Autotrophic antimonate bio-reduction using hydrogen as the electron donor.

Area of Science:

• Environmental Science
• Microbiology
• Geochemistry

Background:

• Antimony (Sb) is a toxic metalloid, with antimonate (Sb(V)) being its soluble form.
• Microbial bio-reduction of Sb(V) is an effective Sb removal method.
• Current methods rely on organic electron donors, limiting efficiency and potentially introducing other contaminants.

Purpose of the Study:

• To demonstrate the feasibility of autotrophic microbial Sb(V) reduction using hydrogen gas (H2) as the sole electron donor.
• To compare the efficiency of H2-driven Sb(V) reduction with organic electron donors.
• To characterize the microbial community involved in H2-driven Sb(V) reduction.

Main Methods:

• Utilized a microbial consortium for Sb(V) reduction with H2 as the electron donor.
• Employed Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) to analyze mineral precipitates.
• Quantified Sb(V) reduction and electron donor utilization.
• Performed high-throughput sequencing to analyze microbial community composition.

Main Results:

• Successfully demonstrated autotrophic microbial Sb(V) reduction using H2, producing Sb2O3 precipitate.
• Achieved complete reduction of 650 μM Sb(V) to Sb(III) in 10 days with H2, comparable to lactate.
• Showed that 98% of H2 electrons were directed to Sb(V) reduction, versus only 12% for lactate.
• Identified a microbial community dominated by Rhizobium in the H2-fed culture.

Conclusions:

• Autotrophic microbial Sb(V) reduction using H2 is a viable and highly efficient method for antimony removal.
• H2 serves as a superior electron donor for Sb(V) reduction compared to organic compounds like lactate.
• This approach offers a promising, carbon-independent strategy for bioremediation of antimony-contaminated environments.