Beyond the Plastisphere: Phylogenetic and Biogeographic Diversity of Marine Microorganisms with Putative Plastic-Degradation Potential

Abstract

Plastic pollution is widespread in marine environments, yet the diversity of microorganisms and enzymes that may contribute to plastic degradation remains poorly understood. To identify promising candidates for future experimental studies, we investigated marine microorganisms with proteins related to enzymes previously associated with plastic degradation. Using PlasticDB and the NCBI RefSeq protein database, we identified 523 distinct protein sequences from microorganisms with documented marine provenance. We then examined their evolutionary relationships, environmental origins, and geographic distributions to assess how these candidate proteins are distributed across marine microbial diversity. Only 10.3% of the curated sequence assignments originated from plastisphere or marine-biofilm records, while most were associated with other marine environments, particularly marine hosts. These findings suggest that searches focused exclusively on plastic-associated biofilms may overlook a substantial portion of the marine microbial diversity relevant to plastic transformation. The identified proteins include candidates for direct polyester hydrolysis as well as proteins that may contribute to oxidative chemistry or cellular protection during plastic-associated metabolism. Together, these phylogenetic and biogeographic analyses establish a targeted resource for the discovery and isolation of marine-derived genes with potential roles in plastic transformation, providing experimentally tractable candidates for biochemical characterization and future development of microbial and enzyme-based plastic recycling strategies.