Molecular Soil Biology 2024, Vol.15, No.2, 59-70 http://bioscipublisher.com/index.php/msb 61 3 Mechanisms of Microbial Decomposition 3.1 Enzymatic breakdown of organic matter Microbial decomposition of organic matter is primarily driven by the enzymatic activities of soil microorganisms, including bacteria and fungi. These microorganisms secrete extracellular enzymes that break down complex organic compounds into simpler molecules that can be assimilated and utilized for growth and metabolism. For instance, enzymes such as cellulases, ligninases, and proteases play crucial roles in the degradation of plant residues and other organic materials in the soil (Murphy et al., 2007; Arcand et al., 2016). The activity of these enzymes is influenced by various factors, including the chemical composition of the organic matter, soil pH, temperature, and moisture content. Studies have shown that the enzymatic breakdown of organic matter is a critical step in the nutrient cycling process, as it releases essential nutrients such as nitrogen, phosphorus, and sulfur, which are then available for plant uptake and microbial use (Murphy et al., 2007). The efficiency of enzymatic breakdown can vary significantly depending on the microbial community composition and the quality of the organic matter. For example, research has demonstrated that soils with higher microbial diversity tend to have more efficient decomposition processes due to the presence of a wider range of enzymatic capabilities. Additionally, the presence of specific microbial taxa that are specialized in degrading certain types of organic matter can enhance the overall decomposition rate. This highlights the importance of maintaining diverse and functionally rich microbial communities in soil ecosystems to ensure effective organic matter decomposition and nutrient cycling (Maron et al., 2018; Raczka et al., 2021). 3.2 Role of microbial communities in nutrient cycling Microbial communities play a pivotal role in nutrient cycling by mediating the transformation and movement of nutrients through the soil ecosystem. These communities are involved in various biogeochemical processes, including the decomposition of organic matter, mineralization of nutrients, and the formation of stable soil organic matter (SOM) (Schimel and Schaeffer, 2012; Crowther et al., 2019). For instance, the decomposition of plant residues by soil microorganisms leads to the release of carbon dioxide (CO2) and the conversion of organic nitrogen into inorganic forms that are readily available for plant uptake (Schimel and Schaeffer, 2012). This process is essential for maintaining soil fertility and supporting plant growth. The composition and diversity of microbial communities can significantly influence nutrient cycling dynamics. Studies have shown that different microbial taxa have distinct functional roles in the decomposition process, with some groups being more efficient at breaking down specific types of organic matter (Raczka et al., 2021; Ma et al., 2023). For example, fungi are often more effective at decomposing complex organic compounds such as lignin, while bacteria are more efficient at degrading simpler substrates (Hicks et al., 2021; Ma et al., 2023). The interaction between these microbial groups can enhance the overall decomposition process and promote the cycling of nutrients in the soil. Additionally, the presence of diverse microbial communities can increase the resilience of soil ecosystems to environmental changes and disturbances, ensuring the continued functioning of nutrient cycling processes (Raczka et al., 2021; Ma et al., 2023). 3.3 Interaction between different microbial species in the decomposition process The decomposition of organic matter in soil is a complex process that involves interactions between different microbial species. These interactions can be synergistic, antagonistic, or neutral, and they play a crucial role in determining the efficiency and outcome of the decomposition process. For example, certain bacteria and fungi may work together to break down complex organic compounds more efficiently than they could individually. This synergistic interaction can lead to the rapid decomposition of organic matter and the release of nutrients (Metcalf et al., 2016; Geisen et al., 2020). On the other hand, competition between microbial species for resources can slow down the decomposition process and affect nutrient cycling dynamics. Research has shown that the presence of specific microbial species can influence the overall structure and function of the microbial community during decomposition. For instance, the introduction of predatory protists into microbial communities has been found to increase CO2 release and litter mass loss, indicating that trophic
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