EMBARGOED FOR RELEASE:
Wednesday, 13 June 2001 at 14:00 U.S. Eastern Time
Scientists describe variation in oceanic
bacterial photopigments that convert light
into biochemical energy
MOSS LANDING, California—Monterey Bay Aquarium Research Institute (MBARI)
microbiologists report in the 14 June 2001 issue of the journal Nature
the discovery of the widespread occurrence and depth-specific adaptation
of a new energy-generating, light-absorbing pigment, proteorhodopsin. Last
fall in the journal Science, MBARI researchers described the
discovery of the first marine bacterium with this photopigment that can
generate cellular energy using light; however, the function of those
microbes in the ocean environment remained a mystery.
"Advances in technology are letting us view the marine microbial
world in new ways," said Ed DeLong, leader of the research group.
First author of the Nature paper, Oded Béjà, adds, "We were
lucky to find these different proteorhodopsins out there in the vast
ocean. The diversity in the field is probably much greater."
In the more recent study, samples of oceanic bacteria collected from
Monterey Bay, Antarctica, and Hawaii were analyzed for the presence of
active photopigment. In collaboration with John and Elena
Spudich from the University of Texas Medical School, the group used
laser flash spectroscopic techniques on naturally occurring marine
microbes to search for the new photochemical activity in oceanic waters.
The scientists observed chemical activity stimulated by the light flashes
in native marine microbes, similar to the activity seen in earlier
laboratory studies of proteorhodopsin and bacteriorhodopsin. These
observations showed that the microbes and active photopigment were present
in abundance at the ocean’s surface.
The researchers also showed that genetic variants of the photoactive
microbes contain different proteorhodopsins in different ocean habitats.
The protein pigments appear to be tuned to absorb light of different
wavelengths that match the quality of light available in a variety of
environments. Specific adaptations in the photopigment structure have
optimized different variants functioning best at different depths in the
DeLong and his colleagues are excited by the implications of this
research for two main reasons. First, the study takes the initial
laboratory observations out to the ocean, showing how common and
widespread this photopigment is throughout the world’s oceans. In
addition, the concentration of the photopigment suggests that it has the
capacity to generate a significant amount of energy for oceanic microbes.
DeLong also notes the variations observed in the photopigment suggest it’s
importance not only at the ocean’s surface, but throughout the photic
zone. This new study further supports the notion that the microbes
containing the rhodopsin-like photopigments significantly impact carbon
and energy cycles in the world’s oceans.
Debbie Meyer, (831) 775-1807, firstname.lastname@example.org
Research article: Béjà, O., E.N.
Spudich, J.L. Spudich, M. Leclerc, and E.F. DeLong (2001). Proteorhodopsin
phototrophy in the ocean. Nature, 411: 786-789.
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