Isolation and Characterization of the Tellurite-Reducing Photosynthetic Bacterium, Rhodopseudomonas palustris Strain TX618

Abstract

A novel tellurite-resistant photosynthetic bacterium, Rhodopseudomonas palustris strain TX618, was isolated from wastewater and reduction of tellurite by this strain was investigated. The results showed that Rhodopseudomonas palustris strain TX618 could reduce tellurite to elemental tellurium, both anaerobically and aerobically. During anaerobic and illuminated growth, strain TX618 possessed a high-level resistance and removal efficiency to tellurite, that it could resist up to 180 mg/L Na2TeO3 in the medium and removed 91.9% of 90 mg/L Na2TeO3 over 8 days. The high efficiency in the removal of tellurite could sustain wide variations in pH (5.0–9.0), temperature (20–40 °C), light intensity (1500–3000 lx), and initial tellurium concentration (30–180 mg/L Na2TeO3). It could be observed by scanning electron micrograph (SEM), transmission electron micrograph (TEM), and X-ray diffraction (XRD) analysis that the cells suffered serious deformation due to the toxicity of tellurite, and the less toxic black precipaite (Te0) generated by bioreduction of tellurite mostly located in the central cytoplasm. This is the first study to observe that Rhodopseudomonas palustris can reduce tellurite to elemental tellurium, which will provide a new microbial species for bioremediation and biotransformation of toxic tellurite.