BIOL/CSES 4684

FRANKIA

SOIL MICROBIOLOGY

This webpage was created by Erika Caruthers

1. IDENTIFYING CHARACTERISTICS

Does not develop infection threads.
Always surrounded by host cell wall material.
Form vesicles.
Filaments .5-2.0 uc in diameter.
Cells stain Gram positive to Gram variable.
Sporangiospores are nonmotile.
Able to fix Nitrogen.
No aerial mycelium.
Formation of small, thick-walled polyhedric sporelike cells.
Form root nodules on nonleguminious plants.
Root-Nodule symbiosos has dinitrogen-fixing capacity.
The percent G+C is about 62%.
Catalase positive.
Chemoorganotrophic.
Mesophilic
Aerobic to microaerophilic.

The above picture shows a Frankia nodule.

2. TAXONOMIC DESCRIPTION
Representatives of the genus Frankia are actinomycete root-nodule symbionts of a large number of nonleguminous plants. They are filamentous gram-positive bacteria with branched and septate hyphae bearing vesicles and sporangia. They invade root hairs of host plants, developing within cortical cells in lobes of the resultantnodules. Nitrogenase activity is associated primaqrily with vesicles. The vesicles can be formed terminally or laterally borne. Vesicles can also be formed under conditions where no nitrogen fixation takes place.

Spores probably serve as propagative agents. These spores are not heat resistant. Cell walls contain meso-diaminopimelic acid, glutamic acid, alanine, muramic acid, and glucosamine. Frankia has vegetative hyphae with limited to extensive branching. Round to irregulary shaped multiocular sporangia are borne terminally, laterally, or in an intercalary position on the vegetative hyphae. Lateral sporangia are usually borne on sporangiosphores; some may be sessile. Sporangia up to 100 um in length are formed by septation in three planes of the cytoplasm of preexisting thin-walled swellings.

The type and only species is Frankia alni.

3. ISOLATION AND ECOLOGY
There are four mediums in which to cultivate Frankia. Two of the mediums are for the isolation and cultivation from root nodules. These two are complex one using a Mannitol Solutiion. The Mannitol solution is used to isolate and cultivate Frankia from root nodules. The other three mediums used to cultivate Frankia are also very complex. One is a sugar medium that is used to cultivate Frankia species from root nodules. The Albumin Fatty Acid Supplement is used for the cultivation and maintenance of Frankia species, and the other medium, is a Basal meduim, also containing Albumin Fatty Acid Supplement. This is also used for the cultivation and maintenance of Frankia species. Frankia is found in root nodules of woody trees, and there are many species of Frankia.

4. ADDITIONAL SOURCES OF INFORMATION
Atlas, R.M. 1993. Handbook of Microbiological Media. CRC Press. Boca Raton, Florida. 1079 pp.

Balows, A., M. Dwarkin, W. Harder, K.H. Schleifer, and H.G. Truper. 1988. The Prokaryotes: A Handbook on the Biology of Bacteria: Ecophysiology, Isolation, Identification, Application. Springer-Verlag. London. pp. 731-733.

Holt, J.G., N.R. Krieg, P.H.A. Sneath, J.T. Staley, and S.T. Williams. 1994. Bergey's Manual of Determinative Bacteriology. Ninth Edition. Williams and Wilkins. Baltimore, Maryland. 787 pp.

Metting, F. Blaine. Soil Microbial Ecology: Applications in Agricultural and Environmental Management. Marcel Dekker, Inc.

5. LINKS TO OTHER SITES ON PSEUDOMONAS

BIONET This site contains a research study done on Frankia.