Assessing the environmental biodegradation of next-generation polyolefin plastics

塑料已成为全球污染物，并已在地球上的每一个环境中检测到。它们对植物群和动物群产生影响，并助长病原体和抗生素抗性基因的传播。为了防止塑料的有害积累，英国塑料公约等倡议旨在到2025年实现100%的塑料包装完全可堆肥和可回收。这导致了新型塑料的开发，一旦达到保质期，其生物降解性将增加，从而使其能够进入循环经济。在本项目中，我们将研究土壤微生物群落生物降解下一代聚烯烃塑料的能力。聚烯烃聚合物（例如聚乙烯和聚丙烯）被广泛用作一次性塑料产品，特别是以膜（例如塑料袋）和纤维（例如面罩）的形式。它们的收集和回收率很低，并且在环境中积累，降解非常缓慢，因为它们需要非生物过程才能通过不太了解的过程被同化。本案例学生奖学金的工业赞助商是Polymateria，一家专注于通过专利生物转化技术生产可生物降解聚烯烃的中小企业。在这个项目中，我们将利用Polymateria在聚合物合成和表征方面的专业知识来评估不同的可持续和工程聚乙烯和聚丙烯材料的生物降解潜力，以及它们对土壤微生物群的影响。然后，我们将试图了解各种环境和加工条件下产生的聚烯烃生物降解的途径和中间体。我们要解决的具体问题如下：1）聚乙烯和聚丙烯的哪些配方可以生物降解？Polymateria将采用一系列广泛应用于塑料行业的聚合物添加剂和共混物。这些塑料将通过暴露于模拟气候条件和广泛回收来进行预处理。材料将与土壤群落一起培养，并将在公司研究所得聚合物和蜡，以确定其降解情况（通过GPC和FTIR等分析方法）。2）可生物降解塑料对土壤微生物群有何影响？微生物群落将与模拟不同环境条件的塑料一起孵育。我们将通过培养、DNA分离和16S rDNA（细菌）和ITS（真菌）的测序来评估微生物的生长和种群动态。3）生物降解的生物体和途径是什么？我们将使用质谱和NMR研究降解产物，这将允许识别来自塑料的相关代谢物。将对塑料降解过程中富集的生物进行分离、测序和进一步表征，以确定对聚烯烃的相关活性。

Plastics have become global pollutants and have been detected in every environment in the planet. They have an impact on flora and fauna and also contribute to the spread of pathogens and antibiotic resistance genes. To prevent the harmful accumulation of plastics, initiatives such as the UK Plastics Pact aim at having a 100% of plastic packaging fully compostable and recyclable by 2025. This has led to the development of novel plastics with increased biodegradability once they reach the end of their shelf life which could enable their entry in a circular economy.In this project we will investigate the ability of soil microbial communities to biodegrade next-generation polyolefin plastics. Polyolefin polymers (e.g. polyethylene and polypropylene) are widely used as single-use plastic products especially in the form of films (e.g. plastic bags) and fibres (e.g. face masks). They have low collection and recycling rates, and accumulate in the environment where their degradation is extremely slow, as they require abiotic processes before they can be assimilated via poorly understood processes.The industrial sponsor in this CASE studentship is Polymateria, a SME specialising in the production of biodegradable polyolefins through a patented biotransformation technology. In this project we will leverage Polymateria's expertise in polymer synthesis and characterisation to evaluate the biodegradation potential of different sustainable and engineered polyethylene and polypropylene materials as well as their impact on the soilmicrobiota. We will then seek to understand the pathways and intermediates of polyolefin biodegradation resulting from various environmental and processing conditions. The specific questions we want to address are the following:1) What formulations of polyethylene and polypropylene can be biodegraded? Polymateria will incorporate a range of polymer additives and blends widely used in the plastic industry.These plastics will be pre-treated through the exposure to simulated weathering conditions and extensive recycling. Materials will be incubated with soil communities and the resulting polymers and waxes will be studied at the company to characterise their degradation (by GPC and FTIR among other analytical methods).2) What is the impact of biodegradable plastics on the microbiota of soil? Microbial communities will be incubated with plastics mimicking different environmental conditions. We will assess microbial growth and population dynamics via culturing, DNA isolation and sequencing of 16S rDNA (for bacteria) and ITS (for fungi).3) What are the organisms and pathways responsible for the biodegradation? We will investigate degradation products using mass spectrometry and NMR, which will allow to identify relevant metabolites derived from plastic. Organisms enriched during plastic degradation will be isolated, sequenced and further characterised in order to identify relevant activities against polyolefins