Biomolecular Analysis of Arctic Microorganisms Capable of Psychrophilic Growth on Biodegradable and Compostable Plastic

As climate change continues to disrupt the polar regions of our planet, a comprehensive understanding of both phenotypic and genotypic characteristics of naturally occurring psychrophilic microorganisms is needed, not only from a microbial profiling and taxonomic aspect but also from an industrial potential standpoint. Knowing and understanding the organisms that have the genetic potential to break down environmental contaminants, such as microplastics, is of great interest. In this research, the primary focus was to isolate and characterize the psychrophilic microorganisms from a snow field near Ilulissat, Greenland and use a multi-omics approach to identify and characterize the biodegradation potential against certain biodegradable plastics. Bacterial stains isolated from Greenland were inoculated into small individual bioreactor tubes containing a minimal salts media combined with either polylactic acid or the proprietary Novamont material used in compostable bags. After 4 weeks of incubations at 6°C, turbidity (growth) was measured, and DNA and RNA were extracted and sequenced to identify putative plastic-degrading genes and biosynthetic gene clusters and determine if they are actively expressed in culture conditions. Cultured bacteria comprise 3 genera of bacteria: <i>Pseudomonas, Duganella,</i> and <i>Massilia.</i> Culture tubes comprised <i>Pseudomonas</i> or <i>Duganella</i> isolates alone or <i>Pseudomonas</i> in combination with either <i>Duganella</i> or <i>Massilia</i> isolates. Genomes assembled from cultures contained genes implicated in plastic degradation, and several contained the complete pathway for octane oxidation. Cultures contained active transcripts for most of the identified genes. Several biosynthetic gene clusters were also identified, which may play a role in biofilm formation or adaptation to psychrophilic growth. These data are believed to be the first laboratory culture experiments of psychrophilic microbial degradation of microplastics by organisms isolated from polar regions.