Taxonomic Characterization, Evaluation of Toxigenicity, and Saccharification Capability of Aspergillus Section Flavi Isolates from Korean Traditional Wheat-Based Fermentation Starter Nuruk

• Published in: Mycobiology Vol. 44; no. 3; pp. 155 - 161
• Main Authors: Bal, Jyotiranjan, Yun, Suk-Hyun, Chun, Jeesun, Kim, Beom-Tae, Kim, Dae-Hyuk
• Format: Journal Article
• Language: English
• Published: Korea (South) The Korean Society of Mycology 01.09.2016; 한국균학회
• Subjects: 생물학; Aspergillus; Nuruk; Amylase; Protease; Aflatoxin
• ISSN: 1229-8093; 2092-9323
• DOI: 10.5941/MYCO.2016.44.3.155

The most economically important species used in a wide range of fermentation industries throughout Asia belong to section , which are morphologically and phylogenetically indistinguishable, with a few being toxigenic and therefore a major concern. They are frequently isolated from Korean fermentation starters, such as and . The growing popularity of traditional Korean alcoholic beverages has led to a demand for their quality enhancement, therefore requiring selection of efficient non-toxigenic strains to assist effective fermentation. This study was performed to classify the most efficient strains of section isolated from various types of traditional wheat , based on a polyphasic approach involving molecular and biochemical evaluation. A total of 69 strains were isolated based on colony morphology and identified as / based on internal transcribed spacer and calmodulin gene sequencing. Interestingly, none were toxigenic based on PCR amplification of intergenic regions of the aflatoxin cluster genes - and the absence of aflatoxin in the culture supernatants by thin-layer chromatography analysis. Saccharification capability of the isolates, assessed through α-amylase and glucoamylase activities, revealed that two isolates, TNA24 and TNA15, showed the highest levels of activity. Although the degrees of variation in α-amylase and glucoamylase activities among the isolates were higher, there were only slight differences in acid protease activity among the isolates with two, TNA28 and TNA36, showing the highest activities. Furthermore, statistical analyses showed that α-amylase activity was positively correlated with glucoamylase activity ( < 0.001), and therefore screening for either was sufficient to predict the saccharifying capacity of the strain.