Advertisement

If you have an ACS member number, please enter it here so we can link this account to your membership. (optional)

ACS values your privacy. By submitting your information, you are gaining access to C&EN and subscribing to our weekly newsletter. We use the information you provide to make your reading experience better, and we will never sell your data to third party members.

ENJOY UNLIMITED ACCES TO C&EN

Environment

Anaerobic Photosynthesis

Extremophile microbes employ arsenic, rather than water, to drive biomass-building process

by Carrie Arnold
August 13, 2008

EXTREME EATING
[+]Enlarge
Credit: Laurence Miller/Shaun Baesman
Ectothiorhodospira bacteria (red), found at Mono Lake, oxidizes AsO33- to AsO43- to drive photosynthesis.
Credit: Laurence Miller/Shaun Baesman
Ectothiorhodospira bacteria (red), found at Mono Lake, oxidizes AsO33- to AsO43- to drive photosynthesis.

Researchers have found two microbial species that use arsenite (AsO33-) to supply electrons for photosynthesis instead of water typically used by most plants (Science 2008, 321, 967).

During photosynthesis, plants use sunlight to extract electrons from water and donate them to carbon dioxide. They then use the carbon and hydrogen to build biomass and release oxygen as a by-product.

But a team led by Ronald S. Oremland of the U.S. Geological Survey discovered red- and green-colored microbes growing in anoxic, hot-spring-fed brine pools at Mono Lake, in California, that extract electrons from arsenite instead of water. The researchers identified the microbes? quirky metabolism while growing the organisms in the lab. Only after exposing each microbe to light did they find that arsenite was being oxidized to arsenate (AsO43-).

These species of microbes and other so-called extremophiles are thought to have evolved almost 3 billion years ago as a consequence of their seemingly inhospitable, low-oxygen environment. The newly discovered chemistry provides a further glimpse of what life might have been like on early Earth, the researchers note.

Article:

This article has been sent to the following recipient:

0 /1 FREE ARTICLES LEFT THIS MONTH Remaining
Chemistry matters. Join us to get the news you need.