The uncertainty of assessing aflatoxin B1-producing ability using aflR gene in Aspergillus species

Abstract

Aspergillus section Flavi consists of many species which are very similar in morphology and very important in human health and food industry. Aspergillus flavus, Aspergillus parasiticus, and Aspergillus toxicarius are notorious aflatoxigenic species. Aspergillus oryzae and Aspergillus sojae are non-aflatoxigenic species and widely used for Oriental fermented food. The presence of the aflR gene and aflatoxin B1 (AFB1) production ability was assessed by PCR detection and HPLC analysis, respectively. The investigation of AFB1 and amplification of the aflR gene in thirty five authentic strains of Aspergillussection Flavi showed that (1) all the AFB1-producing strains were detected to possess theaflR gene; (2) some non AFB1-producing Aspergillus section Flavi strains are constitutional, and are not detected to possess the aflR gene; (3) some strains used in Oriental fermentation have the aflR gene but they are non AFB1-producing aspergilli. The conclusion is that it is uncertain to judge the aflatoxigenicity of an Aspergillus strain using the aflR gene as an indicator. Key words: Aspergillus, aflatoxin, alfR gene, HPLC, PCR.