Department of Chemical Engineering, Yonsei University, 134 Shinchon-Dong, Seodaemoon-Gu, Seoul 120-749, South Korea.
J Hazard Mater. 2009 Dec 15;172(1):491-3. doi: 10.1016/j.jhazmat.2009.07.009. Epub 2009 Jul 9.
In an earlier study, Pseudomonas putida NCIB 9816-4, which was one of the most studied naphthalene-degrading bacteria, showed the preferred adhesion to the naphthalene-contaminated soil when it was in the exponential growth phase. The adhesion was found to take place through a hydrophobic interaction. We postulated that the surface hydrophobicity of P. putida NCIB 9816-4 in the exponential growth phase might be increased during the uptake of naphthalene, which caused the preferred adhesion to the naphthalene-contaminated soil. To verify this postulate, a plasmid-cured strain of P. putida NCIB 9816-4 was obtained in this study and compared with the wild-type for adhesion to the naphthalene-contaminated soil. Only the wild-type in the exponential growth phase showed increased adhesion to naphthalene-contaminated soil. The water contact angles of the two strains were measured in the presence and in the absence of naphthalene as indices of surface hydrophobicity. The water contact angle of the wild-type increased in the presence of naphthalene, whereas that of the cured strain did not change. We conclude that the uptake of naphthalene during naphthalene biodegradation in the exponential growth phase of P. putida NCIB 9816-4 made the cell surface more hydrophobic, resulting in increased adhesion to naphthalene-contaminated soil.
在早期的研究中，假单胞菌 NCIB 9816-4 是研究最多的萘降解细菌之一，当处于指数生长阶段时，它对萘污染土壤表现出优先的附着。这种附着被发现是通过疏水相互作用发生的。我们假设，在吸收萘的过程中，假单胞菌 NCIB 9816-4 的指数生长阶段的表面疏水性可能会增加，这导致了对萘污染土壤的优先附着。为了验证这一假设，本研究获得了假单胞菌 NCIB 9816-4 的质粒缺失菌株，并与野生型菌株进行了萘污染土壤附着的比较。只有野生型在指数生长阶段表现出对萘污染土壤的附着增加。在存在和不存在萘的情况下测量了两株菌的水接触角作为表面疏水性的指标。野生型的水接触角在存在萘的情况下增加，而缺失菌株的水接触角没有变化。我们得出结论，在假单胞菌 NCIB 9816-4 的指数生长阶段进行萘生物降解的过程中吸收萘使细胞表面更加疏水，导致对萘污染土壤的附着增加。
