Diversity of Lactic Acid Bacteria (LAB) in Makgeolli and Their Production of γ-Aminobutyric Acid

Abstract

Makgeolli is made from rice or flour, yeast, and nuruk, a fermentation starter. The flavor of makgeolli is affected by sugars, amino acids, organic acids and volatile flavor compounds produced by various microorganisms. In this study, lactic acid bacteria (LAB) were isolated from unsterilized makgeolli samples collected from several provinces in Korea, and then later identified. Under anaerobic conditions, LAB density ranged from 5.0×10 6 to 1.5×10 8 CFU/mL; yeast density ranged from 2.5×10 7 to 1.5×10 8 CFU/mL. Of the LAB isolated from makgeolli, 1,126 were analyzed using restriction fragment length polymorphism (PCR-RFLP) analysis of 16S rRNA, which allowed for classification into five groups. Of the 1,126 LABs tested, 130 produced γ-aminobutyric acid (GABA).

Screening of lactic acid bacteria strains isolated from Iranian traditional dairy products for GABA production and optimization by response surface methodology

“…Figure 5 A showed that with increasing the concentration of monosodium glutamate and increasing the temperature, the amount of GABA formed increased. This trend is in agreement with the results reported elsewhere by other authors 41 , 42 .

Figure 5 3D plots showing the interaction effect of three variables for GABA production by Lac.

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Effect of millimeter waves on the microbiological and physicochemical properties of Korean rice wine Makgeolli

“…In a Makgeolli produced using modified-nuruk, the numbers of LAB and yeast cells during fermentation were approximately 7 and 8 log CFU/mL, respectively (14). Consistent with the results of the present study, the numbers of LAB and yeast cells in raw Makgeolli from the market were 5-7 and 7-8 log CFU/mL, respectively (24,25). Although millimeter waves are known to affect microbial growth, both increased and decreased growth of the same microorganisms depending on the fermentation conditions have been reported (26).…”

“…In general, fungi are not detected during Makgeolli fermentation, and the major microorganisms are known to be yeasts and LAB (14,24,25). In a Makgeolli produced using modified-nuruk, the numbers of LAB and yeast cells during fermentation were approximately 7 and 8 log CFU/mL, respectively (14).…”