Tsukamurella tyrosinosolvens sp. nov.

This study describes the identification and characterization of a new bacterial species, Tsukamurella tyrosinosolvens, based on analysis of four isolates recovered from clinical specimens. Two strains were isolated from blood cultures of cardiac pacemaker patients, while two were isolated from chronic lung infection sputum samples. Using chemotaxonomic analysis, 16S ribosomal DNA sequencing, and DNA-DNA hybridization studies, the researchers demonstrated that these four strains belong to a single novel species within the genus Tsukamurella. The bacteria are gram-positive, slightly acid-alcohol-fast rods that fragment during growth. Chemically, they contain characteristic wall components including meso-diaminopimelic acid, arabinose, and galactose, along with menaquinone MK-9 as their predominant quinone. Key physiological traits include the ability to hydrolyze tyrosine and xanthine and utilization of various carbon sources. DNA-DNA hybridization showed only 53-55% relatedness to existing Tsukamurella species, establishing this as a distinct species. The type strain IMMIB D-1397 (DSM 44234) has a GC content of 73.6 mol% and was isolated from a patient's blood culture.

Key findings

• Four bacterial isolates from clinical specimens were identified as a new species, Tsukamurella tyrosinosolvens, distinguished from previously described Tsukamurella species by DNA-DNA hybridization showing only 53-55% relatedness to related species.
• The organism is a gram-positive, slightly acid-alcohol-fast bacillus that hydrolyzes tyrosine and xanthine, with a chemotype IV cell wall and menaquinone MK-9 as the major quinone component.
• 16S rDNA sequence analysis showed 99.2-99.9% similarity to existing Tsukamurella species, but physiological and DNA hybridization data confirmed this represents a distinct species with unique characteristics like tyrosine degradation capability.