Breaking down microplastics: insights into the role of actinomycetes in biotic degradation pathways

In today's era, plastics are widely used, and they gradually break down into tiny particles called microplastics. Microplastic (MP) pollution is a serious global issue because it penetrates deeply into soil, water and the atmosphere, which can be consumed by organisms in the food chain and humans, causing them serious health hazards. Minimising the MPs pollution is vital for conserving environment, human health and food security in this period of extreme climate change, and rapid urbanisation. Degradation of MPs in conventional methods i.e., by ozonation, is effective but simultaneously they produce several hazardous byproducts. On the contrary, biological degradation of MPs by microbes is a safer and environmentally friendly solution. Among other microorganisms, actinomycetes, a class of gram-positive filamentous bacteria have remarkable potential in degrading MPs through enzymatic processes, biofilm development, and surface colonization. Species of actinomycetes like Streptomyces, Thermobifida, and Rhodococcus are known to produce biosurfactants along with enzymes like hydrolases and PETases, which degrades complex polymeric materials into environmentally safe substances. Engineering strategies, including genetic modification, metabolic optimization, co-culture systems, and bioremediation techniques, have greatly improved the ability of actinomycetes to degrade plastics. These combined efforts enhance the viability of actinomycetes as eco-friendly biocatalysts for tackling microplastic pollution. However, challenges persist in scaling these techniques and evaluating their long-term environmental effects. This review delves into the diverse functions of actinomycetes in microplastic breakdown and emphasizes the necessity for comprehensive research strategies to optimize and implement these microbial systems effectively in environmental remediation initiatives.