Candidatus Chloracidobacterium thermophilum

Classification

Domain (Bacteria); Super Phylum (Fibrobacteres/Acidobacteria group); Phylum (Acidobacteria); Class (Acidobacteria); Order (Acidobacteriales); Family (Acidobacteriaceae); Genus (Candidatus Chloracidobacterium)

Species

Candidatus Chloracidobacterium thermophilum

Description and Significance

A novel photosynthesizing bacterium named as 'Candidatus Chloracidobacterium thermophilum' (Cab. thermophium) has been recently (2007) discovered in Yellowstone’s hot springs by a collaborative research between Pennsylvania State University and Montana State University.[1] The research was funded by National Science Foundation, Department of Energy, and the NASA Exobiology Program.

Till date, chlorophyll based phototrophy is known to be present in only five groups or phyla of photosynthetic microorganisms (Cyanobacteria, Chloroflexi, Chlorobi, Proteobacteria and Firmicutes).[2] These phototropic microorganisms contain specific type of photosnthetic pigments (bacteriochlorophylls) to absorb specific wavelengths of light and differ in the type of molecular funtions for the conversion of light into chemical energy.Different groups contains different types of bacteriochlorophylls.[3] For example Bacteriochlorophyll a; Purple bacteria, "Cab.thermophilum" :Bacteriochlorophyll b; Purple bacteria :Bacteriochlorophyll c; Green sulfur bacteria, Chloroflexi, "Cab.thermophilum" :Bacteriochlorophyll d; Green sulfur bacteria :Bacteriochlorophyll e; Green sulfur bacteria :Bacteriochlorophyll g; Heliobacteria

Cab.thermophimum has light harvesting antennae (chlorosomes), where each chlorosomes contains 250,000 chlorophylls. Cab.thermophimum synthesizes chlorosomes to form bacteriochlorophylls a and c under oxic connditions unlike the anoxic conditions in other phototrops. Based on metagenomic analysis, it is considered to be a part of Acidobacteria phylum, which was not having any photosynthetic microorganim earlier. It is said that 'This is only the third time in the last 100 years that a new group of phototrophs has been discovered'.[4]

The researchers have found this novel bacterium in three hot springs (Mushroom Spring, Octopus Spring, Green Finger Pool) in Yellowstone National Park. It resides with the microbial mats at moderately high temperature (50-66 degree celsius) and in alkaline environment (pH 8.5).The 16S rDNA analysis shows the relative microorganims to Cab.thermophilum also exist in hot springs in Tibet and Thailand and is expected to have high diversity and complex ecology.[1]

Genome Structure

Describe the size and content of the genome. How many chromosomes? Circular or linear? Other interesting features? What is known about its sequence?

Cell Structure, Metabolism and Life Cycle

Interesting features of cell structure; how it gains energy; what important molecules it produces.

Candidatus Chloracidobacterium thermophilum is a Gram-positive, aerobic, rod-shaped bacterium. It is 2.5 microns long and about 0.7 microns in diameter.

Ecology and Pathogenesis

Habitat; symbiosis; biogeochemical significance; contributions to environment.
If relevant, how does this organism cause disease? Human, animal, plant hosts? Virulence factors, as well as patient symptoms.

References

[1] Donald A. Bryant, Amaya M. Garcia Costas,Julia A. Maresca,Aline Gomez Maqueo Chew,Christian G. Klatt,Mary M. Bateson,Luke J. Tallon, Jessica Hostetler, William C. Nelson,John F. Heidelberg, David M. Ward. "Candidatus Chloracidobacterium thermophilum: An Aerobic Phototrophic Acidobacterium". " Science". 2007. Volume 317. p. 523 - 526

[2] D. A. Bryant, N.-U. Frigaard. "Prokaryotic photosynthesis and phototrophy illuminated". "Trends Microbiology". 2006. Volume 14. p. 488-496

[3] http://en.wikipedia.org/wiki/Bacteriochlorophyll

[4] http://www.bmb.psu.edu/faculty/bryant/lab/Project/Acido/index.html

Author

Page authored by Ahmad Farhan and Anadumaka V. Chike, student of Prof. Jay Lennon at Michigan State University.