Screening Of Adsorption Dominant Bacteria For Copper And Research On Its Features

With the rapid development of industrialization and speeding up process of urban modernization,the problem of heavy metal pollution in our country is getting more serious.At present,more than 92%of the water bodies in China are polluted by heavy metals.The phenomenon of excessive heavy metals is becoming worse with each passing day.In this paper,4 bacterial strains,Citrobacter.Comamonas.Bacillus and Aeromonas were selected from sludge and drilling wastewater in natural gas drilling well.Every single or two types combined complex flora were used to treat heavy metal copper simulated wastewater.The concentration of Cu²⁺ before and after treatment was determined by atomic absorption spectrophotometry.It was found that the predominant strains of copper adsorption were Aeromonas.The tolerance of Aeromonas was determined by spectrophotometry through selecting Aeromonas cells in logarithmic phase and put them into Cu²⁺ medium containing different Cu²⁺ concentrations.The value of OD600 was measured every 3 hours.The results showed that tolerance threshold of Aeromonas to Cu²⁺ was 200mg/L.Using single factor analysis method to study the adsorption behavior of Aeromonas absorbing heavy metal copper,it was found that the best adsorption conditions under experimental condition were:30℃ of temperature,initial pH value 4,biomass dosage 20g/L,initial concentration of Cu²⁺ 100mg/L and adsorption time 90 mins,The adsorption rate reached 86.25%..In the experiment of Cu²⁺ stress,the content of malondialdehyde（MDA）in aeromonas aeruginosa increased rapidly under Cu²⁺ stress,and it caused obvious oxidative damage to Aeromonas.At the same time,the level of late MDA tended to be stable.The reason for this phenomenon is that the enzyme that exists in the cell membrane can effectively clean up excess free radicals in the cell defense system and reduce the damage to cells after the growth and metabolism of bacteria have stabilized.The extracellular complexation of heavy metals can not only improve the adsorption efficiency of Cu²⁺,but also change the biological activity of heavy metals,and alleviate the toxicity of heavy metals to their cell bodies,On the one hand,it is also an important mechanism of heavy metal tolerance.In this study,we screened the dominant strains of Cu²⁺ and studied its adsorption characteristics,which can provide a theoretical basis for the biological treatment of heavy metal wastewater.