Frankia alni ACN14a

Frankia_alni
Names Frankia alni ACN14a
Accession numbers NC_008278
Background Frankia sp. are filamentous bacteria that grow by hyphal branching and tip extension. They produce three cell types during growth: vegetative hyphae, sporangiospores and lipid-enveloped cellular structures known as "diazo-vesicles". Frankia sp. have the ability to form symbiotic nitrogen-fixing root nodules on certain woody angiosperms, termed "actinorhizal plants". The vesicle cell type develops during N-starvation and contains the O2-labile nitrogenase. During symbiosis, they supply sufficient combined nitrogen so that the plant can grow without added nitrogen. Frankia thus can supply most or all of the host plant nitrogen needs. Consequently, actinorhizal plants colonize and often thrive in soils that are low in combined nitrogen. This type of symbiosis adds a large proportion of new nitrogen to several ecosystems. It constitutes the major N2-fixing symbioses in temperate forests, dry chaparral and matorral, coastal dunes, alpine communities and in colder regions such as in Scandinavia, Canada, Alaska or New Zealand where legumes are insignificant or absent. Frankiae have all housekeeping genes necessary for saprophytic existence plus genes for sporulation, vesicle development, symbiosis, N2 fixation and secondary metabolite production. Frankia alni ACN14a strain was isolated from a green alder (Alnus crispa) growing in Tadoussac, Canada. It is a member of the medium host range "Alnus" strains (Cluster 1). This bacterium is able to facultatively establish a nitrogen-fixing symbiosis with alder (Alnus spp. ) and myrtle (Myrica spp. ), as well as other plants in the Betulaceae and Myricaceae. F.alni can be isolated from soils on all continents except Australia and Antarctica. It causes root hair deformation: it penetrates the cortical cells and induces the formation of nodules which resemble those induced by Rhizobium in legumes. These nodules are then colonized by vegetative hyphae (mycelium filaments) which differentiate into diazo-vesicles. It is in these specialized, spherical, thick-walled cells that reductive nitrogen fixation takes place, protected from molecular oxygen by numerous layers of tightly stacked hopanoid lipids. (HAMAP: FRAAA)
Taxonomy
Kingdom:Bacteria
Phylum:Actinobacteria
Class:Actinobacteria
Order:Actinomycetales
Family:Frankiaceae
Genus:Frankia
Species:alni
Strain ACN14a
Complete Yes
Sequencing centre (02-AUG-2006) Genoscope - Centre National de Sequencage : BP 191 91006 EVRY cedex - FRANCE (E-mail : seqref@genoscope.cns.fr
(05-AUG-2006) National Center for Biotechnology Information, NIH, Bethesda, MD 20894, USA
Sequencing quality Level 6: Finished
Sequencing depth NA
Sequencing method Sanger
Isolation site Green alder growing in Tadoussac Canada
Isolation country Canada
Number of replicons 1
Gram staining properties Positive
Shape Tailed
Mobility No
Flagellar presence NA
Number of membranes 1
Oxygen requirements Aerobic
Optimal temperature NA
Temperature range Mesophilic
Habitat HostAssociated
Biotic relationship Symbiotic
Host name Alnus viridis subsp. crispa
Cell arrangement NA
Sporulation Sporulating
Metabolism Nitrogen fixation
Energy source Chemoorganotroph
Diseases None
Pathogenicity No