Lot-to-lot variation in the microbiota during the brewing process of the kimoto-style Japanese rice wine

Authors: YAMANE, MOMOKA - Obihiro University; SAKAI, SHUNTARO - Obihiro University; HIRAI, MIHO - Obihiro University; TAKAYAMA, MIZUKI - Obihiro University; SASAYAMA, KOHYA - Obihiro University; DOUCHI, KAZUTOSHI - Obihiro University; KAWABATA, SHINJI - Obihiro University; Ikeda, Shinya; SUGAWARA, MASAYUKI - Obihiro University

Submitted to: Bioscience of Microbiota, Food and Health
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/10/2024
Publication Date: 3/28/2024
Citation: Yamane, M., Sakai, S., Hirai, M., Takayama, M., Sasayama, K., Douchi, K., Kawabata, S., Ikeda, S., Sugawara, M. 2024. Lot-to-lot variation in the microbiota during the brewing process of the kimoto-style Japanese rice wine. Bioscience of Microbiota, Food and Health. 43:250-259. https://doi.org/10.12938/bmfh.2023-092.
DOI: https://doi.org/10.12938/bmfh.2023-092

Interpretive Summary: The kimoto-type Japanese rice wine or sake has been attracting much attention in recent years compared to the major sokujo-type sake because a wide variety of flavors and tastes are available. The kimono-type sake production relies on the lactic acid bacteria that naturally occur in the starter and produce lactic acid to create an acidic environment that is desirable for eliminating undesirable microorganisms and facilitating the ethanol production by the yeast. However, microbial events occurring during sake production are poorly understood. The objective of this study was to elucidate how the bacterial composition and diversity develop during the kimoto-type sake production at a newly established brewery over two consecutive brewing years. We found that repeated brewing led to an increased microbial diversity and an alteration of the transition pattern of lactic acid bacteria and that the malted rice was the major microbial source for the starter, including the staphylococci that played a major role in nitrite production in the early stage of fermentation. Furthermore, our results demonstrated certain distinctive features of the bacterial composition in the brewery, including that Leu. suionicum, Leu. citreum, and Leu. meseteroides were detected as a predominant species of lactococci and that a unique lactobacillus species was detected as the predominant lactobacilli in place of Lat. sakei. These findings contribute to enhancing our understanding of the development of the bacterial composition during kimoto-type sake brewing and enabling to control the bacterial composition for consistent sake quality.

Technical Abstract: The kimoto-type Japanese rice wine (sake) has a wide variety of flavors since the dominant microbes including lactic acid bacteria (LAB) and nitrate-reducing bacteria that spontaneously proliferate in the fermentation starter vary depending on the brewery. In this study, we traced the microbiota in four lots of the starter manufactured in a newly established sake brewery and evaluated the lot-to-lot variation and characteristics of the microbiota in the brewery. The results of the 16S rRNA amplicon analysis showed that the starters brewed in the second brewing year had a more diverse microbiota than those in the first brewing year. Among the LAB predominated at the middle production stage, lactococci including Leuconostoc spp. were detected in all the lots, while lactobacilli dominated for the first time in the second year. These results suggest that repeated brewing leads to an increased microbial diversity and the alteration the microbial succession pattern in the kimoto-type fermentation starter. The phylogenetic analyses for the LAB isolates from each starter identified Leuconostoc suionicum, Leu. citreum, and Leu. mesenteroides as predominant lactococci as well as a unique lactobacillus in place of Latilactobacillus sakei. We also found that the rice koji-derived Staphylococcus gallinarum having the nitrate-reducing activity was generally predominant during the early production stage, suggesting that the staphylococci established a habitat in the brewery. Additionally, there was a case that staphylococci played a role in nitrite production in the starter. These findings are expected to contribute to the understanding of the diversity of microbiota in kimoto-style sake brewing and enable to control the microbiota for consistent sake quality.