The JGU report investigated whether the one-centimetre creature indeed achieved biochemical digestion and/or bacteria in the caterpillars' digestive tract or whether it, more simply, mechanically milled it; a process that wouldn’t change the state of the polymer.
The science behind the much-publicised, caterpillar-shaped answer to the millions of tonnes of difficult-to-recycle plastic waste is full of holes, according to a group of organic chemistry experts. Johannes Gutenberg University Mainz (JGU), a research-driven university that counts materials sciences among its core research areas, has called for more concrete evidence about the bold claim made by Spanish researchers that the larvae effectively recycles plastic.
As reported in Bio-Based World News in May this year, a researcher for the Spanish National Research Council and Cambridge University scientists claimed that a wax moth known as galleria mellonella could munch its way through 92 milligrams of polyethylene – the variety of polymer used extensively in packaging and bags – in 12 hours. Currently, 80 million tonnes of plastic waste are produced year on year worldwide.
Johannes Gutenberg University Mainz (JGU) hascritically examined the released data and experimental procedures by one of the Spanish National Research Council’s researchers, Federica Bertocchini, and published a counterstatement. According to JGU’s report, the proof that would go some way to providing the evidence for the bio-degradation of polyethylene is missing in the first publication put together by Bertocchini and her fellow researchers.
The plastic-eating caterpillar was discovered by researcher, and bee keeper, Bertocchini, after she put the larvae (and blight of the bee-keeping community) that damages beehives by eating the wax inside them in a plastic bag. Upon returning to the bag at a later date the caterpillars had eaten their way out, leading the Spanish researchers to patent its work for further investigation.
The JGU report investigated whether the one-centimetre creature indeed achieved biochemical digestion and/or bacteria in the caterpillars' digestive tract or whether it, more simply, mechanically milled it; a process that wouldn’t change the state of the polymer. Using an experimental technique that examined cell fragments and constituents after they have been homogenized, JGU said the results were ‘questionable’. The primary area for concern for the German research University was its doubts about the actual detection of ethylene glycol – an organic and decomposable compound that the Spanish National Research Council claimed was produced after the caterpillars digested polyethylene.
The results of the German scientists were published as an author correspondence in Current Biology, the same scientific journal, in which the first study was published. Although the biochemical decomposition has not yet been disproven, the report of plastic eating caterpillars has potentially been thrown into some doubt in light of JGU’s results.
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