Functionally redundant cellobiose-degrading soil bacteria respond differentially to oxygen

Area of Science:

• Soil microbiology
• Environmental science
• Biogeochemistry

Background:

• Oxygen availability critically influences microbial metabolism in soils.
• Soil prokaryotes play a key role in degrading plant-derived saccharides.
• Understanding microbial responses to fluctuating oxygen is vital for soil health.

Purpose of the Study:

• To investigate the impact of fluctuating oxygen availability on soil prokaryote metabolic activity.
• To identify specific microbial taxa involved in cellobiose degradation under varying redox conditions.
• To explore the relationship between cellobiose consumption and changes in soil redox potential.

Main Methods:

• Experimental manipulation of oxygen levels (oxic and anoxic conditions) in agricultural soil slurries.
• Supplementation of slurries with cellobiose as a carbon source.
• Measurement of redox potential and quantification of microbial rRNA using quantitative PCR assays targeting 16S rRNA.

Main Results:

• Cellobiose consumption occurred rapidly irrespective of oxygen availability and redox potential.
• Four out of seven saccharolytic taxa showed distinct responses to oxygen fluctuations.
• Actinobacteria (Micrococcaceae, Cellulomonadaceae) increased under oxic conditions, while Firmicutes and Bacteroidetes increased under anoxic conditions.

Conclusions:

• Cellobiose degradation in soil is robust and not limited by oxygen availability.
• Functionally redundant, diverse microbial taxa are responsible for cellobiose degradation and associated redox potential shifts.
• Microbial community structure and activity are highly sensitive to oxygen dynamics in soil ecosystems.