Abstract: 【Abstract】 Objective To evaluate the effect of age and gender on skin microbiome on the face of healthy adults by metagenomic sequencing. Methods From June 2017 to June 2018, 36 adult volunteers with healthy facial skin were enrolled from the Department of Dermatology, Center for Prevention and Treatment of Chronic Diseases of Shunde, including 16 young volunteers （9 males and 7 females） aged 24 - 31 （27.1 ± 1.3） years and 20 senior volunteers （10 males and 10 females） aged 61 - 84 （75.8 ± 2.2） years. Skin microbe samples were obtained from the cheek of volunteers, and DNA was extracted from these samples and subjected to metagenomic sequencing and bioinformatic analysis, so as to evaluate the effect of age and gender factors on microbiota on the healthy facial skin of adults. Statistical analysis was carried out by using two independent-sample t test, Wilcoxon rank sum test and Pearson correlation analysis. Results The senior group showed significantly higher α diversities of bacterial and fungal communities on the facial skin （Shannon index: 0.98 ± 0.07, 1.11 ± 0.05 respectively） compared with those in the young group （0.72 ± 0.09, 0.81 ± 0.05 respectively; t = 2.201, 3.836, P = 0.035, < 0.001 respectively）. Principal component analysis revealed that age could significantly affect β diversities of bacterial and fungal communities on the facial skin （t = 6.991, 11.591 respectively, both P < 0.001）. There were no significant differences in α diversities of bacterial and fungal communities between males and females （Shannon index: bacteria, 0.83 ± 0.08 vs. 0.92 ± 0.09; fungi, 0.92 ± 0.06 vs. 1.04 ± 0.05; t = 0.801, 1.332 respectively, both P > 0.05）. Gender factor could only affect the β diversity of bacterial communities （t = 2.149, P = 0.020）, but not the β diversity of fungal communities （t = 0.439, P = 0.663）. Moreover, the activity of metabolic pathways in bacterial and fungal communities was significantly lower in the senior group than in the young group （t = 1.995, 2.464, P = 0.020, 0.025, respectively）, while gender factor did not affect the activity of metabolic pathways in bacterial and fungal communities （t = 0.895, 0.483, P = 0.378, 0.631, respectively）. According to the relative abundance of different bacteria and fungi between the senior group and young group, Pearson correlation analysis showed positive or negative correlations between some fungi and bacteria, between some bacteria and bacteria, as well as between some fungi and fungi. Conclusion Age factor, but not gender, markedly affects α and β diversities of, and activity of metabolic pathways in bacterial and fungal communities on the healthy face of adults.

Key words: Skin, Microbial consortia, Bacteria, Fungi, Age factors, Sex factors, Metagenomics