Burkholderia bannensis sp. nov., an acid-neutralizing bacterium isolated from torpedo grass (Panicum repens) growing in highly acidic swamps

Abstract

Two strains of acid-neutralizing bacteria, E25T and E21, were isolated from torpedo grass (Panicum repens) growing in highly acidic swamps (pH 2–4) in actual acid sulfate soil areas of Thailand. Cells of the strains were Gram-negative, aerobic, non-spore-forming rods, 0.6–0.8 µm wide and 1.6–2.1 µm long. The strains showed good growth at pH 4.0–8.0 and 17–37 °C. The organisms contained ubiquinone Q-8 as the predominant isoprenoid quinone and C16 : 0, C17 : 0 cyclo and C18 : 1ω7c as the major fatty acids. Their fatty acid profiles were similar to those reported for other Burkholderia species. The DNA G+C content of the strains was 65 mol%. On the basis of 16S rRNA gene sequence similarity, the strains were shown to belong to the genus Burkholderia. Although the calculated 16S rRNA gene sequence similarity of E25T to strain E21 and the type strains of Burkholderia unamae, B. tropica, B. sacchari, B. nodosa and B. mimosarum was 100, 98.7, 98.6, 97.6, 97.4 and 97.3 %, respectively, strains E25T and E21 formed a group that was distinct in the phylogenetic tree; the DNA–DNA relatedness of E25T to E21 and B. unamae CIP 107921T, B. tropica LMG 22274T, B. sacchari LMG 19450T, B. nodosa LMG 23741T and B. mimosarum LMG 23256T was 90, 42, 42, 42, 45 and 35 %, respectively. The results of physiological and biochemical tests including whole-cell protein pattern analysis allowed phenotypic differentiation of these strains from previously described Burkholderia species. Therefore, strains E25T and E21 represent a novel species, for which the name Burkholderia bannensis sp. nov. is proposed. The type strain is E25T ( = NBRC 103871T  = BCC 36998T).