Understanding the in silico aspects of bacterial catabolic cascade for styrene degradation.

Styrene is a non-polar organic compound used in very high-volume for the industrial scale production of commercially important polymers such as polystyrene (PS) resins as well as copolymers like acrylonitrile butadiene styrene (ABS), latex, and rubber. These resins are widely used in manufacturing of various products including single use plastics such as disposable cups and containers, protective packaging, heat insulation etc. The large-scale utilization leads to the over-accumulation of styrene waste in the environment causing deleterious health risks including cancer, neurological impairment, dysbiosis of central nervous system and respiratory problems. To eliminate the accumulating waste. Microbial enzymes-based system represents the most environmental friendly and sustainable approach for elimination of styrene waste. However, comprehensive understanding of the enzyme-substrate interaction and associated pathways would be crucial for developing large-scale disposal systems. The present study aims to understand the molecular interaction between the protein-ligand complexes of the styrene catabolic reactions by bacterial enzymes of sty operon. Molecular docking analysis for catalytic enzymes namely, styrene monooxygenase (SMO), styrene oxide isomerase (SOI) and phenylacetaldehyde dehydrogenase (PAD) of the bacterial sty operon was carried out with their individual substrates i.e. styrene, styrene oxide and phenylacetic acid, respectively. The binding energy, amino acids forming binding cavity and binding interactions between the protein-ligand binding sites were calculated for each case. The obtained binding energies showed a stable association of these complexes indicating the future scope of their utilization for large-scale bioremediation of styrene, and its commercially used polymers and co-polymers.