Study On Transcriptional Difference During The Growth Of Lactobacillus Paracasei PC-01

Lactobacillus paracasei PC-01 is a strain of lactic acid bacteria isolated from sour yak milk in Longren Township,Damxung County,Lhasa,Tibet.Lactobacillus paracasei PC-01 with good probiotic properties and safety.In this study,Lactobacillus paracasei PC-01 was statically fermented at 37°C for 48 hours.The p H value,OD value and the number of viable bacteria were monitored every 2 hours.According to the phenotypic data,6 key time points in different growth stages of the strain were screened.Using RNA-Seq technology to perform transcriptome sequencing analysis on 6 key time points,and under the premise of function(GO)annotation and metabolic pathway(KEGG)annotation,based on the difference in gene expression in each sample,the differentially expressed genes(DEGs)at different growth stages of the strain were screened and perform GO and KEGG enrichment analysis.The results of this study are as follows:(1)A total of 1519 differentially expressed genes were obtained by comparing the growth of Lactobacillus paracasei PC-01 at two adjacent time points.Among them,there were 349 DEGs in the lag phase;346 DEGs in the early logarithmic phase;324 DEGs in the late logarithmic phase;There are 393 DEGs in the early stable period;there are 107 DEGs in the late stable period.(2)KEGG and GO function enrichment analysis was performed on differentially expressed genes(DEGs).The results of GO function enrichment analysis showed that DEGs were mainly enriched in the functional group of catalytically active molecules and biological pathways of metabolic processes.However,there are fewer DEGs enriched in the functional classification of cellular components.Pathway functional enrichment analysis results show that a large number of DEGs are mainly enriched in nucleotide metabolism,carbohydrate metabolism and amino acid metabolism.(3)In nucleotide metabolism,the expression of purine metabolism-related genes is at a low level,and the expression of pyrimidine metabolism-related genes is significantly up-regulated in the late logarithmic period;galactose metabolism,glycolytic pathway,pyruvate metabolism and fatty acid synthesis pathway are most active during the lag phase;when the fermentation of the strain progressed to the late logarithm,the metabolic pathways of aspartate and glutamine began to be strengthened,with the decrease of p H value.The results showed that different growth stages of Lactobacillus paracasei PC-01 require different metabolic pathways to coordinate the growth of the strains.This provides valuable basic data resources for further understanding of the growth process of Lactobacillus paracasei PC-01 and the dynamic changes of key enzyme genes at different growth stages of the strain.