Team:Austin UTexas/Description
Project Description
Description and Inspiration
Manufacture of most plastic goods begins from nurdles (small plastic pellets) that are then melted down to create the desired product. Every year an estimated 250,000 tons of nurdles wind up in the ocean. Just recently in 2020, a large spill in New Orleans resulted in an estimated 25 tons of plastic pollution, nearly 1.1 trillion nurdles [1]. More shockingly, when these incidents occur, penalties and clean up responsibilities are rarely defined or enforced, leaving locals and environmentalists to inherit the burden. However, due to the small size of the nurdles, currently clean up methods are manual and time-consuming or destructive to the environment. Our project aims to harness the machinery of marine bacteria to produce plastic degradation enzymes using synthetic biology. In doing so we hope to create a novel approach to cleaning common ocean pollutants that surpass current methods and allow clean up in unreached areas.
Nurdles can be spilled along any part of the industrial line, either at a manufacturing plant or at any other point in transit. These plants are commonly located by waterways or rely on shipping for distribution, resulting in a large amount of spills into the ocean. A majority of nurdles float however some may sink and accumulate in the depths of the ocean or other waterways. There are currently no methods for removing nurdles in water and most efforts have been directed towards cleaning accessible beach shores. One of the most common types of plastics found in nurdles is polyethylene terephthalate (PET). This is a type of plastic that sinks in water and recently scientists were able to isolate an enzyme that they named PETase that originated in a strain of marine bacteria known as Ideonella Sakaiensis. Using Golden Gate assembly, we assembled PETase and MHETase (an enzyme that breaks down the subcomponent of PET) with a packaging sequence into one plasmid that allows the bacteriophage P1 to take up the enzymes and deliver them to a wide range of hosts, including marine bacteria. With this delivery system in place, we can target PET that has sunk and become embedded in the soil, specifically of wetlands which commonly neighbor nurdle plants.
The second portion of our project focuses on addressing the issue of oil spills. Over 5.7 million tons of oil spilled between 1970-2010 which can cause serious harm to marine ecosystem. For example, the Deepwater Horizon oil spill in the Gulf of Mexico in 2010 was the most recent large oil catastrophe, and it ended up polluting an estimated 1,100 miles of shoreline and created an oil slick that contaminated about 57,500 square miles of the Gulf of Mexico. Several methods are currently used to remediate these spills, but the chemical methods are much more efficient than the physical methods. However, the chemical dispersants currently being used are harmful, as they are highly flammable and toxic to the environment. Biosurfactants are a good alternative to these chemical surfactants because they're more natural and safe for marine wildlife.
Biosurfactants are naturally produced biological molecules capable of reducing the surface tension between two typically immiscible substances such as air and water or oil and water. The reduced surface tension allows the two substances to emulsify, effectively causing two distinct substances to mix. Furthermore, some biosurfactants utilize unfolding mechanisms to more easily disperse into solution. Both Ranaspumin-2 (produced as a nesting protein by the Tungara frog) and Latherin (produced by horses in sweat) are typically found in folded conformation with only polar amino acids on the outside, allowing them to freely disperse in water rather than aggregating like many chemical surfactants. Then, upon contact with an interface (usually oil-water or air-water), they unfold, exposing the nonpolar, surfactant-acting regions of the proteins.
The goal of the Austin UTexas team is to address the oil pollution problem using the biosurfactants Ranaspumin-2 and Latherin. The proteins can be used to emulsify the oils slicks formed during oil spills, making the oil droplets more accessible to the ocean's natural hydrocarbon-degrading bacteria. The team will deliver these surfactants through a modified P1 bacteriophage that will take advantage of natural host bacteria in the water near oil spills to generate biosurfactants. This delivery system will also run parallel with our plastic degrading genes and function in a similar manner. By desigining our solution with both surfactant and plastic degrading proteins, we can target two of the biggest pollutants to marine ecosystems and increase the scope of application for our project.
