Prochlorococcus: the solitary micro-organism that forms biofilms

The oxygen we breathe comes, in large part, from microscopic cells known as phytoplankton, which float on the surface of the oceans. Among these cells is Prochlorococcus, the smallest and most abundant photosynthetic organism in the seas. It is responsible for about 10% of the carbon that the earth and oceans remove from the atmosphere annually ^1,2.

Since its discovery, Prochlorococcus was known as a solitary micro-organism, floating freely in the sunlit ocean waters. Due to its short lifespan near the surface, it was believed to contribute little to the ocean's biological pump, the natural process of moving carbon to the deep ocean and storing it there ^1,2.

A new behavior

Researchers at MIT discovered that Prochlorococcus can form biofilms, sticky communities of cells adhered to surfaces. This discovery suggests that the micro-organism has another form of life, which may play a greater role in carbon capture ^1,2.

Prochlorococcus can exist in two different, but connected worlds. When the cells are in planktonic form, they float in nutrient-poor waters and can be hundreds of cell lengths away from their nearest neighbors. When adhered to particles, they experience a completely different physical and chemical environment ^1,2.

The research team also found evidence that adhered Prochlorococcus is common in the ocean, from the sunlit surface to 1,000 meters deep ^1,2.