Analysis and optimization of single and composite carbon source substrates for acclimation and screening of 1,2-Dichloropropane degrading bacteria

1,2-Dichloropropane (1,2-DCP) is a highly toxic and environmentally persistent chlorinated hydrocarbon pollutant that causes serious contamination of soil and groundwater. This study investigated 1,2-DCP contaminated soil using single and complex carbon source cultivation strategies to screen and acclimate bacterial communities. Through high-throughput sequencing, community structure and functional analysis, and pure culture isolation and identification, the study compared the effects of different carbon substrates on the succession patterns, functional characteristics, and screening advantages of degrading bacterial communities. Results showed that communities acclimated with a single carbon source were dominated by Proteobacteria and gradually diversified, while communities acclimated with complex carbon sources were dominated by Firmicutes and remained relatively stable. Functional prediction revealed that although the two acclimation strategies led to different community structures, functional stability was maintained, with major differences manifested in energy metabolism, ion transport, and DNA repair functions. Four 1,2-DCP degrading strains were isolated and identified, including Microbacterium proteolyticum , Stutzerimonas stutzeri , Klebsiella pneumoniae , and Pseudomonas aeruginosa . Genomic functional prediction suggested that their degradation mechanisms mainly involve monooxygenases, oxidoreductases, and glutathione-related enzyme systems. The study demonstrated that the single carbon source nutrition with pollution pressure has significant advantages in constructing functional bacterial communities, expressing specific functions, and screening specific strains, while complex carbon source cultivation favors the enrichment of microbial communities with broad metabolic capabilities, providing a theoretical foundation and bacterial resources for 1,2-DCP bioremediation.