Frankia | |
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An alder root nodule. | |
Scientific classification | |
Domain: | Bacteria |
Phylum: | Actinomycetota |
Class: | Actinomycetia |
Order: | Frankiales |
Family: | Frankiaceae Becking 1970 (Approved Lists 1980)[2] |
Genus: | Frankia Brunchorst 1886[1] |
Type species | |
Frankia alni (Woronin 1866) Von Tubeuf 1895 non Steud. 1840
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Species[3] | |
See text | |
Synonyms | |
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Frankia is a genus of nitrogen-fixing bacteria that live in symbiosis with actinorhizal plants, similar to the Rhizobium bacteria found in the root nodules of legumes in the family Fabaceae. Frankia also initiate the forming of root nodules.
This genus was originally named by Jørgen Brunchorst, in 1886 to honor the German biologist Albert Bernhard Frank.[4] Brunchorst considered the organism he had identified to be a filamentous fungus. Becking redefined the genus in 1970 as containing prokaryotic actinomycetes and created the family Frankiaceae within the Actinomycetales. He retained the original name of Frankia for the genus.[5]
Most Frankia strains are specific to different plant species. The bacteria are filamentous and convert atmospheric nitrogen into ammonia via the enzyme nitrogenase, a process known as nitrogen fixation. They do this while living in root nodules on actinorhizal plants. The bacteria can supply most or all of the nitrogen requirements of the host plant. As a result, actinorhizal plants colonise and often thrive in soils that are low in plant nutrients.[6]
Several Frankia genomes are now available which may help clarify how the symbiosis between prokaryote and plant evolved, how the environmental and geographical adaptations occurred, the metabolic diversity, and the horizontal gene flow among the symbiotic prokaryotes.[6]
Frankia can resist low concentration of heavy metals such as, Cu, Co, and Zn.[7] Frankia may be an advantage for degraded soil. Degraded soil is known as soil that is heavy metal rich or nutrient depleted due to a drought. Frankia is a nitrogen-fixed organism, explaining why it is able to resist heavy metals.[8][clarification needed]
Frankia is a gram-positive Bacteria that is found on the roots of plants. The fact that Frankia is gram-positive means that the bacteria is made up of thick cell walls made out of protein called peptidologlycan. This helps with the resistance of the heavy metals that may be in the degraded soil.[9]
Frankia tolerates a narrow range of temperatures and soil pH levels. It grows best at around 30 degrees Celsius with an environment pH between 6.5 and 7.[10] These facts shows that Frankia is very sensitive to its environment. Though Frankia would not be suitable for all agriculture it does demonstrate possibilities in select areas, or in temperature controlled environments.[citation needed]
Main article: Actinorhizal plant |
The currently accepted taxonomy is based on the List of Prokaryotic names with Standing in Nomenclature (LPSN)[3] and National Center for Biotechnology Information (NCBI)[12]
16S rRNA based LTP_08_2023[13][14][15] | 120 marker proteins based GTDB 08-RS214[16][17][18] | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Species incertae sedis: