An update on the taxonomy of the genus Frankia Brunchorst, 1886, 174AL

Abstract

Since the recognition of the name Frankia in the Approved Lists of bacterial names (1980), few amendments have been given to the genus description. Successive editions of Bergey's Manual of Systematics of Archaea and Bacteria have broadly conflicting suprageneric treatments of the genus without any advances for subgeneric classification. This review focuses on recent results from taxongenomics and phenoarray approaches to the positioning and the structuring of the genus Frankia. Based on phylogenomic analyses, Frankia should be considered the single member of the family Frankiaceae within the monophyletic order, Frankiales. A polyphasic strategy incorporating genome to genome data and omniLog phenoarrays, together with classical approaches, has allowed the designation and an amended description of a type strain of the type species Frankia alni, and the recognition of at least 10 novel species covering symbiotic and non symbiotic taxa within the genus. Genome to phenome data will be shortly incorporated in the scheme for proposing novel species including those recalcitrant to isolation in axenic culture.

Genomic Insights Into Plant-Growth-Promoting Potentialities of the Genus Frankia

“…Strains assigned to clusters 1 and 3 were found to have high genetic variability. Cluster 1 encompasses ten strains six of which were assigned to subcluster 1c, belonged to F. casuarinae (Gtari et al, 2019) while subcluster 1a was composed of four strains associated with Alnus – Comptonia – Myrica ; the latter were assigned to three subgroups which enclosed F. alni ACN14a T , Frankia sp. QA3, and strains of F. torreyi .…”

Draft Genome Sequence for Frankia sp. Strain BMG5.11, a Nitrogen-Fixing Bacterium Isolated from Elaeagnus angustifolia

“…Molecular phylogenetic approaches have identified four major Frankia lineages, which also follow host plant specificity groups ( 5 – 8 ), and genomes from each lineage have been sequenced ( 9 ). These Frankia genome databases have enabled the use of “omics” approaches ( 10 – 12 ) and have allowed species identification of the genus ( 13 ). Of the four lineages, Frankia lineage 3 strains are considered to have the widest plant host range, and they also show great diversity ( 8 ) with the potential for many new species.…”

Draft Genome Sequences for the Frankia sp. strains CgS1, CcI156 and CgMI4, Nitrogen-Fixing Bacteria Isolated from Casuarina sp. in Egypt

“…Representative genomes from each cluster have been sequenced [12]. These Frankia genome databases has enabled the use of "omics" approaches [13][14][15] and allowed speciation of the genus [16].…”