Transition from anoxygenic to oxygenic photosynthesis in a Microcoleus chthonoplastes cyanobacterial mat

Journal Article · Sat Feb 01 00:00:00 EST 1986 · Appl. Environ. Microbiol.; (United States)

OSTI ID:6037481

Joergensen, B B; Cohen, Y; Revsbech, N P

Benthic cyanobacteria mats with the filamentous Microcoleus chthonoplastes as the dominant phototroph grow in toxic hypersaline environments. The cyanobacteria are in situ exposed to chemical variations between 200 ..mu..mol of sulfide liter/sup -1/ at night and 1 atm pO/sub 2/ during the day. During experimental H/sub 2/S to O/sub 2/ transitions the microbial community was shown to shift from anoxygenic photosynthesis, with H/sub 2/S as the electron donor, to oxygenic photosynthesis. Microcoleus filaments could carry out both types of photosynthesis concurrently. Anoxygenic photosynthesis dominated at high sulfide levels, 500 ..mu..mol liter/sup -1/, while the oxygenic reaction became dominant when the sulfide level was reduced below 100 to 300 ..mu..mol liter/sup -1/ (25 to 75 ..mu..mol of H/sub 2/S liter/sup -1/). An increasing inhibition of the oxygenic photosynthesis was observed upon transition to toxic conditions from increasing sulfide concentrations. Oxygen built up within the Microcoleus layer of the mat even under 5 mmol of sulfide liter/sup -1/ (500 ..mu..mol of H/sub 2/S liter/sup -1/) in the overlying water. The implications of such a localized O/sub 2/ production in a highly reducing environment are discussed in relation to the evolution of oxygenic photosynthesis under sulfide, is found in cyanobacteria exposed to low H/sub 2/S concentrations in various hot springs. When H/sub 2/S levels exceed 200 ..mu..M another type of adaptation involving partial induction of anoxygenic photosynthesis during the Proterozoic era.

• Research Organization: Hebrew Univ. of Jerusalem, Eilat, Israel
• OSTI ID: 6037481
• Journal Information: Appl. Environ. Microbiol.; (United States), Vol. 51:2
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
CYANOBACTERIA
PHOTOSYNTHESIS
HYDROGEN SULFIDES
ECOLOGICAL CONCENTRATION
METABOLISM
BENTHOS
GROWTH
OXYGEN
AQUATIC ORGANISMS
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
HYDROGEN COMPOUNDS
MICROORGANISMS
NONMETALS
PHOTOCHEMICAL REACTIONS
SULFIDES
SULFUR COMPOUNDS
SYNTHESIS
550500* - Metabolism