flavus,
- aflatoxicosis,
- morphotype,
- vegetative compatibility group,
- heterokaryon
Citation: Alfred Mitema, Naser Aliye Feto. Molecular and Vegetative Compatibility Groups Characterization of Aspergillus flavus Isolates from Kenya[J]. AIMS Microbiology, 2020, 6(3): 231-249. doi: 10.3934/microbiol.2020015

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Abstract

The genus Aspergillus contains diverse species and the identification is complicated. Vegetative compatibility groups (VCGs) and molecular mechanisms were deployed to study the species. The study was randomly conducted in four counties in Kenya based on the history of aflatoxicosis and maize cultivation. Thirty-seven Aspergillus flavus isolates from Nandi, Kisumu, Homa Bay and Makueni were characterized to determine their taxonomic status based on their VCGs and genotypes. A phylogenetic analysis of ITS1 and ITS2 sequences of the isolates investigated revealed ITS primers discriminating some of the A. flavus isolates as 100% sequence identity to the RefSeq. Nit mutants' complementation test revealed strong heterokaryon incompatibility between isolates of Nandi region (67%) and Makueni (33%). The trend based on VCGs and molecular findings showed high incidence of toxigenic A. flavus in Makueni, which could be the reason why the region frequently experiences chronic aflatoxicosis incidences over the last few decades as compared to other regions. Interestingly, we have discovered all S and L-morphotypes including the rare S/L-morphotypes, which implies that Kenya is home to all morphotypes of A. flavus. Thus, the analysis provides a deeper understanding of the taxonomic relationship between the A. flavus isolates and could help contextualise the data obtained for each isolate with respect to VCG genetic diversity and genotypes. Determining the primary causal agents of aflatoxin contamination is critical for predicting risk of contamination events and designing and implementing effective management strategies.

Acknowledgments

The work was supported by the University Science, Humanities and Engineering Partnerships in Africa (USHEPiA) Fund and South African Bio-Design Initiative (SABDI) grant number 420/01 SABDI 16/1021. Also, the authors acknowledge the University of Nairobi, Kenya and Vaal University of Technology, Vanderbijlpark, South Africa for providing laboratory space and funding.

Authors contribution

Data curation, Alfred Mitema; Formal analysis, Alfred Mitema and Naser Aliye Feto; Funding acquisition, Naser Aliye Feto; Investigation, Alfred Mitema; Methodology, Alfred Mitema and Naser Aliye Feto; Resources, Alfred Mitema and Naser Aliye Feto; Validation, Alfred Mitema; Writing – original draft, Alfred Mitema; Writing – review & editing, Alfred Mitema and Naser Aliye Feto.

Conflicts of interest

The authors declare no conflict of interest. The authors are responsible for the content and writing of the paper.

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