Taxonomic significance of 2,4-diaminobutyric acid isomers in the cell wall peptidoglycan of actinomycetes and reclassification of Clavibacter toxicus as Rathayibacter toxicus comb. nov.

Abstract

An HPLC procedure which separates D-and L-amino acid isomers was applied to an analysis of peptidoglycan of 2,4=diaminobutyric acid (DAB)-containing actinomycetes. The cell wall peptidoglycans of species of the genera Agromyces, CIavibacter and Rathayibacter contain DAB and have been differentiated principally by their menaquinone profile. These peptidoglycans are known to be identical in structure, all being of the B2y type, possessing both D-and L-DAB. The type strains of all the subspecies of CIavibacter michiganensis have D-and L-DAB in almost equal proportions in their cell wall peptidoglycan as previously reported. In contrast, the type strains of CIavibacter toxicus and all valid species of the genera Agromyces and Rathayibacter contain the L-isomer of DAB almost exclusively. This characteristic is in good agreement with phylogenetic analyses based on 165 rDNA sequences and menaquinone profiles. On the basis of these data, the transfer of CIavibacter toxicus to the genus Rathayibacter as Rathayibacter toxicus comb. nov. is proposed. The isomer profile of DAB is shown to be a good taxonomic marker to differentiate these genera.Research (RIKEN)r I

Diversity of grass-associated Microbacteriaceae isolated from the phyllosphere and litter layer after mulching the sward; polyphasic characterization of Subtercola pratensis sp. nov., Curtobacterium herbarum sp. nov. and Plantibacter flavus gen. nov., sp. nov.

“…Thus, the type of peptidoglycan is a prominent feature to distinguish them from one another. Comparison of the cell wall composition of genotype C, which corresponds to type B2γ of Schleifer & Kandler (1972), with those of the remaining genera of the family Microbacteriaceae revealed agreement with Clavibacter, Leifsonia, Agromyces, Cryobacterium and Rathayibacter (Evtushenko et al, 2000 ;Sasaki et al, 1998). Whereas Clavibacter and Leifsonia represent a subgroup displaying  and  isomers of DAB in almost equal amounts, genotype C isolates, Rathayibacter, Cryobacterium and Agromyces shared the same amino acid ratio, with -DAB as the predominant isomer (Sasaki et al, 1998), and these species form another subgroup.…”

“…Comparison of the cell wall composition of genotype C, which corresponds to type B2γ of Schleifer & Kandler (1972), with those of the remaining genera of the family Microbacteriaceae revealed agreement with Clavibacter, Leifsonia, Agromyces, Cryobacterium and Rathayibacter (Evtushenko et al, 2000 ;Sasaki et al, 1998). Whereas Clavibacter and Leifsonia represent a subgroup displaying  and  isomers of DAB in almost equal amounts, genotype C isolates, Rathayibacter, Cryobacterium and Agromyces shared the same amino acid ratio, with -DAB as the predominant isomer (Sasaki et al, 1998), and these species form another subgroup. Within this subgroup, Agromyces species are characterized by filamentous cells fragmenting to yield coccoid forms in older cultures and the predominant menaquinones MK-12 and MK-11 and thus, they can easily be distinguished from genotype C by phenotypic features without requiring phylogenetic studies.…”

“…The only effective feature to distinguish them from each other was the ability to Genera : 1, Agrococcus ; 2, Agromyces ; 3, Clavibacter ; 4, Cryobacterium ; 5, Curtobacterium ; 6, Frigoribacterium ; 7, Leifsonia ; 8, Leucobacter ; 9, Microbacterium ; 10, Mycetocola ; 11, Subtercola ; 12, Rathayibacter ;13, Type C ' Plantibacter '. Data obtained in this study and extracted from following references : Davis et al (1984), Evtushenko et al (2000), Groth et al (1996), , Ma$ nnisto$ et al (2000), Sasaki et al (1998), Takeuchi et al (1996), Takeuchi & Hatano (1998), Tsukamoto et al (2001), Wieser et al (1999). Abbreviations : C, cocci ; F, filaments ; R, rods ; DAB, diaminobutyric acid ; GABA, γ-aminobutyric acid ; Orn, ornithine ; Lys, lysine ; S, straight-chain saturated ; A, anteiso-methyl-branched ; I, iso-methyl-branched ; (H), cyclohexyl fatty acids sometimes present ; , not determined ; d, different reaction.…”

“…Elucidation of the peptidoglycan structure was accomplished as described previously (Ma$ nnisto$ et al, 2000). Analysis of enantiomeric diamino acid isomers was performed according to Sasaki et al (1998). Fatty acid methyl esters and 1,1-dimethoxy-alkanes were analysed by GC and GC\MS as described by Schumann et al (1997) using lyophilized biomass obtained after incubation of strains for 48 h at 28 mC.…”

Rathayibacter caricis sp. nov. and Rathayibacter festucae sp. nov., isolated from the phyllosphere of Carex sp. and the leaf gall induced by the nematode Anguina graminis on Festuca rubra L., respectively.

“…Cell-wall sugars consist of glucose, mannose L. V. Dorofeeva and others and rhamnose and minor amounts of xylose. Other chemotaxonomic characteristics are as given previously (Zgurskaya et al, 1993 ;Sasaki et al, 1998). The type strain of the species, VKM Ac-1390 T (l UCM Ac-619 T ), was isolated from the leaf gall induced by the fescue leaf gall nematode Anguina graminis on Festuca rubra L. (Moscow region, Russia).…”