Tenebrio molitor in the circular economy: a novel approach for plastic valorisation and PHA biological recovery

Abstract

The increase in the world population leads to rising demand and consumption of plastic raw materials; only a small percentage of plastics is recovered and recycled, increasing the quantity of waste released into the environment and losing its economic value. The plastics represent a great opportunity in the circular perspective of their reuse and recycling. Research is moving, on the one hand, to implement sustainable systems for plastic waste management and on the other to find new non-fossil-based plastics such as polyhydroxyalkanoates (PHAs). In this review, we focus our attention on Tenebrio molitor (TM) as a valuable solution for plastic biodegradation and biological recovery of new biopolymers (e.g. PHA) from plastic-producing microorganisms, exploiting its highly diversified gut microbiota. TM’s use for plastic pollution management is controversial. However, TM microbiota is recognised as a source of plastic-degrading microorganisms. TM-based plastic degradation is improved by co-feeding with food loss and waste as a dietary energy source, thus valorising these low-value substrates in a circular economy perspective. TM as a bioreactor is a valid alternative to traditional PHA recovery systems with the advantage of obtaining, in addition to highly pure PHA, protein biomass and rearing waste from which to produce fertilisers, chitin/chitosan, biochar and biodiesel. Finally, we describe the critical aspects of these TM-based approaches, mainly related to TM mass production, eventual food safety problems, possible release of microplastics and lack of dedicated legislation.

Effects of Agro-Industrial Byproduct-Based Diets on the Growth Performance, Digestibility, Nutritional and Microbiota Composition of Mealworm (Tenebrio molitor L.)

“…Several microbiota studies have been carried out on TM and products derived from them, focusing on the search for pathogenic microorganisms and aimed at providing the food safety necessary for their adequate consumption [42][43][44][45]. However, articles in which the gut microbiota are sequenced are scarcer and focus on the capacity to degrade certain kinds of plastic [9,27,[46][47][48].…”

Advancements in the Bio-degradation of Plastic Waste into Value-added Chemicals: A Recent Perspective

“…Electrocatalytic treatments involve chemical reactions that facilitate electron transfer through the electrode/electrolyte interface driven by electrical energy [166]. Tenebrio molitor's abundant gut microbiota makes it a promising solution for plastic degradation and the biological retrieval of PHA [167].…”

Blatticomposting of Food Waste, Production Estimates, Chemical Composition and CO2 Emissions Savings: A Case Study

“…Traditionally, this species has been fed a diet based primarily on cereal flours, mainly wheat, oats and barley with vegetable supplements for hydration of the larvae. However, some studies show that the species can degrade wastes as diverse as plastics [17], leachates and solids derived from the olive industry [18], organic garbage [19], coffee grounds [20], etc. An undoubted advantage of mealworm is that the EEC has recently approved its use in human food, which undoubtedly means an upturn for the increase of its industrial exploitation [21].…”