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<p>Polyhydroxybutyrate (PHB) is emerging as a biodegradable alternative to traditional plastics. However, the mechanisms by which environmental factors influence PHB degradation in soil and the functional differentiation between abundant and rare taxa remain poorly understood. In microbial ecosystems, abundant and rare taxa play distinct roles, and their interactions and responses are crucial for soil health and functionality. This 105-day study elucidated the biodegradation kinetics of PHB microplastics and the underlying mechanisms of soil microbial communities. The cumulative degradation rate of PHB stabilized after 49&#xa0;days, reaching a maximum of 53.4% under optimized conditions (temperature of 37&#xa0;°C, 60% moisture, and C/N ratio of 10). Environmental factors exhibited significant regulatory effects: high carbon–nitrogen (C/N) ratios inhibited degradation, while elevated temperature and moisture promoted it. These factors reshaped the microbial community structure, with rare taxa showing significantly higher sensitivity to C/N, moisture, and temperature than abundant taxa. Co-occurrence network analysis revealed that rare taxa served as keystone species (6 out of 7 hubs), driving interspecific cooperation under stress conditions (66.09% positive correlations in the PHB-amended treatments) and enhancing community stability. The assembly of rare taxa was governed by deterministic processes, whereas abundant taxa followed stochastic processes. Partial Least Squares Path Modeling (PLS-PM) confirmed that rare taxa were positively correlated with PHB degradation (+ 0.5955), while abundant taxa were negatively correlated with it (-0.7110). Our study supports a metabolic division of labor where rare taxa, unlike their abundant generalist counterparts, serve as specialized primary degraders initiating PHB hydrolysis through specific pathways. Consequently, these results indicate that optimizing soil parameters (e.g., moisture, temperature, C/N) drives the succession of functionally specialized rare taxa, thereby enhancing the efficiency of plastic pollution mitigation.</p>

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Environmental Drivers and Microbial Community Dynamics Underlying Polyhydroxybutyrate (PHB) Biodegradation in Soil: The Critical Role of Rare Taxa

  • 期刊论文

  • 发表日期：

    2026年4月6日

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  • Beibei Wang,
  • Yun Zhang,
  • Xiaobing Wang,
  • Jinyu Hou,
  • Ke Zhao,
  • Wuxing Liu

摘要

Polyhydroxybutyrate (PHB) is emerging as a biodegradable alternative to traditional plastics. However, the mechanisms by which environmental factors influence PHB degradation in soil and the functional differentiation between abundant and rare taxa remain poorly understood. In microbial ecosystems, abundant and rare taxa play distinct roles, and their interactions and responses are crucial for soil health and functionality. This 105-day study elucidated the biodegradation kinetics of PHB microplastics and the underlying mechanisms of soil microbial communities. The cumulative degradation rate of PHB stabilized after 49 days, reaching a maximum of 53.4% under optimized conditions (temperature of 37 °C, 60% moisture, and C/N ratio of 10). Environmental factors exhibited significant regulatory effects: high carbon–nitrogen (C/N) ratios inhibited degradation, while elevated temperature and moisture promoted it. These factors reshaped the microbial community structure, with rare taxa showing significantly higher sensitivity to C/N, moisture, and temperature than abundant taxa. Co-occurrence network analysis revealed that rare taxa served as keystone species (6 out of 7 hubs), driving interspecific cooperation under stress conditions (66.09% positive correlations in the PHB-amended treatments) and enhancing community stability. The assembly of rare taxa was governed by deterministic processes, whereas abundant taxa followed stochastic processes. Partial Least Squares Path Modeling (PLS-PM) confirmed that rare taxa were positively correlated with PHB degradation (+ 0.5955), while abundant taxa were negatively correlated with it (-0.7110). Our study supports a metabolic division of labor where rare taxa, unlike their abundant generalist counterparts, serve as specialized primary degraders initiating PHB hydrolysis through specific pathways. Consequently, these results indicate that optimizing soil parameters (e.g., moisture, temperature, C/N) drives the succession of functionally specialized rare taxa, thereby enhancing the efficiency of plastic pollution mitigation.