Related Experiment Video
Updated: Jul 14, 2026
06:17
Medium Preparation for the Cultivation of Microorganisms under Strictly Anaerobic/Anoxic Conditions
Published on: August 15, 2019
Nitrite, an electron donor for anoxygenic photosynthesis
Benjamin M Griffin1, Joachim Schott, Bernhard Schink
1Department for Biology, Universität Konstanz, D-78457 Konstanz, Germany. griff113@uiuc.edu
Science (New York, N.Y.)
|June 30, 2007
Summary
Anoxygenic phototrophic bacteria can use nitrite as an electron donor for photosynthesis. This newly discovered process is the first known microbial mechanism for nitrite to nitrate conversion in the absence of oxygen.
Area of Science:
- Microbiology
- Biochemistry
- Environmental Science
Background:
- Anoxygenic phototrophic bacteria utilize various electron donors for photosynthesis.
- The nitrogen cycle involves complex microbial transformations of nitrogen compounds.
- Nitrite's role as a direct electron donor in photosynthesis was previously unknown.
Purpose of the Study:
- To investigate the potential of nitrite as an electron donor for anoxygenic photosynthesis.
- To identify and characterize microorganisms capable of nitrite-driven photosynthesis.
- To elucidate the microbial mechanism of nitrite oxidation in the absence of oxygen.
Main Methods:
- Isolation and characterization of a novel purple sulfur bacterium.
- Cultivation experiments under controlled light and nitrite conditions.
- Stoichiometric analysis of nitrite oxidation to nitrate.
Main Results:
- A purple sulfur bacterium, closely related to Thiocapsa species, was isolated.
- The bacterium stoichiometrically oxidized nitrite to nitrate exclusively in the light.
- Bacterial growth and nitrate production were strictly dependent on light and nitrite availability.
Conclusions:
- This study reveals a novel photosynthetic pathway using nitrite as the electron donor.
- It represents the first known microbial mechanism for stoichiometric nitrite to nitrate oxidation without oxygen.
- Nitrite is identified as the highest-potential electron donor for anoxygenic photosynthesis to date, impacting our understanding of the nitrogen cycle.
More Related Videos
09:45Laboratory Simulation of an Iron(II)-rich Precambrian Marine Upwelling System to Explore the Growth of Photosynthetic Bacteria
Published on: July 24, 2016
13:21Detection of Nitric Oxide and Superoxide Radical Anion by Electron Paramagnetic Resonance Spectroscopy from Cells using Spin Traps
Published on: August 18, 2012
Related Concept Videos
01:30Anoxygenic Photosynthesis
Anoxygenic photosynthesis is a phototrophic process that captures light energy to drive carbon fixation without producing molecular oxygen. Unlike oxygenic photosynthesis, which utilizes water as an electron donor and releases oxygen, anoxygenic phototrophs use alternative electron donors such as hydrogen sulfide (H₂S), elemental sulfur (S⁰), or thiosulfate (S₂O₃²⁻). This process is carried out by diverse groups of bacteria, including purple bacteria, green sulfur bacteria, heliobacteria, and...
01:28Anoxygenic Phototrophic Bacteria
Anoxygenic phototrophic bacteria are a diverse group of microorganisms that perform photosynthesis without producing oxygen. They primarily include purple sulfur bacteria, purple nonsulfur bacteria, green sulfur bacteria, and green nonsulfur bacteria. These bacteria are classified into the Gammaproteobacteria, Alphaproteobacteria, Betaproteobacteria, Chlorobi, and Chloroflexi lineages, each with distinct physiological and ecological adaptations.Purple sulfur bacteria belong to the...
01:26Oxygenic Photosynthesis
Oxygenic photosynthesis is a fundamental process in which light energy is harnessed to drive the oxidation of water, leading to the production of molecular oxygen (O₂), adenosine triphosphate (ATP), and nicotinamide adenine dinucleotide phosphate (NADPH). This process is essential for sustaining aerobic life on Earth and is primarily carried out by cyanobacteria, algae, and plants. The core of oxygenic photosynthesis lies in the thylakoid membranes, where chlorophyll pigments facilitate light...
01:15Metabolism of Chemolithotrophs
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation. However, because inorganic electron donors...
01:28Microbial Nutrition
Organisms exhibit remarkable metabolic diversity, categorized based on how they acquire energy and carbon. These strategies enable survival in various ecological niches and are essential for maintaining energy flow and nutrient cycling within ecosystems.Energy and Carbon SourcesOrganisms are classified as phototrophs or chemotrophs based on energy acquisition. Phototrophs use light as their energy source, while chemotrophs rely on oxidizing chemical compounds. Further differentiation arises...
01:30Bacterial Phylum Cyanobacteria
Cyanobacteria are a diverse group of oxygenic, phototrophic bacteria that played a pivotal role in converting Earth’s atmosphere from anoxic to oxygen-rich billions of years ago. They exhibit remarkable morphological diversity, ranging from unicellular forms to filamentous types, with cell sizes varying between 0.5 μm and 100 μm. Cyanobacteria are classified into five groups: Chroococcales (unicellular, dividing by binary fission), Pleurocapsales (unicellular, dividing by multiple fission),...