Newly Discovered Bacteria Could Worsen Climate Change

A team of researchers led by Georgia Institute of Technology has discovered a new type of bacteria capable of making oxygen-barren waters less hospitable by depleting nitrogen out of the ocean, making virtual dead zones even deader.

"It's an essential nutrient [nitrogen]," said Frank Stewart, an assistant professor at Georgia Tech's School of Biological Sciences, who headed the team, in a statement. "Nitrogen is used by all cells for proteins and DNA."

The newly discovered bacteria belong to a highly prolific bacteria group known as SAR11 that can be found in the world's largest oxygen minimum zone (OMZ). OMZs are region in the ocean with no detectable O₂.

According to a paper published in the journal Nature, SAR11 living in regions without oxygen respire nitrate (NO₃), instead of O₂. As the bacteria take in nitrate, it converts it to nitrite (NO₂), which can ultimately be used to produce gaseous nitrogen. Nitrogen gas can potentially bubble out of the system and leave the ocean.

As the nitrogen bubble out of the ocean, algae and other organisms would have a hard time growing and would eventually die. Algae are known to absorb carbon dioxide. If algae are to disappear, it can leave more carbon dioxide in the atmosphere.

Oxygen minimum zones are natural occurrence. However, researchers believe that global warming plays a crucial role in the spread and expansion of OMZs. OMZ typically occurs in coastlines in tropics where the wind pushes surface water out to the sea, making deeper water to rise up. These waters are full of nutrients that can boost the growth of simple aquatic life like algae.

However, algae will sink slowly and become food for bacteria when they die. These bacteria consume oxygen as they munch on dead algae. The existence of too much algae force the bacteria to consume more oxygen at a faster rate, resulting to the oxygen depletion of the water.

As the OMZ continues to expand, the potential of SAR11 to denitrify the water poses a potential threat in tipping the global balance of nitrogen, greenhouse gases and nutrients.