As an energy-storage substance of microorganisms, polyhydroxybutyrate (PHB) is a promising alternative to petrochemical polymers. Under appropriate fermentation conditions, PHB-producing strains with metabolic diversity can efficiently synthesize PHB using various carbon sources. Carbon-rich wastes may serve as alternatives to pure sugar substrates to reduce the cost of PHB production. Genetic engineering strategies can further improve the efficiency of substrate assimilation and PHB synthesis. In the downstream link, PHB recycling strategies based on green chemistry concepts can replace PHB extraction using chlorinated solvents to enhance the economics of PHB production and reduce the potential risks of environmental pollution and health damage. To avoid carbon loss caused by biodegradation in the traditional sense, various strategies have been developed to degrade PHB waste into monomers. These monomers can serve as platform chemicals to synthesize other functional compounds or as substrates for PHB reproduction. The sustainable potential and cycling value of PHB are thus reflected. This review summarized the recent progress of strains, substrates, and fermentation approaches for microbial PHB production. Analyses of available strategies for sustainable PHB recycling were also included. Furthermore, it discussed feasible pathways for PHB waste valorization. These contents may provide insights for constructing PHB-based comprehensive biorefinery systems.

中文翻译：

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基于循环生物经济的聚羟基丁酸酯（PHB）的生产、回收和增值

作为微生物的能量储存物质，聚羟基丁酸酯（PHB）是石化聚合物的有前途的替代品。在适当的发酵条件下，具有代谢多样性的PHB生产菌株可以利用多种碳源高效合成PHB。富含碳的废物可以作为纯糖底物的替代品，以降低 PHB 的生产成本。基因工程策略可以进一步提高底物同化和PHB合成的效率。在下游环节，基于绿色化学理念的PHB回收策略可以替代使用氯化溶剂的PHB提取，提高PHB生产的经济性，降低环境污染和健康损害的潜在风险。为了避免传统意义上的生物降解造成的碳损失，人们开发了各种策略将 PHB 废物降解为单体。这些单体可以作为合成其他功能化合物的平台化学品或作为 PHB 复制的底物。 PHB的可持续潜力和循环价值由此体现。本文综述了微生物 PHB 生产的菌株、底物和发酵方法的最新进展。还包括对可持续 PHB 回收可用策略的分析。此外，它还讨论了 PHB 废物增值的可行途径。这些内容可为构建基于PHB的综合生物炼制系统提供参考。