Methanospirillum hungatei
Classification
Archaea; Euryarchaeota; Methanomicrobia; Methanomicrobiales; Methanospirillaceae
Species
NCBI: Taxonomy |
Methanospirillum hungatei
Description and Significance
Methanospirillum hungatei was first found in sewage sludge and was named in honor of R.E. Hungate. This genus and species name was first proposed in 1974 by Ferry et. al. The cultures are usually yellow in color, circular in shape, and convex with lobate margins (Ferry et. al. 1974). The cells are spiral shaped and range from 0.5-7.4 microns in diameter and 15 to several hundred microns long and have tufts of polar flagella that provide a small amount of motility (Ferry et. al. 1974).
The optimum habitat for these organisms has a temperature range of 30-37 degrees Celsius (mesophilic) and a pH range of 6.6-7.4 (Ferry et. al. 1974).
Thsi microorganism is very important to the waste treatment and bioenergy industries because it can break down organic wastes and produces methane in the process.
Genome Structure
Methanospirillum hungatei has circular chromosomes of length 3544738; it has 3139 gene proteins and 66 RNA genes (Kanehisa Labs). The guanine and cytosine content is 45% for this organism (Ferry et. al. 1974).
Cell Structure, Metabolism and Life Cycle
Methanospirillum hungatei has very interesting structure. For instance, it is mostly gram negative, but the multicellular filaments at the ends test as gram positive (Beveridge et. al. 1991). It grows in groups consisting of chains of cells about 9-12 cells long, which are encased in a paracrystalline sheath (Beveridge et. al. 1991). It is thought that this proteinaceous sheath acts as a kind of pressure regulator; the sheath is able to expand as the internal pressure of the cell increases due to the production of methane, which increases the permeability of the sheath to allow methane to diffuse out and hydrogen and carbon dioxide to diffuse in (Xu et. al. 1996).
This microorganism is considered a "fastidious anaerobe," meaning it is very sensitive to oxygen (Ferry et. al. 1974). It is also a methanogen and grows best in an atmosphere with a mixture of hydrogen and carbon dioxide, with 80% H2 and 20% CO2 being the optimum conditions (Ferry et. al. 1974). It can use formate or acetate as a carbon source and has been shown to demonstrate a chemotactic response to the presence of acetate (Migas et. al. 1989). According to a study that used magnetic resonance of 13C to tag carbon dioxide and acetate, the acetate and carbon dioxide are first used to form pyruvate, which then goes through the glucogenic pathway to form carbohydrates (Ekiel et. al. 1983). They found that 99% of the carbon in the methane produced comes from carbon dioxide (Ekiel et. al. 1983).
Ecology and Pathogenesis
No pathogenesis is known.
References
1: NCBI. “Methanospirillum hungatei.” Taxonomy Browser.
Author
Page authored by Shannon Henderson and David Hall, students of Prof. Jay Lennon at Michigan State University.
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