Plastic Biodegradation – The Transcriptome

What is plastic?

Plastic is a synthetic organic polymer made from petroleum and is the term commonly used to describe a wide range of synthetic or semi-synthetic materials that are used in a huge and growing range of applications. Everywhere you look, you will find plastic. This material is present in almost every aspect of our daily life [1].

The reason why we use plastic so much is actually pretty simple: it’s versatile and a very resistant material. But the same reasons that make plastic so interesting for multiple applications, makes it a material which is really hard to degrade and has a potential to accumulate in the environment – and that’s what eventually happens.

Due to the fact that plastic takes centuries to degrade, all the plastic that was ever produced – if not recycled or burned – still exists on Earth [2]. And because of that, nowadays there are movements across the globe related to the protection of the environment, and within the wide range of topics related, the plastic problem is of huge importance on that matter.

It is a fact that at least 8 million tons of plastic end up in our oceans every year. Floating plastic debris are currently the most abundant items of marine litter. On top of that, waste plastic makes up to 80% of all marine debris from surface waters to deep-sea sediments. Plastic has been detected on shorelines of all the continents, with more plastic materials found near popular tourist destinations and densely populated areas which can cause diseases in the local communities [3].

The United Nations (UN) postulated 17 sustainable development goals to be achieved by the end of 2030 and some of them are: to work on good health and well being of the population, provide clean water and sanitation, develop sustainable cities and communities, raise awareness on responsible consumption and production, take part on climate action and end life below the poverty line [4].

On all the topics mentioned we can infer that plastic pollution is present and due to the importance of the topic and urgent need to find solutions for that problem, here we discuss how microorganisms can degrade plastic.

Can microorganisms “eat” plastic?

There are reports which revealed that various soil bacteria, fungi and actinomycetes (group of gram-positive, generally anaerobic bacteria noted for a filamentous and branching growth pattern that results, in most forms, in an extensive colony) in the plastic contaminated environment eventually tend to adapt to the extreme conditions and utilize these waste products as carbon and nitrogen sources.

In 2016, scientists from Japan tested different bacteria from a bottle recycling plant and found that Ideonella sakaiensis 201-F6 could digest the plastic used to make single-use drinks bottles: polyethylene terephthalate (PET).

The process works by the secretion of an enzyme (a type of protein that can speed up chemical reactions) known as PETase by the bacteria. This splits certain chemical bonds (esters) in PET, leaving smaller molecules that the bacteria can absorb, using the carbon in them as a food source [4].

Although other bacterial enzymes were already known to slowly digest PET, the new enzyme had apparently evolved specifically for this job. This suggests it might be faster and more efficient and so have the potential for use in bio-recycling.

Also, in 2012 students from Yale University discovered a rare species of mushroom that can eat plastic. The mushroom is called Pestalotiopsis microspora and it comes from the Amazon rainforest. The fungi are capable of surviving on plastic alone! It consumes polyurethane (the main ingredient in plastic products) and converts it into organic matter [5].

Will living organisms solve plastic waste pollution?

We cannot answer this for sure yet, but what we do know is that there’s more to study and further things to investigate about microorganisms that are able to degrade plastic. We imagine that with the continued development of synthetic biology and genome editing we’ll have tools to control plastic pollution in the future [6].

While we don’t achieve that goal, we must think that science is quite far from solving all problems related to plastic pollution and even though tools have been created to degrade and recycle plastic, it is of huge importance to reduce the consumption and avoid utilizing this material on our daily basis. Choosing products that are environmentally-friendly and recycling plastic objects are the best way to reduce plastic waste pollution and help the environment.

References:

Nathália Raquel

Website | + posts