Meiothermus taiwanensis

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A Microbial Biorealm page on the genus Meiothermus taiwanensis

Classification

Higher order taxa

Cellular organisms; Bacteria; Deinococcus-Thermus; Deinococci; Thermales; Thermaceae; Meiothermus; Meiothermus taiwanensis¹

Species

Meiothermus taiwanensis strain WR-220

Description and significance

Meiothermus taiwanensis is a rod-shaped thermophilic bacterium that was isolated from the Wu-rai hot springs of Taipei in northern Taiwan². This bacterium is gram-negative, non-motile, non-sporulating, produces red to red-orange pigments, and forms long filamentous trichomes². The optimal growth temperature is between 55-60°C, but is able to survive in a temperature range of 40-70°C². When tested, the pH range of the samples taken from the hot spring was between 6.2-7.9, but the optimal pH was 8.0 at the optimal growth temperature².

Many thermophiles produce thermozymes that have various applications in the medical, pharmaceutical, biotechnological, food, and detergent industries. Studying these organisms may lead to the discovery of useful thermozymes that could improve the efficiency of reactions, and save money. By researching thermophiles, we may be able to incorporate their specific adaptations (like special membrane construction) to benefit ourselves or other organisms.

Genome structure

After performing PCR and sequencing, the 16S rDNA sequence was determined to be 1482 nt². Comparison of this 16S rDNA sequence to the European Nucleotide Archive (EMBL) database showed that strain WR-220 belongs to the genus Meiothermus². An interesting finding was that strain WR-220 has the same 16S rDNA sequence as strain WR-30 (with a 99.46% similarity), which was isolated from the same hot spring in Taiwan². This was an interesting discovery because it clearly defines strains WR-220 and WR-30 as not only different species of Meiothermus, but also a separate sister cluster from other clusters (M. ruber and M. cerbereus for example). It is not unusual that the two strains have such similar genomes because they came from the same hot spring.

In 2013 the genome of strain WR-30 was sequenced and found to have 3,015,537bp and 74 contigs⁵. Not much is known about the sequence, but 13 of the genes encoded for proteins that are common drug targets⁵. Homology with humans included 30 genes that mostly encoded enzymes⁵.

Cell and colony structure

Colonies of Meiothermus taiwanensis are 2-3mm in diameter and form a thin film that is red-pigmented on Meiothermus medium². The cells form long filaments but are non-motile². TEM analysis revealed a thin electron-dense layer surrounded by a thick ridged layer that was next to the cell membrane².

Thermophiles generally have unique polar lipids in their membranes to improve thermal stability. The major fatty acids identified in WR-220 using GC/MS, MS/MS, and NMR included 15:0 iso and 17:0 iso⁴. The glycoglycerolipid analyzed from WR-220 was found to contain two galactoses, one glucose, one galactosamine, and one glycerol⁴. Bacteria typically have peptidoglycan in their cell walls. The findings of those sugars in the glycoglycerolipid in strain WR-220 was striking because they are different sugars than the ones normally found in Meiothermus (two or three glucoses, one galactose, either galactosamine or glucosamine, and glycerol)⁴. This is just another difference between M. taiwanensis and previously characterized species of Meiothermus.

Metabolism

Strain WR-220 possesses cytochrome oxidase and catalase, utilizes a single carbon source, and hydrolyzes carbohydrate polymers like other strains of the genus Meiothermus². This bacterium is a heterotroph and grows aerobically². The carbon sources L-arabinose, ribitol, and D-trehalose may be assimilated by strain WR-220². Amino acid utilization included L-asparagine, L-glutamine, and L-arginine². Like other members of Meiothermus, this strain can use the amino acids for a carbon or energy source depending on its needs².

In 2014, scientists characterized the novel galactokinase MtGalK from strain WR-2206, and E. coli was used to overexpress the enzyme, which was thermostable at 75°C⁶. In the experiment MtGalK was used to synthesize sugar-1-phosphates, which are useful molecules and hard to synthesize via chemical methods⁶. MtGalK was used in a one-pot three-enzyme system to synthesize globotriose analogs (Gb3), which were used to further synthesize a carbohydrate antigen from breast cancer stem cells⁶. Although the reaction only had a 23% yield, further research may lead to a more optimized process.

Ecology

The eight Wu-Rai hot springs can be found in southeast Taipei, Taiwan³. Within these springs the temperature range appeared to be between 40-70°C². Previously, a research team isolated and identified 25 species of thermophilic fungi from the springs³. The interactions between strain WR-220 and the other organisms residing in the springs has not been conducted, and no symbiotic relationships have been characterized.

Pathology

There are no reports of this bacterium causing disease in humans, animals, or plants. No virulence factors have been characterized.

References

1) "Meiothermus Taiwanensis WR-220." NCBI Taxonomy Browser. U.S. National Library of Medicine, n.d. Web. 03 Nov. 2015. <http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&id=1339250&lvl=3&lin=f&keep=1&srchmode=1&unlock>.

2) Chen, M., Lin, G., Lin, Y., & Tsay, S. (2002). Meiothermus taiwanensis sp. nov., a novel filamentous, thermophilic species isolated in Taiwan. International Journal Of Systematic And Evolutionary Microbiology, 52(Pt 5), 1647-1654.

3) Mao-Yen Chen, Zuei-Ching Chen, Kuei-Yu Chen, & San-San Tsay. (2000). Fungal Flora of Hot Springs of Taiwan: Wu-Rai. Taiwania International Journal of Life Sciences, 45(2): 207-216.

4) Feng-Ling, Y., Chun-Ping, L., Chien-Sheng, C., Mao-Yen, C., Hung-Liang, H., Yeu, S., & ... Shih-Hsiung, W. (2004). Structural determination of the polar glycoglycerolipids from thermophilic bacteria Meiothermus taiwanensis. European Journal Of Biochemistry, 271(22), 4545-4551. doi:10.1111/j.1432-1033.2004.04415.x

5) "PATRIC::Meiothermus Taiwanensis DSM 14542::Genome Overview." PATRIC Pathosystems Resource Integration Center. N.p., n.d. Web. 04 Dec. 2015. <https://www.patricbrc.org/portal/portal/patric/Genome?cType=genome&cId=1122222.3>.

6) Li, Si-Peng, Hsiao, Wei-Chen, Yu, Ching-Ching, Chien, Wei-Ting, Lin, Hong-Jyune, Huang, Li-De, Lin, Chien-Hung, Wu, Wan-Ling, Wu, Shih-Hsiung, Lin, Chun-Cheng. (2014) Characterization of Meiothermus taiwanensis Galactokinase and its Use in the One-Pot Enzymatic Synthesis of Uridine Diphosphate-Galactose and the Chemoenzymatic Synthesis of the Carbohydrate Antigen Stage Specific Embryonic Antigen-3. Advanced Synthesis and Catalysis DOI: 10.1002/adsc.201400066

Edited by Molly Gallagher of Dr. Lisa R. Moore, University of Southern Maine, Department of Biological Sciences, http://www.usm.maine.edu/bio