Biodegradation and Mineralization of Polystyrene by Plastic-Eating Mealworms: Part 1. Chemical and Physical Characterization and Isotopic Tests

Abstract

Polystyrene (PS) is generally considered to be durable and resistant to biodegradation. Mealworms (the larvae of Tenebrio molitor Linnaeus) from different sources chew and eat Styrofoam, a common PS product. The Styrofoam was efficiently degraded in the larval gut within a retention time of less than 24 h. Fed with Styrofoam as the sole diet, the larvae lived as well as those fed with a normal diet (bran) over a period of 1 month. The analysis of fecula egested from Styrofoam-feeding larvae, using gel permeation chromatography (GPC), solid-state (13)C cross-polarization/magic angle spinning nuclear magnetic resonance (CP/MAS NMR) spectroscopy, and thermogravimetric Fourier transform infrared (TG-FTIR) spectroscopy, substantiated that cleavage/depolymerization of long-chain PS molecules and the formation of depolymerized metabolites occurred in the larval gut. Within a 16 day test period, 47.7% of the ingested Styrofoam carbon was converted into CO2 and the residue (ca. 49.2%) was egested as fecula with a limited fraction incorporated into biomass (ca. 0.5%). Tests with α (13)C- or β (13)C-labeled PS confirmed that the (13)C-labeled PS was mineralized to (13)CO2 and incorporated into lipids. The discovery of the rapid biodegradation of PS in the larval gut reveals a new fate for plastic waste in the environment.

Method for Zero-Waste Circular Economy using worms for plastic agriculture: Augmenting polystyrene consumption and plant growth

“…Given that both mealworms and superworms have also been evaluated to be nutritious as fish feed 20 and poultry 11 , the mealworm and superworm are valuable plastic degraders that can also be used to provide cost-effective feed in food production in urban farming. While further research is required to ensure that plasticizers or other plastic degradation products do not bioaccumulate and get introduced into the food chain to humans (see review on plasticizer accumulation in the food chain 21,22 ), the ability of our frass analysis shows promise for reasonably safe degradation of PS, a finding in agreement with many other reports 8,9,16,17,23 .…”

“…Worms such as superworms (Zophobas morio) and mealworms (Tenebro molitor) belongs to the darkling beetle (Tenebrionidae) family and are naturally voracious pests in agriculture, consuming dry grain stock even though they are food sources themselves in many societies 7 . Mealworms have been recently shown to be able to consume and metabolize plastics 8 safely, a capability attributed to commensal gut bacteria in these worms confirmed with 13 Ccarbon isotope tracing experiments 9 . At the worm stage, they can be kept at high density, and excrete nitrogen-rich waste in the form of frass 10 that can be potential fertilizers for plant crops.…”

Bio-upcycling of polyethylene terephthalate

“…Similarly, in 2015, Exiguobacterium was identified as a polystyrene degrading organism 13 from polystyrene-eating mealworms 14 . In 2016 the bacterium Ideonella sakaiensis was reported to degrade amorphous PET when cultured in the presence of yeast extract as an additional carbon source 15 .…”

Utilizing Waste Thermocol Sheets and Rusted Iron Wires to Fabricate Carbon–Fe3O4 Nanocomposite‐Based Supercapacitors: Turning Wastes into Value‐Added Materials

“…For example, a2 015 study showedt hat mealworms could be used to digest polystyrene to enable the composting of EPS. [27] The solubility of polystyrene can also be exploited:i fs olubilized in limonene and precipitated into supercritical CO 2 ,i ti sc onvertedi nto pure microcellular foams with a desirable pore size (8-200 mm) and distribution (3-20 mm). [28] Still, findingt he best alternative for recycling/reusing thermocol waste is one of the challenging tasks for the scientific community.H erein, we report an alternative way for value-added reuse of thermocolw aste by turning it into valuable high-surface-areaA Ca se lectrode materials for SC applications.…”