RUI: Synergistic biodegradation of polyethylene terepthalate (PET) plastic by microbial consortia

每年生产近4亿吨新塑料，回收率仅为9%，大多数塑料最终进入环境。一次性物品，如水瓶和食品容器，以及由聚对苯二甲酸乙二醇酯（PET）制成的纺织品构成了这种废物的很大一部分。为了创造更循环的PET经济，确定了一种能够降解PET塑料废物的土壤细菌群落。该项目的总体目标是确定这种细菌群落如何实现这一环境和潜在商业重要壮举。本科生和高中生将参与这项研究。重点将放在招募代表性不足的少数民族和第一代学生研究人员。 先前的研究确定了在PET塑料上生长的后期指数阶段诱导的细菌基因的快照。这一信息，结合宏基因组分析表明，协同交叉喂养之间的土壤细菌财团是部分负责降解PET塑料的能力。在该项目中，将通过RNA测序探索PET降解的阈值要求，以分析细菌定殖和生长初始阶段聚合物裂解所需的基因产物。通过这些分析，宏基因组中的单个基因将被靶向用于创建缺失突变。靶向删除的基因将包括那些编码生物表面活性剂、摄取系统、已知降解和代谢PET的酶以及感知环境信号的调节剂的基因。将通过HPLC和NMR分析突变体，以监测分解产物，从而推断哪些基因有助于联合体内的PET降解。这种系统方法提供了一种了解PET上观察到的微生物协同生长的途径，并有可能彻底改变对塑料在自然环境中如何回收的理解。该奖项反映了NSF的法定使命，通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With nearly 400 million metric tons of new plastics produced every year and with recycling rates at only 9%, the majority of plastics eventually enter the environment. Single-use items, such as water bottles and food containers, and textiles made from polyethylene terephthalate (PET) comprise a significant proportion of this waste. With the idea of creating a more circular PET economy, a community of soil bacteria with the ability to degrade PET plastic waste was identified. The overall goal of this project is to determine how this bacterial community achieves this environmentally and potentially commercially important feat. Undergraduates and high school students will participate in the research. An emphasis will be placed on recruiting underrepresented minority and first-generation student researchers. Previous research identified a snapshot of bacterial genes induced during the late exponential phase of growth on PET plastic. This information, combined with metagenome analysis indicated that synergistic cross-feeding among a consortium of soil bacteria was partly responsible for the ability to degrade PET plastic. In this project, threshold requirements for PET degradation will be explored by RNA sequencing to analyze the gene products necessary for colonization by the bacteria and for polymer cleavage during the initial stages of growth. Informed by these analyses, individual genes within the metagenome will be targeted for creating deletion mutations. Genes targeted for deletion will include those encoding biosurfactants, uptake systems, enzymes known to degrade and metabolize PET, and regulators that perceive environmental signals. The mutants will be analyzed by HPLC and NMR to monitor breakdown products, thus allowing inference of which genes contribute to PET degradation within the consortium. Such a systems approach offers an avenue to understand the observed synergistic growth of microbes on PET and has the potential to revolutionize understanding of how plastics are recycled in natural environments. In turn, this knowledge could be applied to create a more circular plastics economy using bio-recycling techniques.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.