Curtobacterium ammoniigenes sp. nov., an ammonia-producing bacterium isolated from plants inhabiting acidic swamps in actual acid sulfate soil areas of Vietnam

The ammonia-producing bacteria B55^T, CA73, SA69 and SA72 were isolated from the waterweeds Ludwigia adscendens (B55^T) and Eleocharis dulcis (CA73, SA69 and SA72) grown in highly acidic swamps (pH 2-4) in actual acid sulfate soil areas of Vietnam. The isolates were Gram-positive, irregular rod-shaped, non-spore-forming bacteria. On the basis of 16S rRNA gene sequence similarity, strain B55^T was shown to belong to the genus Curtobacterium of the class Actinobacteria. Chemotaxonomic data (MK-9 as major isoprenoid quinone, D-ornithine as cell-wall diamino acid, acetyl as the acyl type of peptidoglycan) supported the affiliation of all four strains to this genus. Although their 16S rRNA gene sequence similarity was 99 % to species with validly published names within the genus, they formed a group that was distinct in the phylogenetic tree, and DNA-DNA relatedness values to these established species were less than 10%. The results of physiological and biochemical tests and major fatty acids (cyclohexyl-C_17:0, anteiso-C_17:0 and cyclohexyl-C_19:0) allowed phenotypic differentiation of these strains from the species of Curtobacterium with validly published names. Therefore, strains B55^T, CA73, SA69 and SA72 represent a novel species, for which the name Curtobacterium ammoniigenes sp. nov. is proposed. The type strain is B55^T (= NBRC 101786^T=VTCC D6-11^T=JCM 14609^T).