Effects of EDTA and Tween60 on biodegradation of n-hexadecane with two strains of Pseudomonas aeruginosa

Two Pseudomonas aeruginosa strains with different hydrocarbon uptake modes were observed in the previous research. One strain produces biosurfactant during the process of hydrocarbon uptake, and was named as P. aeruginosa S. The other one utilizes hydrocarbon directly and was named as P. aeruginosa Y. For comparison of the characteristics of the two strains, the effects of EDTA and Tween60 on alkane biodegradation and cell surface characteristics were investigated in this paper. The results showed that the bacteria with different hydrocarbon uptake mode also have different response to the addition of EDTA and Tween60. As a result, in the case of P. aeruginosa S, the addition of EDTA inhibited the cell growth and hexadecane biodegradation, but enhanced the lipopolysaccharide (LPS) release and increased the cell surface potential, while the influence of the addition of Tween60 was smaller than that of EDTA. On the other hand, in the case of P. aeruginosa Y, the addition of EDTA or Tween60 not only inhibited the cell growth and hexadecane biodegradation, but also decreased the cell surface hydrophobicity (CSH) dramatically.