Ocean microbes a global source of key vitamin B12

A group of micro-organisms may be responsible for much of the world's vitamin B12 production in the oceans, with implications for the global carbon cycle and climate change, says a study.

This group named Thaumarchaeota has never before been associated with production of vitamin B12, which plays a key role in maintaining the brain and nervous systems in humans, as well as DNA synthesis in cells throughout the body.

"We assumed that most major global sources of something as fundamental as vitamin B12 would have already been characterised, and so this finding changes how we think about global production of this important vitamin," said co-researcher professor Andew Doxey from the University of Waterloo in Canada.

The researchers used computational methods to search through vast amounts of sequenced environmental DNA for the genes that make vitamin B12, identifying the likely producers in marine and freshwater environments.

"Because Thaumarchaeota are among the most abundant organisms on the planet, especially in marine environments, their contribution to vitamin B12 production have enormous implications for ecology and metabolism in the oceans," explained co-researcher professor Josh Neufeld from the University of Waterloo.

The availability of vitamin B12 may control how much or how little biological productivity is carried out by ocean phytoplanktons.

Phytoplanktons remove carbon dioxide from the atmosphere through photosynthesis, much like plants and trees, thus reducing the atmospheric concentration of this greenhouse gas, the largest contributor to global warming.

The findings were published online in the International Society for Microbial Ecology (ISME) Journal.