Photosynthesis

Unicellular nitrogen-fixing cyanobacteriaA team of researchers headed by biologists at Washington University in St. Louis has sequenced the genome of a unique bacterium that manages two disparate operations — photosynthesis and nitrogen fixation — in one little cell during two distinct cycles daily.

A team of researchers headed by biologists at Washington University has sequenced the genome of a unique bacterium that manages two disparate operations — photosynthesis and nitrogen fixation — in one little cell during two distinct cycles daily.

Researchers at Washington University in St. Louis have gained the first detailed insight into the way circadian rhythms govern global gene expression in Cyanothece, a type of cyanobacterium (blue-green algae) known to cycle between photosynthesis during the day and nitrogen fixation at night.

Researchers at WUSTL and Arizona State University have sequenced the genome of a rare bacterium that harvests light energy by making an even rarer form of chlorophyll, chlorophyll d. Chlorophyll d absorbs “red edge,” near infrared, long wave length light that is invisible to the naked eye. In so doing, the cyanobacterium Acaryochloris marina competes with virtually no other plant or bacterium in the world for sunlight.

Researchers at Washington University in St. Louis and Arizona State University have sequenced the genome of a rare bacterium that harvests light energy by making an even rarer form of chlorophyll, chlorophyll d. Chlorophyll d absorbs “red edge,” near infrared, long wave length light that is invisible to the naked eye. In so doing, the cyanobacterium Acaryochloris marina, competes with virtually no other plant or bacterium in the world for sunlight.

David Kilper/WUSTL PhotoRobert Blankenship, professor of biology and chemistry at Washington University in St. Louis, holds the cyanobacteria *Acaryochloris marina*, a rare bacterium that uses chlorophyll d for photosynthesis.Researchers at Washington University in St. Louis and Arizona State University have sequenced the genome of a rare bacterium that harvests light energy by making an even rarer form of chlorophyll, chlorophyll d. Chlorophyll d absorbs “red edge,” near infrared, long wave length light that is invisible to the naked eye. In so doing, the cyanobacterium Acaryochloris marina, competes with virtually no other plant or bacterium in the world for sunlight.

Plants on extrasolar planets resembling Earth could be as black as these eggplants.Washington University biology and chemistry professor Robert Blankenship and his colleagues are seeking clues to life on extrasolar planets by studying various biosignatures found in the light spectrum leaking out to Earth. They are speculating on what kind of photosynthesis might occur on such planets and what the extrasolar plants might look like.

Photosynthesis transforms light, carbon dioxide and water into chemical energy in plants and some bacteria.When it comes to studying energy transfer in photosynthesis, it’s good to think “outside the bun.” That’s what Robert Blankenship, Ph.D., professor of biology and chemistry in Arts & Sciences at Washington University in St. Louis, did when he contributed a protein that he calls the taco shell protein to a study performed by his collaborators at Lawrence Berkeley National Laboratory and the University of California at Berkeley. The protein enabled the surprising discovery of a quantum effect in photosynthesis.

Photo by David Kilper / WUSTL PhotoHimadri Pakrasi explains the photobioreactor in his Rebstock Hall laboratory.The United States Department of Energy (DOE) has devoted $1.6 million to sequencing the DNA of six photosynthetic bacteria that Washington University in St. Louis biologists will examine for their potential as one of the nextgreat sources of biofuel that can run our cars and warm our houses. That’s a lot of power potential from microscopic cyanobacteria (blue-green algae) that capture sunlight and then do a variety of biochemical processes. One potential process, the clean production of ethanol, is a high priority for DOE. Himadri Pakrasi, Ph.D., Washington University Professor of Biology in Arts & Sciences, and Professor of Energy in the School of Engineering and Applied Science, will head a team of biologists at Washington University and elsewhere in the analysis of the genomes of six related strains of Cyanothece bacteria. More…

David Kilper/WUSTL PhotoChristine Kirmaier (left) and Dewey Holten making adjustments in their sophisticated laser laboratory. Their findings advance the understanding of photosynthesis.In the famous Robert Frost poem, “The Road Not Taken,” the persona, forced to travel one of two roads, takes the one less traveled by, and “that has made all the difference.” Chemists at Washington University in St. Louis and Stanford University, in kinship with Frost, have modified a key protein in a bacterium to move electrons along a pathway not normally traveled by. They got this to happen 70 percent of the time. That yield “makes all the difference.” More…