Identification of a bacterial strain isolated from the liver of a laboratory mouse as Microbacterium paraoxydans and emended description of the species Microbacterium paraoxydans Laffineur et al 2003.

A rod-shaped, Gram-positive bacterial strain, designated C57-33, was isolated from the liver of the laboratory mouse strain C57Bl/6J and characterised by a polyphasic approach. 16S rRNA gene sequence similarity placed strain C57-33 in the genus Microbacterium with Microbacterium paraoxydans CF36(T) as the next relative (99.9% sequence similarity). Major fatty acids ai-C(15:0), i-C(16:0) and ai-C(17:0) and peptidoglycan type B2β with ornithine as the diagnostic cell-wall diamino acid and glycolyl residues were in agreement with the description of Microbacterium paraoxydans. The quinone system of C57-33 (major menaquinones MK-12 and MK-11) and polar lipid profile (major polar lipids diphosphatidyl glycerol, phosphatidyl glycerol and two unknown glycolipids) were in accordance with those of Microbacterium paraoxydans strains CF36(T), CF7 and CF40 which were analysed in this study as well. The results of biochemical/physiological characterisation, DNA-DNA hybridization, MALDI-TOF mass spectrometry of cell extracts and comparison of protein patterns after SDS-PAGE demonstrated that our isolate C57-33 (= DSM 15461) is a strain of the species Microbacterium paraoxydans. Based on new characteristics such as quinone system, polar lipid profile and physiological traits analysed for strain C57-33, the type strain of Microbacterium paraoxydans and some additional strains an emended description of the species Microbacterium paraoxydans is provided.