Frankia
| Описание микроба | Frankia is a nitrogen-fixing bacterium that lives in the soil and has a symbiotic relationship with many plants.
"The actinomycete Frankia is of fundamental and ecological interests for several reasons including its wide distribution, its ability to fix nitrogen, differentiate into sporangium and vesicles (specialized cell for nitrogen-fixation), and to nodulate plants from about 24 genera." Species of the Frankia Genus are Gram positive bacteria.Frankia sp. are filamentous nitrogen-fixing bacterium that grow by branching and tip extension and thus resemble the antibiotic-producing Streptomyces sp. . They live in the soil and have a symbiotic relationship with certain woody angiosperms, called actinorhizal plants. During growth, the Frankia sp. produce three cell types: sporangiospores, hyphae, and diazo-vesicles (spherical, thick walled, lipid-enveloped cellular structures). The diazo-vesicles are responsible for the supplying of sufficient Nitrogen to the host plant during symbiosis. Frankia supplies most or all of the host plant nitrogen needs without added nitrogen and thus can establish a nitrogen-fixing symbiosis with host plants where nitrogen is the limiting factor in the growth of the host. Therefore, actinorhizal plants colonize and often prosper in soils that are low in combined nitrogen |
|---|---|
| Верхний таксон | Bacteria; Actinobacteria; Actinobacteria (class); Actinobacteridae; Actinomycetales; Frankineae; Frankiaceae; Frankia |
| Species - виды | Frankia alni; Frankia sp. |
| Genome Structure= структура генома | The genome sequencing project of Frankia alni ACN14a was done at the Genoscope sequencing center and was completed on 03/08/2006. The genome of Frankia alni ACN14a contains a circular chromosome that is 7,497,934 necleotides long. It also cantains plasmids, but the amount was not clear based on my research. It has a high G-C content of 72.8% and contains 88% coding regions. The genome has 6,786 genes, comprising of 6,711 protein coding genes, 63 structural RNAs, and 12 pseudo genes |
| Cell Structure - клеточная структура | Frankia are Gram-positive, aerobic, nitrogen-fixing bacteria. The membranes of Frankia, as well as the membranes of some other bacteria like Bradyrhizobium, Rhizobium, and Streptomyces, contain lipid components called hopanoids. Hopanoids, which are amphiphilic, pentacylic triterpenoid lipids, condense membrane lipids therefore stabilizing the membranes in a similar way to which sterols do in higher organisms. There are many structural variants of hopanoids like polyol- and glyco-derivatives that can be found within various bacteria; the specific functions of each hopanoid derivative have not been found. Some people hypothesize that hopanoids may have more refined functions than just membrane stabilizing. In Frankia specifically, membranes containing hopanoids surround vesicles called diazovesicles that contain nitrogenase, an oxygen-sensitive enzyme. While hopaniods thicken and stabilize the walls which help to keep oxygen away from the nitrogenase, some suggest that the hopanoids themselves play a more specific and molecular role in the oxygen protection mechanism of nitrogenase. |
| Ecology= экология обитания | Organisms in symbiotic relationships with plant hosts are necessary for the health and survival of certain plants. They assist in creating and transporting certain root hormones, controlling pathogens and nematodes, root exploration, water retention, mineral uptake, and resource sharing. Frankia specifically fixes nitrogen in the air and produces molecules that other plants can use. |
https://microbewiki.kenyon.edu/index.php/Frankia
