Selenium Metabolizing Capabilities of 12 Bacterial Strains Isolated from Urban Environmental Samples

Area of Science:

• Environmental Microbiology
• Biogeochemical Cycles
• Bacterial Metabolism

Background:

• Bacterial selenium metabolism is crucial for the selenium biogeochemical cycle.
• Its role in non-polluted environments is not well understood.
• Urban environments can harbor diverse microbial communities with unique metabolic capabilities.

Purpose of the Study:

• To isolate and identify selenium-metabolizing bacteria from urban environmental samples.
• To evaluate the selenium removal efficiency of these isolates.
• To investigate the metabolic pathways of key selenium-reducing bacteria.

Main Methods:

• Isolation of bacteria from urban environmental samples.
• Identification of bacterial isolates using 16S rRNA sequencing.
• Quantification of selenium removal from aqueous solutions.
• Analysis of selenium reduction pathways through intermediate metabolite detection.

Main Results:

• Twelve bacterial isolates were obtained, with 10 identified as Citrobacter spp.
• Citrobacter isolates demonstrated high selenium removal efficiency (>95% of 5 mM selenium in one week).
• Citrobacter spp. primarily reduced selenate directly to elemental selenium, bypassing selenite accumulation.

Conclusions:

• Citrobacter species are highly efficient selenium reducers in urban environments.
• These bacteria play a significant role in the environmental selenium cycle.
• Citrobacter spp. show potential as bioindicators for assessing environmental selenium metabolic capacity.