Structural and functional microbial diversity in deadwood respond to decomposition dynamics

Area of Science:

• Ecology
• Microbiology
• Forest Science

Background:

• Downed wood is a crucial component of forest ecosystems, supporting diverse microbial communities.
• Understanding microbial succession and functional shifts during wood decomposition is vital for nutrient cycling and forest health.

Purpose of the Study:

• To investigate microbial community diversity and functional changes in natural downed wood across various decay stages.
• To analyze the roles of bacteria and fungi in wood decomposition and identify key enzymes involved.

Main Methods:

• Metagenomics analysis to assess microbial community structure and gene content.
• In vitro analysis to study enzyme activities related to wood degradation.
• Sampling of downed oak wood at different decay stages in the Italian Alps.

Main Results:

• Bacterial alpha diversity was influenced by decay stage and log characteristics; beta diversity by log diameter.
• Fungal and archaeal beta diversity were affected by log diameter, with fungi also strongly influenced by decay stage.
• Enzyme abundances shifted, indicating changes in complex hydrocarbon degradation pathways, with bacteria showing higher cellulose and pectin-degrading enzyme activity and fungi higher cellulose and hemicellulose activity.
• Genes for Coenzyme M biosynthesis were abundant in early decomposition stages, but overall methanogenesis was not significantly affected by decay stage.
• Complex intra- and inter-kingdom interactions between bacteria and fungi were observed, responding to the decay stage.

Conclusions:

• Wood decay stage and physical characteristics significantly shape microbial community structure and function.
• Specific enzymatic activities of bacteria and fungi evolve during decomposition, driving the breakdown of wood components.
• Microbial interactions within and between kingdoms are complex and dynamic throughout the wood decomposition process.