Plastics in the environment are a pressing matter. There is a need for methods to hasten the degradation of persistent plastics, even bioplastics. The gradual phasing out of traditional consumer plastics will have a huge impact. A new generation of bioplastics are rapidly gaining ground and worldwide production of polylactide (PLA), for example, has more than trebled in the last few years [Jem, 2020]. Polylactide is a persistent plastic that despite its biodegradability can persist in landfill for many years due to low numbers of PLA degrading organisms in soils [Wei, 2017]. Specific hydrolytic enzymes are an attractive solution. Critically, this route allows the recovery of plastic monomers and the reusing of these monomers to synthesise new plastics or other materials of value. This example of a “circular economy” allows for re-use of plastic degradation products.
We recently reported the predicted 3D structure of a novel cutinase (AML) with plastic degrading activity [Tan, 2021]. The specificity of this enzyme was unusual in degrading certain plastics such as polybutylene succinate (PBS) and polycaprolactone (PCL). However, it did not degrade PLA. Lipases capable of PLA degradation are known [Wei, 2017]. This leads to the exciting prospect of being able to degrade mixed plastic waste. The use of environmentally friendly solvents will be examined.
This project aims to use structural information to guide such site-directed mutagenesis of AML to provide new variants with specificity for specific plastics.
Skill-sets: Protein engineering and Enzyme Mutagenesis; Plastic degradation assays;
References:
K. Jim Jem, Bowen Tan, The development and challenges of poly (lactic acid) and poly (glycolic acid), Advanced Industrial and Engineering Polymer Research, Volume 3, Issue 2, 2020, Pages 60-70, ISSN 2542-5048.
Tan Y, Henehan GT, Kinsella GK, Ryan BJ. An extracellular lipase from Amycolatopsis mediterannei is a cutinase with plastic degrading activity. Comput Struct Biotechnol J. 2021 Jan 20;19:869-879. doi: 10.1016/j.csbj.2021.01.019. PMID: 33598102; PMCID: PMC7851449.
Wei, R., and Zimmermann, W. (2017). Microbial enzymes for the recycling of recalcitrant petroleum-based plastics: how far are we? Mic. Biotech., 10(6), 1308-1322.
Student requirements for this project
min. 2.1 BSc in Biological Science
If you are interested in submitting an application for this project, please complete an Expression of Interest (https://www.dit.ie/media/documents/study/postgraduateresearch/EOI%20Form.doc) and email it to [Email Address Removed].
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