Isolation And Identification Of A Peg Hydrolytic Bacterium And Its Application

A PEG-hydrolyzing bacterium, strain PG-3, was isolated from PEG-polluted soil but was not able to utilize PEG for growth. Based on the analysis of its16S rRNA gene sequence and its morphological, physiological and biochemical properties, strain PG-3was identified as Achromobacter sp.Stain PG-3could use glucose and glyoxylate better as carbon source, and ammonium chloride and yeast extract as nitrogen; The optimum growth temperature was35℃, the strain could still grow at low temperature, and high temperature slowly; The strain could grow at pH4.0～9.0, the best pH was8.0; Ventilation had little effect on the growth of the strain; The strain grew best at the concentration of NaCl0-5g/L, while had little growth when the concentration was over20g/L; Strain PG-3was resistant to tetracycline and chloramphenicol.Study shows PEG hydrolase (PEG-HD) was produced by strain PG-3was induced by PEGs, with PEG1000inducing to the greatest degree. By determining the mol hydroxyl content of PEGs, the characteristics of the PEG hydrolytic enzyme (PEG-HD) were analyzed. Further characterization revealed that the optimum temperature for PEG-HD was40℃C and that the optimum pH was8.0; Cu2+and Zn2+inhibited enzyme activity. The michaelis constant (Km) of PEG-HD was3.97mM, with a maximum enzymatic reaction rate (Vmax) of68.03μmol ml-1min-1. Moreover, PEG-HD produced by strain PG-3has function on PEG400-1500, while PEG800was best. Strain PG-3, with the inoculation0.04%into activated sludge which can degrading PEGs, can effectively improve the system processing efficiency its hybrid colonies best of nitrogen and phosphorus dosing ratio of COD:N:P=800:5:1.When inoculated strain PG-3of0.4g/L, and activated sludge of5g/L and the influent COD concentration of5000mg/L,we got different effluent COD concentration after various HRT. When the HRT=8d, the effluent COD concentration was stability after6days and was about450mg/L, which can reach the sewage discharged into the city under water quality standards (CJ3082-1999) emission requirements; When the HRT=15d, the effluent COD concentration was stability after7days and was about90mg/L, which can reach primary standard of Integrated Wastewater Discharge Standard (GB8978-2002); When the HRT=25d, the effluent COD concentration was stability after7days and was less than60mg/L, which can reach primary B standard of Discharge standard of pollutants for municipal wastewater (GB18918-2002). Take HRT=8d for example, the effluent COD concentration can be stabilized at around350mg/L in continuous operation35days after optimizing the operating parameters.