Genetic Stability of Lactobacillus casei Zhang During Continuous Passaging

Abstract:

[Objective] This study aimed to evaluate the genetic stability of Lactobacillus casei Zhang (LCZ) during continuous passaging. [Method] LCZ was continuously cultured for 100 generations in MRS liquid medium, with samples collected at generations 0, 25, 50, 75, and 100. The morphology, carbohydrate utilization, and genomic changes of LCZ were analyzed. [Result] No significant differences were observed in the morphology and carbohydrate utilization of LCZ across generations 0, 25, 50, 75, and 100. The genome size and GC proportion showed no significant differences compared to the original genome. SNP mutation analysis indicated that the LCZ genome was highly conserved across generations, with a low mutation frequency. Average nucleotide identity (ANI) and phylogenetic tree analyses revealed that the LCZ strains from different generations were closely related to the original genome. No significant differences were found in the annotations of the carbohydrate-active enzyme (CAZymes) among different generations, suggesting consistent carbohydrate utilization ability. [Conclusion] LCZ exhibited high genetic stability during continuous passaging.