Arsenic removal by native and chemically modified lactic acid bacteria

Area of Science:

• Environmental microbiology
• Water treatment technologies
• Bioremediation of heavy metals

Background:

• Arsenic contamination in drinking water poses a significant global health risk.
• Novel and accessible methods for arsenic removal are crucial, particularly for rural communities.
• Microbial capabilities for heavy metal and toxin removal are gaining research interest.

Purpose of the Study:

• To investigate the arsenic removal efficiency of three Lactobacillus strains.
• To evaluate both native and chemically modified bacterial forms for arsenic remediation.
• To determine the specific arsenic species (As(III) vs. As(V)) targeted by these microbes.

Main Methods:

• Testing arsenic removal by native and chemically modified Lactobacillus strains.
• Assessing the impact of pH and arsenic concentration on removal efficiency.
• Quantifying arsenic removal capacity using Langmuir isotherm modeling.
• Investigating arsenic-bacterial interactions through desorption studies.

Main Results:

• Native and methylated Lactobacillus strains showed minimal arsenic removal.
• Aminated Lactobacillus casei DSM20011 effectively removed pentavalent arsenic (As(V)), but not trivalent arsenic (As(III)).
• Maximum As(V) removal of 38.1% was observed at 100 µg/L As(V) and pH 7.
• Calculated maximum As(V) removal capacity was 312 µg/g dry biomass.
• Weak interactions and surface-level binding were indicated by As(V) desorption.

Conclusions:

• Aminated Lactobacillus casei DSM20011 demonstrates selective removal of As(V) from water.
• The removal process is influenced by pH and initial As(V) concentration.
• Surface adsorption is the primary mechanism, with potential for desorption, suggesting limitations for long-term sequestration.