Screening Of Copper Resistant Bacteria And Analysis Of Its Cu²⁺ Biosorption

With the exploit and utilization of metal, a large number of toxic heavy metals wasdischarged into the environment, our living environment was polluted seriously. Thetraditional physical and chemical methods are used in the metal pollution, but these methodsresult in secondary pollution and are costly. Biological methods is promising because ofits high efficiency, low energy consumption, environmental protection.Six strains resisted to high concentration of Cu2+were screened from electroplatingfactory wastewater, sewage treatment plant effluent, the Pearl river water and the Pearl rivermud. According to the classic gram staining, colonial morphology and16S rDNA analysis, itwas showed that six strains were primarily identified as Acinetobacter baumannii A,Pseudomonas sp. B, Serratia sp.C, Citrobacter sp.D and Citrobacter sp.E, Comamonas sp.Frespectively.Six strains bacteria in the logarithmic phase were used as adsorbent to screening onestrain which has best adsorption for Cu2+in the same condition, their adsorption for Cu2+were4.57、3.35、4.34、5.45、5.78、4.32mg/g respectively, and Citrobacter sp.E is the best one.The Cu2+resistance test of Citrobacter sp.E showed that Citrobacter sp.strain E has highresistance ability of Cu2+, the minimum inhibition concentration (MIC) reached400mg/mL.The experiment of Cu2+adsorption of Citrobacter sp.E showed that the adsorptioncapacity and adsorption rate of Citrobacter sp.E increased along with the increasing pH,when pH value was1.0, adsorption capacity and adsorption rate is0.05mg/g,0.47%,but twoindex rose to6.83mg/g,65.08%respectively when pH was4.5. Controlling the temperaturebetween10℃and50℃，the adsorption capacity and adsorption rate raised at first and thendecreased, we get the best adsorption capacity of6.66mg/g and maximum adsorption rate of66%. Along with the increasing bacteria concentration, adsorption capacity increased to7.33mg/g when the concentration reached to10g/L, and decreased subsequently; andadsorption rate increased at first from28.6%and then tend to stable value of82%-84%. If theinitial concentration of Cu2+increased, the maximum adsorption capacity increased and itsadsorption rate decreased. The Cu2+adsorption of Citrobacter sp.E is fast and negative,88% of balance adsorption capacity could be completed in15-30minutes, and the adsorptionbalanced completely after90minutes.Medium components significantly affect the absorption ability of Cu2+. At0.5g/L-2.5g/L range, adsorption quantity raised with the increase of glucose levels, and elevated glucoselevels by2.5g/L to5g/L, the corresponding adsorption capacity decreased from3.85mg/g to1.33mg/g. At0.5g/L-2.0g/L, the adsorption capacity increased with increasing content ofNH4Cl, while more than2.0g/L, the adsorption capacity descended by4.66mg/g to3.91mg/g.Therefore, glucose and NH4Cl can improve the adsorption performance of this strain,but negative effect will be caused by the overusing of these nutrients.