The use of insects, some land and marine invertebrates, in the biodegradation of plastic

Nowadays, environmental pollution caused by plastics, microplastics, and nanoplastics is an indisputable fact. The vast scale of plastic production, combined with the long period of spontaneous degradation (up to 1000 years) and the lack of effective methods of segregation, recycling, utilization, and degradation of waste, has led to continual growth in environmental pollution. This has been ongoing since the 1950s, when production on a global scale began. In addition to the visual aspect, microplastics have been shown to enter and accumulate within the food chain. The presence of microplastics in living organisms is not without consequence. The harmful effects of microplastics on numerous species of plants and animals, including humans, have been described. The detrimental impact has been demonstrated at the population and individual levels, i.e. at the level of behaviour, functioning, systems, organs, physiology, cell structure and function, and multiple aspects at the DNA level. Therefore, scientists are seeking alternative degradation methods, which include biodegradation. In this process, bacteria decompose the plastic and use it as an energy source for their metabolic processes. Unfortunately, these degradation processes are restricted to a narrow range of parameter values, and even then, their efficiency remains insufficient. Therefore, attention has been drawn to invertebrates that can also biodegrade plastics thanks to the appropriate microflora in their intestines. In biodegradation processes, the animal ingests plastic, breaks it down into microplastic, and then the plastic fragments are covered with biofilm. The actual biodegradation process involves the depolymerization of plastics by enzymes produced by bacteria. Due to the fact that most studies on plastic biodegradation have been published on insects, this review focuses only on selected insect species belonging to different taxa, but also presents other examples of land and marine invertebrates participating in this process. These animals biodegrade different types of plastics with different efficiency. However, due to the great potential of animals in this aspect, it is worth considering using them in the biodegradation of plastics globally, although this issue requires further research.