The human skin is home to a wide variety of bacteria. The composition of the community of bacteria—called the "skin microbiota"—has serious implications for skin health. A healthy balance between different species of bacteria on the skin often translates to healthy skin. The loss of this balanced skin microbiota can lead to diseases such as atopic dermatitis, acne, and psoriasis. Since the skin microbiota can vary based on various factors such as age, sex, climate, and an individual's occupation understanding its composition is crucial for identifying bacteria that cause skin diseases and targeting them with specialized treatments.
Culturing skin microbiota in the lab setting can be challenging due to several reasons such as difficulty in replicating the unique environment of skin and the lack of effective culturing methods. In a recent study that was published in Alternatives to Animal Testing and Experimentation on November 14 2024, researchers addressed the limitations in culturing skin microbiota by developing a novel culture system that facilitates cultivating several skin bacteria species in the lab setting.
"We have developed the first complex culture system that can cultivate multiple indigenous skin bacteria in a balanced state. Detailed analysis of the biology of indigenous skin bacteria, which affect the condition of human skin, is now possible. Going forward, the system can be used in the research and development of cosmetics and drugs for numerous skin diseases" explains Associate Professor Yuuki Furuyama of Tokyo University of Science, the lead researcher in the study.
Since culturing skin microbiota in the lab is challenging, researchers have traditionally used metagenomic analysis to study them—an approach that involves extracting the combined genome of all bacteria in a community. While metagenomic analysis can offer useful insights, it might not be effective in uncovering interactions between different species. The newly created growth medium called "TUS Skin Bacteria Co-culture (TSBC)" medium can allow researchers to jointly cultivate multiple bacteria and study their interactions. In the study, researchers including Dr. Furuyama, along with Mr. Ikuya Yamamoto and Professor Kouji Kuramochi of Tokyo University of Science, successfully cultivated four skin bacteria namely Staphylococcus epidermidis, Staphylococcus capitis, Cutibacterium acnes, and Corynebacterium tuberculostearicum. They found that the bacterial composition within the lab-grown community was balanced and similar to those found in Japanese skin.
"Research on the indigenous microbiota of the skin has mainly focused on metagenomic analysis, which does not involve culture methods, or on the analysis of individual bacteria in pure culture. However, since multiple bacteria interact with each other in the actual skin environment, we thought that a model culture system that reproduced the interaction relationship was necessary", notes Dr. Furuyama.
The skin microbiota is highly individualized and can vary even across different areas of the same person's skin. Skin properties such as sebum levels, moisture, and dryness all influence the composition of the microbiota. This new co-culture technique opens avenues to study how both internal and external factors, including skincare products, affect the microbiota in various skin locations. In addition, future research can explore how skincare routines impact microbiota across different ethnicities and skin types.
As skin sensitivity and conditions like eczema continue to rise, driven by factors like climate change and environmental stressors, a more holistic understanding of skin microbiota imbalances offers a pathway to new treatments. By targeting the microbiota, researchers can potentially develop tailored, preventive solutions that support healthier, more resilient skin—improving quality of life for millions around the world.
