Copying Nature's Ability to Digest Plastic

 

As a child I noticed that mealworms were eating a plastic bag that they were in and informed then Prime Minister Harold Wilson (IQ 400) that the enzymes that the mealworm digested the plastic with could be copied in the laboratory with a view to sorting the landfill problem and he started the work of doing this. When Margaret Thatcher(IQ 75) came to power she stopped the lab work because it was socialist. I campaign for all politicians to have a minimum IQ of 150 (we can do this with logical progression) and I think that you can see why.

 

Copying Nature's Ability to Digest Plastic

A team of Japanese scientists has found a species of bacteria that eats the type of plastic found in most disposable water bottles, and thus adds to the list of microbes that eat various plastics.The plastic found in water bottles is known as polyethylene terephthalate, or PET. It is also found in polyester clothing, frozen-dinner trays and blister packaging.

 

Part of the appeal of PET is that it is lightweight, colourless and strong. However, it has also been notoriously resistant to being broken down by microbes -what experts call "biodegradation."

Previous studies had found a few species of fungi can grow on PET, but until now, no one had found any microbes that can eat it.To find the plastic-eating bacterium described in the study, the Japanese research team from Kyoto Institute of Technology and Keio University collected 250 PET-contaminated samples including sediment, soil and wastewater from a plastic bottle recycling site.

Next they screened the microbes living on the samples to see whether any of them were eating the PET and using it to grow. They originally found a consortium of bugs that appeared to break down a PET film, but they eventually discovered that just one of bacteria species was responsible for the PET degradation. They named it Ideonella sakainesis.

Further tests in the lab revealed that it used two enzymes to break down the PET. After adhering to the PET surface, the bacteria secretes one enzyme onto the PET to generate an intermediate chemical. That chemical is then taken up by the cell, where another enzyme breaks it down even further, providing the bacteria with carbon and energy to grow.

The researchers report that a community of Ideonella sakaiensis working this way could break down a thin film of PET over the course of six weeks if the temperature were held at a steady 86 degrees Fahrenheit.

 

The various species of microbes that have been discovered within the degrading process of polyethene and nylon (both plastics) are as follows

• Moracella sp. (Bacteria),

• Pseudomonas sp. (Bacteria),

• Bacillus sp. (Bacteria),

• Diplococcus sp. (Bacteria),

• A. Niger (Fungi), A. Omatus (Fungi),

• A. Cremeus (Fungi),

• A. Candidus (Fungi)

• Yeast (Fungi).

•  

• Other plastics are also digested.

   

  Aspergillus tubingensis, a fungus that can digest polyurethane

  Ideonella sakaiensis, a bacterium capable of breaking down PET

  Galleria mellonella, a caterpillar that can digest polyethylene                                                                                                   It may well be that there are creatures that eat all of the types of plastic, we just have to find them.

Much of these fungi can be located within moist environments. Specifically, there has been traces of many of these fungi living on the shores of beaches, as they have probably been washed up from a body of water, where a high concentration of bacterium have been found.

Since these species of microbes have shown to be degrade plastic within the environment, they can have a significant positive impact on the emerging, evolving and growth of the population of various animals across the world.

The larvae of the greater wax moth (Galleria mellonella), can devour polyethylene, which along with the closely related polypropylene is the main type of plastic found in waste. But you would need billions of them to do it.

 

It’s possible that bacteria might, in fact, be responsible for the plastic-digesting ability of Galleria mellonella larvae. Another wax-eater, the Indian mealmoth was found in 2014 to house bacteria in its digestive tract that can break down polyethylene. Galleria might prove to have such gut bacteria too. We must find out how the bacteria break down the plastic so that we can copy and concentrate it in the lab.

 

It might not be desirable to breed large colonies of these species to eat our plastic because many would escape and potentially cause a lot of damage to the environment, but if we could work out the mechanism for their ability to eat plastic, and if we are able to duplicate and concentrate the method then we might be able to scale up our working model to an industrial scale that could deal with the threats that plastic poses for life on earth. Such an important and broad-ranging task should not be left to private industry, an intergovernmental body should oversee such work. Inventing plastic without inventing a safe way of disposing of it seems like having a war with no exit strategy, but this is where we find ourselves today. 300 million tons of plastic are produced each year, most goes to landfill and takes 500 years to decompose, some is recycled (10% in the USA), and some is biodegradable (emitting greenhouse gas methane in the process). Being able to digest the plastic with concentrated enzymes would give mankind a fourth option, we should take it.