Microdiversity And Biological Characteristics Offaecalibacterium Prausnitzii From A Healthy Man In Vitro

Faecalibacterium prausnitzii is one of the most abundant butyrate-producing commensal bacteria in the healthy human colon.Diseases such as IBD,obesity and T2D harbored a lower abundance of F.prausnitzii.Treatment of GQD improved the clinlcal symptoms of type 2 diabetes mellitus and enriched F.prausnitzii.Recently,the isolation and researches of F.prausnitzii were rare and the studied strains were from different hosts.The micobial ecology of this species in one host have remianed unclear and different F.prausnitzii strains showed difference in physiological-biochemical and bioactivities characteristics.So we isolated F.prausnitzii from one host and analyzed its micro-diversity and biological characteristics and function in the strain-level.We got 20 ERIC patterns of isolates through specific-primer PCR and ERIC-PCR finger-printing.15 of them were identitied to be Faecalibactrium sp.by full-length 16S rRNA gene sequensinga as they shared?98%with F.prausnitzii..Based on isolates number and results of GQD and PWS project,strains as F18,F20,F22,F31,F33,F109and F139 were chosen and F.prausnitzii A2-165?purchsed from DMSZ?as the positive control were selected to analyze the physiological and biochemical characteristics and bioactives in vitro.All the isolates were showed to be fusiform without motile-related structure.The8 strains showed difference in carbohydrates utililation.All the 8 strains can ferment host-derived N-Acetylglucosamine except F18 and F33.F22,F31 and F139 had a wide range of substrates utilization relatively.All the isolates can degrade inulin and FOS and F31 had a very poor ability in these two probiotics utilization while F139 had the highest OD₆₀₀ value following by A2-165.We observed reduction in the concentration of acetate followed by concomitant increase in the concentration of butyrate in supernatants fermented by 8 strains in the glucose,FOS and inulin.Significant difference in the butyrate-production were found among these strains.Inhibition at mildly acidic pH was strain-dependent,F31 and F20 survived at pH 5.0 while the rest strains didnot.The growth of isolates were totally inhibited when the pH was lower than 4.All strains tested were bile sensitive,showing at least 80%growth inhibition in the presence of 0.25%bile salts,while F22,F109 and F139 survived when bile salts concerntration was higher than 0.5%.Bile acids detected by UPLC-TOF-MS/MS indicated that all the isolates can hydrolyze taurine or glycine conjuncted bile acdis to free type bile salts.IL-8 secretion by TNF-?induced HT-29 cells could be significantly suppressed by supernatants of 8 strains and bacterial supersonic lysates of F22;Supernatants of F31,F109 and F139 can upregulate the expression of IL-10 on transcriptional level:all these suggested that 8 F.prausnitzii had anti-inflammatory capacity.In summary,our study indicated that F.prausnitzii isolated from a healthy adult man gut had a rich micro-diversity and variation in biological characteristics,suggesting that these strains worked together to influence metabolism and healthy of host while they played different roles.So it is necessary to study the relationship between gut microbiota and diseases in the strain-level.