Molecular Identification and Phylogenetic Tree of Mycotoxigenic Fungi from Sorghum (Sorghum bicolour) In Niger Republic, Africa

Abstract

Sorghum is a member of the Poaceae grass family and is considered the fifth most important cereal in the world after wheat, maize, rice and barley and second in Africa after maize. Millions of dollars are lost annually in Africa due to fungal contamination of vital crops like sorghum, threatening food security and livelihoods. This study focused on the molecular identification of mycotoxigenic fungi in sorghum samples from Niger Republic. Samples were collected from stores and markets across the four major zones of Niger. The standard pour plate method was used for estimating and isolating potentially mycotoxigenic fungi, which were then identified based on morphological characteristics and confirmed using molecular techniques. BioEdit Sequence Alignment Editor version 7.2.5 was used for sequence editing. The edited sequences were compared to known sequences in a database using the NCBI BLAST search tool to identify the specific fungal species. The phylogenetic tree was constructed using Mega 11 and the UPGMA platform at default settings. The study revealed variations in the average fungal count between zones and between store and market samples within each zone. No statistically significant (p<0.05) difference was found in average fungal counts between zones for store samples. However, a statistically significant difference was observed in market samples, with Zone I recording significantly lower average counts (1.75x102 CFU/g) compared to other zones. The average fungal counts ranged from 8.50x102 to 19.0x102 CFU/g in store samples and 1.75x102 to 17.67x102CFU/g in market samples. The most commonly isolated fungal genera, in descending order, were Aspergillus niger, Aspergillus flavus, Mucor sp., Aspergillus fumigatus, Penicillium sp., Aspergillus glaucus, Trichoderma sp., Fusarium sp., Chrysosporium sp., and Curvularia sp.. Molecular techniques confirmed the presence of Penicillium glandicola, Aspergillus flavus, Aspergillus fumigatus, and Fusarium solani and their phylogenetic relationships and origin were determined from their gene sequences. This study identified fungal contamination, particularly in stored sorghum, as a threat to food security due to reduced grain quality and potential health risks, highlighting the need for improved post-harvest practices to minimise fungal growth and ensure the safety of this vital food source. This study identified fungal contamination, particularly in stored sorghum, as a threat to food security due to reduced grain quality and potential health risks.