Screening Of Arsenic-tolerant Strains And Their Absorption,Adsorption And Occurrence Characteristics Of As(?)

In recent years,with the rapid development of industry and mining,a large amount of arsenic(As)pollutants have entered the environment,causing the As pollution of water to intensify,seriously threatening human health and ecological safety,and the treatment of As pollution in water bodies has received much attention.Among the numerous water pollution treatment methods,microbial remediation has proved to be a green and efficient treatment method,which has been continuously applied and popularized,but it lacks functional strains with high tolerance and systematic and in-depth studies on adsorption and absorption characteristics.In order to provide ideal materials and necessary theoretical basis for microbial bioremediation of arsenic-contaminated soil,two high arsenic-resistant strain was screened and isolated from a mining area in hunan province,and their characteristics of adsorption,absorption and occurrence of As were systematically studied.The main findings are as follows:(1)Two high-resistance strains A4 and G1 were screened and isolated by As-stress culture,and identified as Microbacterium and Bacillus by 16S r RNA sequence analysis.The tolerance threshold for As was 53 mmol./L and 40 mmol/L,respectively.(2)The optimal adsorption conditions for As(?)by strain A4(bacteria powder)were 0.02 g/L,adsorption time 2 h,pH 8.0 and temperature 20?;the optimal adsorption conditions of strain G1(bacteria powder)for As(III)The dosage of the powder was 0.05 g/L,the adsorption time was 2 h,the pH was 7.0,and the temperature was 40?.The Langmuir equation and the quasi-first-order kinetic equation can be well used to describe the isothermal adsorption characteristics and kinetic characteristics of A4 and G1 bacterial powder on As(?),with a fitting degree of 0.98.According to the first-order kinetic equation,the maximum adsorption capacity of strain A4 and G1 on As(?)was 132.5mg/g and 139.3mg/g,respectively.(3)The best time of resistant strains A4 and G1 to remove As(?)is 36 h,the best solution pH is 6,the best solution temperature at 30?,optimum amount of bacteria was 1.5 mL(OD600=0.8),compared with high concentration of As(?)high arsenic resistant strains A4 and G1 to low concentration of As(?)removal effect is better.The highest removal rate of strain A4 was 47.3%,and that of strain G1 was 69.3%.(4)When the culture time was 24 h,high arsenic resistant strains A4 and G1 in various subcellular components of As(?)occurrence followed:soluble fraction>cell wall>cell organelle,while the culture time was 72 h,strain G1 various subcellular components of As(?)occurrence for:soluble fraction>cell wall>cell organelle,strain A4 various subcellular components of As(?)occurrence for:cell wall>cell organelle>soluble fraction.As the concentration of As(?)increases,intracellular absorption also increases,and as time increases,intracellular absorption decreases.