Leptospira strain Eri-1(T) was isolated from a water sample in the campus of Kyushu University, Fukuoka, Japan. The motility and morphology of the isolate were similar to those of the genus Leptospira but spiral structure of the isolates was more sharp under dark-field microscopy. Cells were 10.6±1.3 µm long and 0.2 µm in diameter, with a wavelength of 0.9 µm and an amplitude of 0.4 µm. Strain Eri-1T grew in Korthof's medium at both 13 and 30 °C, and also in the presence of 8-azaguanine. 16S rRNA gene-based phylogenetic analysis placed strain Eri-1(T) within the radiation of the genus Leptospira, and formed a unique lineage within the clade of the known saprophytic Leptospira species. The strain was not pathogenic to hamsters. Strain Eri-1(T) exibited low levels (11.2-12.6%) of relative similarity by DNA-DNA hybridization to the three most closely related Leptospira species. The G+C content of the genome of strain Eri-1(T) was 42.5±0.1 mol%. These results suggested that strain Eri-1(T) is a novel species of genus Leptospira, for which the name Leptospira idonii sp. nov. is proposed. The type strain is Eri-1(T) (= DSM 26084(T) = JCM 18486(T)).
This new species has not been discussed and recognized yet by the TSC
*Saito M, Villanueva SY, Kawamura Y, Iida KI, Tomida J, Kanemaru T, Kohno E, Miyahara S, Umeda A, Amako K, Gloriani NG, Yoshida SI. Leptospira idonii sp. nov., isolated from an environmental water in Fukuoka, Japan. International Journal of Systematic and Evolutionary Microbiology 2013:63;2457-2462.
Conventionally, Leptospira were separated into two valid species, Leptospira interrogans for pathogenic leptospires and Leptospira biflexa for saprophytic ones (Brenner et al., 1999).
Current Leptospira speciation is based on DNA heterogeneity as determined by hybridization experiments.
The first of such studies was by Yasuda et al., 1987 followed by Ramadass et al., 1992.
The most complete study, also summarizing the observation of the previous two studies is by Brenner et al., 1999. Brenner and co-workers described 17 DNA hybridization groups (species), representing the 12 previously describes species and five new ‘genomospecies’, including Leptospira alexanderi.
Smythe et al., 2012 re-named the four remaining ‘genomospecies’ 1, 3, 4 and 5 later on to Leptospira alstonii, L. vanthielii , L. terpstrae and L. yanagawae, respectively.
To date, speciation is increasingly based on other molecular techniques, mainly DNA sequences of the rrs gene or multilocus sequence genotyping, which likely will completely replace the DNA hybridization method.
* Yasuda PH, Steigerwalt AG, Sulzer KR, Kaufmann AF, Rogers F, Brenner DJ. Deoxyribonucleic acid relatedness between serogroups and serovars in the family Leptospiroceae with proposals for seven Leptospira species. Int J Syst Bacteriol 1987, 37, 407-415
* Ramadass P, Jarvis BDW, Corner RJ, Penny D, Marshall RB. Genetic characterization of pathogenic Leptospira species by DNA hybridization. Int J Syst Bacteriol 1992, 42, 215-219
* Brenner DJ, Kaufmann AF, Sulzer KR, Steigerwalt AG, Rogers F, Weyant RS. Further determination of DNA relatedness between serogroups and serovars in the family Leptospiroceae with a proposal for Leptospira alexanderi sp. nov. and four new Leptospira genomospecies. Int J Syst Bacteriol 1999, 49, 839-858
* Smythe L, Adler B, Hartskeerl RA, Galloway RL, Turenne CY, Levett PN. Classification of Leptospira genomospecies 1, genomospecies 3, genomospecies 4 and genomospecies 5 as Leptospira alstonii sp. nov., Leptospira vanthielii sp. nov., Leptospira terpstrae sp. nov., Leptospira yanagawae sp. nov., respectively. Int J Syst Evol Microbiol 2012;
* Ahmed A, Grobusch MP, Klatser P, Hartskeerl RA. Molecular Approaches in the Detection and Characterization of Leptospira. J Bacteriol Parasitol 2012, 3:2 http://dx.doi.org/10.4172/2155-9597.1000133
* Adler, B., & de la Peña Moctezuma, A. (2010). Leptospira and leptospirosis. Veterinary microbiology 140, 287-296.
* Cerqueira, G.M. & Picardeau, M. (2009). A century of Leptospira strain typing. Infection, Genetics and Evolution 9, 760-768.