Methylorubrum extorquens

Methylorubrum extorquens is a Gram-negative bacterium. Methylorubrum species often appear pink, and are classified as pink-pigmented facultative methylotrophs, or PPFMs.^[4] The wild type has been known to use both methane and multiple carbon compounds as energy sources.^[4] Specifically, M. extorquens has been observed to use primarily methanol and C₁ compounds as substrates in their energy cycles.^[5] It has been also observed that use lanthanides as a cofactor to increase its methanol dehydrogenase activity^[6][7]

Methylorubrum extorquens
Scientific classification
Domain:	Bacteria
Kingdom:	Pseudomonadati
Phylum:	Pseudomonadota
Class:	Alphaproteobacteria
Order:	Hyphomicrobiales
Family:	Methylobacteriaceae
Genus:	Methylorubrum
Species:	M. extorquens
Binomial name
Methylorubrum extorquens (Urakami and Komagata 1984) Green and Ardley 2018[1]
Synonyms[2][3]
Bacillus extorquens Bassalik 1913 Vibrio extorquens (Bassalik 1913) Bhat and Barker 1948 Pseudomonas extorquens (Bassalik 1913) Krasil'nikov 1949 Flavobacterium extorquens (Bassalik 1913) Bassalik et al. 1960 Protomonas extorquens (ex Bassalik 1913) Urakami and Komagata 1984 Methylobacterium chloromethanicum McDonald et al. 2001 Methylobacterium dichloromethanicum Doronina et al. 2000 Methylobacterium extorquens (Urakami and Komagata 1984) Bousfield and Green 1985 Methylobacterium dichloromethanicum subsp. chloromethanicum (McDonald et al. 2001) Hördt et al. 2020

Genetic structure

After isolation from soil, M. extorquens was found to have a single chromosome measuring 5.71-Mb.^[8] The bacterium itself contains 70 genes over eight regions of the chromosome that are used for its metabolism of methanol.^[9] Within a section of the chromosome, of M. extorquens AM1 are two xoxF genes that enable it to grow in methanol.^[9]

M. extorquens AM1 genome encodes a 47.5 kb gene of unknown function. This gene encodes an over 15,000 residue-long polypeptide along with three unique compounds that are not expressed.^[10] The microbe uses the mxa gene^[11] as a way to dehydrogenate methanol and use it as an energy source.^[10]

Chemical use

Methylorubrum extorquens uses primarily C₁ and C₂ compounds to grow.^[9] Utilizing compounds with few carbon-carbon bonds allows the bacterium to successfully grow in environments with methanol, such as on the surface of leaves whose stomata emit methanol.^[12] The ability to use methanol as both a carbon and energy source was show to be advantageous when colonizing Medicago truncatula.^[13]

H₄MPT-dependent formaldehyde oxidation was first isolated in M. extroquens AM1 and has been used to define if an organism is utilizing methylotrophic metabolism.^[10]

Relationships with other organisms

Many bacteria within the family Methylobacteriaceae live in different biotic environments such as soils, dust, and plant leaves.^[14] Some of these bacteria have been found in symbiotic relationships with the plants they inhabit in which they provide fixed nitrogen or produce vitamin B₁₂.^[14] M. extorquens also produces PhyR which plants use to regulate stress response, allowing the plant to survive in different conditions.^[15] In addition to PhyR, the bacterium can produce a hormone related to overall plant and root growth.^[9]

M. extorquens has been found to have a mutualistic relationship with strawberries.^[16] Ultimately, M. extorquens is used to oxidize 1,2-propanediol to lactaldehyde, which is later used in chemical reactions.^[17] If introduced to blooming plants, furaneol production increases, changing the way the strawberry tastes.^[16]

See also

• Methylacidiphilum fumariolicum
• Methylobacterium radiotolerans