title: Taxonomic Characterization, Evaluation of Toxigenicity, and Saccharification Capability ofAspergillusSectionFlaviIsolates from Korean Traditional Wheat-Based Fermentation StarterNuruk.
abstract: The most economically important species used in a wide range of fermentation industries throughout Asia belong toAspergillussectionFlavi, 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 asnurukandmeju. 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 ofAspergillussectionFlaviisolated from various types of traditional wheatnuruk, based on a polyphasic approach involving molecular and biochemical evaluation. A total of 69 strains were isolated based on colony morphology and identified asAspergillusoryzae/flavusbased on internal transcribed spacer and calmodulin gene sequencing. Interestingly, none were toxigenic based on PCR amplification of intergenic regions of the aflatoxin cluster genesnorB-cypAand 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 (p< 0.001), and therefore screening for either was sufficient to predict the saccharifying capacity of theAspergillusstrain.
authors: Department of Molecular Biology, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.; Department of Bioactive Material Sciences, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.
authors: Jyotiranjan
authors: J
authors: Bal
authors: Department of Molecular Biology, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.; Department of Bioactive Material Sciences, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.
authors: Suk-Hyun
authors: SH
authors: Yun
authors: Department of Molecular Biology, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.; Department of Bioactive Material Sciences, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.
authors: Jeesun
authors: J
authors: Chun
authors: Department of Bioactive Material Sciences, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.
authors: Beom-Tae
authors: BT
authors: Kim
authors: Department of Molecular Biology, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.; Department of Bioactive Material Sciences, Institute for Molecular Biology and Genetics, Chonbuk National University, Jeonju 54896, Korea.
authors: Dae-Hyuk
authors: DH
authors: Kim
keywords: Aflatoxin; Amylase; Aspergillus; Nuruk; Protease