Research On The Isolation,Identification And Immobilization Of The Phenoldegrading Bacteria

Two strains having better ability to degrade phenol are isolated from the samples by enriching, isolating, purifying, which is from a paper mill in Wudang District, Guiyang city. After domestication, the two strains can grow in the synthetic waster water with a initial concentration of phenol at 1.0g/L, and remove it completely. The mixture of the two strains can degrade concentration of phenol up to 1.3g/L. According to the morphological, physiological and biochemical characteristics, the two strains are identified as Acetobacter sp. and Pseudomonas sp.. The influence of temperature, concentration of phenol, carbon source, nitrogen source, concentration of NaCl and heavy metal ions on phenol decomposition are studyed in the experiment. The results show that the two strains can grow between 20℃and 50℃, however the optimum temperature for degrading phenol is 30℃; While raising the pH of synthetic waster water, the efficiency of phenol decomposition of the strains increases gradually. However, the sedimentation of the medium will aggravate, that is, the nutrient components lose seriously. Therefore, pH7.0 will be best choice for the strains to degrade phenol. NaCl is also considered to evaluate the efficiency of phenol removal, and the result shows the efficiency of phenol decompositiom of the strain descends gradually with the increase of NaCl concentration in synthetic waster water. The best nitrogen source for phenol decomposition is NH4NO3 in experiment. Putting glucose into the medium will not increase the decomposition of phenol. Cu²⁺ and Co²⁺ can decelerate the velocity of phenol decomposition; Zn²⁺ and Mn²⁺ have no obvious influence on the velocity of phenol decomposition. Finally, the immobilization of 5^# strain is performed. By orthogonal design, the best combination of the parameters influencing the effect of immobilized cell is determined. Namely, concentration of crosslinking agent is 2%, the ratio of embedding medium and suspending liquid of strain is 20:1, and the time of crosslinking is 24h. Results show that immobilized cells have some advantages over free cells by studying the effect of the factors mentioned above on phenol removal. Immobilized cell can degrade the phenol in synthetic waster water at 1.0g/L inintial concentration of phenol; the ability to remove phenol is enhanced in the synthetic waster water containing 2% and 3% NaCl; except for NH₄NO₃, NH₄Cl and (NH₄)₂SO₄ can be served as better nitrogen sources in the process of degradation of immobilized cell; Additionally, immobilized cells display resistancy to Cu²⁺ and Co²⁺.Yet for all that the results of the experiment can provide theoretic basis and technical directions for practice.