Role of Synthetic Biology in Pollution Control: A Much Awaited Plot Twist

“To live, to err, to fall, to triumph, to recreate life out of life.”    

- James Joyce

Synthetic Biology is the design and construction of new biological parts, devices, and systems, and the re-design of existing, natural biological systems for useful purposes. One specific area where SYNBIO applications seem to hold great promise, even though research is still limited, is combating environmental pollution. With more than 2 million tons of human waste disposed in water bodies every day, a broad range of harmful substances ends up in the environment, contaminating terrestrial and aquatic ecosystems. Persistent micro-plastics, pharmaceuticals, personal care products and other hazardous contaminants from industrial and agricultural activities are accumulating more and more on a global scale, reaching critical levels of toxicity. 

Nina Pollak, at the University of Sunshine Coast in Queensland is synthesizing jellyfish to clean up toxic spills.

In 2012, the Austrian-born scientist was inspired by a bold study, published by Kevin Kit Parker at Harvard’s Wyss Institute for Biologically Inspired Engineering. Parker’s group had transformed rat heart muscle cells into a swimming creature dubbed a 'medusoid' (medusa being the scientific name for the typical form of a jellyfish).

Beginning with a computer design, the researchers laid rat heart muscle cells on a scaffold of silicone polymer shaped like an eight-petalled flower. The creation could be made to swim with pulses of electricity: flowing current caused the muscle to contract; when the current stopped it relaxed and the medusoid’s elastic silicone pulled it back to its original shape. The motion echoed that used by jellyfish to propel themselves .

Parker’s goal with the medusoid was to model the beating of a heart and test new drugs; Pollak envisioned the possibility of creating an aquatic rover to detect and clean up ocean pollutants. Her approach relies on coaxing mouse embryonic stem cells to form heart cells whose beat should provide locomotion. The stem cells will also be engineered to carry a gene that senses toxic organophosphate  - a pesticide common in agricultural run - off – and other genes that can then break toxic chemicals down. The end result: a jellyfish-like organism that can hunt and destroy pollutants. 

Biopolymers are polymers produced by living organisms. Cellulose and starch, proteins and peptides, and DNA and RNA are all examples of biopolymers in which the monomeric units are sugars, amino acids and nucleotides, respectively. Bioplastics or organic plastics are forms of plastics derived from renewable biomass sources, such as vegetable oil, starch or sugar, rather than fossil-fuel plastics, which are derived from petroleum. Some biopolymers are biodegradable: they are broken down into carbon dioxide and water by microorganisms. In addition, some of these biodegradable biopolymers are compostable. The primary applications of bioplastics are food packaging , food waste collection bags and agricultural mulch films to suppress weed growth. 

The types of bioplastics are here for further reading.

The production of cement (a key ingredient of concrete) is responsible for about eight percent of global greenhouse gas emissions because of the energy needed to mine, transport and prepare the raw materials. bioMASON  in North Carolina provides an alternative by placing sand in molds and injecting it with bacteria, which are then fed calcium ions in water. The ions create a calcium carbonate shell with the bacteria’s cell walls, causing the particles to stick together. A brick grows in three to five days. BioMASON’s bricks can be customized to glow in the dark, absorb pollution, or change color when wet. 

Water pollution can be human driven (domestic or industrial wastewater, contaminated groundwater) or natural (heavy metals of geogenic origin). Contaminated groundwater stems from industrial activities in the past and can be considered  as a finite problem because intense care is being taken today to protect groundwater from pollution. Furthermore, groundwater contamination is always associated with soil contamination. In contrast, sewage and industrial wastewater are inevitable byproducts of human activities. They will accrue indefinitely and in great bulk, even if their extent is reduced by intelligent measures. 

Finding means of preserving and restoring natural environments constitutes a major challenge facing modern society. Metal-oxidizing or metal-reducing bacteria represent an attractive tool to restore contaminated sites, but they remain fairly poorly characterized, in particular in terms of their metabolic capacities. Some bacteria thriving in such harsh environments have been somewhat characterized at the genome level. They display significant metabolic versatility and the ability to restore life-nurturing conditions in  the environment. An important feature is to avoid gasification of arsenic (same is true for mercury) and to promote its mineralization into insoluble material. 

Yeast-produced farnesene is being used to make personal-care products such as vitamin E , patchouli oil and squalene, a compound once harvested from the livers of sharks, which is prized for its attributes as a skin moisturizer and other therapeutic benefits. 

As some SYNBIO applications are starting to move out of the lab, there are worries about its potential environmental risks. If an engineered organism, such as those used in gene drives, is released into nature, could it prove more successful than existing species in an ecosystem and spread unchecked?