Microbial degradation of short-chain chlorinated paraffins in marine environment: bacterial community responses, functional genes, transformation products, and metabolic mechanisms.

Short-chain chlorinated paraffins (SCCPs) are persistent organic pollutants that pose ecological risks to marine ecosystems. Their impacts on bacterial communities and environmental fate remain poorly understood. In this study, SCCP exposure significantly altered sediment bacterial diversity and composition, enriching key genera such as Halomonas, Pseudomonas, and Marinobacter. Six SCCP-degrading strains from these genera were isolated. Whole-genome and transcriptomic analyses identified key functional genes involved in 1,2,5,6,9,10-hexachlorodecane degradation, including oxidative stress response genes (katG, katE, superoxide dismutases, mmcO), the alkene reductase gene nemA, alkyl hydroperoxide reductase genes (aphC, aphF), and multiple alcohol dehydrogenase genes. Nine transformation products were identified using UPLCOrbitrap-HRMS, including chlorinated intermediates, hydroxylated derivatives, and unsaturated compounds. This study revealed microbial mechanisms underlying SCCP transformation in marine sediments and provides a basis for developing bioremediation strategies.