Development of an innovative protocol to detect the plastic degradation process: biodegradation of 13C labeled HDPE by Rhodococcus ruber

Plastic is nowadays one of the most concerning pollution materials. Traditional and new biodegradable and bio-based plastics are continuously object of biodegradation assays and experiments using different plastic degrading organisms. The traditional approaches to verify the positive outcome of the biodegradation tests are generally the measurement of CO2 production or the reduction of plastic mass. We propose an innovative method to verify and to follow the biodegradation process by means of spectroscopic techniques using 13C labeled HDPE. The bioassimilation test is performed using the bacterial strain Rhodococcus ruber (ATCC 29672), well known to be able to degrade plastic material from the literature. CO2 produced during bio assimilation was trapped in the flask and measured by titration. A significantly higher production of CO2 within 45 days compared with blank and control conditions was an indication of the positive trend of bioassimilation test, which was then confirmed by NMR experiments. The bioassimilation test, the innovative technique to measure CO2 and the timing of the process are positive features for the development of a new standard legislation to measure and follow the biodegration of plastic materials or even only to follow plastic materials in the environment. The source and fate of plastic materials in the environment is one of the pivotal issues for plastic pollution, so a secure detection with carbon might be very helpful in decision making for the restoration from plastic pollution. The method would be applicable to all the plastic materials to test in order to verify the real biodegradable feature, or to follow in the environmental compartments the path of a plastic material.