biostudies-literatureCasanovas-Massana ANational Institute of Allergy and Infectious DiseasesNIAID NIH HHSFIC NIH HHS1450-1456https://www.ebi.ac.uk/biostudies/studies/S-EPMC10197099biostudies-literatureUnknown70(3)Four spirochetes (F1^T, B21, Yale^T and AMB6-RJ) were isolated from environmental sources: F1^T and B21 from soils of an urban slum community in Salvador (Brazil), Yale^T from river water in New Haven, Connecticut (USA) and AMB6-RJ from a pond in a horse farm in Rio de Janeiro (Brazil). Isolates were helix-shaped, aerobic, highly motile and non-virulent in a hamster model of infection. Draft genomes of the strains were obtained and analysed to determine the relatedness to other species of the genus <i>Leptospira</i>. The analysis of 498 core genes showed that strains F1^T/B21 and Yale^T/AMB6-RJ formed two distinct phylogenetic clades within the 'Pathogens' group (group I). The average nucleotide identity (ANI) values of strains F1^T/B21 and Yale^T/AMB6-RJ to other previously described <i>Leptospira</i> species were below <84 % and <82 %, respectively, which confirmed that these isolates should be classified as representatives of two novel species. Therefore, we propose <i>Leptospirayasudae</i> sp. nov. and <i>Leptospirastimsonii</i> sp. nov. as new species in the genus <i>Leptospira</i>. The type strains are F1^T (=ATCC-TSD-163=KIT0259=CLEP00287) and Yale^T (=ATCC-TDS-162=KIT0258=CLEP00288), respectively.International journal of systematic and evolutionary microbiology<i>Leptospira yasudae</i> sp. nov. and <i>Leptospira stimsonii</i> sp. nov., two new species of the pathogenic group isolated from environmental sources.PMC10197099R25 TW009338R01 AI121207U01 AI088752D43 TW010540R01 AI052473R01 TW009504Hacker KPMedeiros MAHamond Cde Oliveira DCasanovas-Massana AKo AIReis MGWunder EACosta FSantos LABalassiano Ifalse<i>Leptospira yasudae</i> sp. nov. and <i>Leptospira stimsonii</i> sp. nov., two new species of the pathogenic group isolated from environmental sources.Four spirochetes (F1^T, B21, Yale^T and AMB6-RJ) were isolated from environmental sources: F1^T and B21 from soils of an urban slum community in Salvador (Brazil), Yale^T from river water in New Haven, Connecticut (USA) and AMB6-RJ from a pond in a horse farm in Rio de Janeiro (Brazil). Isolates were helix-shaped, aerobic, highly motile and non-virulent in a hamster model of infection. Draft genomes of the strains were obtained and analysed to determine the relatedness to other species of the genus <i>Leptospira</i>. The analysis of 498 core genes showed that strains F1^T/B21 and Yale^T/AMB6-RJ formed two distinct phylogenetic clades within the 'Pathogens' group (group I). The average nucleotide identity (ANI) values of strains F1^T/B21 and Yale^T/AMB6-RJ to other previously described <i>Leptospira</i> species were below <84 % and <82 %, respectively, which confirmed that these isolates should be classified as representatives of two novel species. Therefore, we propose <i>Leptospirayasudae</i> sp. nov. and <i>Leptospirastimsonii</i> sp. nov. as new species in the genus <i>Leptospira</i>. The type strains are F1^T (=ATCC-TSD-163=KIT0259=CLEP00287) and Yale^T (=ATCC-TDS-162=KIT0258=CLEP00288), respectively.2020-01-01T00:00:00Z2020 Mar2026-05-28T08:22:29.532Z2025-04-05T21:08:31.44ZS-EPMC101970993118456810.1099/ijsem.0.003480