Kinetic analysis and Dual biodegradation pathway for chlorobenzenes removal by Serratia marcescens strain TF-1 and its performance in contaminated soil

Abstract

Abstract Microorganisms with specific functions have significant potential for use in the remediation of contaminated sites. In the past, this study investigated the optimal growth conditions and chlorobenzene (CB) degradation capability of the Serratia marcescens strain TF-1, a strain known for its CB degradation abilities, and its application in soil remediation projects. Under laboratory conditions, TF-1 exhibited its highest CB degradation capability and cell density at pH 7, with a 5% inoculum size, and a temperature of 30°C. The results indicated that TF-1 possessed robust pH tolerance and was suitable for use in contaminated soils with varying pH levels. Within a concentration range of 20–200 mg·L− 1, TF-1 demonstrated a CB assimilation and degradation rate ranging from 0.32 to 1.65 mg·L− 1·h− 1, which was 1–6 times higher than that of known CB-degrading bacteria. Furthermore, the study confirmed that TF-1 could co-metabolically degrade CB and 1,2-dichlorobenzene (1,2-DCB) using sodium succinate and sodium citrate as substrates, with significantly higher co-metabolic degradation rates compared to assimilative degradation rates. The addition of TF-1 and a remediation agent composed of sodium succinate to the contaminated soil enabled the removal of various chlorobenzene pollutants. Comparative diversity analysis before and after remediation demonstrated that TF-1 successfully colonized the contaminated soil and enriched the local microorganisms, such as Azoarcus, in the co-degradation of pollutants. As a novel CB-degrading bacterial strain, TF-1 had been applied for the first time in situ in the remediation of CB-contaminated soil, providing valuable theoretical guidance and practical experience for in situ CB-contaminated soil remediation techniques.