發酵在微生物界中是一個代謝的過程，透過酵素使碳源轉換成短鏈脂肪酸等代謝產物，而人體上的微生物會透過人類汗水產生各式樣得短鏈脂肪酸。皮膚電導是一測量皮膚電阻的係數，在本實驗室之前的研究顯示，利用皮膚益生菌中表皮葡萄球菌透過代謝甘油可以產生電子，因此我們假設細菌會利用發酵來影響皮膚電導。在本研究中，乳酸鈉做為益生源來引導表皮葡萄球菌發酵並產生電壓。在體外實驗中，糠醛之衍生物：5-甲糠醛顯著地抑制微生物發酵途徑之α乙醯乳酸合成酶的活性，本結果說明了5-甲糠醛阻斷表皮葡萄球菌透過乳酸鈉進行發酵，進而阻止小鼠皮膚之電壓產生。藉由手心、手背、手臂及脖子來測量皮膚電導，在汗水充足的條件下，皮膚產生電導的特性比一般未留汗水的的條件下來得多。在含有與人體相同濃度下的醋酸，可以上調小鼠在皮膚上的皮膚電導。我們的結果演示了皮膚細菌可以透過汗水來發酵並產生皮膚電導。;Fermentation in microorganisms is a metabolic process that enzymes convert carbon sources to metabolites such as short chain fatty acids (SCFAs). Bacteria in human sweats may mediate fermentation to generate various SCFAs. Skin conductance is the measurement of the electrical conductivity of the skin. Previous results in our laboratory demonstrated that Staphylococcus epidermidis (S. epidermidis), a skin probiotic bacterium, can metabolize glycerol to SCFAs and produce electricity. We thus hypothesize that bacterial fermentation affects the skin conductance. In this study, sodium lactate, a component in sweats, was used as a carbon source to induce fermentation of S. epidermidis and generated a voltage. In vitro experiment, the methyl furfural, an analog of furfural, significantly inhibited the activity of alpha acetolactate synthase (ALS), an enzyme in the pathway of bacterial fermentation. Our results have illustrated that methyl furfural blocked the sodium lactate fermentation of S. epidermidis as well as voltage induction in ICR mice. A voltage measured by skin conductance four different locations which are dorsal hand, palm, arm, and neck. Skin conductance in sweaty skin is significantly higher than that in normal skin. Acetic acid at the dose of 0.01%, which is approximately equivalent to the concentration of acetic acid in human sweats, up-regulated the voltage in the skin conductance in ICR mice. Our results suggest that skin bacteria can mediate sweat components to undergo fermentation and electricity production.
