Microbes helping shape the weather?

Lots of things are up in the air these days, ...

Recent research published in PNAS suggests that the diversity of microbial life in the air is on par with the soil, at least in urban areas, yet the air remains vastly understudied in comparison.

"Just seven or ten years ago we didn't realize bacteria existed in clouds," said Anne-Marie Delort, professor of microbiology and organic chemistry at Université Blaise Pascal in France. Now researchers know microbes act as a surface for the condensation of water vapor in the atmosphere, thus forming clouds. Recent research publish in Science shows microbes also play the same role during snowflake formation and other types of precipitation. The next step, Delort said, is to uncover their metabolic activity in clouds and influence on atmospheric processes. If they are metabolically active, she added, microbes could not only be acting as cloud condensers, but affecting the carbon and nitrogen cycles as well.

It all rather reminds one of Michael Denton's view, in Nature's Destiny that just about all ecological niches are actually occupied (plenitude of life).

Can anyone think of a niche that could be occupied but isn't?