Isolation, Identification, and Characterization of an Efficient Siderophore Producing Bacterium From Heavy Metal Contaminated Soil

Abstract

An efficient siderophore producing strain, YQ9, was isolated from heavy metal contaminated soil and identified as Burkholderia vietnamiensis. To the best of our known, the strain owns the highest siderophore producing capacity among genus Burkholderia with 96.6% siderophore unit. Moreover, B. vietnamiensis YQ9 has good adaptability to different pH values, temperatures, NaCl, and Fe³⁺ concentrations. In addition, the minimum inhibitory concentration (MIC) of heavy metals and antibiotics were also tested. It was found that the MIC values of strain YQ9 to several major soil heavy metal pollutants, such as Pb²⁺, Zn²⁺, Cu²⁺, and Cd²⁺ reached 3000, 5000, 4500, and 1000 μmol·L⁻¹, respectively. And YQ9 was sensitive to 4 of 8 test antibiotics, including rifampicin, kanamycin, doxycycline hyclate, and gentamicin (25, 25, 30, and 30 μg·mL⁻¹, respectively). Strain YQ9 also owns the ability to produce indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and dissolve phosphorus. The IAA production capacity was 6.93 mg·L⁻¹, the ACC deaminase activity was 8.71 μmol α-KA·(h·mg)⁻¹, and the phosphorus dissolving capacity of YQ9 was 104.05 mg·L⁻¹. The traits were excellent, and the strain was qualified as a candidate for microbial reinforcement of phytoremediation in soil contaminated by heavy metals.