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Plastic biodegradation: Do Galleria mellonella Larvae Bioassimilate Polyethylene? A Spectral Histology Approach Using Isotopic Labeling and Infrared Microspectroscopy
journal contribution
posted on 2021-12-21, 19:38 authored by Agnès Réjasse, Jehan Waeytens, Ariane Deniset-Besseau, Nicolas Crapart, Christina Nielsen-Leroux, Christophe SandtEnvironmental pollution by the nearly
nonbiodegradable polyethylene
(PE) plastics is of major concern; thus, organisms capable of biodegrading
PE are required. The larvae of the Greater Wax Moth, Galleria
mellonella (Gm), were identified as a potential candidate
to digest PE. In this study, we tested whether PE was metabolized
by Gm larvae and could be found in their tissues. We examined the
implication of the larval gut microbiota by using conventional and
axenic reared insects. First, our study showed that neither beeswax
nor LDPE alone favor the growth of young larvae. We then used Fourier
transform infrared microspectroscopy (μFTIR) to detect deuterium
in larvae fed with isotopically labeled food. Deuterated molecules
were found in tissues of larvae fed with deuterium labeled oil for
24 and 72 h, proving that μFTIR can detect metabolization of
1 to 2 mg of deuterated food. Then, Gm larvae were fed with deuterated
PE (821 kDa). No bioassimilation was detected in the tissues of larvae
that had ingested 1 to 5 mg of deuterated PE in 72 h or in 19 days,
but micrometer sized PE particles were found in the larval digestive
tract cavities. We evidenced weak biodegradation of 641 kDa PE films
in contact for 24 h with the dissected gut of conventional larvae
and in the PED4 particles from excreted larval frass. Our study confirms
that Gm larvae can biodegrade HDPE but cannot necessarily metabolize
it.
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nearly nonbiodegradable polyethyleneldpe alone favorgreater wax mothgalleria mellonella excreted larval frasscannot necessarily metabolizeaxenic reared insects821 kda ).larval gut microbiotaisotopically labeled foodevidenced weak biodegradationdeuterium labeled oiltested whether pelarvae bioassimilate polyethyleneplastic biodegradationdissected gutdeuterated fooddetect deuteriumyoung larvaeusing conventionalpotential candidateped4 particlesorganisms capableneither beeswaxmajor concerngm larvaegm ),digest pedeuterated pedeuterated moleculesdetect metabolizationconventional larvaebiodegrading pebiodegrade hdpe72 h5 mg2 mg19 days