| Title | Comprehensive analysis of fungal diversity and enzyme activity in nuruk, a Korean fermenting starter, for acquiring useful fungi |
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| Author | Emily Carroll1, Tran Ngoc Trinh1, Hokyoung Son2, Yin-Won Lee3, and Jeong-Ah Seo1* |
| Address | 1School of Systems Biomedical Science, Soongsil University, Seoul 06978, Republic of Korea, 2Center for Food and Bioconvergence, Seoul National University, Seoul 08826, Republic of Korea, 3Department of Agricultural Biotechnology, Seoul National University, Seoul 08826, Republic of Korea |
| Bibliography | Journal of Microbiology, 55(5),357-365, 2017, |
| DOI | 10.1007/s12275-017-7114-z |
| Key Words | fungal diversity, nuruk, Saccharomycopsis fibu-ligera, enzyme activity, application |
| Abstract | Nuruk is a fermenting starter that is involved in the pro-duction of alcoholic beverages, and has been used in South Korea for a very long time. To analyze the fungal diversity, we collected a total of 59 nuruk samples from several com-panies and persons in 2013 to 2014, and obtained 364 iso-lates. All of the single isolated fungi were identified, both morphologically and molecularly, based on the sequences of ribosomal RNA gene [18S, ITS1-5.8S-ITS2, and 26S (D1/D2 region)]. In 46 nuruk samples out of 59 (78%), Saccharo-mycopsis fibuligera, a dimorphic yeast, was most frequently isolated. Among the filamentous fungi, Aspergillus and Lich-theimia were found in more than 50% of the samples with lower colony forming unit (CFU/g of sample) than those of yeasts. The yeasts S. fibuligera and Wickerhamomyces ano-malus were counted with maximum 1.3 – 1.8 × 108 CFU/g. Among Mucorales fungi, Lichtheimia and Mucor were iso-lated in much higher numbers than Rhizopus and Rhizo-mucor. Overall, the home-made nuruks tend to contain more diverse filamentous fungi than the commercial nuruks. To acquire industrially useful filamentous fungi and yeasts, we analyzed the enzyme activities of α-amylase, glucoamylase and acid protease associated with brewing properties for 131 strains. Aspergillus oryzae and S. fibuligera had high α- and glucoamylase activities and most isolates of Lichtheimia ramosa had high acid protease activity. For further applica-tions, 27 fungal strains were chosen based on isolation fre-quencies from nuruk, and the ability to produce useful en-zyme. |