Isolation, identification and fermentation conditions of highly acetoin-producing acetic acid bacterium from Liangzhou fumigated vinegar in China

Abstract

Liangzhou fumigated vinegar is famous in China for its distinct flavor. How to enhance flavor in traditional fermented foods, such as vinegar, has attracted a large interest in recent years. Acetoin (ACT) is a precursor of tetramethylpyrazine (TTMP), a popular food flavor found in different traditional fermented foods. We obtained 200 acid-producing isolates from the solid fermentative substrate of Liangzhou fumigated vinegar by the method of forming transparent zones on GYC agar, and 28 bacteria producing ACT by Voges-Proskauer colorimetric assay and gas chromatography analysis, including 15 strains of Acetobacter, eight strains of Lactobacillus and five strains of Staphylococcus. Based on ACT level, the isolate C92 with the highest yield was selected for further analysis. It was identified as Acetobacter pasteurianus by physiological and biochemical characteristics, as well as 16S rRNA gene sequence similarities. We examined the ACT level of strain C92 under different conditions, and found that a temperature of 31.31°C, pH of 6.67, shaking speed of 209 rpm, and inoculation volume of 8.27 % were the best conditions for strain C92 to produce a yield of 19.04 g/L at 40 h postculture. In a time-ACT curve, ACT reached the maximum value at 40 h and then decreased afterward, suggesting that ACT produced by C92 is a growth-associated primary metabolite from sugar. Therefore, the C92 isolate is regarded as a strain with promising ACT-production ability in vinegar. More studies are needed before C92 is applied in the industrial production of vinegar.

Investigating the mechanism of the flavor formation in Sichuan sun vinegar based on flavor-orientation and metagenomics

“…Furthermore, 2,3-butanediol is positively correlated with Lactobacillus and Streptococcus during wine fermentation ( Chen et al, 2020 ). Acetobacter pasteurianus has high acetoin production capacity ( Zhao and Yun, 2016 ). Therefore, 2,3-butanediol and tetramethylpyrazine formation may be related to Acetobacter pasteurianus as well as.…”

Co‐fermentation metabolism characteristics of apple vinegar with Acetobacter pasteurianus and Lactobacillus plantarum

“…It is a key flavor substance in vinegar (Lu et al, 2016). Some studies have demonstrated that Acetobacter cocultured with Lactobacillus simulated the fermentation of vinegar and that Acetobacter promoted the accumulation of acetoin, which was also enhanced in cocoa bean fermentation (Chai et al, 2020; Moens et al, 2014; Zhao & Yun, 2015). Studies have suggested that lactic acid produced by Lactobacillus is transformed into acetoin by Acetobacter during co‐fermentation.…”

Characterization and Regulation of the Acetolactate Synthase Genes Involved in Acetoin Biosynthesis in Acetobacter pasteurianus

“…Zhang et al inoculated Bacillus amyloliquefaciens producing acetoin and TMP at a high level in the fermentation starter and elevated the acetoin and TMP contents in Baoning bran vinegar [ 22 ]. Zhao and Yun screened highly acetoin-producing AAB from the solid substrate of Liangzhou fumigated vinegar in order to apply these strains in the industrial production of vinegars [ 23 ]. Chai et al accelerated the acetoin and TMP production in the vinegar fermentation process through Lactobacillus sp.- A. pasteurianus joint bioaugmentation [ 13 ].…”