Alternative approach for polystyrene biodegradation by selected bacteria

Abstract

Plastics pose a growing concern towards the environment. Mitigating actions are required as most of them do not report significant biodegradation. Biodegradable plastics are proposed as alternatives. Unfortunately, it remains difficult to compete with traditional petroleum-based polymers. Besides technical and economic obstacles, intrinsic biodegradability also shows some negative effects. For applications like food packages, biodegradable polymers are single-use items. Recycling of Biodegradable polymers is difficult and it contaminates current recycling stream. Reuse and recycling of plastics saves a lot of resources and associated greenhouse gas (GHG) emissions. These savings will be reduced by increased use of biodegradable plastics. It seems a catch 22: traditional petroleum-based plastics are not biodegradable and accumulate in nature, but their biodegradable alternatives exhibit other adverse effects on the environment by increased use of resources and GHG emissions. An alternative approach could be to search for specific microorganisms capable of degrading current petroleum-based plastics. While a practical method to apply them is not available yet, a first requirement is to search for useful microorganisms. This knowledge can contribute to the development of alternative biotechnological solutions for the environmental threats posed by plastics. In this study the extraction and enrichment of polystyrene (PS) consuming bacteria is reported. After 2 enrichment cycles, five bacteria were identified using PS as their sole carbon source. In a subsequent mass loss experiment over 5 months period on PS film material, a small loss (0.5 wt.%) was detected. These results confirm bacterial degradation of PS. As biodegradation rates are relatively small, more research is required to make it applicable for plastic waste remediation.