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

Honghui Zhu,Jianhua Guo,Guangda Feng,Meibiao Chen,Qing Yao,Vishal Shah

doi:10.1371/journal.pone.0050225

Honghui Zhu, Jianhua Guo + Show 4 more

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https://doi.org/10.1371/journal.pone.0050225

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Abstract

Heavy-metal-tolerant bacteria, GIMN1.004T, 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 C16∶0, summed feature 8 (C18∶1 ω7c and C18∶1 ω6c), C18∶0, summed feature 3 (C16∶1 ω7c or iso-C15∶0 2-OH), C17∶0 cyclo, C18∶1 ω9c, C19∶0 cyclo ω8c, C14∶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, GIMN1.004T was considered to be in the genus Burkholderia. The similarities of 16S rRNA gene sequence between strain GIMN1.004T 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 18235T (99.4%); Levels of DNA-DNA hybridization with DSM 18235T 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 GIMN1.004T 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 Cd2+.Therefore, the strain GIMN1.004T represented a new cadmium resistance species, which was tentatively named as Burkholderia dabaoshanensis sp. nov. The strain type is GIMN1.004T ( = CCTCC M 209109T = NRRL B-59553T ).

Highlights

Activities such as mineral excavation, or transportation, smelting, refining, disposal of the tailings and waste waters around mines are important causes of heavy metals contamination [1], [2]
Burkholderia species is an ubiquitous, microbe that are highly resistant to heavy metals (HMs)
Many novel species of the genus Burkholderia have been described in recent years, certain species of Burkholderia have proved to be highly efficient in biocontrol, bioremediation [7], [8] and several mechanisms of heavy metal resistance are known, such as the formation and sequestration of heavy metals in complexes, reduction of a metal to a less toxic species, and direct efflux of a metal out of the cell

Summary

Introduction

Activities such as mineral excavation, or transportation, smelting, refining, disposal of the tailings and waste waters around mines are important causes of heavy metals contamination [1], [2]. Conventional methods including chemical precipitation, ion exchange or reverse osmosis processes were used to remove heavy metals from polluted soils, but there kinds of treatments were costly and showed several disadvantages, such as high reagent requirements and the generation of toxic sludge [5]. Bioremediation using heavy-tolerant microorganism is an alternative method to remove or recover heavy metals efficiently from polluted environment, and isolation of heavy-metal-tolerant microbes as bioremediation agent is fundamentally important.

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