Whole Genome Sequencing And Potential Probiotics Of Lactobacillus Plantarum Derived From Human Breast Milk

Breast milk microbiota is one of the important factors affecting the health of newborns,ealthy breast milk is an important screening pool for probiotics.Among the typical probiotics,Lactobacillus plantarum has the characteristics of wide application and strong adaptability.However,there are strain differences in the probiotic functions,and the existing physiological and biochemical methods are still insufficient for their potential probiotic mechanisms.Therefore,this study aims to screen out strains with potential probiotic functions from breast milk,and select Lactobacillus plantarum for genome-wide sequencing,explore the phenotype of the genome on the structure of the genome,and finally hope to commercialize these strains.After being added as infant formula food,they can simulate the ingredients of the breast milk in an optimal way,and the infants and young children who cannot be breastfed for some special reasons are provided to ensure their health.In this experiment,10 healthy breast milk samples were selected for the isolation,culture and identification of probiotic strains.A total of 59 potential probiotics(a total of 9 species)were obtained.Two strains of the Lactobacillus plantarum were selected for probiotics.By using the Illumina Hiseq X ten sequencer,the strains'whole genome was sequenced and functional gene was predicted.The following results were obtained:1.Two strains of Lactobacillus plantarum derived from breast milk were named as Lactobacillus plantarum MP37 and MP55;2.MP37 and MP55 can use various carbon sources as substrates;the optimal initial pH of MP37 is 6.8,the optimum culture temperature is 37°C;the optimum initial pH of MP55 is 6.5,and the optimum culture temperature is 37°C;3.The number of viable bacteria of MP37 and MP55 after digestion by artificial stomach and intestinal juice was more than 1×10~6 CFU/mL;the adhesion rate of Caco-2 cell line was 76%and 0.56%,respectively;4.both MP37 and MP55 were non-hemolytic strains;Its probiotics include the ability to produce-galactosidase,bacteriostasis,and the ability to fight liver fat lesions caused by a high-fat diet;5.The whole genome sequencing results showed that the genome size of MP55and MP37 were 3299180 bp and 3204421 bp respectively.GC contents were44.46%and 44.36%respectively.There were 3101 and 3012 gene coding sequences respectively.Four genes related to intestinal fluid tolerance and four gene clusters related to bacteriocin synthesis were found in the genome based on the biochemical characteristics of the bacterial strain.And neither strain had movable genetic resistance elements.To sum up,Lactobacillus MP37 and MP55 from Lactobacillus plantarum are two potential candidate strains of probiotics.The results of this experiment provide a genetic basis for further elucidate the functional mechanism of their probiotics.