Abstract:Organochlorine pesticides (OCPs) contaminated sites threaten human health and ecosystem safety seriously, therein high activity of degradation microorganisms is necessary to promote degradation efficiency of OCPs in soil. In this study, high-throughput sequencing and real-time quantitative PCR (qPCR) technologies were combined to explore the degradation kinetics of 1,4-dichlorobenzene, the variations of microbial composition and degradation potentials with exogenous addition of degradation genes (e.g., xylH, dmpB or catE expressed by plasmid pUC19, 102-103 copies/μl) and flora (e.g., xylH, dmpB or catE expressed by E.coli DH5α, 105-106 CFU/μl). Results show that the degradation rates of 1,4-Dichlorobenzene reach to 38.43% (genes) and 44.74% (flora), respectively, which are promoted by 1.74-2.41 times compared to the control treatments. Meanwhile, the proportions of relative abundance of dominant phyla and keystone taxa are facilitated significantly with degradation genes and flora addition exogenously (P<0.05). Furthermore, qPCR analysis illustrates that the increasing slopes of degradation genes are better significantly in flora than genes addition, yielding growth rates of 1.24 to 2.89 times (P<0.05). This research is conductive to verifying microbial response of indigenous flora, especially the response mechanisms of keystone taxa to OCPs with exogenous addition of degradation genes and flora, which may provide support for regulating and optimizing microbial ecological outcomes of their remediation process in OCP-contaminated sites.