萘降解性质粒的筛选及其在炼油污水处理场中的转移

从炼油污水处理场活性污泥中分离到一株能以萘为唯一碳源的假单胞杆菌(Pseudomonas sp.)S13。通过质粒接合转移、质粒消除以及分子杂交,证明假单胞杆菌S13降解萘的功能是由质粒编码的。应用膜扩散器在炼油污水处理场进行的现场试验证明,假单胞杆菌S13的萘降解性质粒,可在污水处理场里通过接合转移传递到另一个从同一环境分离的假单胞杆菌T9中去,并使后者获得利用萘的能力。这一结果表明,当条件合适时,降解性质粒可在自然环境里的细菌群体中扩散。

ISOLATION OF A NAPHTHALENE-DEGRADING PLASMID AND ITS TRANSFER IN WASTEWATER TREATMENT SYSTEM

A pseudomonas strain S₁₃, capable of utilizing naphthalene as its sole carbon source, was isolated from the activated sludge of a wastewater treatment plant of Wuhan Oil Refinery. Plasmid detection, curing, transfer by conjugation and DNA-DNA molecular hybridization experiments demonstrated that the naphthalene-degrading ability of the pseudomonas strain S₁₃ was plasmid borne. In situ Nah+ plasmid (pWE2) transfer by conjugation was conducted in modified membrane diffusion chambers in the aeration basin at the wastewater treatment plant and the results indicated that the pseudomonas strain S₁₃ could transfer its naphthalene-degrading piasmid(pWE2) to another pseudomonas strain T9, isolated from the same source as the S₁₃ was. The transfer frequency was 8.7×10^-8 in the wastewater treatment system, compared with 1.6×10^-7 observed in the laboratory. Pseudomonas strain T9 could grow on naphthalene after obtaining the plasmid(pWE2), suggesting the possibility of degra-dative plasmid transfer in natural environment.