Burkholderia dabaoshanensis sp. nov., a Heavy-Metal-Tolerant Bacteria Isolated from Dabaoshan Mining Area Soil in China

Heavy-metal-tolerant bacteria, GIMN1.004(T), was isolated from mine soils of Dabaoshan in South China, which were acidic (pH 2-4) and polluted with heavy metals. The isolation was Gram-negative, aerobic, non-spore-forming, and rod-shaped bacteria having a cellular width of 0.5-0.6 µm and a length of 1.3-1.8 µm. They showed a normal growth pattern at pH 4.0-9.0 in a temperature ranging from 5 °C to 40 °C.The organism contained ubiquinone Q-8 as the predominant isoprenoid quinine, and C(16:0), summed feature 8 (C(18:1)ω7c and C(18:1)ω6c), C(18:0), summed feature 3 (C(16:1)ω7c or iso-C(15:0) 2-OH), C(17:0) cyclo, C(18:1)ω9c, C(19:0) cyclo ω8c, C(14:0) as major fatty acid. These profiles were similar to those reported for Burkholderia species. The DNA G+C % of this strain was 61.6%. Based on the similarity to 16S rRNA gene sequence, GIMN1.004(T) was considered to be in the genus Burkholderia. The similarities of 16S rRNA gene sequence between strain GIMN1.004(T) and members of the genus Burkholderia were 96-99.4%, indicating that this novel strain was phylogenetically related to members of that genus. The novel strain showed the highest sequence similarities to Burkholderia soli DSM 18235(T) (99.4%); Levels of DNA-DNA hybridization with DSM 18235(T) was 25%. Physiological and biochemical tests including cell wall composition analysis, differentiated phenotype of this strain from that closely related Burkholderia species. The isolation had great tolerance to cadmium with MIC of 22 mmol/L, and adsorbability of 144.94 mg/g cadmium,and it was found to exhibit antibiotic resistance characteristics. The adsorptive mechanism of GIMN1.004(T) for cadmium depended on the action of the amide,carboxy and phosphate of cell surface and producing low-molecular-weight (LMW) organic acids to complex or chelated Cd(2+).Therefore, the strain GIMN1.004(T) represented a new cadmium resistance species, which was tentatively named as Burkholderia dabaoshanensis sp. nov. The strain type is GIMN1.004(T) (= CCTCC M 209109(T) = NRRL B-59553(T)).