皮膚為人體最大的器官被各式各樣的微生物所定殖，其中大部分的微生物對宿主無害甚至有益。藉由定序與大數據分析等實驗技術，人體菌相的相關研究發展迅速，其中包含了消化道、皮膚、生殖道等等，相異的微生物組體系統彼此間互相影響。現在有許多研究顯示，不同的微生物及微生物發酵皆可以產生不同的電壓訊號，且微生物發電其實已被開始廣泛應用於有機物質的電能，加速處理廢水或降低廢水處理過程的能源成本。因此發酵原理亦可套用於皮膚上的細菌且藉由發酵產生電，而其中皮膚上具有相對高比例的表皮葡萄球菌(Staphylococcus epidermidis, S. epi)及痤瘡丙酸桿菌(Propionibacterium acnes, P. acnes)，由於微生物及微生物在發酵過程中所產生的酸會釋放出質子及電子，而電子會傳遞至電極並發出電壓，每一株不同的菌種及發酵後的電訊號特徵亦不同，因此本研究想探討皮膚微生物發酵及發電之間的關係，並找出電訊號對於人類有什麼幫助，希望在未來將此理論應用於人體皮膚上並針對不同的疾病進行治療或是預防。;Harmful bacteria could cause human diseases. However, the diseases can result from the imbalance between the harmful and beneficial bacteria. Staphylococcus epidermidis (S. epi) and Propionibacterium acnes (P. acnes), now named as Cutibacterium acnes (C. acnes) are two main bacteria in the human skin microbiome. Data from our laboratories demonstrated that both bacteria can use glycerol as a carbon source for fermentation. Electron is produced during the production of short chain fatty acids (SCDAs) from glycerol fermentation of skin bacteria. An electronic skin patch was fabricated in our laboratory to detect the electron from mouse and human skin. The studies here demonstrate that S. epi can mediate glycerol fermentation to produce higher level of electricity than P. acnes in skin of ICR mice. In vitro data illustrated that electricity was produced to the highest level 10 min after glycerol fermentation of S. epi and declined to a baseline 60 min after. To test whether electron can function as an antioxidant to reduce free radicals induced by ultraviolet (UV), skin of ICR mice were topically applied with S. epi with glycerol for 10 and 60 min. The lipid peroxidation derived 4-hydroxynonenal (4-HNE) was used as a biomarker for the production of UV-induced free radicals. Our western blot results here demonstrate that the production of UV-induced 4-HNE was detectable when mouse skin was exposed to the culture of S. epi plus glycerol for 60 min. However, the production of UV-induced 4-HNE was dramatically reduced 10 min after exposure of skin to the culture of S. epi plus glycerol. This result suggests that electron generated by glycerol fermentation of S. epi in skin may be able to eliminate the free radicals induced by UV. Our studies here provide the novel of biological roles of endogenous glycerol and skin beneficial bacteria in the UV-induced skin damages.
