Soil bacteria play a fundamental role in the process of organic matter decomposition, acting as the primary agents responsible for transforming dead plant and animal residues. These microorganisms secrete specialized enzymes that break down the complex structures of cellulose, lignin and proteins, converting them into bioavailable nutrients that plants can absorb.
This decomposition mechanism has critical implications for the global carbon cycle. Bacteria facilitate the mineralization of organic matter, in which organic carbon is split into CO₂ that returns to the atmosphere and inorganic substances such as CO₃²-, which become incorporated into sedimentary deposits. It is estimated that around 70% of the total carbon in terrestrial ecosystems is stored in microbial biomass and soil organic matter, making this biome one of the planet's largest carbon sinks.
In addition, bacterial activity influences the formation of humus and the retention of water in soil, although the efficiency of this process varies depending on environmental conditions and the composition of local microbial communities.
