Mooney Brian P
University of Missouri, Interdisciplinary Plant Group, Division of Biochemistry, and Charles W. Gehrke Proteomics Center, 214 Christopher S. Bond Life Sciences Center, 1201 Rollins St., Columbia, MO 65211, USA.
Biochem J. 2009 Mar 1;418(2):219-32. doi: 10.1042/BJ20081769.
Biodegradable plastics are those that can be completely degraded in landfills, composters or sewage treatment plants by the action of naturally occurring micro-organisms. Truly biodegradable plastics leave no toxic, visible or distinguishable residues following degradation. Their biodegradability contrasts sharply with most petroleum-based plastics, which are essentially indestructible in a biological context. Because of the ubiquitous use of petroleum-based plastics, their persistence in the environment and their fossil-fuel derivation, alternatives to these traditional plastics are being explored. Issues surrounding waste management of traditional and biodegradable polymers are discussed in the context of reducing environmental pressures and carbon footprints. The main thrust of the present review addresses the development of plant-based biodegradable polymers. Plants naturally produce numerous polymers, including rubber, starch, cellulose and storage proteins, all of which have been exploited for biodegradable plastic production. Bacterial bioreactors fed with renewable resources from plants--so-called 'white biotechnology'--have also been successful in producing biodegradable polymers. In addition to these methods of exploiting plant materials for biodegradable polymer production, the present review also addresses the advances in synthesizing novel polymers within transgenic plants, especially those in the polyhydroxyalkanoate class. Although there is a stigma associated with transgenic plants, especially food crops, plant-based biodegradable polymers, produced as value-added co-products, or, from marginal land (non-food), crops such as switchgrass (Panicum virgatum L.), have the potential to become viable alternatives to petroleum-based plastics and an environmentally benign and carbon-neutral source of polymers.
可生物降解塑料是指那些能够在垃圾填埋场、堆肥场或污水处理厂中通过自然存在的微生物的作用而完全降解的塑料。真正的可生物降解塑料在降解后不会留下有毒、可见或可区分的残留物。它们的生物降解性与大多数石油基塑料形成鲜明对比，石油基塑料在生物学环境中基本上是不可破坏的。由于石油基塑料的广泛使用、它们在环境中的持久性以及它们来源于化石燃料，人们正在探索这些传统塑料的替代品。在减少环境压力和碳足迹的背景下，讨论了围绕传统和可生物降解聚合物的废物管理问题。本综述的主要重点是基于植物的可生物降解聚合物的发展。植物天然产生多种聚合物，包括橡胶、淀粉、纤维素和贮藏蛋白，所有这些都已被用于生产可生物降解塑料。用植物的可再生资源喂养的细菌生物反应器——所谓的“白色生物技术”——也成功地生产出了可生物降解聚合物。除了这些利用植物材料生产可生物降解聚合物的方法外，本综述还讨论了在转基因植物中合成新型聚合物的进展，特别是那些聚羟基脂肪酸酯类的聚合物。尽管转基因植物，特别是粮食作物，存在一种污名，但作为增值副产品或从边际土地（非粮食）作物如柳枝稷（Panicum virgatum L.）生产的基于植物的可生物降解聚合物，有可能成为石油基塑料的可行替代品，以及聚合物的环境友好和碳中和来源。
