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Molecular identification of Aspergillus and Eurotium species isolated from rice and their toxin-producing ability
D Yazdani1, M A Zainal Abidin, Y H Tan
1Department of Plant Protection, Faculty of Agriculture, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia.
Abstract:
Thirty milled rice samples were collected from retailers in 4 provinces of Malaysia. These samples were evaluated for Aspergillus spp. infection by direct plating on malt extract salt agar (MESA). All Aspergillus holomorphs were isolated and identified using nucleotide sequences of ITS 1 and ITS 2 of rDNA. Five anamorphs (Aspergillus flavus, A. oryzae, A. tamarii, A. fumigatus and A. niger) and 5 teleomorphs (Eurotium rubrum, E. amstelodami, E. chevalieri, E. cristatum and E. tonophilum) were identified. The PCR-sequencing based technique for sequences of ITS 1 and ITS 2 is a fast technique for identification of Aspergillus and Eurotium species, although it doesn't work flawlessly for differentiation of Eurotium species. All Aspergillus and Eurotium isolates were screened for their ability to produce aflatoxin and ochratoxin A (OTA) by HPLC and TLC techniques. Only A. flavus isolate UPM 89 was able to produce aflatoxins B1 and B2.
Insights
Milled rice in Malaysia may be contaminated with Aspergillus and Eurotium species. Only one Aspergillus flavus isolate produced aflatoxins B1 and B2, indicating a low risk of mycotoxin contamination in these rice samples.
Area of Science:
- Food microbiology
- Mycology
- Food safety
Background:
- Milled rice is a staple food globally and susceptible to fungal contamination.
- Aspergillus and Eurotium species are common molds that can produce harmful mycotoxins.
Purpose of the Study:
- To identify Aspergillus and Eurotium species in Malaysian milled rice.
- To assess the mycotoxin-producing potential of these fungal isolates.
Main Methods:
- Fungal isolation using malt extract salt agar (MESA).
- Species identification via rDNA ITS 1 and ITS 2 sequencing.
- Mycotoxin analysis (aflatoxins and ochratoxin A) using HPLC and TLC.
Main Results:
- Identified five Aspergillus anamorphs and five Eurotium teleomorphs.
- PCR-sequencing proved effective for species identification, though Eurotium differentiation was challenging.
- Only one Aspergillus flavus isolate (UPM 89) produced aflatoxins B1 and B2.
Conclusions:
- Malaysian milled rice samples showed a low incidence of mycotoxin-producing fungi.
- Molecular techniques offer rapid fungal identification but require refinement for certain species.
- Further surveillance is recommended to ensure ongoing food safety.
