Microorganisms
can eat plastic, and it could save the Earth
(or almost)
A taste of Dara Nguyen &
Paul-Henry’s review:
Each year, 250 million tons of plastic are produced but only 8% of it is
recycled. A large part of it is released in nature, mostly in soils and in the
oceans, thus highly disrupting ecosystems. In particular, the ingestion of
small plastic fragments can cause wildlife cancers, and big fragments can lead
to malformations (see picture below).
Plastics, that are polymers, are not easy to degrade because the strong
bonds linking the monomers, which gives it interesting properties, are hard to
break. Different methods exist, but it seems that there is no efficient and
eco-friendly way to take care of these wastes. A new approach is being
developed using the ability of some microorganisms to digest polymers.
What are these microorganisms?
What kind of plastics can they digest?
For this
review, we did a bibliography of articles dealing with plastic-degrading
microorganisms and tried to see the connections between them: how similar and
different the mentioned microorganisms are, according to what criteria? What
families of plastics are concerned? What can we deduce on the enzymatic
mechanism implied? As we expected, we observed a large variety of species and
polymers. We mainly focused on this diversity. Indeed, if several
microorganisms can digest several polymers, it makes it a better weapon against
the vast enemy that is plastic waste.
Our work could be summarized with the figure
below. The most common classes of plastic polymers are represented with an
example on the left. Microorganisms which can attack them are linked with a
green dash. Else if we could not find any species that can deal with this
class, it is followed by a red dash. As for the mechanism, they are not
accurately identified and they are not the same for all species, so they do not
appear on this figure. We can already see the diversity of polymer structure
with their chemical formula; as for the microorganisms, you will find more
details in the review and especially in the attached references (in brackets on
the figure).
Our main conclusions are that plastic-digesting
microorganisms can be bacteria or fungus, from any habitat, but they are all
saprophytic – which seems obvious, saprophytic meaning that they can feed on
non-living organic matter). As a consequence, they can attack several organic
polymers although not all of them, but they have some trouble dealing with
inorganic polymers. Maybe we could understand why some organisms and not
others, why some plastics and not others, by better understanding the
mechanisms. Studying and modeling this process could open the way to
technologies that function the same and that we would control better.
If you want to know more…
TED talk: “Two
young scientists break down plastics with bacteria”
[1] greenhome.com,
2016. The life of a plastic bottle [online]. Available at:
[2] Moore,
C. J., 2008. Synthetic polymer in the marine environment: A rapidly increasing,
long-term threat. Environmental Research. 108, 131-139.
[3] Pathma,
J., Sakthivel, N., 2012. Microbial diversity of vermicompost bacteria that
exhibit useful agricultural traits and waste management potential. SpringerPlus.
1:26.
[4] Stloukal,
P., Pekarova, S., Kalendova, A., Mattausch, H., Laske, S., Holzer, C., Chitu,
L., Bodner, S., Maier, G., Slouf, M., Koutny, M., 2015. Kinetics and mechanism
of the biodegradation of PLA/clay nanocomposites during thermophilic phase of
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[5] Morét-Ferguson,
S., Lavender, K., Proskurowski, G., Murphy, E. K., Peacock, E. E., Reddy, C.
M., 2010. The size, mass, and composition of plastic debris in the western
North Atlantic Ocean. Marine Pollution Bulletin. 60, 1873–1878.
[6] Nakkabi, A., Sadiki, M.,
Ittobane, N., Ibnsouda Koraichi, S., Barkai, H., El Abed, S.,2015. Biodegradation of Poly(ester urethane)s by Bacillus
subtilis. International Journal of Environmental Research. 9,
157-62.
[7] Nakkabi,
A., Sadiki, M., Koraichi Saad, I., Fahim, M., 2015. Biological degradation of
polyurethane by a newly isolated wood bacterium. International
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[8] Delafield,
F. P., Doudoroff, M., Palleroni, N. J., Lusty, C. J., Contopoulos, R., 1965.
Decomposition of poly-β-hydroxybutyrate
by Pseudomonads. Journal of Bacteriology. 90, 1455-1466.
[9] Yang, Y., Yang, J., Wu, W. M., Zhao,
J., Song, Y., Gao, L., Yang, R., Jiang, L., 2015. Biodegradation and
mineralization of polystyrene by plastic-eating mealworms: Part 2. Role of gut
microorganisms. Environmental Science and Technology. 49, 12087-93.
[10] Espinosa-Valdemar, R. M., Turpin-Marion,
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biodegradation by the fungus Pleurotus Ostreatus. Waste Management.
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[11] Shinozaki,
Y., Morita, T., Cao, X. H., Yoshida, S., Koitabashi, M., Watanabe, T., Suzuki,
K, Sameshima-Yamashita, Y., Nakajima-Kambe, T., Fujii, T., Kitamoto, H. K.,
2013. Biodegradable plastic-degrading enzyme from Pseudozyma antarctica:
cloning, sequencing, and characterization. Applied Microbiology and
Biotechnology. 97, 2951–2959.
[12] Tsujiyama,
S., Okada, A., 2013. Biodegradation of polyvinyl alcohol by a brown-rot fungus,
Fomitopsis pinicola. Biotechnology Letters. 35, 1907-11.
[13] Santo,
M., Weitsman, R., Sivan, A., 2013. The role of the copper-binding enzyme –
laccase – in the biodegradation of polyethylene by the actinomycete Rhodococcus
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204-210.
[14] Mohan,
A. J., Sekhar, V. C., Bhaskar, T., Nampoothiri, K. M., In press. Microbial
assisted High Impact Polystyrene (HIPS) degradation. Bioresource Technology.
[15] Ishigaki,
T., Sugano, W., Ike, M., Kawagoshi, Y., Fukunaga, I., Fujita, M., 2000.
Abundance of polymers degrading microorganisms in a sea-based solid waste
disposal site. Journal of Basic Microbiology. 40,
177-186.
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