Flying toward a plastic-free world: Can Drosophila serve as a model organism to develop new strategies of plastic waste management?

Drosophila melanogaster as a tractable eco-environmental model to unravel the toxicity of micro- and nanoplastics

Micro- and nanoplastics have emerged as pervasive environmental pollutants with potential ecotoxicological impacts on various organisms, including the model organismDrosophila melanogaster. Here we comprehensively synthesize current research on the adverse effects of micro- and nanoplastics onDrosophila, highlighting key findings and identifying gaps in the literature. Micro- and nanoplastics can lead to physical damage, oxidative stress, inflammation, genotoxicity, epigenetic changes, apoptosis, and necrosis inDrosophila. Exposure to plastic debris affects nutrient absorption, energy metabolism, and reproductive health, often in a sex-specific manner. For instance, male flies are generally more susceptible to the toxic effects of polystyrene microplastics than female flies, showing greater mortality and metabolic disruptions. Furthermore, the combined exposure of plastics with heavy metals can exacerbate toxic effects, leading to enhanced oxidative stress, genotoxicity, and gut damage. While antagonistic effects have been identified particularly with silver compounds, where polystyrene microplastics reduce the bioavailability and toxicity of silver. The adverse effects of plastic particles onDrosophiladepend on size, with smaller particles penetrating deeper into tissues and eliciting stronger toxic responses. The chemical composition of the plastics and the presence of additives also play crucial roles in determining toxicity levels. Chronic exposure to low levels can be as harmful as acute high-dose exposure, highlighting the need for comprehensive, long-term studies to fully understand the ecological and biological impacts of plastic pollution.

Consumption and Digestion of Plastics by Greater Hive Moth Larvae

The accumulation and unsustainable management of plastic waste generate environmental pollution that affects ecosystems, wildlife, and human health. We studied the possibility of using the consumption and digestion of oxo-biodegradable, compostable plastics and polypropylene from face masks by the fifth-instar larvae of G. mellonella as a strategy for the sustainable management of plastic waste. We used Fourier transform infrared spectrophotometry (FTIR) to determine the percentage of consumption and presence of microplastics in the digestive tract and excreta for 10 treatments evaluated for 135 h. The effects of plastics on the continuity of the life cycle of the greater hive moth were also determined. We established that the larvae fragmented and consumed 35.2 ± 23% of the plastics evaluated, with significant differences between treatments. Larvae were able to consume more of the intermediate layers of masks (86.31%) than the other plastics. However, none of the plastics were digested. Instead, microplastics accumulated in the excreta, resulting in nutritional deficits that affected the continuity of the life cycle, including the induction of the early formation of pupae after 24 h and a reduction in the number of eggs laid by the females.

Diverting organic waste from landfills via insect biomanufacturing using engineered black soldier flies (Hermetia illucens)

A major roadblock towards the realisation of a circular economy are the lack of high-value products that can be generated from waste. Black soldier flies (BSF; Hermetia illucens) are gaining traction for their ability to rapidly consume large quantities of organic wastes. However, these are primarily used to produce a small variety of products, such as animal feed ingredients and fertiliser. Using synthetic biology, BSF could be developed into a novel sustainable biomanufacturing platform to valorise a broader variety of organic waste feedstocks into enhanced animal feeds, a large variety of high-value biomolecules including industrial enzymes and lipids, and improved fertiliser.

Biodegradation of polystyrene (PS) and polypropylene (PP) by deep-sea psychrophilic bacteria of Pseudoalteromonas in accompany with simultaneous release of microplastics and nanoplastics

Plastics dumped in the environment are fragmented into microplastics by various factors (UV, weathering, mechanical abrasion, animal chewing, etc.). However, little is known about plastic fragmentation and degradation mediated by deep-sea microflora. To obtain deep-sea bacteria that can degrade plastics, we enriched in situ for 1 year in the Western Pacific using PS as a carbon source. Subsequently, two deep-sea prevalent bacteria of the genus Pseudoalteromonas (Pseudoalteromonas lipolytica and Pseudoalteromonas tetraodonis) were isolated after 6 months enrichment in the laboratory under low temperature (15 °C). Both showed the ability to degrade polystyrene (PS) and polypropylene (PP), and biodegradation accelerated the generation of micro- and nanoplastics. Plastic biodegradation was evidenced by the formation of carboxyl and carboxylic acid groups, heat resistance decrease and plastic weight loss. After 80 days incubation at 15 °C, the microplastic concentration of PS and PP could be up to 1.94 × 107/L and 5.83 × 107/L, respectively, and the proportion of nanoplastics (< 1 μm) could be up to 65.8 % and 73.6 %. The film weight loss were 5.4 % and 4.5 % of the PS films, and 2.3 % and 1.8 % of the PP films by P. lipolytica and P. tetraodonis, respectively; thus after discounting the weight loss of microplastics, the only 3.9 % and 2.8 % of the PS films, and 1.3 % and 0.7 % of the PP films, respectively, were truly degraded by the two bacteria respectively after 80 days of incubation. This study highlights the role of Pseudoalteromonas in fragmentation and degradation of plastics in cold dark pelagic deep sea.

Progress in polystyrene biodegradation by insect gut microbiota

Polystyrene (PS) is frequently used in the plastics industry. However, its structural stability and difficulty to break down lead to an abundance of plastic waste in the environment, resulting in micro-nano plastics (MNPs). As MNPs are severe hazards to both human and environmental health, it is crucial to develop innovative treatment technologies to degrade plastic waste. The biodegradation of plastics by insect gut microorganisms has gained attention as it is environmentally friendly, efficient, and safe. However, our knowledge of the biodegradation of PS is still limited. This review summarizes recent research advances on PS biodegradation by gut microorganisms/enzymes from insect larvae of different species, and schematic pathways of the degradation process are discussed in depth. Additionally, the prospect of using modern biotechnology, such as genetic engineering and systems biology, to identify novel PS-degrading microbes/functional genes/enzymes and to realize new strategies for PS biodegradation is highlighted. Challenges and limitations faced by the application of genetically engineered microorganisms (GEMs) and multiomics technologies in the field of plastic pollution bioremediation are also discussed. This review encourages the further exploration of the biodegradation of PS by insect gut microbes/enzymes, offering a cutting-edge perspective to identify PS biodegradation pathways and create effective biodegradation strategies.