U.S. Department of Energy

Pacific Northwest National Laboratory

Microbes ‘Show’ How Vitamin B12 is Used in Real-Time

Wright's paper was featured on the cover of Applied and Environmental Microbiology.

Researchers track B12 cellular uptake and distribution to link B12 to key cellular processes.

The Science

To predict how microbial communities will respond to environmental changes, scientists must first understand how microbes interact to exchange vitamin B12, a scarce but essential compound for cellular growth and reproduction. In this study researchers designed a molecular probe that not only supports microbial growth and reproduction, but also showed real-time assimilation of a vitamin B12 mimic.

The Impact

Application of this molecular probe demonstrates how vitamin B12 affects the real-time regulation of DNA, RNA, and protein functions in microbes. This knowledge gives us insight into how we can predict microbial response to environmental changes and design biological processes that support the development of clean energy, such as the creation of biofilms for biofuels and the transformation of contaminants in different environments.


In 2017, PNNL researchers uncovered the important role cobalamin, or vitamin B12, plays in microbial cellular metabolism and growth. Until now, the challenge scientists have faced is acquiring data on the mechanics of how microbes assimilate nutrients without interfering in cellular activities, destroying enzymes, or relying on metagenomics for after-the-fact analysis.

Building on five years of research into vitamin B12’s influence on cellular activities, chemical biologist Aaron Wright’s team created a B12 mimic probe that functions like vitamin B12. Attached to the probe is a “reporter tag”–in this case a fluorescent chemical compound–that allows researchers to detect, track, and visualize protein movements occurring in situ as microbes assimilate the B12 mimic. The probe, able to enter microbial cells through the vitamin B12 transporter protein BtuB, demonstrated the ability to control gene expression and measure shifts in the abundance of B12 dependent enzymes in cells.

Three species of microbes were used to test the probe’s success across microbial kingdoms: the gut bacteria Escherichia coli; a common bacteria found in biofilms, Rhodobacteraceae; and the extremophile Archaea species Haloferax volcanii.

Application of this probe allows researchers to move beyond studying B12 assimilation in individual cells, to assessing nutrient processing in complex microbial communities. Vitamin B12’s role in cellular activities provides crucial information into many microbial processes, including how biofilms are formed and how contaminants affect different environments.

October 2018
| Pacific Northwest National Laboratory