Molecular Microbiology Research 2024, Vol.14, No.2, 79-91 http://microbescipublisher.com/index.php/mmr 84 to significantly alter soil properties, affecting microbial biomass and enzyme activities, which are essential for soil fertility (Jia et al., 2020). The management of agricultural practices, such as the use of organic amendments, can also impact microbial communities and their role in maintaining soil structure and fertility (Arcand et al., 2016). 5.3 Suppression of soil-borne diseases Microbial decomposition can suppress soil-borne diseases by enhancing the diversity and activity of beneficial soil microbes. These microbes compete with or inhibit pathogenic organisms, thereby promoting plant health. The composition of soil microbial communities, influenced by factors such as nitrogen fertilization and organic amendments, plays a critical role in disease suppression. For instance, nitrogen fertilization can alter microbial community dynamics, potentially affecting the suppression of soil-borne diseases (Li et al., 2019; Jia et al., 2020). Additionally, the application of biogas slurry in paddy soils has been shown to regulate microbial communities and functional gene expression, which can influence the suppression of soil-borne diseases (Wang et al., 2021). 6 Decomposition in Aquatic Ecosystems 6.1 Role of decomposers in freshwater systems Decomposition in freshwater ecosystems is a critical process driven by a variety of microbial communities, including fungi and bacteria. Fungi, particularly aquatic hyphomycetes, play a significant role in the turnover of organic matter and are central to detrital food webs. These fungi are responsible for breaking down leaf litter, which is a major source of energy and nutrients in forested freshwater systems (Pimentão et al., 2019; Pérez et al., 2021). The complexity of decomposer communities, including microbes and invertebrates, significantly influences the rate of litter decomposition, with factors such as litter quality and environmental conditions (e.g., climate, soil/water fertility) playing crucial roles (García‐Palacios et al., 2016). Additionally, subsurface zones in intermittent streams have been identified as hotspots for microbial decomposition during non-flow periods, highlighting the importance of sediment habitats in sustaining microbial activity and ecosystem functioning (Arias-Real et al., 2019). 6.2 Marine decomposition processes In marine ecosystems, decomposition is similarly driven by diverse microbial communities, but the process is influenced by different environmental factors such as salinity gradients. Studies have shown that microbial communities, including archaea, bacteria, and fungi, assemble along salinity gradients and exhibit habitat-specific abundance patterns. This suggests that habitat filtering plays a significant role in maintaining distinct decomposer communities in freshwater, estuarine, and marine habitats (Ferrer et al., 2022). The decomposition of animal tissues, such as fish, also follows a strong successional pattern, with specific bacterial taxa dominating at different stages of decomposition. For instance, the putative pathogen Aeromonas veronii has been identified as a dominant member of the decomposition community in fish, peaking early in the process and contributing to nutrient cycling through the production of hemolytic toxins (Lobb et al., 2020). 6.3 Impact on water quality The decomposition process in aquatic ecosystems has a significant impact on water quality. Microbial decomposers release nutrients and other compounds into the water as they break down organic matter, influencing biogeochemical cycles and overall ecosystem health. For instance, pathogens such as Escherichia coli in agricultural runoff can alter the composition and function of benthic microbial communities, affecting nutrient cycling and potentially leading to water quality issues (Bernabé et al., 2018). In aquatic ecosystems, carcasses or animal remains represent important nutrient and energy subsidies; their rapid decomposition and concentrated nutrient release can have lasting impacts on water quality and ecosystem structure (Benbow et al., 2020). The decomposition of decaying organic matter, such as animal carcasses, not only affects water quality but can also lead to localized oxygen depletion, forming "dead zones" (Figure 2). Additionally, the decomposition of plant litter in freshwater systems may be affected by climate change, such as warming, which can weaken the synergistic effects between decomposers and detritivores, ultimately impacting ecosystem function and nutrient flow (Bernabé et al., 2018).
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