Microbial hitch-hikers of marine plastics: the survival, persistence & ecology of microbial communities in the 'Plastisphere'

Lead Research Organisation: University of Stirling
Department Name: Biological and Environmental Sciences

Abstract

The most abundant form of litter in the marine environment is plastic, and the negative and detrimental consequences of plastic debris on fish, reptiles, birds and mammals are well documented. The hard surface of waterborne plastic provides an ideal environment for the formation of biofilm for opportunistic microbial colonisers; however, our knowledge of how microorganisms interact with microplastics and alter the dispersal behaviour of marine plastics in the environment is a significant research gap. Biofilm at the interface between the plastic surface and the environment has been termed the 'Plastisphere', and although plastics are extremely resistant to decay, variability in composition determines their specific buoyancy and surface rugosity, which will dictate the extent of microbial colonisation and their ability for long distance dispersal. Furthermore, because plastic debris can persist in the marine environment longer than natural substrates, e.g. feathers and wood, it offers an opportunity for the wider dissemination of pathogenic and harmful microorganisms.

Microplastics from clothes, cosmetics and sanitary products are now common constituents of sewage systems and they frequently bypass the screening mechanisms designed to remove larger waste items from being exported to coastal waters. Microplastics entering aquatic systems from waste water treatment plants (WWTPs) come in close contact with human faeces, hence providing significant opportunity for colonisation by faecal indicator organisms (FIOs) and a range of human bacterial pathogens. Importantly however, there have never been any studies investigating the ability of enteric viruses binding to microplastics (or binding to the biofilm on the plastic surface), and this now needs critical evaluation in order to understand this potentially novel mechanism for the environmental dispersal of enteric viruses. Furthermore, there is growing evidence that the plastisphere can promote gene exchange, and so determining the potential of plastisphere biofilms for providing the surface for anti-microbial resistance (AMR) gene transfer is of the utmost importance. There is currently a lack of fundamental understanding about the mechanisms by which microorganisms, particularly pathogenic bacteria and viruses, can "hitchhike" on microplastic particles and be transported to beaches, bathing waters, shellfish harvesting waters and high benthic diversity zones. Consequently, it is not yet possible to determine the risk from these potential pathways, or establish environmental monitoring guidelines for informing future policy or environmental regulation. Therefore, the novelty of this project is to quantify the processes that are occurring within the plastisphere, and understand the potential for the vectoring of pathogenic viruses and bacteria.

Previous research on chemical co-pollutants present on plastics often fails to consider the likely impacts of plastisphere communities. Microplastics in the environment are potential vectors for these chemicals, which often desorb when ingested by marine species, and can accumulate in the food chain. Microbes in the plastisphere may either mitigate this problem through biodegradation, or enhance it by increased biofilm binding; however, most laboratory-based studies are carried out with pristine non-colonised plastics, and ignore the pivotal role the plastisphere plays on defining the risk of microplastics in the environment. By understanding the multi-pollutant and multi-scale effects of microplastics, the "Plastic Vectors Project" will help to establish a more accurate risk assessment of microplastics by taking into consideration the effects of harmful plastic-associated microbes together with chemical co-pollutants.

Therefore, the "Plastic Vectors Project" aims to quantify the significance and function of microbes in the 'plastisphere', and will deliver feasible solutions for reducing these multi-pollutant risks

Planned Impact

This project addresses an issue of global relevance, and therefore the impact will be far-reaching. A range of key stakeholders have been actively engaged in the formulation and writing of this proposal to ensure that it directly meets their needs, complements existing research and is fit for purpose. Specifically, this proposal will be of benefit to policy makers and regulators, both national and international. The main UK beneficiaries will be Defra, Scottish Environmental Protection Agency, Environment Agency (and devolved equivalents), the NHS, and NGOs, e.g. Surfers Against Sewage, as well as UK academia. In addition, our research output will be of use to those water companies gearing up to significantly invest in measures to update wastewater infrastructure; our project offers a time-limited opportunity to prepare for the developing legislation aimed at mitigating the release of microplastics from WWTPs. The project will also benefit healthcare providers (e.g. NHS) by generating additional knowledge of the potential health impact of microplastics and the unknown dimension of how microplastics may in fact support other human health hazards and exposure pathways. Internationally, the work will directly inform the European Environment Agency, EU-DG MARE and EU-DG SANCO; additionally, data from this project will be significant for European legislation on the use of microplastics as ingredients in cosmetics and sanitary products.

The project team are well-placed to ensure that research findings are disseminated with highest impact given existing links to Defra, SEPA & other bodies. UK regulators will gain access to more complete and integrated understanding of how multiple hazards can interact in aquatic systems. Our results will provide more certainty with regard to the multi-pollutant and multi-scale effects of microplastics, and will deliver a more accurate risk assessment of microplastics by integrating the effects of harmful plastic-associated microbes together with chemical co-pollutants. Importantly, the "Plastic Vectors Project" will benefit from an advisory board of invited experts (see letters of support) who will enable critical evaluation of the direction of the project, and thus endorse our approach as 'fit-for-purpose' for a wide range of relevant stakeholders

We propose a multifaceted way of disseminating our project findings and realising impact. To engage with our stakeholders we will capitalise on our strengths of disseminating results to public, scientific, regulatory and policy audiences by using radio and TV interviews, public meetings (e.g. Café Scientifique), stakeholder and KE workshops, bespoke websites, social media, scientific and non-scientific publications. We aim to stimulate interest in the multi-pollutant impacts of microplastics covered in our project by targeting young people and children at science fairs and festivals (in Scotland, Wales and England), and inspiring change in the way we interact with plastics in our everyday lives.

Publications

10 25 50
 
Description ARCH UK ECR working group co-lead 
Organisation ARCH-UK
Sector Academic/University 
PI Contribution Post-doc, Dr Vanessa Moresco, was invited to be co-lead for the ARCH UK working group 4 "Human health and food safety" to provide knowledge exchange within the network on micoplastics
Collaborator Contribution The aim of the ARCH UK is to increase UK capacity for solving important issues preventing the sustainable development of aquaculture
Impact Active co-lead of the ARCH UK network; engaging with regulatory and industry stakeholders
Start Year 2019
 
Description Biannual group meeting - stakeholder engagement (SEPA and Fidra) 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Professional Practitioners
Results and Impact Biannual group meeting with stakeholders (Scottish Environmental Protection Agency, and the environmental charity Fidra). The objective of this meeting was to plan future sampling and experimental strategies with our stakeholders to make sure our approach was policy relevant
Year(s) Of Engagement Activity 2020
 
Description IWA video and blog post 
Form Of Engagement Activity A broadcast e.g. TV/radio/film/podcast (other than news/press)
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact The International Water Association (IWA) made a short video and news item available on their website. This item is in direct response to the project
Year(s) Of Engagement Activity 2019
URL https://www.thesourcemagazine.org/pathogen-concern-over-plastic-pellets/
 
Description Interview with national newspaper (The Guardian) 
Form Of Engagement Activity A magazine, newsletter or online publication
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Interview with journalist for The Guardian (online and print: 12th March, 2019)
Print: "Toxic bacteria hitch lift on plastic beads washed up on UK beaches".
Online: "Pathogens hitchhiking on plastics 'could carry cholera from India to US"
Year(s) Of Engagement Activity 2019
URL https://www.theguardian.com/environment/2019/mar/11/pathogens-hitchhiking-on-plastics-could-carry-ch...
 
Description Official meeting with Scottish Minister for Environment: Mairi Gougeon MSP 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Policymakers/politicians
Results and Impact Official meeting with Scottish Minister for Environment, Mairi Gougeon MSP, who visited specifically to hear about this project. She later spoke about the project in the Scottish Parliament
Year(s) Of Engagement Activity 2019
URL https://www.stir.ac.uk/news/2019/02/minister-visits-stirling-to-hear-about-innovative-research/
 
Description Website and Twitter 
Form Of Engagement Activity Engagement focused website, blog or social media channel
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Public/other audiences
Results and Impact Dedicated project website and Twitter account
Year(s) Of Engagement Activity 2019
URL https://plasticvectors.stir.ac.uk/our-science/