Investigation of Microbial Community of Korean Soy Sauce (Ganjang) Using Shotgun Metagenomic Sequencing and Its Relationship with Sensory Characteristics

The microbial community of a soy sauce is one of the most important factors in determining the sensory characteristics of that soy sauce. In this study, the microbial communities and sensory characteristics of twenty samples of Korean soy sauce (<i>ganjang</i>) were investigated using shotgun metagenome sequencing and descriptive sensory analysis, and their correlations were explored by partial least square (PLS) regression analysis. The metagenome analysis identified 1332 species of bacteria, yeasts, molds, and viruses across 278 genera, of which <i>Tetragenococcus</i>, <i>Bacillus</i>, and <i>Enterococcus</i> accounted for more than 80% of the total community. In the fungal community, <i>Zygosaccharomyces rouxii</i>, <i>Candida versatilis</i>, <i>Rhodotorula taiwanensis</i>, <i>Debaryomyces hansenii</i>, and <i>Aspergillus oryzae</i> were dominant, while the viral community consisted entirely of bacteriophages, with <i>Bacillus</i> phages SIOphi accounting for 93%. According to the results of the PLS analysis, desirable sensory characteristics, such as umami, sweet, and roasted soybean, as well as preference, were associated with <i>Tetragenococcus</i>, <i>Lysinibacillus</i>, <i>Enterococcus</i>, <i>Staphylococcus</i>, <i>Lactobacillus</i>, <i>Pediococcus</i>, and <i>Weissella</i>. The musty flavor, which is a typical property of traditional fermented foods, was related to <i>Halomonas</i> and <i>Psychrobacte</i>, while the bitter, acrid taste and sour smell were closely associated with <i>Chromohalobacter</i>. The results of this study provide comprehensive information on the microbial community of <i>ganjang</i> and may be used to select starter cultures for soy sauces.