Screening Of Rhodopseudomonas Palustris Gh32 And Removal Of Cu²⁺

Rhodopseudomonas palustris belongs to purple non-sulfur bacteria of photosynthetic bacteria.The bacterium has many kinds of nutrition type,strong adaptability to the environment,tolerance to wastewater with high concentration and strong ability to remove heavy metals.Rhodopseudomonas palustris had been applied in wastewater treatment,biological hydrogen production,and extraction of biological pigments.Heavy metal pollution has now become a very serious problem.Most heavy metals are discharged into the environment through industrial activities,causing environmental pollution and endangering human health.Heavy metal copper pollution is relatively common.The heavy metal copper is often treated by ion exchange methods,electrochemical treatment methods,etc.However,these treatment methods are often subject to economic and technical limitations.The biological method has the advantages of low processing cost,obvious effect,and less pollution,etc.,and it would be preferentially selected to removeheavy metal copper.Therefore,it is of great significance to screen the strains that can efficiently remove heavy metal copper.In this study,a Rhodopseudomonas palustris strain that can efficiently remove heavy metal copper was screened out from muddy water samples.The growth characteristics of the bacteria and the removal of heavy metal copper were studied,which provided a new strain and theoretical basis for the treatment of heavy metal copper.The main research results are as follows:(1)Screening and identification of strainThe enrichment medium of purple non-sulfur bacteria was used for enrichment,and the mineral salt-sodium succinate separation medium was used for separation and purification.A total of 8 red pigment-producing strains were isolated from the muddy water samples.A strain gh32 with strong red pigment and good growth was selected for follow-up research.The strain gh32 was identified as Rhodopseudomonas palustris through the method of classical morphology and molecular biology.The strain gh32 was a Gram-negative bacterium,which is rod-shaped and has a size of(0.52-0.87)?m ×(1.83-3.43)?m.The strain gh32 could utilize hydrogen sulfide and monosaccharides such as fructose,glucose and mannose,which was a new characteristic of this strain.(2)Growth characteristics of strain gh32The optimal growth temperature of strain gh32 was 30?.The strain grew well in the range of pH 5.0-9.0,indicating that the strain could grow in a wide pH range and has strong ability to adapt to the environment.The strain gh32 grew well in 1%-6%NaCl,indicating that the strain was more resistant to NaCl.The strain gh32 could grow normally in 0-3 mmol/L CuSO4,indicating that the strain was highly resistant to CuSO4.(3)Removal of Cu2+by strain gh32 The optimum temperature range for removing Cu2+by strain gh32 was 20?-40?.The optimum treatment time was 24 h and the optimum pH was 0.When the pH was higher than 3.0,the treatment capacity was reduced,which indicated that the strain was suitable for removing copper under acidic conditions.When the strain gh32 was treated with 400-600 mg Cu2+,the removal rate was more than 99%.The removal rate reached a maximum of 99.46%when 600 mg Cu2+ was treated.The treatment capacity was 1 331 g/g dry bacteria weight or 167.6 g/g wet bacteria weight.It showed that strain gh32 has a better removal capacity of Cu2+,and it is a potential strain for treating Cu2+-containing wastewater.