Culture-independent analysis of yeast diversity in Korean traditional fermented soybean foods (doenjang and kanjang) based on 26S rRNA sequence

Abstract

The yeast-26S rRNA libraries were constructed from two different fermented soybean foods, doenjang and kanjang. A total of 42 clones, containing the partial 26S rRNA sequences, 0.6 kb in length, were sequenced and subjected to an online similarity search. All doenjang yeast (DY) clones only appeared in the Saccharomycotina class. The 21 clones from the doenjang library were classified into five groups: Debaryomyces hansenii (DY I, 76.0 %), Zygosaccharomyces pseudorouxii (DY II, 9.6 %), Candida versatilis (DY III, 4.8 %), Candida etchellsii (DY IV, 4.8 %), and Debaryomyces castellii (DY V, 4.8 %). The 21 kanjang yeast (KY) clones were affiliated with the Saccharomycotina (52.4 %), Urediniomycetes (19.0 %), Ustilaginomycetes (23.8 %), and Hymenomycetes (4.8 %) classes and divided into six groups: D. hansenii (KY I, 38.0 %), Sterigmatomyces halophilus (KY II, 19.0 %), Malassezia restricta (KY III, 23.8 %), Cryptococcus magnus (KY V, 4.8 %), and Pichia triangularis (KY VI, 9.6 %). Yeast belonging to the Saccharomycotina class was predominant (76.2 %) in fermented soybean foods, doenjang and kanjang. These findings are of fundamental value for understanding the complexity of two different fermented soybean foods.