Moorella thermoacetica

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Figure 1: Moorella thermoacetica cells in culture

Classification

Kingdom: Bacteria

Phylum: Firmicutes

Class: Clostridia

Order: Thermoanaerobacterales

Family: Thermoanaerobacteriaceae

Genus: Moorella

Species: thermoacetica

Species

Moorella thermoacetica

Significance

Moorella thermoacetica is a model acetogen. Its simple metabolism and location within anaerobic, warm waters have suggested that this organism is related to some of the earliest forms of life on Earth.

Genome Structure

The complete genome of M. thermoacetica was sequenced in 2008. Upon completion it was the first acetogen to be mapped.

The genome consists of a single circular chromosome with 2,628,784 base pairs with a GC (guanine-cytosine) content of 56%. Seventy percent of the predicted 2523 protein-encoding genes had been assigned known functions, with the remaining having an unknown purpose.

Specific clusters including those linked to the Wood-Ljungdahl pathway and autotrophy were confirmed.

Further analysis of the 16S rRNA sequences were pivotal in proving that acetogenesis is a metabolic trait rather than a phylogenetic trait.

Cell Structure and Metabolism

Moorella thermoacetica cells are gram-positive and rod shaped, they ranging in size from 0.4 to 2.8 micrometers and possess peritrichous flagella though it lacks motility; the cells will form circular, opaque colonies. M. thermoacetica spores are spherical and most often are formed sub-terminally within the sporangium. Moorella thermoacetica is an acetogenic bacteria that can autotrophically produce acetate by reducing carbon dioxide. Acetogenesis can be formed via the acetyl coenzyme A pathway or the Wood–Ljungdahl pathway.exception. Indeed, M. thermoacetica is one if the most metabolically diverse acetogens that uses a variety of substrates. This bacterium grows hetrotrophically and autotrophically , and it uses nicotinic acid, the only organic nutritional requirement.

Ecology

Moorella thermoacetia's acetyl-CoA pathway is centrally important in cycling of carbon in various environments .
In nature, Moorella thermoacetica is found in soil, at the bottom of stagnant ponds. M. thermoacetatia is globally distributed in soils that experience periodic thermophilic temperatures and is anaerobic. The bacterium is a thermophile, growing at 58°C (140°F).

References

Drake, H.L., Daniel, S.L. (2004) Physiology of the thermophilic acetogen Moorella thermoacetica. Research in Microbiology 155: 869-883.

Jiang, B., Henstra, A.M., Paulo, P.L., Balk, M., Van Doesburg, W., and Stams, A.J.M. (2009) Atypical one-carbon metabolism of an acetogenic and hydrogenogenic Moorella thermoacetica strain. Archives of Microbiology 191: 123-131.

Pierce. E., et al, 2008. The complete genome sequence of Moorella thermoacetica (f. clostridium thermoacetica) Environ Microbiol. 10 (10):2550-73

Author

Page authored by Thomas Wilson, Leena Babiker and Esther Dzikushie, students of Professors Ned Walker and Kaz Kashefi, Michigan State University.