Chlorobium tepidum
A Microbial Biorealm page on the genus Chlorobium tepidum
Classification
Higher order taxa
Bactera; Chlorobi; Chlorobia; Chlorobiales; Chlorobiaceae
Species
Chlorobaculum; Chlorobium tepidum
Description and significance
Cholobium tepidum is an anaerobic phototrophic bacterium that is also a thermophile. As a member of the Chlorobiaceae family, it is a model organism of green sulfur bacteria. The habitats of this bacterium include anoxic and sulfide-rich waters, mud, sediments, microbial mats, and even microbial consortia. The cells of this bacterium are gram-negative nonmotile rods of varying lengths that photooxidize reduced sulfur compounds. C. tepidum was isolated from certain acidic high sulfide New Zealand hot springs. Under photoautotrophic conditions, the growth rate of this bacterium is faster than any other anaerobic phototroph as generations are produced about every two hours. Consequently, it is an ideal candidate for studying photosynthesis and autotrophy in green bacteria.
Genome structure
The genome of C. tepidum has been completely sequenced. Its genome is one circular DNA molecule that consists of 2,154,946 basepairs. Through genome comparisons, it has been identified that many genes in C. tepidum are highly conserved among photosynthetic species, and though they have no clear function, they may play important roles in photosynthesis or photobiology.
Cell structure and metabolism
C. tepidum are gram-negative cells that harvest light through special photosynthetic systems known as chlorosomes. Chlorosomes contain highly aggregated light-harvesting centers, including bacteriochlorophyll c and carotenoids that are surrounded by a protein-stabilized galactolipid monolayer that lies at the inner surface of the cytoplasmic membrane. Two unusual features of this bacterium are its inability to produce oxygen and its low toleration of oxygen despite being a photosynthetic organism. In addition, C. tepidum has the ability to fix carbon dioxide using a reverse tricarboxylic acid cycle using electrons from hydrogen or reduced sulfur.
Ecology
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Pathology
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Application to Biotechnology
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Current Research
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References
Edited by student of Rachel Larsen and Kit Pogliano
