Biodegradation of PCL, PBS, and PBAT at low temperatures by Aeromicrobium sp. JJY06: A newly isolated strain for cold-environment plastic cleanup.

The widespread use of plastics has created a significant environmental challenge due to the accumulation of plastic waste. In this study, we isolated a bacterial strain, named JJY06, from rice field soil in the Republic of Korea. Based on 16S rRNA gene sequencing, the strain was identified as an Aeromicrobium species, showing 99.93 % similarity to Aeromicrobium tamlense SSW1-57. JJY06 demonstrated the ability to degrade several commercial bio-plastics, including poly(ε-caprolactone) (PCL), polybutylene succinate (PBS), and poly(butylene adipate-co-terephthalate) (PBAT), even at low temperatures (10 °C). After 25 days, JJY06 achieved 100 % degradation of PCL, while after 40 days, it degraded 38.6 % of PBS and 33.5 % of PBAT. When tested at 25 °C, the degradation rates increased significantly, with complete degradation of PCL occurring within 8 days, and degradation of PBS and PBAT reaching 55.6 %, respectively, within 21 days. Interestingly, the strain formed clear zones on agar plates emulsified with PCL, PBS, and PBAT at 4 °C after one month of incubation. The degradation was confirmed by SEM and GPC analyses. Genome sequencing revealed that JJY06 has genome size of 4.52 Mb, containing 4076 protein-coding genes. Cold-shock proteins and plastic-degradation-related gene clusters suggests their adaptation to low temperatures and biodegradation potential. RAST annotation also identified genes associated with antibiotic and heavy metal resistance, suggesting adaptive mechanisms for survival in harsh environments. This study highlights Aeromicrobium sp. JJY06 as a promising candidate for degrading bio-plastics in cold environments.