Microdiversity Of Lactic Acid Bacteria Enriched By Dietary Intervention In The Gut Of A Child With Prader-Willi Syndrome

The gastrointestinal tract of human and animals is colonized by numerous and diverse microorganisms. Gut microbiota influences human health by modulating the nutrition, metabolism and immunity of host. Lactobacillus spp. and Bifidobacterium spp. are the representative beneficial species, which exhibit multiply important physiological functions. Gut microbiota plays a pivotal role in the development of diet-induced obesity. However, the relationship between gut microbiota and human genetic obesity is still unclear. Prader-Willi syndrome(PWS) is the most common genetic obesity in human, which arise from deficiency, mutation or gene imprinting of paternal chromosome 15q11.2-q13. Children with PWS become morbidly obese. In our previous study, one PWS child with morbid obesity was recruited for a hospitalized intervention with a diet rich in non-digestible carbohydrates and prebiotics. Concomitant with alleviation of metabolic deteriorations and decrease of body-weight, the structure of the gut microbiota was significantly changed in the PWS child’s gut during the dietary intervention. Lactobacillus spp. and Bifidobacterium spp. became the dominant bacteria.In this study, we obtained 182 isolates using MRS Agar medium under anaerobic condition from the post-intervention fecal sample of this PWS child. Denatured gradient gel electrophoresis(DGGE), Enterobacterial Repetitive Intergenic Consensus(ERIC)-PCR fingerprinting, 16 S rRNA gene sequencing were used for molecular profiling and identification of the isolates. 94 isolates are Lactobacillus, 74 isolates are Bifidobacterium. 88 Lactobacillus mucosae isolates were classified into 4 ERIC types; 3 Lactobacillus crispatus isolates belong to one ERIC type; 3 Lactobacillus gasseri isolates belong to one ERIC type. 73 Bifidobacteria pseudocatenulatum isolates were classified into 5 ERIC types; One Bifidobacterium longum isolate belong to one ERIC type.In order to explore physiological function of dominant species, short-chain fatty acids(SCFAs) production, inhibition effects of cell-free culture supernatants(CFCS) and carbohydrate utilization capacity were measured. The results showed that Lactobacili and Bifidobacteria isolates both produced acetate. CFCS of representative isolates had no inhibition effects on 4 indicator strains, including Escherichia isolates from the same child before dietary intervention, Escherichia coli MG1655 and Enterobacter cloacae B29.Bifidobacterium pseudocatenulatum C95 had higher ability to utilize scFOS and HP inulin than Bacteroides thetaiotaomicron ATCC 29148 and E.coli D45; This strain also had higher ability to utilize Formula No.3 than Bacteroides thetaiotaomicron ATCC 29148, E.coli D45 and Anaerostipes hadrus BPB5.In conclusion, dominant lactic acid bacteria in gut were obtained from a PWS child after dietary-intervention. Significant strain-level diversity of the isolates was observed. Compared to other intestinal symbiotic strains, Bifidobacterium pseudocatenulatum isolates have stronger carbohydrate utilization capacity. COG and KEGG function annotation also showed that this strain possessed abundant carbohydrate degradation genes. This may be the reason that Bifidobacterium pseudocatenulatum became the predominant species in the PWS child’s gut after dietary intervention. Bifidobacterium pseudocatenulatum C95 is an attractively potential probiotics whose isolation was based on volunteer’s health improvement.