Isolation and Characterization of Mercury-Resistant Bacteria for Biofiltration-Based Mercury Removal from Wastewater

Background & Objectives: Industrial and economic development, along with the production of various chemical materials and compounds, have led to increased pollution from heavy metals and toxic substances in different environments. This poses significant risks to ecosystems and human health. Biofiltration, a method of bioremediation, involves the dissolution of pollutants in a liquid layer, where they undergo biodegradation by microorganisms in a biofilm. Mercury, a toxic heavy metal, is one of the major environmental pollutants. This study aims to identify mercury-resistant bacterial strains and evaluate their potential for use in water biofiltration.
Materials & Methods: Samples were collected from industrial wastewater, and mercury-resistant bacteria were isolated and characterized. The Minimum Inhibitory Concentration (MIC) test was used to determine mercury resistance. Biochemical tests as well as 16S rRNA sequencing were performed to identify the most resistant strains. These strains were then applied in a biofiltration system to remove mercury from contaminated water.
Results: Among six mercury-resistant bacterial strains, a gram-negative bacterium isolated from detergent manufacturing wastewater exhibited the highest resistance to mercury (52 ppm). 16S rRNA sequencing identified this strain as Raoultella planticola. Biofiltration experiments      demonstrated a 90% removal efficiency for mercury compounds.
Conclusion: This study identified R. planticola as a highly mercury-resistant strain, making it a promising candidate for biofiltration-based mercury removal from wastewater.