Microbial and Enzymatic Degradation of Synthetic Plastics.
Microbial and Enzymatic Degradation of Synthetic Plastics.
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DOI：
10.3389/fmicb.2020.580709
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发表时间：
2020
影响因子：
5.2
通讯作者：
Levin DB
中科院分区：
文献类型：
--
作者：
Mohanan N;Montazer Z;Sharma PK;Levin DB
合成塑料在我们当前的生活方式中起着关键作用，因此，它的积累是环境和人类健康的一个主要问题。石油衍生的聚合物，如聚乙烯（PE）、聚对苯二甲酸乙二醇酯（PET）、聚氨酯（PU）、聚苯乙烯（PS）、聚丙烯（PP）和聚氯乙烯（PVC），对自然生物降解途径是非常难的。一些在体外条件下具有降解石油聚合物能力的微生物已经被分离出来并进行了表征。在某些情况下，这些微生物表达的酶已经被克隆和测序。聚合物的生物降解速率取决于几个因素，包括化学结构、分子量和结晶度。聚合物是具有规则晶体（结晶区）和不规则基团（无定形区）的大分子，后者为聚合物提供了灵活性。高结晶聚合物，如聚乙烯（95%），是刚性的，抗冲击能力低。pet基塑料具有很高的结晶度（30-50%），这是其微生物降解率低的主要原因之一，预计在自然环境中完全降解需要50年以上，如果丢弃到海洋中需要数百年，因为它们的温度和氧气可用性较低。酶降解发生在两个阶段：酶在聚合物表面的吸附，然后是氢化过氧化/水解键。塑料降解酶的来源可以在各种环境中的微生物以及一些无脊椎动物的消化道中找到。废石油塑料的微生物和酶降解是一种很有前途的策略，可以将废石油塑料解聚成可回收的聚合物单体，或通过矿化将废塑料转化为高价值的生物产品，如可生物降解的聚合物。本文综述了微生物降解合成塑料的研究进展，并对参与生物降解的酶进行了综述。
Synthetic plastics are pivotal in our current lifestyle and therefore, its accumulation is a major concern for environment and human health. Petroleum-derived (petro-)polymers such as polyethylene (PE), polyethylene terephthalate (PET), polyurethane (PU), polystyrene (PS), polypropylene (PP), and polyvinyl chloride (PVC) are extremely recalcitrant to natural biodegradation pathways. Some microorganisms with the ability to degrade petro-polymers under in vitro conditions have been isolated and characterized. In some cases, the enzymes expressed by these microbes have been cloned and sequenced. The rate of polymer biodegradation depends on several factors including chemical structures, molecular weights, and degrees of crystallinity. Polymers are large molecules having both regular crystals (crystalline region) and irregular groups (amorphous region), where the latter provides polymers with flexibility. Highly crystalline polymers like polyethylene (95%), are rigid with a low capacity to resist impacts. PET-based plastics possess a high degree of crystallinity (30–50%), which is one of the principal reasons for their low rate of microbial degradation, which is projected to take more than 50 years for complete degraded in the natural environment, and hundreds of years if discarded into the oceans, due to their lower temperature and oxygen availability. The enzymatic degradation occurs in two stages: adsorption of enzymes on the polymer surface, followed by hydro-peroxidation/hydrolysis of the bonds. The sources of plastic-degrading enzymes can be found in microorganisms from various environments as well as digestive intestine of some invertebrates. Microbial and enzymatic degradation of waste petro-plastics is a promising strategy for depolymerization of waste petro-plastics into polymer monomers for recycling, or to covert waste plastics into higher value bioproducts, such as biodegradable polymers via mineralization. The objective of this review is to outline the advances made in the microbial degradation of synthetic plastics and, overview the enzymes involved in biodegradation.
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影响因子：
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