Regulatory Mechanisms of L-Lactic Acid and Taste Substances in Chinese Acid Rice Soup (Rice-Acid) Fermented With a Lacticaseibacillus paracasei and Kluyveromyces marxianus

Rice-acid has abundant taste substances and health protection function due to the various bioactive compounds it contains, including organic acids. L -lactic acid is the most abundant organic acid in rice-acid, but the regulatory mechanisms of L -lactic acid accumulation in rice-acid are obscure. In this study, we analyzed the dynamic changes in organic acids and taste substances in rice-acid in various fermentation phases and different inoculation methods. We identified the key genes involved in taste substance biosynthesis by RNA-Seq analysis and compared the data of four experimental groups. We found that the interaction of the differences in key functional genes ( L -lactate dehydrogenase and D -lactate dehydrogenase) and key metabolism pathways (glycolysis, pyruvate metabolism, TCA cycle, amino acid biosynthesis, and metabolism) might interpret the accumulation of L -lactic acid, other organic acids, and taste substances in rice-acid fermented with Lacticaseibacillus paracasei . The experimental data provided the basis for exploring regulatory mechanisms of taste substance accumulation in rice-acid.