Study on Construction and Application of High-Efficiency Degrading Microbial Communities for Petroleum Hydrocarbon-Contaminated Soil

The leakage of petroleum hydrocarbons easily causes severe hazards such as soil functional degradation and groundwater pollution. The natural degradation cycle is long, and the governance is difficult. Physical and chemical remediation technologies have limitations such as high energy consumption and the potential for secondary pollution. Microbial remediation has become a research hotspot due to its environmental friendliness. However, the strains traditionally selected have low degradation rates and long remediation cycles. There is an urgent need to develop efficient and stable remediation microbial agents by means of strain improvement and microbial community construction technologies to solve practical governance challenges. This study systematically carried out research on the screening, improvement, construction, and application verification of high-efficiency degrading strains, using petroleum hydrocarbon-contaminated soil samples from the Baoding area and the Baiyangdian Basin as the research objects. Through enrichment culture, physiological and biochemical identification, and 16S rDNA sequencing, 6 dominant degrading strains (such as Klebsiella pneumoniae AY12, Enterobacter cloacae BY4, etc.) were screened from 34 isolated strains. After ARTP-ultraviolet composite mutagenesis, the degradation rate of the strains was increased by up to 37.67% compared with the original strain (Klebsiella oxytoca BY6). Moreover, the degradation rate fluctuation was ≤3% after 10 consecutive subcultures, indicating good genetic stability. By constructing 57 different combinations of composite microbial communities, efficient degrading microbial communities Y23, Y26, and Y4 targeting diesel, kerosene, and gasoline were screened out, with degradation rates of 70.94%, 82.66%, and 76.04%, respectively. After optimizing key parameters such as inoculation amount, temperature, pH value, and salt concentration through orthogonal experiments, the highest kerosene degradation rate reached 83.13%. In the indoor remediation experiment, the multiple inoculation strategy of the microbial agent was adopted. Within 30 days, the degradation rates of gasoline-contaminated soil with an initial concentration of 493 mg/kg and diesel-contaminated soil with an initial concentration of 817 mg/kg reached 90.23% and 81.43%, respectively. The high-efficiency degrading microbial community constructed and the optimized application technical scheme developed in this study provide high-quality microbial resources and technical support for the efficient remediation of petroleum hydrocarbon-contaminated soil.