Isoptericola cucumis sp nov., isolated from the root tissue of cucumber (Cucumis sativus)

A Gram-stain-positive, aerobic organism, showing an irregular cell morphology, was isolated from the root tissue of cucumber (Cucumis sativus) and investigated in detail for its taxonomic position. On the basis of the 16S rRNA gene sequence analysis, strain AP-38(T) was shown to be most closely related to Isoptericola variabilis (99.1 %) and Isoptericola nanjingensis (98.9 %). The 16S rRNA gene sequence similarity to all other species of the genus Isoptericola was <= 98.5 %. DNA-DNA relatedness to Isoptericola variablis DSM 10177(T) and Isoptericola nanjingensis DSM 24300(T) was 31(reciprocal 41 %) and 34 (reciprocal 34 %), respectively. The diagnostic diamino acid of the peptidoglycan was L-lysine. The quinone system contained predominantly menaquinones MK-9(H-4) and MK-9(H-2). In the polar lipid profile, major compounds were diphosphatidylglycerol, phosphatidylglycerol, phosphatidylinositol and two phosphatidylinositol mannosides. The polyamine pattern contained the major components spermidine and spermine and significant amounts of tyramine. In the fatty acid profile, anteiso-C-15:0 and iso-C-15:0 were present in major amounts. These data support the allocation of the strain to the genus Isoptericola. The results of physiological and biochemical characterization additionally provide phenotypic differentiation of strain AP-38(T) from I. variabilis and I. nanjingensis. AP-38(T) represents a novel species of the genus Isoptericola, for which we propose the name Isoptericola cucumis sp. nov., with AP-38(T) (= LMG 29223(T) = CCM 8653(T)) as the type strain.