Chlorobium tepidum

From MicrobeWiki, the student-edited microbiology resource

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

Describe any interactions with other organisms (included eukaryotes), contributions to the environment, effect on environment, etc.

Pathology

How does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

Application to Biotechnology

Does this organism produce any useful compounds or enzymes? What are they and how are they used?

Current Research

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References

[Sample reference] Takai, K., Sugai, A., Itoh, T., and Horikoshi, K. "Palaeococcus ferrophilus gen. nov., sp. nov., a barophilic, hyperthermophilic archaeon from a deep-sea hydrothermal vent chimney". International Journal of Systematic and Evolutionary Microbiology. 2000. Volume 50. p. 489-500.

Edited by student of Rachel Larsen and Kit Pogliano