摘要：lastic contamination of aquatic environments from waste discharges, industrial raw materials, manufactured pellets or fragments of fishing nets, is becoming a future research priority, since it has been recognized to be an emerging global threat for its multiple (social and environmental) implications. Each year, approximately 140 million tonnes of synthetic polymers are estimated to be produced and several studies aim at investigating their global impact and interactions with organisms at several trophic levels [1-5]. Additional sources of plastic pollution in the ocean are given by secondary microplastics originating from the breakdown of larger plastic items. In fact, although plastics are extremely persistent in the marine environment, exposure to physical, chemical and biological processes results in their fragmentation down into smaller pieces. Plastics present in surface waters are more prone to degradation compared to those on the seafloor, for which decomposition is made longer because of the cold water temperature and reduced sunlight (UV) penetration [5]. The products of this fragmentation process are microplastics, i.e. plastic particles having a size lower than 5 mm in diameter, which are a global concern since these small particles can be ingested by many organisms including zooplankton, mussels, fish, seabirds and cetaceans. To solve this important environmental problem, many operational clean-up programs have started; for example, UNEP has engaged more than 40 million people from 120 Countries, setting educational measures to promote reduction of plastic use, waste recycling or disposal facilities. In November 2014, the European Union agreed binding targets for Member States to reduce the use of thin plastic bags by 2019, but other kind of plastic products may continue to be a threat for the sea. So, which actions could be performed? Apart from innovations in solid waste management and sewage treatment to trap smaller particles before discharging of effluents into the sea, an interesting approach could be provided by the use of microbes able to degrade plastics. Biodegradation is the capacity of one or more strains of microorganisms to utilize a synthetic polymer as the sole source of carbon and energy; some types of plastics such as polyhydroxyalkanoates (polyhydroxybutyrate PHB), and polylactic acid (PLA) are highly biodegradable, while synthetic polymers such as polyethylene (PE) polycaprolactone (PCL) and polystyrene (PS) have low biodegradability [6]. The degree of polymer biodegradation in natural ecosystems is affected by several factors, such as the nature of the substrate to be degraded and by environmental and microbiological factors [7].
