Francisella asiatica sp. nov. isolated from farmed tilapia (Oreochromis sp.) and elevation of Francisella philomiragia subsp. noatunensis to species rank as Francisella noatunensis comb. nov., sp. nov.

Abstract

Bacterial isolates from diseased farmed tilapia (Oreochromis sp.) from Costa Rica (PQ 1104), Atlantic salmon (Salmo salar) from Chile (PQ 1106) and three-line grunt (Parapristipoma trilineatum) from Japan (Ehime-1) were characterized by phenotypic and molecular taxonomic methods. These isolates were Gram-negative, oxidase negative, non-motile, strictly aerobic cocco-bacilli, produced H2S from cysteine supplemented media, which is phenotypically consistent with the genus Francisella. Comparison of 16S rRNA gene sequences and five partial housekeeping gene sequences (groEL, shdA, rpoB, rpoA and pgm) confirmed these isolates to be members of the genus Francisella, with high 16S rRNA similarity (> 99 %) to Francisella philomiragia subsp noatunensis, F. piscicida and Francisella philomiragia subsp philomiragia isolates. Despite the close 16s rRNA relationship with the aforementioned Francisella taxa, isolates PQ 1104 and Ehime-1 form a separate clade on phylogenetic analysis of the 16s rRNA gene and all housekeeping genes investigated, whereas isolate PQ 1106 is highly similar to F. philomiragia subsp noatunensis (NCIMB 14265T) and F. piscicida (DSM 18777T). DNA-DNA hybridization studies revealed mean reassociation values of 60.3 and 72.6 % between isolate PQ 1104 and F. philomiragia subsp noatunensis (NCIMB 14265T) and F. philomiragia subsp philomiragia (ATCC 25015), respectively. Thus, on the basis of molecular genetic evidence, we propose that isolates PQ 1104 and Ehime-1 should be recognised as Francisella asiatica sp. nov. with type strain PQ 1104T (NCIMB and CCUG number not received yet). No separation between F. piscicida and F. philomiragia subsp noatunensis were identified by the same methods and these species constitute heterotypic synonyms for which the epithet noatunensis has priority. However, given the increased evidence of ecological differentiation within the F. philomiragia group and the existence of a specific fish pathogenic clade, we propose that the F. philomiragia subsp noatunensis be elevated to species level as F. noatunensis comb. nov., sp.

Development of a real-time PCR assay for identification and quantification of the fish pathogen Francisella noatunensis subsp. orientalis

“…F. noatunensis subsp. noatunensis is a recently described member of the genus Francisella isolated from farmed Atlantic cod displaying chronic granulomatous disease (Mikalsen et al 2007, Mikalsen & Colquhoun 2009, Ottem et al 2009) and was kindly donated by Dr. Anne-Berit Olsen, National Veterinary Institute, Bergen, Norway. Francisella isolates 1, 2, and 3 recovered from moribund hybrid striped bass (Ostland et al 2006) and F. victoria recovered from tilapia (Kay et al 2006) and showing > 99% identity with F. noatunensis subsp.…”

“…noatunensis isolated from diseased Atlantic cod in Norway (Euzéby 2009, Ottem et al 2009), by sequence comparison of the 16S rRNA. The LADL 07-285A and 07-285B isolates used in this study also belong to the same group described as F. asiatica (Mikalsen & Colquhoun 2009); however, this name does not yet have valid taxonomic standing (J. Euzéby pers. comm.…”

Francisella guangzhouensis sp. nov., isolated from air-conditioning systems

“…noatunensis (Mikalsen et al, 2007), later reclassified as Francisella noatunensis (Ottem et al, 2009), Francisella piscicida (Ottem et al, 2007b), Francisella noatunensis subsp. orientalis (Ottem et al, 2009) and 'Francisella asiatica' (Mikalsen & Colquhoun, 2009; although the latter name was effectively published in 2009, this paper has not yet appeared in print and the name 'Francisella asiatica' is not validly published).…”

“…A wide range of fish hosts has been reported, such as three-line grunt (Parapristipoma trilineatum), tilapia (Orechromis niloticus), hybrid striped bass (Morone saxatilis), Atlantic salmon (Salmo salar) and Atlantic cod (Gadus morhua) (Hsieh et al, 2006;Ottem et al, 2007aOttem et al, , b, 2009. Two types of fish pathogens phylogenetically close to F. philomiragia were characterized by sequencing of several housekeeping genes and determination of phenotypic traits (Mikalsen & Colquhoun, 2009;Ottem et al, 2009), and various species or subspecies have been proposed as Francisella philomiragia subsp. noatunensis (Mikalsen et al, 2007), later reclassified as Francisella noatunensis (Ottem et al, 2009), Francisella piscicida (Ottem et al, 2007b), Francisella noatunensis subsp.…”

Identification of Francisella tularensis by Whole-Cell Matrix-Assisted Laser Desorption Ionization-Time of Flight Mass Spectrometry: Fast, Reliable, Robust, and Cost-Effective Differentiation on Species and Subspecies Levels

“…The genus Francisella was recently rearranged (12,23) and is currently divided into four species, including F. tularensis and F. philomiragia. The species Francisella tularensis is further subdivided into four subspecies, F. tularensis subsp.…”