Molecular detection of mycobiota and the associated mycotoxins in rice grains imported into Saudi Arabia

Abstract

Rice is a staple food consumed across the world and its purity is essential to manage human health. However, fungal mycotoxins are one of the real challenges for maintaining the purity of rice intended for human consumption. The present study was designed to detect the fungal isolates present in the imported rice cultivars obtained from the local markets of the Kingdom of Saudi Arabia and the mycotoxins they produce using molecular approaches. The morphological analysis and PCR-based sequencing of ITS-rDNA specify that the isolates in the contaminated rice belonged to Aspergillus and Penicillium genera. The phylogenetic analysis based on sequences of ITS-rDNA regions of the isolates confirmed that the Aspergillus isolates were homological to A. flavus and A. nidulans. Whereas, the Penicillium isolates were homological to P. commune and P. chrysogenum. The identification of mycotoxins using LC-MS revealed that the isolates of the genus Aspergillus produced aflatoxin and ochratoxin. The isolates of Penicillium genus produced citreoviridin and citrinin. The levels of mycotoxins varied among each variety of the rice samples tested in total. Ochratoxin was produced at the least concentration (184.7 µg/kg) in the contaminated samples. Citrinin (23170.5 µg/kg) was produced at higher volumes in comparison to other mycotoxins. These levels of mycotoxin contamination are alarming and raise significant queries regarding the purity of the imported rice grains throughout the period of harvest and storage. Therefore, the development of practical control is required for consumer safety.