Novel approach to engineering complex microbial traits generates tens of millions of gene combinations, enabling gain-of-function traits beyond those observed from individual genes

SAN DIEGO, April 8, 2026 /PRNewswire/ -- Primrose Bio, Inc. (Primrose), a company with proprietary biologic manufacturing technologies, today announced the publication of a peer-reviewed study in the Proceedings of the National Academy of Sciences (PNAS), a leading scientific journal, demonstrating a combinatorial gene fusion approach that expands the capabilities available for microbial strain engineering.

The study introduces Function Generator™, a patented technology that combines protein-coding sequences across an entire genome to create large libraries of gene fusions. In a proof-of-concept study, 20 million unique gene combinations from more than 5,000 Saccharomyces cerevisiae (budding yeast) protein-coding sequences were screened, identifying gain-of-function variants that conferred resistance to toxic metal ions. This approach expands how complex biological design space can be explored. Primrose has successfully applied the same approach to the accelerated development of productivity and robustness traits in several microbes.

"Function Generator offers a new way to address complex challenges in strain and cell line engineering," said Drew Burch, Chief Executive Officer of Primrose Bio. "Building on processes found in evolution at much greater scale and diversity, Function Generator enables discovery of new traits and phenotypes that are difficult to achieve with traditional methods, with broader potential in areas such as protein engineering and de novo protein design."

"By combining protein-coding sequences at a whole-genome scale, we generated new genetic architectures that give rise to gain-of-function phenotypes not observed from individual genes," said Helge Zieler, PhD, scientific advisor to Primrose Bio and corresponding author on the publication. "The technology has been successfully explored and validated in microbes but also holds promise for cell and strain improvements in higher organisms, and for biologic drug discovery."

Primrose continues to advance strain engineering capabilities within its Pseudomonas fluorescens-based Pfenex Expression Technology® platform, with a focus on improving growth, titer, robustness, and secretion performance.

The full publication is available in PNAS and can be accessed at: https://www.pnas.org/doi/10.1073/pnas.2527695123

About Primrose Bio, Inc.
Primrose Bio is focused on developing and commercializing its validated technologies that address industry gaps in production systems and deliver scalable, efficient manufacturing solutions. Primrose's major offerings include Pfenex Expression Technology®: a proprietary production system used in six approved products with up to 20x higher yields and unparalleled success in supporting a broad range of protein modalities; Prima RNApols®: improved enzymes for mRNA manufacturing; and PeliCRM197®: a commercially validated CRM197 carrier protein used for conjugate vaccines. Several of the world's leading pharmaceutical companies use Primrose's technologies in marketed products, including Merck, Jazz Pharmaceuticals, Alvogen, and Serum Institute of India. For more information, please visit: www.primrosebio.com.

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SOURCE Primrose Bio