Plastics are essential in modern life, but their conventional production is problematic due to environmental pollution and waste management issues. Polylactic acid (PLA) is a widely used bioplastic that is bio-based and biodegradable, making it a key player in the bioeconomy. PLA has been proven to be degradable in various settings, including aqueous, soil, and compost environments. However, monitoring and optimizing PLA biodegradation remains challenging. This study proposes methods to improve the quantification of PLA biodegradation by Amycolatopsis spp. Ultrasound treatments (10 s) significantly improved the enumeration of viable Amycolatopsis cells by breaking the pellets into quantifiable individual cells. A separation technique combining ultrasound (120 s) and 40 μm cell strainers effectively isolated PLA particles from biomass to quantify PLA weight loss. This enabled the monitoring of PLA biofragmentation. Finally, CO2 production was measured according to ISO 14852 to quantify mineralization. Integrating these methods provides an improved quantification for PLA biodegradation along its different stages. In a case study, this led to the construction of a carbon balance where 85.1% of initial carbon content was successfully tracked. The developed techniques for monitoring of PLA biodegradation are essential to design future waste management strategies for biodegradable plastics.
Environmental pollution from packaging, has led to a need for sustainable alternatives. This study investigates the biodegradation of polylactic acid (PLA) by Amycolatopsis orientalis and Amycolatopsis thailandensis after thermal and thermal-alkaline pretreatments. The biodegradation was assessed based on weight loss, CO2 evolution, carbon balance analysis and scanning electron microscopy (SEM). The analysis showed that pretreatment at 37 °C for 8 h provided effective enhancement of the biodegradation performance. Combining thermal pretreatment with alkaline conditions led to chemical degradation of PLA, but is less suitable as a pretreatment for biodegradation. It was also demonstrated that the mineralization rate over a two-week period was higher following thermal than thermal-alkaline pretreatment. SEM confirmed improved biodegradation as illustrated by increased surface roughness. These findings suggest that thermal pretreatment at 37 °C for 8 h is the most effective strategy for enhancing PLA biodegradation by Amycolatopsis spp., promoting a sustainable approach to plastic waste management.