Abstract:

Influence of two kinds of petroleum sulfonate (PS) on the growth of three strains of Pseudomonas marginata and on the biodegradation of crude oil are investigated.The elementary chemical structures of the two PS are determined by

infrared spectra.The results show that,influence of the two PS on the three strain is significant,owing to the structure difference between the two types of PS.Microbial growth is completely discouraged spiked with 5mg/L of PS-B,whereas the growth is observed even spiked with 50mg/L of PS-A.As increasing of PS concentration,bacterial growth reduces more slowly in oil than in sucrose condition,for some PS in the water phase diffuses into the oil phase and so the PS concentration in the water decreases.Despite high toxicity to bacteria,the two types of PS contribute to crude oil biodegradation.In the presence of PS-A(<30mg/L for strain DY-A,20mg/L for strain H,15mg/L for strain I,respectively),biodegradation rates are gradually enhanced as increasing of PS-A concentrations from 55.4％ to 74.2％(for strain DY-A),48.3％ to 59.5％(for strain H) and 43.1％to 49.4％(for strain H) after 5 days,due to enhanced solubility of crude oil by PS.Spiked with low concentration of PS-B (<10mg/L),degradation is discovered to a certain degree,and in some cases,oil degradation rates are not

directly proportional to bacterial growth.Dehydrogenase activity is boosted by 5mg/L of PS-A.

Key words: petroleum sulfonate, crude oil, surfactant, biodegradation, dehydrogenase