Frankia colletiae sp. nov., a nitrogen-fixing actinobacterium isolated from Colletia cruciata

A nitrogen-fixing actinobacterium strain (Cc1.17(T)) isolated from a root nodule of Colletia cruciata was subjected to polyphasic taxonomic studies. The strain was characterized by the presence of meso-diaminopimelic acid in its peptidoglycan, galactose, glucose, mannose, rhamnose, ribose and xylose as cell-wall sugars, phosphatidylinositol, diphosphatidylglycerol, glycophospholipids, phosphatidylglycerol, glycophospholipid and uncharacterized lipids as its polar lipids, and C-16:0, iso-C-16:0, C-17:1.9 omega 9 and C-18:1. omega 9 as major fatty acids (>10%). Strain Cc1.17(T) showed 16S rRNA gene sequence similarities of 97.4-99.8% to validly named Frankia species. Phylogenetic trees based on 16S rRNA gene and genome sequences placed strain Cc1.17(T) in a new lineage within the genus Frankia. Digital DNA-DNA hybridization and average nucleotide identity values between strain Cc1.17(T) and its closest phylogenomic neighbours were well below the thresholds recommended for prokaryotic species delineation. Therefore, strain Cc1.17(T) (=DSM 43829(T)=CECT 9313(T)) merits recognition as the type strain of a new species for which the name Frankia colletiae sp. nov. is proposed.