Isolation, Identification, and Whole Genome Sequencing of Lactic Acid Bacteria from Pit Mud of Jiangxiangxing Baijiu

Abstract:

[Objective] This study aims to develop functional microbial strain resources from the pit mud of Jiangxiangxing Baijiu and explore their potential in optimizing the fermentation process and improving Baijiu quality.[Method] Lactic acid bacteria were screened from the pit mud of Jiangxiangxing Baijiu by the spread plate method and then identified by morphological and molecular biological methods. The metabolites of the strains were detected by high performance liquid chromatography and gas chromatography, and the whole genomes of the strains were sequenced via the Illumina sequencing technology. [Result] Eleven strains of lactic acid bacteria were isolated and screened from the pit mud of Jiangxiangxing Baijiu. Among them, Lactobacillus plantarum r-JN-1 had the faster growth and the strongest acid production capacity. Lactobacillus plantarum r-JN-1 tolerated pH 4.0~10.0, temperatures of 25~40 ℃, and NaCl solutions with the concentrations of 0~7 g/dL. Meanwhile, it could use a variety of sugars for fermentation. The determination of volatile components in the culture liquid of Lactobacillus plantarum r-JN-1 showed that fermentation with this strain could produce various key aroma components of Jiangxiangxing Baijiu, such as 3-hydroxy-2-butanone and ethyl lactate. The whole genome sequencing results showed that the genome sequence of Lactobacillus plantarum r-JN-1 was 3 330 678 bp, with the GC content of 44.32% and 3 301 protein-encoding genes. The gene annotation results in COG, GO, KEGG, and CAZy databases showed that Lactobacillus plantarum r-JN-1 carried extensive genes associated with the metabolism of carbohydrates. [Conclusion] This study provided a theoretical basis for further exploring functional microorganisms in the brewing of Baijiu and expanding the application of lactic acid bacteria.