Post created by Liz
Everything is created and eventually destroyed. We eat a banana and the peel is easily biodegradable, as are other items, but the one item that is said to outlast all of us is plastic. We use it for a lot of things and it comes in handy for water bottles, holding our groceries, containers, and so much more. Some people might even think of plastic as cheap and easy to get rid of, but in actuality, when plastic is in a landfill it will take up to 450 years to decompose. Under different conditions, such as the ocean where a big portion of plastic collects, it still takes up to three years for plastic to decompose. Efforts to clean up some of the debris does little help, but a discovery in Japan might just be the answer to cleaning up this plastic mess.
Ideonella sakaiensis is a bacterium that is colorless, smooth, and circular and it produces two enzymes that each perform their own task. The first is PETase, which then generates intermediates MHET. It is then taken back up by the cell and hydrolyzed by the second enzyme. The second enzyme, MHET hydrolase, converts MHET into two benign monomers: terephthalic acid an ethylene glycol. With that on our side, the bacterium was able to degrade Polyethylene terephthalate, PET, within 6 weeks. These enzymes naturally evolve the ability to eat plastic, enabling the full recycling of PET, a huge breakthrough for the environment. There are some drawbacks to these bacteria though.
Due to most of our plastic problems mostly being in the ocean, these bacteria will have to be modified or a system will have to be made for that environment. Meaning that they will have to be self-sustainable, efficient, still environmentally friendly, and less-costly. This bacterium is our best hope in turning away from what we currently do to get rid of plastic, which is using chemicals and using heat up to 700 degrees Fahrenheit. The problem with this solution is that it releases chemicals in the plastic into the environment and we are left with ashes that need to be properly disposed of. With future genetic modifications of the bacterium, it opens a whole new opportunity to dispose of plastics in an environmentally friendly way, fully getting rid of the harmful disposable way we use now.
Another issue, that is currently being looked at, is the self-sustainability of the bacterium. In order for Ideonella sakaiensis to really thrive, there needs to be genetic modifications made that allows them to establish themselves and reach a size that will actually make a difference. A current study is being done to look more closely at the enzymes themselves. In this case, there will be a serious improvement on protein engineering, where they try to deal with and understand how to make the enzymes work faster. With the process of self-sustainability and protein engineering underway, once the PET is broken down into ethylene glycol and DMT, the products can be used directly or as the starting point of creating another product. Ultimately, making plastic an easy and reusable product.
With these future advancements well underway, it will not be long before we hopefully have the solution to decomposing plastic in 6 weeks rather than 450 years. It will be a self-sustaining cycle, where plastic is recycled, decomposed into ethylene glycol and DMT, and then reused. This fast rate of biodegradation is significant and will be evolutionary, opening so many doors and new fields of synthetic biology as well as biotechnological applications. So, be on the lookout for a plastic-eating bacterium that will soon be the solution of to biodegradable plastic.
Source:
Chan, A. (2016). The Future of Bacteria Cleaning Our Plastic Waste. Berkeley Scientific
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