Evaluation Of The Skin Microorganism In A Health Chinese Population By High-throughput Sequencing

Background The skin is exposed to the external environment and forms the body's first line of defense against physical and biochemical invasion.In addition,the skin provide a habitat for various microorganism,including bacteria,fungi,viruses and mites,which constitutes a complex and dynamic microecosystem.The skin microbiota participates in and regulates innate and adaptive skin immunity,thus plays an important role in the maintainment of skin health and development and progression of skin diseases.Objective To characterize the skin bacterial and fungal communities in a healthy Chinese population by high-throughput sequencing and understand their association with skin site,age,and gender.Methods Fifty healthy subjects were divided into five age groups,namely children,adolescents,young adults,middle-aged adults and elders.The skin samples of the cheeks,upper backs and volar forearms were collected by swabbing.Microbial genome DNA was extracted from the skin swabs,and then the target fragment was amplified by PCR(the V3-V4 region of 16 S r DNA was used as the bacterial target fragment and the ITS2 region was used as the fungal target fragment)and PCR products were purification.Finally,library construction,sequenceing,quality filtration and bioinformatics analysis were performed.Results A total of 9,574,365 high-quality 16 Sr DNA V3-V4 region sequences and10,382,475 high-quality ITS2 region sequences were generated and annotated as two archaea phyla—Thaumarchaeota and Euryarchaeota,the four dominant bacterial phyla—Actinobacteria,Proteobacteria,Firmicutes and Bacteroidetes,two dominant fungal phyla—Ascomycota and Basidiomycota.The backs were dominated by Propionibacterium,Staphylococcus,Basidiomycota,Malassezia and Malassezia globosa.The cheeks and volar forearm possessed similar bacterial and fungal communities,but the volar forearm has higher bacterial and fungal species diversity,with Alphaproteobacteria as the dominant,while the cheeks facilitated the survival of Betaproteobacteria.The elders had a higher richness and diversity of bacterial species,while children had a higher richness and diversity of fungal species and was prevalent for filamentous fungi such as Cladosporium,Aspergillus,Alternaria,Penicillium and non-Malassezia yeast microbiota such as Debaryomyces,Saccharomycopsis,Candida.Reversely,lipophilic Propionibacterium and Malassezia were lesser abundance at childhood.The growth of Propionibacterium and Malassezia depend on the level of sebum.Their abundance increased sharply at puberty,peaked on the young adults,then gradually decreased with age.Males had higher richness of bacterial species than females.Females owned more abundant Ascomycetes,while males habored greated Malassezia restricta.In addition,a higher proportion of airborne fungi were detected on the skin surface,which indicated that the skin also formed a deposition surface to passively collect transient fungi from the environment or clothing besides a growth habitat for the resident fungi.Conclusion The skin bacterial and fungal communities of healthy Chinese were identified and their community composition and abundance were affected by skin sites,age and gender,which provide a basics for identifing the skin microbiota under skin diseases or abnormal skin barrier function and understanding the functional roles of normal microbiota.