J. Craig Venter is retiring as the CEO of San Diego-based Human Longevity, Inc., about five months after reassuming the role.

In December, Venter was reappointed as CEO of Human Longevity, a company he also co-founded. He replaced Cynthia Collins, who held the role for less than a year.

“I am retiring from HLi and will be returning to the J Craig Venter institute to continue my work,” wrote Venter on Twitter May 24.

The nonprofit genomics research institute was founded by Venter. Scientists, led by the institute, are working on a five-year project with the U.S. Department of Energy to substantially increase oil, or lipid production, in hopes of spurring next-generation biofuels and bioproducts.

Requests to Human Longevity for further information and comment the morning of May 25 went unanswered.

Human Longevity’s Health Nucleus delivers what it bills as actionable insights into health.