Molecular characterization and strain typing of fungal contaminants of Processed Manihot esculenta Crantz (“Garri”) in Ogun State, Nigeria

  • B T Thomas Olabisi Onabanjo University
  • L A Ogunkanmi
  • B A Iwalokun
  • G C Agu
Keywords: Aspergillus species, Electrophoresis, Fungi, Genetic diversity, Processed Manihot esculenta (Garri), Random Amplified Polymorphic DNA (RAPD)


Background: The lack of standard biochemical tests, coupled with the limitation of the number of micro and macro morphology that can be scored for fungal diagnosis, makes the identification of fungal organisms using microbiological methods less reliable.

Objective: To determine the fungal contaminants of processed Manihot esculenta Crantz (Garri) and provide information on their diversity.

Methods: In this study, fungal contaminants of processed Manihot esculenta Crantz (Garri) were characterized by sequencing the hyper-variable 18S ribosomal RNA as well as type the isolated organisms using Random Amplified Polymorphic DNA markers.

Results: The  PCR amplification of the 18S ribosomal RNA gene of the  isolated fungi from  processed Manihot esculenta Crantz yielded a single fragment of an approximately between 600 and 700 bp. BLAST search using Genbank database showed that the isolate percentage similarity with GenBank accessions ranged between 98% and 100%. The molecular technique successfully identified all the isolated organisms resulting in 100% accurate diagnosis as against 79.3%accurate diagnosis made with the microbiological method. The forty isolated Aspergillus species were further resolved into 27 RAPD haplotypes with Simpson Index of Genetic Diversity approaching one for all the isolates. The mean genetic diversity within (GL) and among (GS) the isolated Aspergillus species were found to be 89% and 11% respectively. The total genetic diversity (HT) for these organisms was approximately 48%.  These results connoted significant strain diversity in the sampled specimens as shown by differences in their electrophoretic patterns.

Conclusion: The study revealed significant strain diversity in the sampled specimens as shown by differences in their electrophoretic patterns.

Author Biography

B T Thomas, Olabisi Onabanjo University
Microbiology/Lecturer II


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