【摘要】 为获得高效降解2-氯苯酚的菌株,以红假单胞菌1D为出发菌株进行紫外诱变处理,确定了紫外诱变时间,考察了诱变前后菌株对2-氯苯酚的耐受性与降解能力的变化。紫外诱变时间与致死率效应试验确定该菌株的最佳诱变时间为50 s。不同质量浓度2-氯苯酚对出发菌株和诱变菌株脱氢酶活性的影响试验结果表明,出发菌株与诱变菌株脱氢酶活性随2-氯苯酚浓度增加都逐渐降低,而诱变菌株脱氢酶活性下降程度明显小于出发菌株。在此基础上运用化学品对水生生物急性毒性试验的标准方法研究了2-氯苯酚对出发菌株和诱变菌株生长的安全质量浓度、半致死质量浓度(IC₅₀)。结果表明,2-氯苯酚对诱变菌株的安全质量浓度和半致死质量浓度较出发菌株分别提高700%和60.4%。此外,经紫外诱变后菌株对2-氯苯酚的降解率可达到67.1%,较诱变前提高了98%。因此,经过紫外诱变处理后的菌株对2-氯苯酚的耐受性及降解能力均得到明显改善。更多还原

【Abstract】 This paper is to present the findings of our research on the isolation and screening of a strain of Rhodopseudomonas sp. named 1D with the degradation of o-chlorophenol from the downstream sediments of the insecticide factory discharge outlets. The strain 1D has been mutated by using ultraviolet during the optimal mutation time limit. In so doing, careful comparison has been done in hoping to obtain highly efficient o-chlorophenol degrading mutant, with the ochlorophenol tolerance and refractory organic substance removal ability of the strain before and after the mutation was done. As a result, 50 seconds has been found to be the optimal length of ultraviolet mutation time and the best lethality effect curve. In addition, we have also studied the effects of different concentrations of o-chlorophenol on the dehydrogenase activity of the original strain and mutant strain respectively. The results of our study show that the dehydrogenase activity of the original strain tends to drop significantly with the increase of o-chlorophenol concentration in culture medium for the same mutant strain. But the decreasing rate of dehydrogenase activity tends to be smaller than that of the original strain. Our experiments prove that, when the o-chlorophenol concentration was 570 mg/L, the declining rate of the activity of the original strain turned to reach 100%. In contrast, the dehydrogenase activity of mutant strain would remain at a certain value, with the exhibiting decrease of 83.8 %. The results gained by using a standard method of aquatic bioassay for evaluating the toxicity of chemicals in our experiments also show that the safe concentration of 2-CP in culture medium to the original strain growth and mutant strain growth were 9.375 mg/L and 75 mg/L, respectively. The safe concentration of 2-CP can also be raised by 700% after the mutation. Furthermore, the half-inhibitory concentration (IC₅₀ of o-chlorophenol on the inhibition of the mutant strain growth proves to be 426.6 mg/L, much higher than the original strain—265.9 mg/L while the degeneration rate of the mutant strain turns to be still higher, that is, by 67 %, which means 33 % higher than that of the original strain. The results demonstrate that the stain 1D after ultraviolet mutation keeps higher tolerance to o-chlorophenol and turns to be more suitable for degradation of o-chlorophenol.更多还原