References
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September 21). Biodegradation and Mineralization
of Polystyrene by Plastic-Eating Mealworms: Part
1. Chemical and Physical Characterization and
Isotopic Tests. Environmental Science&Technology,
49(20), 12080-12086. doi:https://doi.org/10.1021/
acs.est.5b02661
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molitor.jpg
Burak ALANYALIOĞLU
10 - C
THE CLAPPER 2018 - 2019
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crater-like shapes on the Styrofoam blocks by eating. The
investigation was repeated more than three times under
the same conditions. In all the trials, it is figured out that
the mass of Styrofoam blocks decreased. For instance,
in figure 1b, 500 mealworms that were obtained from
Beijing ate and caused a total mass loss of 31.0 ± 1.7%
in a Styrofoam block, that initially weighed 5.6 grams,
in 30 days. In the same investigation, it is obvious in
figure 1b that the survival rate of the Styrofoam-feeding
mealworms had no significant difference from bran-
feeding mealworms which proves that the Styrofoam
diet does not decrease the survival rate of Tenebrio
molitor more than the mealworms that were fed by
bran. (Yang Y., et al., 2015, p. 12082)
12-24 hours after the ingestion of Styrofoam blocks,
the mealworms started to egest fecula. The fresh fecula
was collected from the experimental system to test
and observe the chemical changes in the structure of
Styrofoam after passing through the alimentary canal of
mealworms. The figure presents how the Styrofoam is
depolymerized in the gut of mealworms. The chewing
activity of the larvae reduces the size of Styrofoam pieces
and increases the contact surface area of the polystyrene
molecules with the microbes and enzymes in the gut. As
the ingested pieces are mixed with the microbes in the
gut (stage 2 and 3), enzymes are secreted to increase
the rate of depolymerization of the polystyrene particles
into smaller molecule forms. The majority of those small
molecules are biodegraded and mineralized into carbon
dioxide (stage 5). Furthermore, a minority of those
carbon products are converted into biomass (stage
6). Some of the gut microbes and residual Styrofoam
particles are egested from the mealworm body as fecula
in stage 7. Beyond this stage, further degradation may
continue. (Yang Y., et al., 2015, p. 12085)
To conclude, the gut system of Tenebrio molitor
biodegraded a noticeable percentage of the Styrofoam
blocks in 30 days without having a significant decrement
in population compared to the mealworms that
experienced a regular diet. By this investigation,
the researchers concluded that this discovery will
enable further studies about biodegradation and
depolymerization to reach their targets successfully since
they will be able to modify the mealworm gut system
furthermore by using the results in this experiment. The
researchers also have an aspiration of depolymerizing
other petroleum-based plastics by improving their
methods. (Yang Y., et al., 2015, p. 12086)