Abstract:The optimal conditions of solid state fermentation of Paracoccus aminovorans HPD-2 and the remediation effect of microbial agents on PAH-contaminated soil were studied. As for the solid state fermentation, we selected three kinds of organic materials included organic manure A, organic manure B and alfalfa, and discussed the effects of the amount of solid matrix, inoculum size, moisture content, incubation time and its remediation potential in PAH-contaminated soil. The results showed the best organic material was organic manure A and the optimal conditions for the bacteria growth in the solid state fermentation included 20 g solid matrix and 5% inoculum size, and 1:1 moisture content (w/v) with 144 h of incubation period. After 28 days, bioaugmented microcosms of microbial agents showed a 22.8% decrease in total PAHs, with the concentration declined from 9.96 mg/kg to 7.64 mg/kg. The degradation percentage of 3-ring, 5-ring, 4-ring and 6-ring PAH were 35.1%, 27.0%, 20.7%, 20.4% respectively. This microbial agent had some extent remediation potential in PAH-contaminated soil.