Scientists film penicillin being made in real time — and it could reshape the antibiotic pipeline

Researchers at the University of Oxford, working with international partners, have created a frame-by-frame "molecular movie" of penicillin biosynthesis — capturing fleeting chemical steps that have eluded scientists for over four decades. Published in Nature Catalysis, the study used ultrafast X-ray free-electron lasers (XFELs) to observe the enzyme isopenicillin N synthase (IPNS) as it assembles the iconic β-lactam ring at the heart of penicillin's bacteria-killing power.

The team discovered previously unseen reaction intermediates — including a thioaldehyde intermediate and a monocyclic β-lactam intermediate — and showed that water molecules inside the enzyme play a critical role in guiding the reaction. The findings resolve a long-standing mechanistic question and open new doors for engineering enzymes to produce novel or improved antibiotic scaffolds.

By the Numbers

• 1 in 6 bacterial infections is now resistant to antibiotics
• The β-lactam ring formation was captured at atomic resolution across milliseconds to seconds of reaction time
• The study resolves a mechanistic question unanswered for 40+ years

Why it matters: With antimicrobial resistance threatening cancer care, transplant surgery, and global health systems, understanding exactly how nature builds antibiotics is a crucial step toward replenishing a dangerously thin antibiotic development pipeline.