Occurrence of Aflatoxigenic Aspergillus Species in Corn Harvested from Different Locations in Korea

Introduction:  Corn is one of cereals vulnerable to aflatoxin contamination. In South Korea, low levels of aflatoxin have been detected in corn and corn-based products, but information about the fungi involved in this contamination is limited.

Purpose: The aim of this study was to determine, identify and characterize the occurrence of aflatoxin-producing species in corn harvested from 25 locations in South Korea. 

Methods:  A total of 216 fungal isolates were obtained from 66 corn samples in Korea collected in 2010. After incubation in pure culture, aflatoxin production in those isolates was investigated via multiplex PCR assay, thin layer chromatography and high performance chromatography. Repetitive sequence based PCR (rep-PCR) DNA fingerprinting was also performed to determine genomic relationships.

Results:  A range of 0-1.5×10⁶ CFU/g fungal flora counted from corn samples. Mycological analyses showed that Fusarium and Penicillium species (22.2%) were the most predominant species, followed by Mucor species (12.0%), Aspergillus species (11.1%) and other fungal genera. Out of 24 Aspergillus isolates, 14 isolates of Aspergillus section flavi were screened through morphological and genetic identification. Among 14 isolates, three isolates showed complete amplified patterns in all target genes, and produced aflatoxin B1. Rep-PCR DNA fingerprinting showed that five isolates from corn were clustered with aflatoxigenic A. flavusKCCM60330 (98-98.8% similarity).

Significance:  These results suggest that occurrence and abundance of aflatoxigenic Aspergillus in corn were low.