Isolation and identification of carbon monoxide producing microorganisms from compost

Area of Science:

• Microbiology
• Environmental Science
• Biotechnology

Background:

• Carbon monoxide (CO) formation is observed in organic waste composting, potentially linked to microbial activity.
• Existing research lacks identification of specific microbial communities responsible for CO production in compost.

Purpose of the Study:

• To isolate and identify microorganisms responsible for carbon monoxide (CO) production in compost.
• To investigate the correlation between microbial communities and CO concentration in different biowaste pile locations.

Main Methods:

• Isolation and identification of bacterial strains from compost samples with varying CO concentrations (low: 118 ppm, high: 785 ppm).
• Incubation of isolated bacterial strains in sealed bioreactors for 4 days.
• Measurement of CO, O2, and CO2 levels in the bioreactor headspace.

Main Results:

• Predominantly rod-shaped, Gram-positive bacteria were isolated, with Bacillus species being the most common.
• Bacillus paralicheniformis, Bacillus licheniformis, and Geobacillus thermodenitrificans showed significant CO production (>600 ppm).
• High CO levels correlated with low oxygen (<6%) and high carbon dioxide (>8%) concentrations.

Conclusions:

• Specific bacterial strains, notably Bacillus species, are key players in CO production during composting.
• Further analysis of the CODH gene is recommended to confirm the CO2-to-CO conversion capability of identified strains.