Marine bacteria and fungi: the hidden treasure of oceans in the biodegradation of microplastics and hydrocarbons integrated with omics technologies.

Marine microorganisms play a crucial role in maintaining oceanic ecosystem stability by mediating essential biogeochemical cycles, nutrient cycling and natural attenuation of environmental pollutants through diverse metabolic processes. Owing to their remarkable metabolic diversity, marine bacteria, fungi, and archaea possess the ability to utilize complex organic compounds as carbon and energy sources enabling them to transform and degrade a wide range of contaminants in aquatic environments, making them key agents in marine bioremediation. Among these, the most persistent pollutants threatening the marine ecosystem are the Microplastics (MPs) and hydrocarbons, both of which originate largely from anthropogenic activities including plastic waste accumulation, industrial discharge, petroleum extraction and accidental spills. MPs, are plastic particles of size less than or equal to 5 mm, produced due to the fragmentation of larger plastic debris while hydrocarbons consist of complex mixtures of aliphatic and aromatic compounds including polycyclic aromatic hydrocarbons (PAHs) and BTEX compounds. In marine systems, MPs frequently act as carriers for hydrocarbons and other contaminants, facilitating the formation of specialized microbial biofilms known as the plastisphere. Microbial degradation of these pollutants involves sequential processes including surface colonization, enzymatic depolymerization, biofragmentation, assimilation and mineralization. Several studies have reported the potential of marine bacteria and fungi in the degradation of MPs and HCs through the synthesis of key enzymes such as PETase and MHETase for MPs and laccases, peroxidases for HCs. Recent advances in omics technologies including metagenomics, metabolomics, proteomics, and transcriptomics have significantly improved our understanding of microbial community dynamics, degradation pathways, and functional genes involved in pollutant degradation. Therefore, integration of recent technologies alongside conventional methods could enhance the remediation process. In this review, we have collated the collective role of marine microorganisms in the biodegradation of MPs and hydrocarbons, highlighting their key degradation mechanisms, microbial interactions and the contributions of omics based approaches in advancing marine bioremediation research.