Ronald Ríos Santacruz, a Colombian chemist based at Universidad del Valle in Cali, has co‑authored a study published in Nature on 4 February 2026 that reveals how vitamin B12 acts as a light sensor in bacteria. The work shows, for the first time, the exact structural changes that allow bacteria to switch on their natural protection against ultraviolet radiation.
This breakthrough puts Colombia in rare company. According to the Nature paper’s authors, it is only the fourth article linked to Colombian researchers in the journal since 2020. Worth noting, the study involved solving more than 300 protein structures, a body of work led by Valle del Cauca researchers that has trained a new generation of Colombian scientists for global laboratories.
Ríos’ path to this achievement began with his undergraduate thesis in 2017 at Universidad del Valle under professor Rodolfo Moreno Fuquen. He completed his PhD at Université Grenoble Alpes in France, defending it in September 2024. In reality, his Colombian training provided the foundation that secured him a leading role in an international team using some of the world’s most advanced X‑ray facilities.
How vitamin b12 switches on bacterial sun protection
In the dark, the CarH protein in bacteria binds tightly to vitamin B12, a common molecule found in food and supplements, unlike the rare pigments used in human eyes. This binding creates a four‑part cluster that locks onto DNA and blocks genes needed to produce carotenoids, natural pigments that act like sunscreen against damaging UV rays.
When sunlight hits, the process unfolds in billionths of a second. Light breaks a specific chemical bond in the B12 molecule, creating unstable charged particles that no previous study had captured. Within millionths of a second, this destabilizes the CarH cluster, freeing the DNA so the bacteria can produce their protective pigments.
Put simply, bacteria have evolved a cheap, built‑in light switch using an everyday vitamin. The Nature study tracked these changes with ultrafast X‑ray “movies” taken at four major facilities: France’s ESRF, SwissFEL in Switzerland, Japan’s SACLA, and the US LCLS. Around 50 scientists from 10 countries combined laser pulses with X‑rays to match experimental data with computer models of the protein’s movements.
Colombian University builds global ties through ultra‑fast x‑ray science
Universidad del Valle’s crystallography group, led by Moreno Fuquen, has published more than 200 papers in top journals like Acta Crystallographica since 2010. The team collaborates with labs in Venezuela’s IVIC and Chile, building a South American network for protein research.
Ríos brought samples from Valle to these international beamlines, where equipment captures atomic movements too fast for standard labs. Colombian groups now book time at ESRF annually and have trained around 50 students in structural biology. Nevertheless, steady funding remains essential to compete for limited slots at these global facilities.
As a reminder, most vitamin B12 sensors rely on this common nutrient, not unusual chemicals like rhodopsins found in some other organisms. Previous studies had imaged CarH only in the dark; Ríos’ team illuminated the light‑activated changes.
Colombian science steps onto the world stage through x‑ray collaborations
This Nature paper highlights how Colombian talent, when paired with international tools, can lead cutting‑edge research. For a country where research spending lags behind OECD averages, it shows the potential of groups like Valle’s to produce work that rivals Europe and Asia.
Pharmaceutical companies may draw ideas from the B12 bond‑breaking reaction for new drugs activated by light or acidity. Bacteria’s simple UV defense could also inspire better sunscreens or light sensors. In reality, Colombia needs more local equipment to reduce travel costs and retain scientists like Ríos.
Further advances will depend on expanding access to advanced X‑ray sources and consistent funding. Valle’s example proves that small labs can drive major discoveries when connected to the world stage.