Heliobacteria
Encyclopedia
The heliobacteria are phototrophic
, that is to say, they convert light energy into chemical energy by photosynthesis
; they use a PSI type reaction center. The primary pigment involved is bacteriochlorophyll g, which is unique to the group and has a unique absorption spectrum; this gives the heliobacteria their own environmental niche. Phototrophy takes place at the cell membrane, which does not form folds or compartments as it does in purple phototrophic bacteria. Even though heliobacteria are phototrophic, they can grow without light by fermentation of pyruvate.
RNA trees place the heliobacteria among the Firmicutes
but they do not stain gram-positively. They have no outer membrane and like certain other firmicutes (clostridia) they form heat resistant endospore
s, which contain high levels of calcium and dipicolinic acid. Heliobacteria are the only firmicutes known to conduct photosynthesis.
Heliobacteria are photoheterotroph
ic, requiring organic carbon sources, and they are exclusively anaerobic
. So far heliobacteria have only been found in soils, and are apparently widespread in the waterlogged soils of paddy fields. They are avid nitrogen fixers and are therefore probably important in the fertility of paddy fields.
Notes:
♠ Strain found at the National Center for Biotechnology Information
(NCBI) but has no standing with the Bacteriological Code (1990 and subsequent Revision) as detailed by List of Prokaryotic names with Standing in Nomenclature (LPSN) as a result of the following reasons:
• No pure culture isolated or available for Prokayotes.
• Not validly published because the effective publication only documents deposit of the type strain in a single recognized culture collection.
• Not approved and published by the International Journal of Systematic Bacteriology or the International Journal of Systematic and Evolutionary Microbiology
(IJSB/IJSEM).
Phototrophic
Phototrophic may refer to:*Phototrophic may refer to Phototroph type plants and bacteria* Phototrophic by Desert rock band Kyuss from their album ...And the Circus Leaves Town...
, that is to say, they convert light energy into chemical energy by 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...
; they use a PSI type reaction center. The primary pigment involved is bacteriochlorophyll g, which is unique to the group and has a unique absorption spectrum; this gives the heliobacteria their own environmental niche. Phototrophy takes place at the cell membrane, which does not form folds or compartments as it does in purple phototrophic bacteria. Even though heliobacteria are phototrophic, they can grow without light by fermentation of pyruvate.
RNA trees place the heliobacteria among the Firmicutes
Firmicutes
The Firmicutes are a phylum of bacteria, most of which have Gram-positive cell wall structure. A few, however, such as Megasphaera, Pectinatus, Selenomonas and Zymophilus, have a porous pseudo-outer-membrane that causes them to stain Gram-negative...
but they do not stain gram-positively. They have no outer membrane and like certain other firmicutes (clostridia) they form heat resistant endospore
Endospore
An endospore is a dormant, tough, and temporarily non-reproductive structure produced by certain bacteria from the Firmicute phylum. The name "endospore" is suggestive of a spore or seed-like form , but it is not a true spore . It is a stripped-down, dormant form to which the bacterium can reduce...
s, which contain high levels of calcium and dipicolinic acid. Heliobacteria are the only firmicutes known to conduct photosynthesis.
Heliobacteria are photoheterotroph
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...
ic, requiring organic carbon sources, and they are exclusively anaerobic
Anaerobic organism
An anaerobic organism or anaerobe is any organism that does not require oxygen for growth. It could possibly react negatively and may even die if oxygen is present...
. So far heliobacteria have only been found in soils, and are apparently widespread in the waterlogged soils of paddy fields. They are avid nitrogen fixers and are therefore probably important in the fertility of paddy fields.
Taxonomy
Family Heliobacteriaceae- Candidatus Helioclostridium♠ Girija et al. 2006
- Candidatus Helioclostridium ananthapuram♠ Girija et al. 2006
- Heliorestis Bryantseva et al. 2000
- H. baculata Bryantseva et al. 2001
- H. convoluta♠ Asao et al. 2005
- H. daurensis Bryantseva et al. 2000
- Heliophilum Ormerod et al. 1996
- Heliophilum fasciatum Ormerod et al. 1996
- Heliobacillus Beer-Romero and Gest 1998
- Candidatus H. elongatus♠ Girija et al. 2006
- H. mobilis Beer-Romero and Gest 1998
- Heliobacterium Gest and Favinger 1985
- H. aridinosum♠ Girija et al. 2006
- H. chlorum Gest and Favinger 1985
- H. gestii Ormerod et al. 1996
- H. modesticaldum Kimble et al. 1996
- H. sulfidophilum Bryantseva et al. 2001
- H. undosum Bryantseva et al. 2001
Notes:
♠ Strain found at the National Center for Biotechnology Information
National Center for Biotechnology Information
The National Center for Biotechnology Information is part of the United States National Library of Medicine , a branch of the National Institutes of Health. The NCBI is located in Bethesda, Maryland and was founded in 1988 through legislation sponsored by Senator Claude Pepper...
(NCBI) but has no standing with the Bacteriological Code (1990 and subsequent Revision) as detailed by List of Prokaryotic names with Standing in Nomenclature (LPSN) as a result of the following reasons:
• No pure culture isolated or available for Prokayotes.
• Not validly published because the effective publication only documents deposit of the type strain in a single recognized culture collection.
• Not approved and published by the International Journal of Systematic Bacteriology or the International Journal of Systematic and Evolutionary Microbiology
International Journal of Systematic and Evolutionary Microbiology
The International Journal of Systematic and Evolutionary Microbiology is a peer-reviewed scientific journal in the field of microbial systematics, first published in 1951...
(IJSB/IJSEM).