Isolation and Characterisation of Polypropylene Microplastic-Utilising Bacterium from the Antarctic Soil

Abstract: Despite its remoteness from other continents, the Antarctic region cannot escape the aftermath of human activities as it is highly influenced by anthropogenic impacts that occur both in the regional and global context. Contamination by microplastics, mostly caused by the improper disposal of plastic waste, is widely recognised as a serious environmental threat due to its ubiquity. In recent years, most researchers have focused on microplastic pollution in the marine ecosystem of Antarctica, while pollution in the terrestrial environment continues to be neglected. This study was conducted to investigate the ability of Antarctic soil bacteria to use polypropylene (PP) microplastics as the sole carbon source. Bushnell Haas (BH) medium inoculated with bacteria and supplemented PP-microplastics as the sole carbon source was used in the utilisation test. In this study, the growth response of Dermacoccus sp. strain AYDL3 was assessed after exposure to PP-microplastics in a basal medium for 40 days. The weight reduction of the polymer was determined to further support the growth response. The highest and lowest weight loss percentages were observed on day 20 (23.0%) and day 10 (7.75%), respectively. Fourier transforms infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) analyses were used to confirm the utilisation of PP-microplastics by strain AYDL3. Results indicate that the soil bacteria possess a mechanism for breaking down microplastics allowing them to utilise plastics as energy sources without any pre-treatment. This emphasises the significance of these soil bacteria to adapt and subsequently manage the plastic fragments in the soil in the future.