Expanding the Toolbox for Assessing Polymer Biodegradation

This research project will develop tools and methods for the robust and accurate assessment of biodegradation for a new era of polymers in consumer products that are disposed down the drain.

Biodegradation assessment is a critical step in determining “benign-by-design” chemicals, such as candidate novel biodegradable polymers or biopolymers (polymers of a biological origin). Novel biopolymers are of global interest, research, and investment as substitutes for low molecular weight (LMW) petrochemical-based chemicals, and non-biodegradable polymers. The latter substances are ubiquitously present in the environment with concerns over their potential harmful effects to health and earth system processes, in addition to their sizeable carbon-footprint.

Biodegradation is an important endpoint for evaluating environmental safety of consumer product chemicals disposed down the drain. These chemicals move from the home through a sewer system and wastewater treatment plant where biodegradation often occurs. Any chemical or metabolite not mineralized completely during wastewater treatment enters the freshwater environment via effluent, or, if sorbed to wastewater sludge, can enter the soil environment via land applied biosolids (treated sludge), where they can pose an exposure risk. For this reason, there are standardized regulatory tests to evaluate consumer product chemical biodegradability in many of these environmental compartments.  

Most consumer product chemical safety assessment methods were developed for LMW, soluble molecules, the properties of which differ from polymers, thereby representing a challenge in applying them to accurately assess polymer biodegradation. The EU Commission is drafting a detailed proposal for the registration of polymers under the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH), recognising the above challenge. There is significant regulatory focus on developing technically robust methods for assessing polymer biodegradation.

Polymers are complex mixtures with varying structural components (i.e. molecular weight range and substitution type and level, varying monomers and repeat units) and physical chemical properties (i.e. solubility, bioavailability, sorptivity, charge density). These attributes make it challenging to develop fundamental biodegradation knowledge such as biodegradation pathways, rates of primary and ultimate biodegradation, and mineralization extent in different environmental compartments. There is a need to systematically develop and expand the toolbox available for assessing biodegradation for polymers, especially those in down the drain consumer products. 

This project will focus on the development of accurate, reproducible, and robust methods to assess polymer biodegradation in the freshwater compartment, using biopolymers for down the drain consumer products as case studies. It will involve the following:

• A literature review to identify main classes of polymers, their modifications, properties, and characteristics, and the types and availability of enzymes (and the microbes containing them) in the freshwater environment that catalyse the breakdown of such polymers.
• Conceptual and experimental evaluation of the suitability of analytical techniques to assess polymer biodegradation. Specific approaches will vary depending on polymer structural characteristics but may include size separation methods, nuclear magnetic resonance, chromatographic-mass spectrometry, and antibody microarray/spectrophometric techniques. Non-specific analytical approaches will include respirometric endpoints; e.g. carbon dioxide evolution, oxygen consumption and dissolved organic carbon (for water soluble polymers).
• The use of contemporary molecular techniques (e.g. genomic and transcriptomic quantitative polymerase chain reaction and sequencing, and flow cytometry) and enzymatic studies to understand the enzyme activity and microbes that facilitate such biodegradation processes.

The PhD student will gain training and understanding of specific and non-specific analytical approaches from the Newcastle University and P&G to evaluate mineralization potential for different polymer classes to expand the toolbox for other key compartments for down the drain polymer assessments including sewer, wastewater treatment, and freshwater mixing zones.

How to apply:

• Candidates wishing to apply for a studentship must apply directly to this E-mail address [Email Address Removed] by 5^th Dec 2022 by sending 4 documents:

1. Current CV: [maximum 2 pages] – this needs to include qualifications & two references.
2. A personal statement (maximum 500 words).
3. A completed BISCOP CTP Equal Opportunities Monitoring form
4. A cover note indicating which project within the CTP you are applying for as their first choice and whether interested in any of the other projects.

• Name all the documents with your ‘Name and Type of Form’ e.g., Joe Bloggs CV, Joe Bloggs Personal Statement.
• For more information, please see the Policies & Procedures for applicants.
• In the meantime, if you have any issues or questions, please contact [Email Address Removed]

More information about the BiSCoP CTP

This studentship is part of the second cohort of the BiSCoP CTP (Bioscience for Sustainable Consumer Products Collaborative Training Partnership), a BBSRC-funded inclusive, collaborative environment for high quality doctoral training that will prepare over 30 students with the knowledge and skills needed for successful careers at the forefront of global bioscience. This will help ensure the UK maintains a leadership position in bioscience with improved translation of frontier research into economic and societal impact.

The BiSCoP CTP will be an outstanding environment for PhD research between Durham, Northumbria, Newcastle and other UK universities, biotech company Prozomix and consumer products company Procter & Gamble. The second cohort of 11 PhD students starting in October 2023 will embark upon a 4-year research training programme with modules in hands-on lean innovation, an Accredited Certificate in Strategic Management and Leadership Practice (a Durham University mini-MBA), Intellectual Property, at least a 3-month placement (P&G UK or USA innovation centre or Prozomix UK) and other events.