Nocardia aciditolerans sp. nov., isolated from a spruce forest soil

Abstract

Actinomycetes growing on acidified starch-casein agar seeded with suspensions of litter and mineral soil from a spruce forest were provisionally assigned to the genus Nocardia based upon colonial properties. Representative isolates were found to grow optimally at pH 5.5, have chemotaxonomic and morphological features consistent with their assignment to the genus Nocardia and formed two closely related subclades in the Nocardia 16S rRNA gene tree. DNA:DNA relatedness assays showed that representatives of the subclades belong to a single genomic species. The isolates were distantly associated with their nearest phylogenetic neighbour, the type strain of Nocardia kruczakiae, and were distinguished readily from the latter based on phenotypic properties. On the basis of these data it is proposed that the isolates merit recognition as a new species, Nocardia aciditolerans sp. nov. The type strain is isolate CSCA68(T) (=KACC 17155(T) = NCIMB 14829(T) = DSM 45801(T)).

Fig. 1

Neighbour-joining tree based on nearly complete 16S rRNA gene sequences showing relationships between the isolates and between them and the most closely related Nocardia species. Numbers at the nodes indicate the levels of bootstrap support based on a neighbour-joining analyses of 1,000 re-sampled datasets, only values above 50 % are given. Asterisks indicate the branches of the tree that were also recovered using the maximum-likelihood and maximum-parsimony tree-making algorithms. T type strain. Bar 0.005 substitutions per nucleotide position.The root position of the tree was obtained using Nocardia acidivorans GW4-1778^T as outgroup

Fig. 2

Two-dimensional thin-layer chromatography of polar lipids of isolate CSCA68^T stained with molybdenum blue spray (Sigma). Chloroform: methanol: water (32.5: 12.5: 2.0) was used in the first direction and chloroform: acetic acid: methanol: water (40: 7.5: 6: 2) in the second direction. DPG diphosphatidylglycerol, PE phosphatidylethanolamine, PI phosphatidylinositol, PG phosphatidylglycerol and PIMS phosphatidylinositol mannosides