Search

Background and Aims: The large monophyletic genus Mimosa comprises approx. 500 species, most of which are native to the New World, with Central Brazil being the main centre of radiation. All Brazilian Mimosa spp. so far examined are nodulated by rhizobia in the betaproteobacterial genus Burkholderia. Approximately 10 Mya, transoceanic dispersal resulted in the Indian subcontinent hosting up to six endemic Mimosa spp. The nodulation ability and rhizobial symbionts of two of these, M. hamata and M. himalayana, both from north-west India, are here examined, and compared with those of M. pudica, an invasive species., Methods: Nodules were collected from several locations, and examined by light and electron microscopy. Rhizobia isolated from them were characterized in terms of their abilities to nodulate the three Mimosa hosts. The molecular phylogenetic relationships of the rhizobia were determined by analysis of 16S rRNA, nifH and nodA gene sequences., Key Results: Both native Indian Mimosa spp. nodulated effectively in their respective rhizosphere soils. Based on 16S rRNA, nifH and nodA sequences, their symbionts were identified as belonging to the alphaproteobacterial genus Ensifer, and were closest to the 'Old World' Ensifer saheli, E. kostiensis and E. arboris. In contrast, the invasive M. pudica was predominantly nodulated by Betaproteobacteria in the genera Cupriavidus and Burkholderia. All rhizobial strains tested effectively nodulated their original hosts, but the symbionts of the native species could not nodulate M. pudica., Conclusions: The native Mimosa spp. in India are not nodulated by the Burkholderia symbionts of their South American relatives, but by a unique group of alpha-rhizobial microsymbionts that are closely related to the 'local' Old World Ensifer symbionts of other mimosoid legumes in north-west India. They appear not to share symbionts with the invasive M. pudica, symbionts of which are mostly beta-rhizobial.

A Gram-reaction-positive, rod-shaped bacterium, designated strain CC-VM-Y(T), was isolated from the faeces of the pill millipede Arthrosphaera magna Attems from India and was subsequently studied to determine its taxonomic position. Based on16S rRNA gene sequence similarities, the isolate clearly grouped with members of the genus Microbacterium. On the basis of pairwise comparisons of the 16S rRNA gene sequences, strain CC-VM-Y(T) was most closely related to Microbacterium insulae DS-66(T) (98 %), Microbacterium hydrocarbonoxydans DSM 160809(T) (97.8 %) and Microbacterium hominis NBRC 15708(T) (97.9 %). The peptidoglycan contained the amino acids ornithine (Orn), alanine (Ala), glycine (Gly), homoserine (Hsr) and glutamic acid (Glu) in an approximate molar ratio of 1.0 : 0.8 : 2.2 : 0.8 : 0.3. In addition, substantial amounts of threo-3-hydroxy glutamic acid (Hyg) were detected, which is characteristic of peptidoglycan type B2β. The acyl type of the peptidoglycan was glycolyl. The menaquinones of strain CC-VM-Y(T) were MK-13 (72 %), MK-12 (25 %) and MK-11 (3 %). The polar lipids consisted of phosphatidylglycerol, diphosphatidylglycerol, one unknown phospholipid and one unknown glycolipid. The fatty acid profile comprised anteiso-C(15 : 0), iso-C(16 : 0) and anteiso-C(17 : 0) as the major fatty acids, which was congruent with fatty acid profiles of other members of the genus Microbacterium. The results of physiological and biochemical tests as well as DNA-DNA hybridizations with the most closely related species, M. insulae, M. hydrocarbonoxydans and M. hominis, revealed clear phenotypic and genotypic differences between strain CC-VM-Y(T) and other members of the genus Microbacterium. Based on these results, strain CC-VM-Y(T) ( = DSM 22421(T)  = CCM 7681(T)) represents a new species of the genus Microbacterium, for which the name Microbacterium arthrosphaerae sp. nov. is proposed.

A Gram-positive actinobacterium (CC-NMPT-T3(T)) was isolated from iron-ore-contaminated soil near New Mangalore Port, Karnataka, India. Based on 16S rRNA gene sequence similarity studies, strain CC-NMPT-T3(T) belongs to the genus Georgenia and is most closely related to Georgenia muralis (98.6 %), Georgenia ruanii (97.4 %) and Georgenia thermotolerans (97.4 %). The peptidoglycan is of the type A4alpha l-Lys<--l-Glu. The predominant isoprenoid quinone is menaquinone MK-8(H(4)) and the polar lipid profile is composed of the predominant compound diphosphatidylglycerol, moderate amounts of a phosphatidylinositol-mannoside, phosphatidylinositol and minor amounts of another phosphatidylmannoside and phosphatidylglycerol. The major fatty acids of strain CC-NMPT-T3(T) are anteiso-C(15 : 0) and iso-C(15 : 0). The results of DNA-DNA hybridizations, and physiological and biochemical tests allowed a clear phenotypic differentiation of strain CC-NMPT-T3(T) from all other Georgenia species. Strain CC-NMPT-T3(T) represents a novel species, for which the name Georgenia soli sp. nov. is proposed. The type strain is CC-NMPT-T3(T) (=DSM 21838(T)=CCM 7658(T)).

A bacterial isolate obtained from soil from a municipal landfill site in India was characterized using a polyphasic taxonomic approach. The colonies of the isolate were found to be yellow and highly mucoid. Comparative analysis of the 16S rRNA gene sequence showed that this isolate constitutes a distinct phyletic line within the genus Lysobacter, displaying >3 % sequence divergence with respect to recognized Lysobacter species. The generic assignment was confirmed by chemotaxonomic data, which revealed the presence of a fatty acid profile characteristic of members of the genus Lysobacter and consisting of saturated, unsaturated, straight-chain and branched-chain fatty acids as well as iso-C(11 : 0) 3-OH as hydroxylated fatty acid, and the presence of an ubiquinone with eight isoprene units (Q-8) as the predominant respiratory quinone. The genotypic and phenotypic data show that strain IMMIB APB-9(T) merits classification as representing a novel species of the genus Lysobacter, for which the name Lysobacter defluvii sp. nov. is proposed. The type strain is IMMIB APB-9(T) (=CCUG 53152(T)=DSM 18482(T)).