Assistant Professor Julia Oh, PhD, probes the depths of human skin to characterize the microbial communities that contribute to health and disease. “The skin microbiome is really remarkable,” says Oh. “It is constantly being repopulated and yet, across different body sites, we see that healthy individuals’ skin microbiomes are quite stable in composition. That’s surprising considering how exposed the skin is – to the environment and to other people.”

Although it is tempting to imagine it as one uniform system, the skin is actually a patchwork of many varied environments, each with distinct conditions. Facial skin is typically oily, while the forearms are dry. Feet, tucked inside socks and shoes for most of the day, are often damp and sweaty. Such differing ecologies attract and support the growth of unique microbial communities.

One of the first detailed views of these communities emerged as part of the Human Microbiome Project, a sweeping, five–year effort to catalog the microbes living throughout the human body. In June 2012, the consortium published a flurry of papers that described the results of a broad microbial census involving nearly 250 healthy volunteers. It spanned various body sites, including the skin behind the ears and along the inner crease of the elbows. Oh sees great potential in these types of studies, not only for enabling scientists to understand more about the tiny passengers that reside in skin, but also to lay the groundwork for deep, mechanistic studies that will guide the development of innovative microbial–based treatments for a variety of skin conditions, including psoriasis, eczema and cancer.

Though she started her laboratory at JAX less than two years ago, her team has already blazed bold new trails in microbiome research. Recently, Oh and her colleagues took a careful look at the dynamics of the skin microbiome. As published in Cell, they examined how the number and diversity of skin microbes change over time, both short periods (months) and long periods (years). Called a tour de force by experts in the field, the work helps illuminate the astonishing stability of the skin’s bacterial, viral and fungal inhabitants. Moreover, it suggests that the unique makeup of skin microbiomes in healthy individuals can be regulated by biological factors, such as genetics, immune health, skin physiology and skin health, as well as environmental factors like hygiene.

Oh remembers the precise moment when her interest in the microbiome emerged. She was roughly midway through her graduate work in Ronald Davis’ lab at Stanford, when a colleague presented the results of a recent research paper about the microbes in soil. “That paper just blew my mind,” she recalls. “I didn’t really think of microbes as living in complex communities. E. coli, Saccharomyces cerevisiae, those were the model organisms I worked with – and naively, how I thought they existed in the world.”

Indeed, some of the early tools for exploring microbial communities were first honed through studies of soil and seawater. Perhaps the most critical tool: genomic sequencing. “The application of sequencing technology to this problem was just so elegant. I was utterly captivated,” says Oh. With rapidly falling costs and increasing throughput, examinations of other microbial worlds soon became feasible.