Characterization of the psychrotrophic lactic acid bacterium, Leuconostoc gelidum subsp. aenigmaticum LS4 isolated from kimchi based on comparative analyses of its genomic and phenotypic properties

With the aim of developing a new food starter culture, twenty-three psychrotrophic lactic acid bacteria (LAB) were isolated from 16 kimchi samples. One strain, Leuconostoc gelidum subsp. aenigmaticum LS4, which had typical psychrotrophic characteristics, was selected, and its phenotypic and genomic properties as a starter culture were investigated. The complete genome of L. aenigmaticum LS4 consisted of one circular chromosome (1,988,425 bp) and two plasmids (19,308 bp and 11,283 bp) with a guanine-cytosine content of 36.8%. L. aenigmaticum LS4 could grow at 5 ℃ but not at 37 ℃, and maximum cell growth was obtained at 15~25 ℃. L. aenigmaticum LS4 did not show any harmful characteristics such as hemolysis, undesirable enzyme activities, biogenic amine production, or antibiotic resistance. L. aenigmaticum LS4 was investigated for suitability for technological processes (pH, temperature, and NaCl treatment). L. aenigmaticum LS4 exhibited strong antimicrobial activity caused by production of organic acids and bacteriocin, and produced an exopolysaccharide composed of glucose with a molecular weight of 3.7 × 106 Da. Furthermore, L. aenigmaticum LS4 improved the organoleptic qualities of kimchi juice. Our results indicate that L. aenigmaticum LS4 could be used as a functional starter culture for food (vegetable or fruit) fermentation at low temperatures.