鼠李糖乳杆菌Probio-M9连续传代过程中的遗传稳定性

Genetic Stability of Lacticaseibacillus rhamnosus Probio-M9 during Continuous Subculturing

目的:探究鼠李糖乳杆菌Probio-M9在连续传代过程中的遗传稳定性。方法:以鼠李糖乳杆菌Probio-M9为研究对象,对其传代过程中第0,25,50,75,100代的菌株形态变化、碳水化合物利用能力以及菌株代谢特性进行比较,同时应用比较基因组学分析其在连续培养100代过程中基因组水平的变化。结果:鼠李糖乳杆菌Probio-M9在连续培养100代过程中,其菌体形态、碳水化合物利用能力等表型特征及代谢特性均无显著性(P>0.05)变化,表型特征稳定。同时以鼠李糖乳杆菌Probio-M9原始菌株基因组作为参考序列,对不同代时15株菌进行测序,基因组大小及GC含量表明15株连续培养的菌株与鼠李糖乳杆菌Probio-M9原始菌株基因组均无明显差异。系统发育关系表明15株菌与原始基因组具有较近的亲缘性。从识别到的SNP位点来看,每两个代时菌株间均未发现稳定遗传的突变位点,且菌株共线性良好,从基因组水平编码基因的突变水平证实了鼠李糖乳杆菌Probio-M9在连续培养100代过程中具有稳定表型特征及代谢特性。结论:鼠李糖乳杆菌Probio-M9在连续传代过程中具有良好的遗传稳定性,为其进一步开发研究以及产业化提供了理论基础。

Objective:To investigate the genetic stability of Lacticaseibacillus rhamnosus Probio-M9(L.rhamnosus Probio-M9)during continuous passage.Methods:The morphological changes,carbohydrate utilization capacity,activity and metabolic characteristics of L.rhamnosus Probio-M9 were compared in the 0,25,50,75 and 100 passages of the probiotic strain.At the same time,comparative genomics was used to analyze the changes of genome level during the continuous culture of 100 generations.Results:There were no significant changes(P>0.05)in phenotypic characteristics and metabolic characteristics of L.rhamnosus Probio-M9 during 100 generations of continuous culture,and the phenotypic characteristics were stable,and the strain activity was maintained well.At the same time,using the genome of L.rhamnosus Probio-M9 as the reference sequence,15 strains of different generations were sequenced,and the genome size and GC content showed no significant difference between the 15 strains cultured continuously and L.rhamnosus ProbioM9.Phylogenetic relationships showed that the 15 strains were closely related to the original genome.From the identified SNP loci,no mutation locus with stable inheritance was found in every two generations,and the collinear strain was good.The mutation level of the coding gene at the genome level confirmed that L.rhamnosus Probio-M9 had stable phenotypic characteristics and metabolic characteristics during the continuous culture of 100 generations.Conclusion:L.rhamnosus Probio-M9 has good genetic stability during continuous passage,which provides a theoretical basis for further development,research and industrialization of L.rhamnosus Probio-M9.