Characterization of a novel biocatalyst system for sulfide oxidation

Area of Science:

• Microbiology
• Environmental Science
• Biotechnology

Background:

• Hydrogen sulfide (H2S) is a toxic gas requiring efficient removal.
• Microbial sulfide oxidation is a key process in sulfur cycling and bioremediation.
• Thiomicrospira sp. CVO offers potential as a biocatalyst for H2S removal.

Purpose of the Study:

• To evaluate the efficacy of Thiomicrospira sp. CVO enrichment cultures for H2S oxidation.
• To compare the performance and robustness of CVO-based cultures against Thiobacilli.
• To assess the tolerance of CVO cultures to environmental extremes.

Main Methods:

• Culturing Thiomicrospira sp. CVO in suspended culture with H2S as the energy source and nitrate as the electron acceptor.
• Measuring H2S removal efficiency and oxidation to sulfate.
• Determining maximum biomass loading for sulfide oxidation.
• Assessing tolerance to pH, temperature, and salinity.

Main Results:

• Complete removal of 10,000 ppmv H2S from feed gas within 3 seconds of gas-liquid contacting time.
• Maximum sulfide oxidation loading of 5.8 mmol H2S/h-g biomass protein, comparable to Thiobacillus denitrificans.
• Enrichment culture demonstrated greater tolerance to pH extremes and elevated temperatures than T. denitrificans.
• CVO cultures exhibit tolerance to up to 10% NaCl.

Conclusions:

• Thiomicrospira sp. CVO enrichment cultures are highly effective for H2S oxidation.
• CVO-based biocatalysts are more robust and tolerant to environmental variations than Thiobacilli.
• These findings suggest CVO cultures are a superior system for industrial sulfide oxidation applications.