Bacteria: many new phylia (Evolution)

by David Turell , Monday, October 24, 2016, 17:48 (2738 days ago) @ David Turell

In soil the research has expanded the bacterial branches of life enormously and the branches help each other:

http://phys.org/news/2016-10-bacteria-groups-stunning-diversity-underground.html

"One of the most detailed genomic studies of any ecosystem to date has revealed an underground world of stunning microbial diversity, and added dozens of new branches to the tree of life.

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"As reported online October 24 in the journal Nature Communications, the scientists netted genomes from 80 percent of all known bacterial phyla, a remarkable degree of biological diversity at one location. They also discovered 47 new phylum-level bacterial groups, naming many of them after influential microbiologists and other scientists. And they learned new insights about how microbial communities work together to drive processes that are critical to the planet's climate and life everywhere, such as the carbon and nitrogen cycles.

"These findings shed light on one of Earth's most important and least understood realms of life. The subterranean world hosts up to one-fifth of all biomass, but it remains a mystery.

"Another big outcome is a deeper understanding of the roles subsurface microbes play in globally important carbon, hydrogen, nitrogen, and sulfur cycles. This information will help to better represent these cycles in predictive models such as climate simulations.

"The scientists conducted metabolic analyses of 36 percent of the organisms detected in the aquifer system. They focused on a phenomenon called metabolic handoff, which essentially means one microbe's waste is another microbe's food. It's known from lab studies that handoffs are needed in certain reactions, but these interconnected networks are widespread and vastly more complex in the real world.

"To understand why it's important to represent metabolic handoffs as accurately as possible in models, consider nitrate, a groundwater contaminant from fertilizers. Subsurface microbes are the primary driver in reducing nitrate to harmless nitrogen gas. There are four steps in this denitrification process, and the third step creates nitrous oxide—one of the most potent greenhouse gases. The process breaks down if microbes that carry out the fourth step are inactive when a pulse of nitrate enters the system.

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"The scientists found the carbon, hydrogen, nitrogen, and sulfur cycles are all driven by metabolic handoffs that require an unexpectedly high degree of interdependence among microbes. The vast majority of microorganisms can't fully reduce a compound on their own. It takes a team. There are also backup microbes ready to perform a handoff if first-string microbes are unavailable.

""The combination of high microbial diversity and interconnections through metabolic handoffs likely results in high ecosystem resilience," says Banfield."

Comment: Note the balance of nature among bacteria which support making Earth a stable platform for living organisms. Why bother with multicellularity?