By Danielle 
Scientists have developed a novel biomanufacturing method that converts human urine into hydroxyapatite—a high-value, biocompatible mineral commonly used in dental and bone implants.
The process, led by researchers at the University of California, Irvine, involves genetically engineered yeast that transforms waste into hydroxyapatite (HAp), a calcium phosphate compound that can also be used to restore archaeological artifacts and for other commercial applications.
Their findings, published in Nature Communications, outline a system that not only creates a valuable biomaterial but also helps divert urine from wastewater streams—reducing pollution and the buildup of excess nutrients.
“This process achieves two goals at the same time,” said study co-author David Kisailus, a professor of materials science and engineering at UCI. “On the one hand, it helps remove human urine from wastewater streams, mitigating environmental pollution and the buildup of unwanted nutrients; and on the other hand, it produces a material that can be commercially marketed for use in a variety of settings.”
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The research was supported by the U.S. Department of Energy, the Defense Advanced Research Projects Agency (DARPA), and the Air Force Office of Scientific Research.
A techno-economic analysis presented in the study estimates that the market for hydroxyapatite could exceed US$3.5 billion by 2030, highlighting the commercial potential of the approach.
Top 5 things to know about ‘osteoyeast’
The team, which also included scientists from Lawrence Berkeley National Laboratory, the University of Illinois Urbana-Champaign, and Japan’s Hokkaido University and Tokyo University of Agriculture and Technology, dubbed their engineered yeast “osteoyeast.” The system mimics a biological process seen in mammals.
- In humans and other animals, osteoblasts are specialized cells that extract calcium phosphate from body fluids and secrete it as hydroxyapatite for bone formation.
- However, osteoblasts are not suitable for industrial-scale production of hydroxyapatite.
- The researchers engineered synthetic yeast that uses enzymes to break down urea, increasing the pH of its surroundings. This triggers the yeast to form small cavities that accumulate calcium and phosphate, which are later secreted and crystallized into hydroxyapatite.
- The entire conversion process takes less than one day.
- The yeast is inexpensive, can be cultured in large vats at relatively low temperatures—similar to brewing beer—and is accessible to use in developing economies.
Not the first time
This isn’t the first time researchers have explored the connection between urine and dental tissue.
In 2013, scientists at the Guangzhou Institutes of Biomedicine and Health in China reported using stem cells derived from urine to generate tooth-like structures in mice. The effort was part of a broader push to develop alternative methods of regenerating teeth in people suffering from conditions such as severe periodontitis, where dental implants may be necessary.
Together, these initiatives reflect growing global interest in innovative, sustainable ways to produce bio-implants—possibly transforming both waste management and oral health care.