Varying CO2/O2 ratio in Prochlorococcus

Note the paper

The ISME Journal , (7 April 2015) | D FOR
Sarah C Bagby
Sallie W Chisholm
Response of Prochlorococcus to varying CO2:O2 ratios

Sarah C Bagby and Sallie W Chisholm

From PMS on Sallie Chisholm:



Over the years, Chisholm and her students have studied in detail the genomes of these organisms, finding them to be incredibly diverse, with variations depending on both their geographic location and the depth at which they live. Prochlorococcus come in two broad categories: low-light adapted, which live in deep water, and high-light adapted, which thrive in shallow water with plenty of light.

After analyzing the genetic makeup of these species, which contain only about 2,300 genes, Chisholm concluded: “It’s absolutely the minimal life form. It’s the smallest amount [of genetic coding] that can convert inorganic compounds into organic ones.”

But for a tiny and simple creature, Prochlorococcus is remarkably diverse, she said. Of those 2,300 genes, only about 1,200 are common to all varieties of the organism. A vast number of other genes — perhaps as many as 80,000 — can occur in some varieties, but not others. (By comparison, humans have a total of about 20,000 genes).

Though the creature is tiny, its impact is huge, Chisholm has found: Its photosynthesis, which converts carbon dioxide into organic compounds that mostly sink to the seafloor, is so extensive that if it didn’t exist, the carbon dioxide in Earth’s atmosphere — the main agent of global warming — would be double or even triple what it actually is.

These tiny creatures, Chisholm said, have turned out to be “the gift that keeps on giving,” yielding ever-new insights — and new questions — that have driven her life’s research. Ongoing research with Prochlorococcus, she said, holds the prospect of uncovering entirely new kinds of antibiotics, or perhaps even a new way of producing biofuels.