Shared Microbial Taxa Respond Predictably to Cyclic Time-Varying Oxygen Limitation in Two Disparate Soils

Area of Science:

• Soil Microbiology
• Environmental Science
• Molecular Ecology

Background:

• Periodic oxygen limitation is common in terrestrial soils and influences microbial communities.
• Understanding microbial responses to fluctuating oxygen is crucial for soil ecosystem functioning.
• Responses of microbial taxa to anoxia can vary significantly across different soil types.

Purpose of the Study:

• To investigate whether specific microbial taxa exhibit consistent responses to periodic anoxia in contrasting soil environments.
• To determine if microbial community composition and abundance are predictable indicators of oxygen availability in soils.

Main Methods:

• Incubation of rainforest Oxisol and cropland Mollisol under cyclic anoxic/oxic conditions with varying anoxic period durations (0-12 days).
• Analysis of microbial community composition using 16S rRNA gene sequencing at 48 days and 384 days.
• Statistical analysis to identify taxa with consistent responses to anoxic period duration across both soil types.

Main Results:

• Microbial taxa abundance varied significantly with anoxic period duration, often differing between soils.
• Only a small fraction of operational taxonomic units (OTUs) were shared between soils, but these were disproportionately abundant.
• Abundant OTUs showed directionally consistent responses to anoxic period duration in both soils, including increases in Actinobacteria, Ruminococcaceae, methanogens, and methanotrophs, and decreases in nitrifiers.
• Taxonomic groups like nitrifiers (Nitrospira) and certain Actinobacteria decreased with increasing anoxic duration in both soils.

Conclusions:

• While most microbial taxa respond differently to anoxia in disparate soils, abundant taxa often show predictable responses to oxygen limitation.
• Periodic anoxia influences microbial community structure in a manner that can be partially inferred from community data.
• These findings highlight the potential for adaptation and niche partitioning within microbial communities in environments with variable oxygen availability.