Molecular Characterization of Fungal Isolates of Locally Processed Rice from Five Agro-Ecological Zones of Nigeria

Abstract

The purpose of this study was to characterize fungal isolates contaminating locally processed rice in Nigeria and to assess the genetic similarity in the fungi isolates. Fungal species were characterized by amplification of a segment of the β-tubulin gene using Bt2aF (5’-GGTAACCAAATCGGTGCTGCTTTC-3’) and Bt2bR (5’ACCCTCAGTGT GT GACCCTTGGC-3’) primers and phylogenetic relationship established using the Maximum Likelihood method. Amplification of between 450 and 550bp of the β-tubulin region of the genomic DNA of the fungal isolates was obtained from thirty-eight samples (89%). Members of Aspergillus section flavi and section nigri groups were differentiated as A. flavus, A. parasiticus, A. tubigensis, A. sydowii and A. niger respectively. Molecular method identified Paecilomycesformosus with 99% similarity index while all the morphologically identified Penicillium species were identified to genus level as P. formosus, P. steckii and P. citrinum with a percentage similarity ranging from 95%-100%. Collectotrichum fruticola and Talaromyces flavus from SGS and NGS zone respectively were documented for the first time in the locally processed rice with 100% and 89% similarity index respectively. All the Aspergillus species were closely related to one another and narrowly diverged from the Penicillium species. Aspergilla and Penicillia were the predominant genera identified and the isolates were genetically similar irrespective of their agroecological zones.