Rhodobacter sphaeroides
Encyclopedia
Rhodobacter sphaeroides is a kind of purple bacteria
; a group of bacteria that can obtain energy through photosynthesis
. Its best growth conditions are anaerobic
phototrophy (photoheterotrophic
and photoautotrophic) and aerobic
chemoheterotrophy in the absence of light. R. sphaeroides is also able to fix nitrogen
. It is remarkably metabolically diverse, as it is able to grow heterotrophically
via fermentation
and aerobic
and anaerobic
respiration.
R. sphaeroides has been isolated from deep lakes and stagnate waters.
R. sphaeroides is one of the most pivotal organisms in the study of bacterial photosynthesis. It requires no unusual conditions for growth and is incredibly efficient
. The regulation of its photosynthetic machinery is of great interest to researchers, as R. sphaeroides has an intricate system for sensing O2 tensions. Also, when exposed to a reduction in the partial pressure of oxygen, R. sphaeroides develops invaginations in its cellular membrane. The photosynthetic apparatus is housed in these invaginations. These invagiantions are also known as chromatophores.
The genome of R. sphaeroides is also somewhat intriguing. It has two chromosomes, one of 3 Mb (CI) and one of 900 Kb (CII), and five naturally occurring plasmids. Many genes are duplicated between the two chromosomes but appear to be differentially regulated. Moreover, many of the open reading frames (ORFs) on CII seem to code for proteins of unknown function. When genes of unknown function on CII are disrupted, many types of auxotrophy result, emphasizing that the CII is not merely a truncated version of CI.
Purple bacteria
Purple bacteria or purple photosynthetic bacteria are proteobacteria that are phototrophic, that is capable of producing energy through photosynthesis...
; a group of bacteria that can obtain energy through photosynthesis
Photosynthesis
Photosynthesis is a chemical process that converts carbon dioxide into organic compounds, especially sugars, using the energy from sunlight. Photosynthesis occurs in plants, algae, and many species of bacteria, but not in archaea. Photosynthetic organisms are called photoautotrophs, since they can...
. Its best growth conditions are anaerobic
Anaerobic
Anaerobic is a word which literally means without oxygen, as opposed to aerobic.In wastewater treatment the absence of oxygen is indicated as anoxic; and anaerobic is used to indicate the absence of a common electron acceptor such as nitrate, sulfate or oxygen.Anaerobic may refer to:*Anaerobic...
phototrophy (photoheterotrophic
Photoheterotroph
Photoheterotrophs are heterotrophic organisms that use light for energy, but cannot use carbon dioxide as their sole carbon source. Consequently, they use organic compounds from the environment to satisfy their carbon requirements. They use compounds such as carbohydrates, fatty acids and...
and photoautotrophic) and aerobic
Aerobic
Aerobic is a word that means "requiring air", where "air" usually means oxygen.Aerobic may also refer to:* Aerobic exercise, prolonged exercise of moderate intensity* Aerobics, a form of aerobic exercise...
chemoheterotrophy in the absence of light. R. sphaeroides is also able to fix nitrogen
Nitrogen fixation
Nitrogen fixation is the natural process, either biological or abiotic, by which nitrogen in the atmosphere is converted into ammonia . This process is essential for life because fixed nitrogen is required to biosynthesize the basic building blocks of life, e.g., nucleotides for DNA and RNA and...
. It is remarkably metabolically diverse, as it is able to grow heterotrophically
Heterotroph
A heterotroph is an organism that cannot fix carbon and uses organic carbon for growth. This contrasts with autotrophs, such as plants and algae, which can use energy from sunlight or inorganic compounds to produce organic compounds such as carbohydrates, fats, and proteins from inorganic carbon...
via fermentation
Fermentation
Fermentation may refer to:* Fermentation , the use of fermentation in food preparation* Fermentation , a metabolic process whereby electrons released from nutrients are ultimately transferred to molecules obtained from the breakdown of those same nutrients* Fermentation , the process of...
and aerobic
Aerobic
Aerobic is a word that means "requiring air", where "air" usually means oxygen.Aerobic may also refer to:* Aerobic exercise, prolonged exercise of moderate intensity* Aerobics, a form of aerobic exercise...
and anaerobic
Anaerobic
Anaerobic is a word which literally means without oxygen, as opposed to aerobic.In wastewater treatment the absence of oxygen is indicated as anoxic; and anaerobic is used to indicate the absence of a common electron acceptor such as nitrate, sulfate or oxygen.Anaerobic may refer to:*Anaerobic...
respiration.
R. sphaeroides has been isolated from deep lakes and stagnate waters.
R. sphaeroides is one of the most pivotal organisms in the study of bacterial photosynthesis. It requires no unusual conditions for growth and is incredibly efficient
Photosynthetic efficiency
The photosynthetic efficiency is the fraction of light energy converted into chemical energy during photosynthesis in plants and algae. Photosynthesis can be described by the simplified chemical reactionwhere CH2O represents carbohydrates such as sugars, cellulose, and lignin.The value of the...
. The regulation of its photosynthetic machinery is of great interest to researchers, as R. sphaeroides has an intricate system for sensing O2 tensions. Also, when exposed to a reduction in the partial pressure of oxygen, R. sphaeroides develops invaginations in its cellular membrane. The photosynthetic apparatus is housed in these invaginations. These invagiantions are also known as chromatophores.
The genome of R. sphaeroides is also somewhat intriguing. It has two chromosomes, one of 3 Mb (CI) and one of 900 Kb (CII), and five naturally occurring plasmids. Many genes are duplicated between the two chromosomes but appear to be differentially regulated. Moreover, many of the open reading frames (ORFs) on CII seem to code for proteins of unknown function. When genes of unknown function on CII are disrupted, many types of auxotrophy result, emphasizing that the CII is not merely a truncated version of CI.
Synonyms
- Rhodococcus minor Molisch 1907
- Rhodococcus capsulatus Molisch 1907
- Rhodosphaera capsulata (Molisch) Buchanan 1918
- Rhodosphaera minor (Molisch) Bergey et al. 1923
- Rhodorhagus minor (Molisch) Bergey et al. 1925
- Rhodorhagus capsulatus (Molisch) Bergey et al. 1925
- Rhodorrhagus capsulatus Bergey et al. 1939
- Rhodopseudomonas sphaeroides van Niel 1944
- Rhodopseudomonas spheroides van Niel 1944
- Rhodorrhagus spheroides (van Niel) Brisou 1955