To analyze the composition of bacteria and fungi on the facial skin of healthy women aged 20-25 years in Beijing by using high-throughput sequencing technology, and to compare the composition and diversity of microbes among 4 kinds of subjective skin types.

Totally, 31 female undergraduates were enrolled from Beijing Technology and Business University, and classified into 4 groups, including dry skin group (n=6) , neutral skin group (n=8) , mixed skin group (n=9) and oily skin group (n=8) , according to their subjective feeling of facial skin greasiness and dryness. On 24^th December 2017, the facial skin water content, transepidermal water loss (TEWL) , sebum content and pH value were determined for these undergraduates, and these physiological parameters of the skin were compared among the 4 kinds of subjective skin types. Skin samples were collected with swabs from the cheeks of these subjects. After DNA extraction and PCR amplification, the bacterial 16S rRNA regions V1-V2 and fungal internal transcribed spacer regions 1 and 2 (ITS-1-ITS-2) were sequenced separately, and sequences were grouped by OUT cluster analysis at 97% sequence similarity followed by classification and annotation of species. One-way analysis of variance was used for intergroup comparison, and least significant difference (LSD) -t test for multiple comparison.

The sebum content and bacterial diversity of the facial skin both significantly differed among the 4 kinds of subjective skin types. The skin sebum content in the dry skin group, neutral skin group, mixed skin group and oily skin was 5.50 ± 4.60 μg/cm², 7.69 ± 5.26 μg/cm², 10.56 ± 5.42 μg/cm², 22.81 ± 8.53 μg/cm² respectively (F=11.685, P < 0.001) , and the Shannon index of bacterial diversity in the above 4 groups was 3.49 ± 0.70, 2.97 ± 1.43, 2.49 ± 0.63 and 1.59 ± 0.59 respectively (F=5.634, P=0.004) . Propionibacterium, Staphylococcus and Streptococcus were the main bacterial florae on the face. The relative abundance of Propionibacterium was significantly higher in the oily skin group (68.24% ± 14.78%) than in the dry skin group (18.83% ± 14.49%, P < 0.001) , neutral skin group (32.18% ± 36.29%, P < 0.001) and mixed skin group (35.22% ± 22.58%, P < 0.001) . In addition, the relative abundance of Staphylococcus was highest in the mixed skin group, and the relative abundance of Streptococcus was highest in the neutral skin group. There was no significant difference in the fungal diversity (Shannon index) or richness (Chao index) among the 4 groups (both P > 0.05) . The fungi on the facial skin of these subjects mainly consisted of Ascomycota and Basidiomycota, and no significant difference in their relative abundance was observed among the 4 groups (both P > 0.05) . Moreover, there was no significant difference in the composition of fungal genera at relative abundance > 1% among the 4 groups (all P > 0.05) .

The physiological parameters and bacterial diversity of the cheek skin differed among young women of different subjective skin types, while there was no difference in the fungal diversity or richness, suggesting that the colonization of skin bacteria is associated with subjective skin types.

Skin; Microbial consortia; Bacteria; Fungi; Subjective skin types; High-throughput sequencing