8/8/2022 - Technology and Innovation

Microorganisms could end plastic contamination

By Sahira Janeir Garazatúa

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Biotechnology in the environment

August is the month of Pachamama (mother earth). Andean communities, especially from the Argentine northwest, thank you for everything that nature provides. They deposit their faith and pay you a tribute to rituals and offerings (which can be products collected from the region or products valued by communities). This custom that comes from generation to generation over several centuries by little begins to extrapolate to the rest of the population. Not only on the side of adding respectfully to this custom, but also on the side of the understanding of the thought of being grateful to our land. Environmental awareness is becoming increasingly focused on collaboration with the care of our planet Earth, while we wonder what we give it back in return? And this is where various tools come into play, such as the adoption of certain customs in our homes: to separate the garbage and to recycle, as the dissemination to awareness of what I have next to and reach more people, and especially what I care to highlight, the use of biotechnological tools that collaborate with the care of the environment.

The plastic industry and a possible biological solution

It is known that the plastic industry is one of the most polluted. Its deposited take years to degrade affect soils, oceans and biodiversity by disrupting natural processes of living beings, and intoxicating them. It is expected that by 2050 there is more plastic than fish in weight (Kg). Specifically, polyethylenes (composed much used for plastics) are carbon polymers and hydrogen resistant to biological decomposition, so that it is calculated that in 100 years it would degrade less than 0.5%. It is said that this product is not biodegradable because no living organism would be able to feed and degrade. However, it has been discovered for some time that the use of microorganisms presents itself positively as a possible tempting solution to these problems. In what way? Using as a substrate (food) the pollutant waste and generating products released at least harmful.

Today, there are dozens of microorganism species (bacteria, protozoos and fungi) capable of digesting and assimilating, so that research groups inquire how to increase the percentage of effectiveness and accelerate this ability to lead you to production in the industry. A very particular case is that of Ideonella sakaiensi, discovered in 2016 by a Japanese group led by Shosuke Yoshida. This bacteria found inside a plastic bottle recycling plant was the only strain that was present capable of degrading polyethylene terephthalate (PET) to terephthalic acid and ethylenglicol. In other words, this bacterial strain lives using as the main source of energy (food) to PET, one of the most widely used plastics such as beverage, pharmaceutical and textile packaging. This bacteria is able to degrade in just 6 weeks to temperatures between 30-40 degrees according to PET degrade or PET films. To do this, it uses two hydrolase enzymes (ISF6_4831 or PETasa and ISF6_0224 or MHETasa) in a degradation process in the presence of H2O. The first enzyme generates as a product an intermediate and the second takes as substrate to finally release the terephthalic acid and ethylenglicol which are less benign to the environment. It is worth highlighting, which is believed that Ideonella sakaiensi Just 70 years ago, probably, having evolved in parallel with the plastic industry, so it did not have as many mutations as other strains that exist much longer.

To perform this process, a PETase enzyme was patented. Ideonella sakaiensi muted in its catalytic center that optimizes the decomposition of plastic (up to 10% faster). In addition, a fusion protein was generated with both enzymes (PETa and MHETasa) forming a single supernzima which triples PET degradation. And it was found that this modification also gives it the ability to degrade pure polyethylene (PEF), a bioplastic. On the other hand, a team integrated by researchers from TBI, Université de Toulouse, CRITT Bio-Industries and Carbios, Biopôle Clermont Limagne came even further and in 2020 they took the skin enzyme of leaf and branch compost (LLC), also with the ability to degrade PET and redesigned by a 10.000 times more efficient mutant enzyme in PET degradation than natural LCC hours. In addition, it is stable at 72 °C, temperature where PET becomes malleable being easier to dissolve. Fortunately, it is already in a pilot phase at the industrial level.

Microorganisms can also contribute to the production of plastics from renewable and less harmful carbon sources. Polyhydroxyalcanates (PHA), for example, are biopolyesters synthesized intracellularly by some microorganisms such as carbon and energy reserve that, once extracted from the cell, present physical properties similar to petroleum-derived plastics such as polyethylene and polypropylene, and then can be assimilated by several microorganisms whether toxic from waste soils, mares, or toxic effects. The most studied PHA is P3HB (poli-3-hydroxybutyrate), produced by the bacteria Ralstonia eutropha From Acetil CoA (a molecule present in our organisms essential to energy formation), from 3 enzymes that perform 3 reactions and then can be easily degraded by releasing carbon dioxide or methane. Currently, one of the great advantages of this biopolymer is that they can be used in biomedicine, as they are compatible with human tissue and are re-abundred at a low speed.

Bioplastics vs petroleum-derived plastics

Although bioplastics are currently produced at a commercial level, the plastic industry is not as viable as oil derivatives as the price is higher. To mitigate this economic problem, measures are taken to make them more accessible to the population, including improvements in the fermentation and extraction process, as well as the development of more productive microbial strains that can use low-cost substrates.

As for the current world situation, although oil prices continue volatile without stabilizing and fear of a slowdown in oil demand, an increase in production and an increase in crude oil and gasoline reserves, these days have been decreasing. However, beyond the current panorama, in the long run it is estimated that it will continue to rise as the last year. In addition, it is estimated that the demand for plastic products will increase dramatically to what it will be necessary to use 50% of the available oil at this time. Such a situation would have an impact on the price of plastics, which would be expected to increase dramatically. If so, this would be positive for the bioplastics industry for production costs.

In this way, the revolution of plastics production and recycling would use elements of nature to produce them, decompose them and restart them in the environment, generating a circular economy that favors the population not only by production costs, but also by reducing harmful effects to the environment. It is a matter of continuing to act towards change.

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sahira janeir

Sahira Janeir Garazatúa

Hi, I'm Sahira, Biotechnologist Biomedical! I studied in Buenos Aires where I focused on epigenetics and reproduction, but now I find myself in Spain developing cell therapy and neuronal regeneration of the spinal cord, and combining AI for early detection of diseases. In addition, the CDTM Technology Management, Valencia-Munich study, which develops innovative digital products and solutions for companies such as Lufthansa and S2group.

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