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, <i>Leuconostoc gelidum</i> subsp. <i>aenigmaticum</i> LS4, which had typical psychrotrophic characteristics, was selected, and its phenotypic and genomic properties as a starter culture were investigated. The complete genome of <i>L. aenigmaticum</i> 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%. <i>L. aenigmaticum</i> LS4 could grow at 5 ℃ but not at 37 ℃, and maximum cell growth was obtained at 15~25 ℃. <i>L. aenigmaticum</i> LS4 did not show any harmful characteristics such as hemolysis, undesirable enzyme activities, biogenic amine production, or antibiotic resistance. <i>L. aenigmaticum</i> LS4 was investigated for suitability for technological processes (pH, temperature, and NaCl treatment). <i>L. aenigmaticum</i> 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, <i>L. aenigmaticum</i> LS4 improved the organoleptic qualities of kimchi juice. Our results indicate that <i>L. aenigmaticum</i> LS4 could be used as a functional starter culture for food (vegetable or fruit) fermentation at low temperatures.