Genome And Methylome Comparative Analysis Of Bifidobacterium Animalis Subsp.lactis Probio-M8 And V9

Bifidobacterium animalis subsp.lactis is often used as a probiotic in functional foods,and has broad application prospects and high economic value.In this study,two strains of Bifidobacterium animalis subsp.lactis Probio-M8 and V9 with excellent probiotic properties were used as the research objects to analyze the differences between Probio-M8 and V9 at the genome,methylome and transcriptome levels.Revealing the intrinsic link genotype and carbohydrate metabolism p Henotype between Probio-M8 and V9.The main findings are as follows:(1)By comparative genomic analysis,it was found that there were only 22 SNP in the genomes of Bifidobacterium animalis subsp.lactis Probio-M8 and V9.The genomic differences between the two strains were small and their genetic backgrounds were similar.Strain Probio-M8 and V9 had the same restriction modification enzyme and carbohydrate active enzyme,but API 50 CHL sugar fermentation results found that there were differences in the utilization of L-arabinose(LARA),D-xylose(DXYL),mannitol(MAN),D-pine triose(MLZ)and D-tagatose(TAG)between the two strains.(2)Two types of DNA methylation modifications,m6 A and m4 C,were detected in the genomes of Bifidobacterium animalis subsp.lactis Probio-M8 and V9.Among them,the average methylation level of m6 A is more than 97%,while that of m4 C is less than 26%.Three methylated motif motifs were identified in Probio-M8 and V9 genomes,and there were differences in the location of methylation and the function of methylation genes.There are significant differences in the function of hair methylation genes in carbohydrate transport and metabolism.There were differences in ara A methylation of L-arabinose isomerase gene,in which there were only three m6 A methylation motifs and no m4 C methylation motifs in Probio-M8,but five m6 A methylation motifs and two m4 C methylation motifs in V9.It is speculated that the above differences may lead to differences in L-arabinose metabolism between strain Probio-M8 and V9.(3)In the verification experiment using L-arabinose as the sole carbon source,it was found that both Probio-M8 and V9 did not utilize L-arabinose at 24 h,while V9 began to utilize L-arabinose at 34 h,Probio-M8 still do not utilize L-arabinose.Transcriptome analysis based on this time point found that Bifidobacterium animalis subsp.lactis Probio-M8 and V9 had high expression of MFStransporter and ABCtransporter protein family during transcription,while L-arabinose metabolic enzyme gene ara A was not highly expressed during transcription.It is showed that the difference of methylation of genes related to MFStransporter and ABCtransporter protein family may be the main reason for the difference in L-arabinose utilization between strain Probio-M8 and V9.To sum up,this study revealed that the carbohydrate metabolism of Bifidobacterium animalis subsp.lactis strains Probio-M8 and V9 is possibly regulated by gene methylation from the level of genomics,methylome and transcriptomics.Provide basic data for further analysis of carbohydrate metabolism of Bifidobacterium animalis subsp.lactis Probio-M8 and V9.