Opitutus terrae

A Microbial Biorealm page on the genus Opitutus terrae

Classification

Higher order taxa

Bacteria; Chlamydiae/Verrucomicrobia group; Verrucomicrobia; Opitutae; Opitutales; Opitutaceae; Opitutus; Opitutus terrae

Species

NCBI: Taxonomy

Opitutus terrae

Description and significance

Cells are coccus, .4-.6 um in diameter, motile by means of a Flagellum.(Chin et al. 2001) Agar colonies are unpigmented and granular. Diplococci were commonly observed, but only one cell of these ever had a flagellum, but can also be seen in rods of 3 or 4. The habitat in which is usually found is always anoxic, but can either be a bog or a paddy. These were originally discovered in the rice paddies. They are obligate anaerobic which caused a pain for them to be studied until proper culturing methods were identified. Gram-negative bacteria.

Should be a new genus due to the fact that it only shares approximately 74% of the 16S rRNA with similiar verrucomicrobia. This was not only hard to culture alone, but also hard to produce in a mixed culture. The fermentation end products produced too much H2 to allow for the growth of hydrogen-utilizing methanogen Methanospirillum hungatei.

Genome structure

Genes: 4705, Protein coding: 4612 Topology: circular Length: 5,957,605 nt. A majority of these proteins are hypothetical, this is possibly due to the fact that not much of this organism is actually known.

Cell structure and metabolism

it is an obligate anaerobic. The type strain grows at pH values of 5.5 to 9.0, with maximum growth rates at pH 7.5-8.0. Growth of the type strain is possible at temperatures of 10 to 37 °C, but not at 4 or 40 °C. Aesculin is hydrolysed, but gelatin and urea are not. mono- di and polysaccharides support growth by fermentation end products are usually Propionate and acetate, with some H2 as well. Nitrate can be reduced to nitrite. No catalase or oxidase activity.

Ecology

As stated lives in the anoxic region of rice paddy soil. The end products of fermentation are reduced sugars, such as acetate and propionate and hydrogen. Both of these products are important in the process of methanogeneis. Studies have shown that O. terrae has a higher growth rate in the presense of methane-generating bacteria such as the Methanospirillum hungatei. Very slow growing. Using the method developed by Janssen takes about 2 months for O. terrae colonies to actually appear.

Also takes part in the nitrogen cycle, reducing the Nitrate to a nitrite leaving this for other bacteria to further convert. The denitrification allows for the Nitrate, or Nitrite whichever it may be, to actually become the terminal electron acceptor. The products from fermentation yet again aid in the completion of this denitrification, due to the fact that the H2 that is produced from the fermentation of poly and disaccharides can be used in the reduction of nitrogen products.

It has been stated that much of the methane that is present in the atmosphere was probably produced in the rice paddy. approximately 25 times as much H2 was produced in the methanogenic cocultures as in the pure cultures. It is true that sometimes there can be close coordination between the two microbacteria, the anaerobic fermenters and the methane-generating, such that the process of methanogenesis can simply use the end products of the fermentation process, however it is rarely seen that the usual main product from pure culture, the propionate is reduced by so much in contrast to the addition of acetate.

Current Research

Most of the current research revolves around evolution of the entire bacterial group the Verrucomicrobia. Verrucomicrobia in general have been found not only in the paddy soil, but also in environments as diverse as drinking water, to the debths of the oceans right back into bog soils. Verrucomicrobia have even been found in human intestines.

It is also being researched to see how the bacteria Opitutus terrae are actually evolved such as the fact that they are mostly adapted to low substrate concentrations.

References

Chin, K., Liesack, W., Janssen, P. H. ". Opitutus terrae gen. nov., sp. nov., to accommodate novel strains of the division ‘Verrucomicrobia’ isolated from rice paddy soil ". "Int J Syst Evol Microbiol.". 2001. Volume 51. p. 1965-1968.

Chin, K., Janssen, P. H. ". Propionate Formation by Opitutus terrae in Pure Culture and in Mixed Culture with a Hydrogenotrophic Methanogen and Implications for Carbon Fluxes in Anoxic Rice Paddy Soil ". " Applied and Environmental Microbiology". 2002. Volume 68. p. 2089-2092.

Choo,Y., Lee, K., Song, J., Cho, J.,". Puniceicoccus vermicola gen. nov., sp. nov., a novel marine bacterium, and description of Puniceicoccaceae fam. nov., Puniceicoccales ord. nov., Opitutaceae fam. nov., Opitutales ord. nov. and Opitutae classis nov. in the phylum ‘Verrucomicrobia". " Int J Syst Evol Microbiol ". 2007. Volume 57. p. 532-537.

Edited by student of Emily Lilly at University of Massachusetts Dartmouth.