Isolation and Characterization of Psychrotrophic Lactic Acid Bacteria for Use as Starter Cultures in Green Onion Kimchi: Safety, Fermentation Performance, and Genome Insights

Abstract

Psychrotrophic lactic acid bacteria (LAB) play a pivotal role in kimchi fermentation under refrigerated conditions. However, their application as starter cultures remains limited. This study aimed to isolate psychrotrophic LAB from green onion kimchi and characterize them to evaluate their potential as effective starter cultures for low-temperature fermentation. Leuconostoc gasicomitatum B4106, selected based on its favorable phenotypic characteristics, was subjected to whole-genome analysis to further evaluate its potential as a starter culture. Safety and fermentation were assessed under refrigerated conditions, and genome sequencing with comparative pan-genomics was conducted to investigate the genetic traits related to stress tolerance and safe adaptation to fermentation. B4106 exhibited γ-hemolysis, antibiotic susceptibility within European Food Safety Authority (EFSA) limits, and no production of harmful enzymes. It maintained a high dominance rate (>80%) and improved the sensory attributes, particularly carbonation and sweetness. Genomic analyses revealed antimicrobial biosynthesis clusters and 21 unique genes involved in stress adaptation, detoxification, and redox stability. Importantly, no antibiotic resistance or virulence genes were detected. These findings demonstrated that Leu. gasicomitatum B4106 is well adapted to low-temperature fermentation and enhances both the microbial stability and sensory quality of kimchi. These results support B4106 as a next-generation psychrotrophic starter for industrial kimchi fermentation.

Keywords: Psychrotrophic LAB, Leuconostoc gasicomitatum, Green onion kimchi, Starter, Fermentation, Genome