Seong-Yeol Baek

Taxonomy of Eurotium species isolated from meju

Eurotium strains were isolated from 77 loaves of meju (dried fermented soybeans), in various regions of Korea from 2008 to 2010. Morphological characteristics and DNA sequences of β-tubulin were examined. They were identified as Eurotium amstelodami, E. chevalieri, E. herbariorum, E. repens, E. rubrum, and E. tonophilum. Of these species, E. chevalieri and E. tonophilum had not been previously reported in association with meju. E. chevalieri and E. repens were the species isolated most frequently. This paper summarizes the morphological characteristics of six Eurotium species and provides key to identify the species from meju.

Zygomycota associated with traditional meju, a fermented soybean starting material for soy sauce and soybean paste.

Various zygomycota species were detected during a study of the mycobiota of meju, a brick of dried fermented soybeans, used in Korean cuisine. Two hundred and sixty-eight strains were isolated from 98 finished meju products collected in various regions of Korea from 2009 to 2011, and 96 strains were isolated from in-process meju on various farms from 2010 to 2011. The isolated zygomycota were identified using phenotypic characteristics combined with DNA sequences of the internal transcribed spacer regions of ribosomal DNA and the D1/D2 nuclear ribosomal large subunit. Of 364 zygomycota strains, 108 were identified as Mucor circinelloides, 96 as M. racemosus, 60 as Lichtheimia ramosa, 22 as Rhizopus stolonifer, 16 as Lichtheimia corymbifera, and the other 62 strains comprised 10 other species. The psychrotrophic species, Mucor circinelloides and M. racemosus were predominantly present during low temperature fermentation (LTF) and the thermotolerant species Lichtheimia ramosa and Rhizomucor species were predominant during high temperature fermentation (HTF). The results suggest that temperature has a large influence on the zygomycota composition during the fermentation process of meju.