Isolation and characterization of cesium-accumulating bacteria

Area of Science:

• Microbiology
• Environmental Science
• Bioremediation

Background:

• Radioactive cesium (137Cs) contamination poses environmental risks.
• Microbial bioremediation offers a sustainable approach for heavy metal removal.
• Isolation and characterization of cesium-accumulating microorganisms are crucial for developing effective remediation strategies.

Purpose of the Study:

• To isolate and identify cesium-accumulating bacteria from soil.
• To evaluate the cesium removal efficiency and accumulation capacity of isolated strains.
• To assess the potential of these bacteria for radioactive cesium bioremediation.

Main Methods:

• Isolation of cesium-accumulating bacteria using radioactive autoradiography with 137Cs.
• Characterization of bacterial strains based on morphology, cell wall components (mesodiaminopimelic acid, mycolic acids, tuberculostearic acids), and menaquinone analysis.
• Determination of cesium removal efficiency, cellular cesium content, and concentration factors in liquid cultures.

Main Results:

• Two cesium-accumulating strains, CS98 and CS402, were isolated and identified as Rhodococcus erythropolis and a member of the genus Rhodococcus, respectively.
• Strain CS98 demonstrated a maximum cesium removal efficiency of 90% and accumulated 52.0 µmol/g (dry weight) of cesium, with a concentration factor of 3.5 x 10(4).
• Strain CS402 showed a maximum cesium removal efficiency of 47% and accumulated 18.8 µmol/g (dry weight) of cesium, with a concentration factor of 3.6 x 10(3).

Conclusions:

• Rhodococcus erythropolis CS98 and Rhodococcus sp. CS402 are effective cesium-accumulating bacteria.
• These strains exhibit significant potential for the bioremediation of radioactive cesium-contaminated environments.
• Further research into optimizing conditions for cesium accumulation by these Rhodococcus strains is warranted.