Revision of the genus Massilia La Scola et al. 2000, with an emended description of the genus and inclusion of all species of the genus Naxibacter as new combinations, and proposal of Massilia consociata sp. nov.

Abstract

A Gram-stain-negative, rod-shaped, non-spore-forming bacterium originating from a human clinical specimen was studied for its taxonomic position. 16S rRNA gene sequence similarity studies clearly allocated this strain (CCUG 58010T) to the class Betaproteobacteria, closely related to members of the genera Massilia and Naxibacter. Naxibacter varians was shown to be the most closely related species on the basis of 16S rRNA gene sequence similarity (97.5 %), followed by Massilia niastensis (96.8 %) and Massilia aerilata (96.4 %). Similarities to all other species of the genera Naxibacter and Massilia were in the range 93.9–96.2 %. Chemotaxonomic data (major ubiquinone: Q-8; major polar lipids: phosphatidylethanolamine, phosphatidylglycerol and diphosphatidylglycerol; and major fatty acids: summed feature 3 (C16 : 1ω7c and/or iso-C15 : 0 2-OH), C16 : 0, C18 : 1ω7c and C12 : 0, with C10 : 0 3-OH as hydroxylated fatty acid) supported the affiliation of the isolate to these genera, which share these chemotaxonomic traits. DNA–DNA hybridization of strain CCUG 58010T with the type strain of N. varians CCUG 35299T resulted in a relatedness value of 39.2 % (reciprocal, 50 %) and physiological and biochemical tests also allowed phenotypic differentiation of the isolate from the most closely related species. There is currently no justification for a division of the genera Massilia and Naxibacter and for this reason a proposal is made to transfer all species of the genus Naxibacter to the genus Massilia, as Massilia alkalitolerans comb. nov., Massilia varians comb. nov., Massilia haematophila comb. nov. and Massilia suwonensis comb. nov. Strain CCUG 58010T represents a novel species, for which the name Massilia consociata sp. nov. is proposed, with the type strain CCUG 58010T ( = CCM 7792T).