Molecular Identification of Aspergillus Strains and Quick Detection of Aflatoxin from Selected Common Spices in Tanzania

Abstract

Twenty three Aspergillus species isolated from nine commonly used spices in Tanzania were characterized to determine presence of potential aflatoxin producers. PCR of one regulatory (aflR) and three structural (aflD, aflM and aflO) aflatoxin biosynthetic pathway genes followed by nucleotide sequence analysis of 5.8S ITS rDNA region identified the potential aflatoxin producing strains.  Four Aspergillus strains had all four genes which were missing in two strains while the other strains had 1 to 3 genes. Among the four strains having all four genes, three were identified as A. flavus and one A. parasiticus.  Red chill was contaminated with three potential aflatoxin producer strains: A. flavus, A. parasiticus and A. tamarii. A. flavus was identified from red chill, black pepper and ginger. Using lateral flow immune-chromatographic assay, red chill tested positive with detectable ≥ 4 ppb of total aflatoxins. These results demonstrated that A. flavus is the most contaminant strain in the spices tested and thus may have risk implications based on their potential to produce aflatoxin. Further, both PCR of genes involved in aflatoxin production pathway and quick detection of total aflatoxin can be used to assess the quality of spices and predict its safety to consumers.