Acidocella aluminiidurans sp. nov., an aluminium-tolerant bacterium isolated from Panicum repens grown in a highly acidic swamp in actual acid sulfate soil area of Vietnam.

An aluminium-tolerant bacterium, strain AL46(T), was isolated from a waterweed, Panicum repens, grown in a highly acidic swamp (pH 3) at an actual acid sulfate soil area of Vietnam. Cells were Gram-negative, aerobic, non-spore-forming, non-motile rods (0.3 microm wide and 1.2-1.6 microm long). 16S rRNA gene sequence analysis indicated that strain AL46(T) belongs to the genus Acidocella, class Alphaproteobacteria. Strain AL46(T) was related most closely to the type strains of Acidocella facilis and Acidocella aminolytica (99.4 and 97.8 % 16S rRNA gene sequence similarity, respectively). Levels of DNA-DNA relatedness between strain AL46(T) and the above type strains were 40 %. The results of physiological and biochemical tests allowed the novel strain to be differentiated phenotypically from the two recognized Acidocella species. Data for predominant cellular fatty acids (cyclopropyl C(19 : 0) and C(18 : 1)), major isoprenoid quinone (Q-10) and DNA G+C content (65.6 mol%) were in accordance with those reported for the genus Acidocella. Therefore, strain AL46(T) is considered to represent a novel species of the genus Acidocella, for which the name Acidocella aluminiidurans sp. nov. is proposed. The type strain is AL46(T) (=NBRC 104303(T) =VTCC-D9-1(T)).

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)).