Abstract: Seven PAH-degrading strains were isolated from PAHs-contaminated soil around an iron and steel company in Benxi using the enrichment procedure and tablet sublimation method. Their degradation ability of PAHs was studied in flasks with pyrene or benzo\[a\]pyrene as the single carbon source. The results showed that G1, G2 and G3 strains had stronger degradation ability for heavy PAHs. Further studies on the degradation ability of G1, G2, G3 and their mixture in PAHscontaminated soil indicated that at 80 days, the total PAH-degradation rates in the four treatments were in order of the mixture > G2 > G1 > G3. Compared to the treatments that inoculated with G1, G2 and G3 alone, the degradation rate in the treatment inoculated with the mixture was enhanced by 9.17%, 11.49%, and 16.11%, respectively. Compared with the control treatment, the degradation rates of 4-6-ring PAHs increased in the four treatments and the times of their increase were enhanced with the number of rings. Meanwhile, there was a positive correlation between the dehydrogenase activity and PAHs degradation. The degradation rates of 4-, 5-, and 6-ring PAHs were enhanced by 12.13%, 13.35%, and 14.52% in BioEK experiment than in the Bio experiment, which indicated that G1, G2 and G3 have good ability of adapting to electric field. G1, G2 and G3 strains were identified as Sphingomonas sp., Ochrobactrum sp. and Achromobacter sp. respectively based on their physiological characteristics and the sequence analysis of 16S rRNA.

Key words: peanut, calcium fertilizer, drought stress, physiological characteristics, yield and quality.