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Colombian chemist Ronald R\u00edos co-leads Nature study on vitamin B12 as bacterial UV light sensor. Ronald R\u00edos Santacruz, Universidad del Valle graduate and co-author of the Nature study on vitamin B12 in bacteria. Credit: Universidad del Valle<\/a>.<\/p>\n Ronald R\u00edos Santacruz, a Colombian chemist based at Universidad del Valle in Cali, has co\u2011authored 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.\u200b<\/p>\n This breakthrough puts Colombia<\/a> in rare company. According to the Nature paper\u2019s 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.\u200b<\/p>\n R\u00edos\u2019 path to this achievement began with his undergraduate thesis in 2017 at Universidad<\/a> del Valle under professor Rodolfo Moreno Fuquen. He completed his PhD at Universit\u00e9 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\u2019s most advanced X\u2011ray facilities.\u200b<\/p>\n How vitamin b12 switches on bacterial sun protection<\/p>\n 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\u2011part cluster that locks onto DNA and blocks genes needed to produce carotenoids, natural pigments that act like sunscreen against damaging UV rays.\u200b<\/p>\n 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.\u200b<\/p>\n Put simply, bacteria have evolved a cheap, built\u2011in light switch using an everyday vitamin. The Nature study tracked these changes with ultrafast X\u2011ray \u201cmovies\u201d taken at four major facilities: France\u2019s ESRF, SwissFEL in Switzerland, Japan\u2019s SACLA, and the US LCLS. Around 50 scientists from 10 countries combined laser pulses with X\u2011rays to match experimental data with computer models<\/a> of the protein\u2019s movements.\u200b<\/p>\n Colombian University builds global ties through ultra\u2011fast x\u2011ray science<\/p>\n Universidad del Valle\u2019s 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\u2019s<\/a> IVIC and Chile, building a South American network for protein research.\u200b<\/p>\n R\u00edos 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.<\/p>\n As a reminder, most vitamin B12 sensors rely on this common nutrient<\/a>, not unusual chemicals like rhodopsins found in some other organisms. Previous studies had imaged CarH only in the dark; R\u00edos\u2019 team illuminated the light\u2011activated changes.\u200b<\/p>\n Colombian science steps onto the world stage through x\u2011ray collaborations<\/p>\n This Nature paper highlights how Colombian talent, when paired with international tools, can lead cutting\u2011edge research. For a country where research spending lags behind OECD averages<\/a>, it shows the potential of groups like Valle\u2019s to produce work that rivals Europe and Asia.<\/p>\n