Molecular characterization of aflatoxin producing fungi associated with maize in selected areas of Morogoro municipality, Tanzania

Abstract

Aspergillus species remain to be a doughty species for the safety of agricultural crops by colonizing and contaminating them via mycotoxin production, particularly aflatoxin. This study aimed at conventionally screening and molecularly detect and characterize Aflatoxin producing fungi particularly Aspergillus spp from Maize selling markets and maize grain milling machines in Morogoro urban and Mvomero district.  Thirty maize grain samples were collected from Morogoro Municipality and Mvomero district in Tanzania. The laboratory analysis was done using the blotter technique, where maize grain samples were subjected to a blotter test and the resultant growing mycelia were transferred to Potato Dextrose Agar (PDA). Thereafter, colony morphology, colour and texture for fungal identification was observed. Macro and microconidia, seriate and septate were used for initial identification of fungi and finally confirmed by a molecular technique through extracting fungal Deoxyribonucleic acid (DNA) from mycelia followed by subjecting them to Polymerase Chain Reaction (PCR) by amplifying the Internal Transcribed Spacer (ITS) region finalizing with DNA sequencing through sanger sequencing method. The results of conventional screening showed that the majority of the maize grain samples were contaminated with Fusarium spp. 36.7% (11/30), followed by Penicillium spp. 30.0% (9/30), Aspergillus spp. 20.0% (6/30) and Rhizopus spp. 13.3% (4/30). Sequence analyses of Aspergillus species revealed that out of 6 Aspergillus isolates, 3 were Aspergillus spp namely; Aspergillus flavus, Aspergillus niger and Aspergillus wentii while 1 was Talaromyces flavus. These results confirm the presence of potential aflatoxin-producing fungi that may colonize the maize. In conclusion, the presence of diverse fungal genera, including aflatoxin-producing Aspergillus species, highlights the need for broader screening by expanding the sample size while considering the spatial and temporal characteristics to plan for fungal contamination mitigation measure in future.