Chen Yan-Min, Lin Tsair-Fuh, Huang Chih, Lin Jui-Che, Hsieh Feng-Ming
Department of Environmental Engineering, National Cheng Kung University, Tainan City 70101, Taiwan, ROC.
J Hazard Mater. 2007 Sep 30;148(3):660-70. doi: 10.1016/j.jhazmat.2007.03.030. Epub 2007 Mar 14.
The degradability of phenol and trichloroethene (TCE) by Pseudomonas putida BCRC 14349 in both suspended culture and immobilized culture systems are investigated. Chitosan beads at a size of about 1-2mm were employed to encapsulate the P. putida cells, becoming an immobilized culture system. The phenol concentration was controlled at 100 mg/L, and that of TCE was studied from 0.2 to 20 mg/L. The pH, between 6.7 and 10, did not affect the degradation of either phenol or TCE in the suspended culture system. However, it was found to be an important factor in the immobilized culture system in which the only significant degradation was observed at pH >8. This may be linked to the surface properties of the chitosan beads and its influence on the activity of the bacteria. The transfer yield of TCE on a phenol basis was almost the same for the suspended and immobilized cultures (0.032 mg TCE/mg phenol), except that these yields occurred at different TCE concentrations. The transfer yield at a higher TCE concentration for the immobilized system suggested that the cells immobilized in carriers can be protected from harsh environmental conditions. For kinetic rate interpretation, the Monod equation was employed to describe the degradation rates of phenol, while the Haldane's equation was used for TCE degradation. Based on the kinetic parameters obtained from the two equations, the rate for the immobilized culture systems was only about 1/6 to that of the suspended culture system for phenol degradation, and was about 1/2 for TCE degradation. The slower kinetics observed for the immobilized culture systems was probably due to the slow diffusion of substrate molecules into the beads. However, compared with the suspended cultures, the immobilized cultures may tolerate a higher TCE concentration as much less inhibition was observed and the transfer yield occurred at a higher TCE concentration.
研究了恶臭假单胞菌BCRC 14349在悬浮培养和固定化培养系统中对苯酚和三氯乙烯（TCE）的降解能力。使用尺寸约为1-2mm的壳聚糖珠来包封恶臭假单胞菌细胞，形成固定化培养系统。苯酚浓度控制在100mg/L，TCE浓度则在0.2至20mg/L范围内进行研究。在悬浮培养系统中，pH值在6.7至10之间时，不会影响苯酚或TCE的降解。然而，发现在固定化培养系统中，pH值是一个重要因素，仅在pH>8时观察到显著降解。这可能与壳聚糖珠的表面性质及其对细菌活性的影响有关。基于苯酚的TCE转移产率在悬浮培养和固定化培养中几乎相同（0.032mg TCE/mg苯酚），只是这些产率出现在不同的TCE浓度下。固定化系统在较高TCE浓度下的转移产率表明，固定在载体中的细胞可以免受恶劣环境条件的影响。为了解释动力学速率，采用莫诺德方程描述苯酚的降解速率，而用霍尔丹方程描述TCE的降解速率。根据从这两个方程获得的动力学参数，固定化培养系统中苯酚降解的速率仅为悬浮培养系统的约1/6，TCE降解的速率约为1/2。固定化培养系统中观察到的较慢动力学可能是由于底物分子向珠内的缓慢扩散。然而，与悬浮培养相比，固定化培养可能耐受更高的TCE浓度，因为观察到的抑制作用要小得多，并且转移产率出现在更高的TCE浓度下。
