Construction of bioreactors for the degradation of volatile organic chlorinated solvents

四氯乙烯（或全氯乙烯，PCE）和三氯乙烯（TCE）是许多国家已知的严重的环境污染物。本研究旨在培养能够高效降解PCE和TCE的菌株，并构建生物反应器。由于PCE不能被好氧菌降解，我们尝试分离厌氧菌，并成功分离出菌株Y51，该菌株通过TCE有效地将PCE脱氯为顺式-1,2-二氯乙烯（DCE）。在添加0.2%酵母提取物、50 mM丙酮酸钠和5 mM富马酸盐的培养基中，在浓度高达100 ppm时，将PCE完全脱氯为DCE， Y51在O.D.660 nm的最小培养基中可以生长到0.4。我们还构建了甲苯双加氧酶和联苯双加氧酶的杂交双加氧酶，该酶对TCE和DCE具有很强的降解能力。我们通过将厌氧Y51和表达杂交双加氧酶的好氧假单胞菌D3结合，证明了PCE的完全降解。菌株D3在砂填充的玻璃柱中可以很好地生长到1.2*10^9/ml，并在5 h内降解TCE (10 ppm)，但菌株Y51的厌氧生物反应器仍有待构建。

Tetrachloroethylene (or perchloroethylene, PCE) and trtichloerothylene (TCE) are known to be serious environmental pollutants in many countries. The present research aimed to develop strains which are able to degrade PCE and TCE efficiently, and construct bioreactors. Since PCE is not able to be degraded by aerobic bacteria, we attempted to isolate anaerobic bacteria and succesfully isolated strain Y51 which showed efficient dechlorination from PCE to cis-1,2-dichloroetnylene (DCE) via TCE.Y51 could grow up to 0.4 at O.D.660 nm in a minimum medium supplemented with 0,2% yeast extract, 50 mM sodium pyruvate and 5 mM fumarate, and dechlorinated PCE completely to DCE at a concentration of as high as 100 ppm. We have also constructed a hybrid dioxygenase from toluene dioxygenase and biphenyl dioxygenase, which showed tremendous degradation capability for TCE and DCE.We demonstrated total degradation of PCE by combining anaerobic Y51 and aerobic Pseudomonas strain D3 expressing the hybrid dioxygenase. The strain D3 could grow well to 1.2*10^9/ml in a glass colmn packed with sand, and degraded TCE (10 ppm) in 5 h. Anaerobic bioreactor using strain Y51, however, remained to be constructed.