When Michiko Taga began her post-doc at the Massachusetts Institute of Technology in 2003, she never imagined that it would lead her to solving a longstanding mystery about vitamin B12, a vitamin that is fundamental to human health. The structure and biosynthesis of vitamin B12, the only vitamin that is produced solely by bacteria, had been almost entirely elucidated since its discovery in the 1920s. But the biosynthesis of one double-ringed fragment, called dimethylbenzimidazole, or DMB, which helps orchestrate some of the chemical reactions that vitamin B12 is responsible for, had remained elusive.
Taga, now an assistant professor in the Department of Plant and Microbial Biology at the University of California, Berkeley, initially set out to study the symbiotic relationship between nitrogen-fixing bacteria and their host plants. Through a series of serendipitous findings, Taga and JCC fellow, Nicholas Larsen, discovered that a bacterial enzyme called BluB produces the DMB fragment by cannibalizing it from another vitamin. This is the only known case in which one vitamin is used to make another vitamin.
Taga credits the JCC fellowship with making it possible for her to pursue the research questions that led to the vitamin B12 discovery. “This is basic science research – we’re not looking for a cure for a specific disease,” says Taga. “Basic research is very important for human health, not because of what might be discovered in the short term,” says Taga, “but also in the long term, because we have no way to predict what kind of impact our research might have on human health when combined with future discoveries.”
Now, in her own laboratory, Taga is drawing on her experience with vitamin B12 to study how bacteria interact in their natural environments. Bacteria in nature – including those that thrive in our own skin, intestines, and noses, for instance – exist in complex microbial communities. But most research up to now has focused on bacteria in isolation within a Petri dish or culture tube. Taga notes that only 10 percent of our bodies are made up of human cells – the rest are microbial cells. “But we don’t actually understand the contributions that these microbes make to our health,” says Taga.
Taga is also involved in collaborations to study microbial communities that are useful for bioremediation. And her newest project involves studying microbes in the termite gut, both as a model for the human intestine and as a means of understanding the microbial decomposition of wood for future applications in biofuels research.
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