Soot biodegradation by psychrotolerant bacterial consortia

Area of Science:

• Environmental microbiology
• Biogeochemistry
• Atmospheric science

Background:

• Atmospheric soot aerosols absorb organic matter, influencing biogeochemical transformations and the global carbon cycle.
• Soot contains recalcitrant condensed aromatics, but its potential as a microbial nutrient source is under investigation.
• Increasing soot emissions necessitate understanding its environmental fate and microbial interactions.

Purpose of the Study:

• To investigate the impact of psychrotolerant bacterial consortia on soot bioavailability.
• To determine if soot can serve as a carbon and nutritional substrate for microbial life.
• To analyze the structural and compositional changes in soot upon microbial degradation.

Main Methods:

• Incubation of soot with psychrotolerant bacterial consortia.
• Measurement of bacterial biomass, water-insoluble organic carbon (OC), and elemental carbon (EC).
• Analysis of soot morphology and composition using Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive X-Ray analysis (EDX).

Main Results:

• Significant increase in bacterial biomass and water-soluble OC, with a decrease in water-insoluble OC and EC in soot residues.
• FTIR, SEM, and EDX analyses indicated soot degradation, with variations in spectral patterns and reduced carbon content.
• Reduction in optical density over incubation time confirmed OC and EC consumption by microbes.

Conclusions:

• Soot serves as a viable carbon and nutritional substrate for psychrotolerant bacterial consortia.
• Microbial activity leads to the degradation and transformation of soot's organic and elemental carbon components.
• Soot plays a significant role in the microbial food web, emphasizing the need to focus on microbe-mediated soot processes.