Study On Genome Microevolution Of Probiotics Lactobacillus Plantarum P-8 In Vivo

The effects of probiotics on the gut of host health have become a hot spot in the field of probiotic research.However,the impact of host intestinal environment on probiotics remains limited.Lactobacillus plantarum P-8(L.plantarum P-8)is a probiotic bacterium isolated from spontaneously fermented yoghurt of Inner Mongolia,China,with functional properties of modulating intestinal bacterial structure,improving the immunity of body.This study performed a whole genomic sequencing on 92 L.plantarum P-8 intestinal re-isolates of humans and rats by genome resequencing.The aim was to clarify the genomic microevolution of L.plantarum P-8 under the intestinal environment of humans and rats,which will widen the view of probiotics research.In this study,there were three test groups:the first group was that the healthy volunteers ingested L.plantarum P-8(with viable count of 6 × 1010 CFU every day)for twenty-eight days;the second group was that the healthy volunteers ingested L.plantarum P-8(with viable count of 6 × 1010 CFU)for one time;the third group was that the healthy rats were fed with L.plantarum P-8(vwith viable count of 6 × 1010 CFU)for one time.The fecal samples of volunteers,as well as the fecal and intestinal mucosal scraping samples of rats were collected.The quantity of L.plantarum P-8 in the intestine of volunteers and rats was determined by quantitative polymerase chain reaction(q-PCR).The strains L.plantarum P-8 were re-isolated from the fecal samples of volunteers and rats.The genome variations of L.plantarum P-8 re-isolates were analyzed by genome resequencing.The main results and conclusions were as follows:(1)L.plantarum P-8 was able to survive and colonize in the gut of humans and rats.After intake of L.plantarum P-8 only one time,the strains could remain in the intestine of volunteers and rats for 4 and 3 weeks at least,respectively.After a 28-day intake of L.plantarum P-8,the strain could be kept in the intestine of volunteers roughly for 4 months.(2)Single nucleotide polymorphism(SNP)variations were observed in the genome of L.plantarum P-8 re-isolates.A variation located in the gene coding cell wall anchor protein was found.This kind of protein probably affected the adhesion of strains to intestinal epithelial cell,which suggested that the evnolution style of L.plantarum P-8 was nich-adaptability.(3)The loss of plasmid-borne genes was observed in the genome of L.plantarum P-8 intestinal re-isolates.Certain genes which located in the plasmids of LBPpl,LBPp2,LBPp4 and LBPp7 of L.plantarum P-8 sgenmoe have been lost,which were related to carbohydrate utilizing,amino acid metabolism,lipid metabolism,and ion transport regulation.L.plantarum P-8 probably improved the adaptability to the gut of humans and rats by gene loss.(4)There was no genes gain in the genome of L.plantarum P-8 re-isolates.In conclusion,this study proved the viavility of L.plantarum P-8 in the gut of humans and rats at the whole-genomic level.L.plantarum P-8 showed an adaptive evolution in intestinal environment.It decreased the energy utilization for dispensable gene expression by genomic attenuation.This study is the first time to discuss the interaction between probiotics and intestinal environment from the perspective of the gut actting on probiotics and its genome,which provided a new horizon and theoretical basis for the metabolism of probiotics and intestinal environment.