Research

Project Overview

UCL iGEM proposes a synthetic biology approach for the bioremediation of micro-plastic pollutants within the marine environment, with emphasis on regions of excessive debris accumulation, such as the North Pacific ‘garbage patch’.

We intend to engineer enhanced adhesive properties in Escherichia coli and marine bacteria Roseobacter denitrificans & Oceanibulbus indolifex, of the Roseobacter clade. To alter the composition and dynamics of resultant biofilms for the adhesion of micro-plastic pollutants, with an extended vision of creating mass aggregates, or ‘Plastic Islands’.

We will attempt to demonstrate micro-plastic particle aggregation and several additional genetic components, including plastic degradation, salinity/osmotic tolerance in E. coli, bacterial buoyancy and novel active biological containment strategies, for an integrative approach to marine bioremediation.

In many of the worlds oceans, currents carry debris and pollution originating from coastlines. This waste accumulates in regional gyres, where the worlds ocean currents meet, and can reach extremely high concentrations. Plastic is estimated to account for 60-80% of this debris, and is known to be gradually broken down by solar energy and the mechanic action of the sea. This means the majority of the plastic waste are several millimetres in size or less, which has made efforts to clean them from the ocean largely unsuccessful. These tiny plastic fragments - microplastics - enter the digestive systems of resident organism, which are affected either by the physical size of the plastic or its toxicity from adsorbing organic pollutants.

Aim

We aim to genetically engineer a bacterial machine capable of constructing 'islands' from microplastics. Using Roseobacter denitrificans, a marine bacterium, we will insert genes that allow it to adhere to, aggregate and buoy fragments. While relatively small, these ‘Plastic Islands’ could be collected and recycled, or alternatively clumped into large artificial ‘islands’. Our vision is to reclaim waste by ‘terraforming’ it into a habitable island – dubbed by our team as the ‘Plastic Republic’.

We are pursuing this project as several separate modules which we will assemble once we have tested their competence.

Detection Module

Receptors Based Detection is a first step for both aggregation and degradation. The main receptor is human oestrogen receptor that binds to different types of micro-plastics.

Aggregation Module

In the case of aggregation, receptors on bacteria detect microplastics and induce the production of Curli Adherent Proteins. First this allows bacteria stick to the plastics and once covered in bacteria allows microplastics to stick to one another.

Degredation Module

The degradation module, which is separate from aggregation module, also comes after receptor detection. This system secretes a Laccase Enzyme that metabolises the microplastics and their derivatives that are otherwise toxic to the environment. As a result of degradation these materials are converted into non-toxic ones.

Buoyancy Module

The microplastics that contaminate our oceans float just below the surface. In order to ensure that our bacteria stay in the same locality as their targets, the buoyancy module allows the cells to produce Gas Vesicles, and increase their production as the temperature falls.

irrE a global regulator from Deinococcus radiodurans for increased salinity tolerance in E. coli BBa_K729001

irrE, a global regulator of radiation resistance confers resistance to various abiotic stresses through regulation of numerous effectors, including DNA recombination protein recA (Earl et al. 2002). We will specifically investigate the ability of irrE to confer salinity tolerance in E. coli, as previously demonstrated by (Pan et al. 2009).

Containment Module

Arguably the most important module for a system released into the environment, this module prevents Horizontal Gene Transfer, preventing the gene in our cells from being spread into the environment.