Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

News Spotlight

NLM Researchers Solve an Enzyme Mystery

Despite identifying urobilin as the yellow pigment in urine more than 125 years ago, the enzyme responsible for its production has remained a mystery. Now, NLM Intramural Research Program investigator Xiaofang Jiang, PhD, and her team have identified the microbial enzyme responsible for giving urine its yellow hue. The results found that this enzyme is almost always present in the guts of healthy adults but is often missing in young infants and adults with Inflammatory Bowel Disease. These findings have the potential to guide future work related to developing new probiotic therapies that could lead to clinical improvements and outcomes for patients. Their paper, “Discovery of a gut microbial enzyme that reduces bilirubin to urobilinogen,” was published in the journal Nature Microbiology.

Watch the video to learn more!

Research at NLM

NLM Intramural Research Program

Intramural research at NLM consists of the development and application of computational approaches to a broad range of problems in biomedicine, molecular biology, and health.


IRP home no text.

Historical Collections at NLM

Biomedical and Clinical Informatics at NLM

About NLM

  • Old photo of NLM

    The Library started as a shelf of books in the Surgeon General’s office in 1836 but has grown to a collection of millions of print and electronic resources.

  • Current photo of NLM

    The diverse centers, divisions, advisory bodies and other organizational units that make up NLM contribute in myriad ways to the Library’s mission.

  • Strategic Plan cover

    This ten year plan outlines NLM's role in a future where data and information transform and accelerate biomedical discovery and improve health and health care.