RT Journal Article SR Electronic(1) A1 LÉVY-FRÉBAULT*, VÉRONIQUE A1 RAFIDINARIVO, ÉLIE A1 PROMÉ, JEAN-CLAUDE A1 GRANDRY, JEANNINE A1 BOISVERT, HENRI A1 DAVID, HUGO L.YR 1983 T1 Mycobacterium fallax sp. nov. JF International Journal of Systematic and Evolutionary Microbiology, VO 33 IS 2 SP 336 OP 343 DO https://doi.org/10.1099/00207713-33-2-336 PB Microbiology Society, SN 1466-5034, AB A new species, Mycobacterium fallax, is described. A study of 22 strains showed that they form a homogeneous group with an internal phenotypic similarity value of 94.6 ± 4.1%. The colony morphology resembled that of Mycobacterium tuberculosis, with cord formation on solid medium. The characteristic features of these strains were that they were nonchromogenic and grew rapidly at 30°C but slowly at 37°C. Most formed a thermolabile catalase and produced nitrate reductase. A lipid analysis showed that tuberculostearic acid was present and that only α-mycolic acids were formed. These α-mycolic acids were di- and tri-unsaturated acids, a feature that has not been described previously in the mycobacteria. The type strain has been deposited in the Collection Nationale de Cultures de Microorganismes, Paris, France, as strain CIP 8139., UL https://www.microbiologyresearch.org/content/journal/ijsem/10.1099/00207713-33-2-336