| Frankia alni |
| Morphology | Frankia alni |
| CELLULAR |
| Staining | Gram-positive to Gram- variable. |
| Morphology | Vegetative hyphae with limited to extensive branching, 0.5-2.0 um in diameter and occasionally wider. No aerial mycelium formed. Round to irregularly shaped multilocular sporangia borne terminally, laterally, or in an intercalary position on the vegetative hyphae. Lateral sporangia usually borne on sporangiophores; some may be sessile. Sporangia up to 100 um in length formed by septation in three planes of the cytoplasm of preexisting thin-walled swellings. Sporangiospores nonmotile, of irregular (often somewhat polygonal) shape, 1-5 um in size, colourless to black, showing multilaminar outer membrane-like layers in thin section. Spores not thermally resistant. Sporangiospores do not usually develop and mature simultaneously so that developing sporangia may contain spores of various ages and sizes. Terminal or laterally borne "vesicles" may be formed. These are thick-walled swellings that show various irregular septations in thin section and are probably the site of nitrogenase activity in strains fixing atmospheric nitrogen. Vesicles may also be formed under conditions where no nitrogen fixation takes place. All these morphological characteristics may be expressed both in vitro and in plant, although nitrogen- fixing nodules without vesicles are known. Intra- and extracellular pigments common. |
| Motility | |
| Specialized structures |
| Division | Usually very slow-growing (doubling time of 1-7 days |
| COLONIAL |
| Solid surface |
| Liquid |
| Growth Parameters | Frankia alni |
| PHYSIOLOGICAL |
| Tropism | Chemoorganotrophic. |
| Oxygen | Aerobic to micoaerophilic. Will not grow under anaerobic conditions |
| pH | |
| Temperature | Mesophilic. |
| Requirements | |
| Products | Most strains capable of fixing atmospheric nitrogen in vitro and in plant |
| Enzymes | Catalase positive |
| Unique features | . Cell walls contain meso-diaminopimelic acid (meso-DAP) glutamic acid, alanine, muramic acid, and glucosamine. No mycolates present. Phospholipids comprised of phosphatidylinositol mannosides, phosphatidylinositol, and diphosphatidyl- glycerol. Fatty acids are normal, branched chain, and monounsaturated. Whole-cell sugar patterns show xylose (without arabinose), madurose, or fucose or cells may contain only glucose or galactose, sugars not previously found to have taxonomic significance in the Actinomycetales. Many strains contain 2-O-methyl-D-mannose and most contain rhamnose. |
| ENVIRONMENTAL |
| Habitat | May be found free in the soil. |
| Lifestyle | Most strains are symbiotic with certain angio spermous plants, inducing nodules on the roots of suitable hosts. |
| Pathogenicity |
| Distribution |
| Genome | Frankia alni |
| G+C Mol % | 66-71 (Tm) |
| Reference | Frankia alni |
| First citation | Brunchorst,J. 1886. Ueber einige wurzelanschwellungen besonders die jenigen von Alnus and den Elaeagnaceen. Botanisches Institut zur Tubingen 2: 151-177 |
| The Prokaryotes | |
| Bergey's Systematatic | p 2410 M. P. Lechevalier and H. A. Lechevalier |
| Bergey's Determinative | p 651 |
| References |