Study On The Mechanism Of Silver Nanoparticles Formation Promoted By Siderophore In Fermented Supernatant Produced Of Acinetobacter Sp.11-02

The fermented supernatant produced siderophore of Acinetobacter sp.11-02 mixed with AgNO₃ solution can be used to prepare silver nanoparticles and it was found that siderophore in the fermented supernatant plays a vital role in the reaction.Firstly,the article studied the optimum conditions of preparation of silver nanoparticles,also the relationship between the content of siderophore in the fermentation supernatant and the yield of nano-silver prepared under different Fe³⁺concentration in the culture medium of Acinetobacter sp.11-02 was explored.In this paper,the single factor test and response surface analysis methods were used to optimize the content of siderophore.Two methods of extraction-TLC purification and ion exchange resin purification were used to separate and purify siderophore in the fermentation supernatant.Finally,the mechanism of siderophore promoting the formation of silver nanoparticles was studied from the influence of the light.The experiment content is as follows:Optimization of conditions for preparation of nano silver.The article studied the optimum conditions of preparation of silver nanoparticles by mixed fermentation supernatant of Acinetobacter sp.11-02 and AgNO₃ solution,when the reaction under the mixed ratio of 1:2,pH 9.0,30?for 24 h,the production is highest,the yield of silver nanoparticles was 1.927,increased by 12%.Study on the influence of siderophore on the synthesis of silver nanoparticles.The concentrations of siderophore and the yield of silver nanoparticles decreased simultaneously with the concentrations of Fe³⁺increasing in the fermentation medium,both fitting coefficient R²=0.992,it is speculated that the siderophore play an important role in process of the formation of silver nanoparticles.Optimization of siderophore production conditions.After the single factor and response surface analysis test,the optimized condition of Acinetobacter sp.11-02,K₂HPO₄ 0.65 g,MgSO₄·7H₂O 0.1 g,0.5 g and 0.4 g NaNO₃ NH₄NO₃,C₆H₅Na₃O₇·2H₂O3.5 g and 0.05 g CaCl₂,40 h of incubation time,shaker speed 180 r/min,culture temperature 25?,inoculation amount 5%and pH 7.0.The content of siderophore in the fermentation supernatant obtained 88.7?M after optimization,28.1?M before optimization and increased by 3.2 times.Two methods were used to separate and purify phenolic siderophore.The extraction-TLC purification method including initial extraction of ethyl acetate and purification of TLC plate and ion exchange resin purification method for the combination of adsorption and gradient elution to purification of siderophore.The two methods are simple operation,and can obtain relatively pure siderophore.Research on the mechanism of siderophore promoting the formation of nano silver.Light plays an vital role in the formation mechanism of nano-silver promoted by siderophore.The yield of silver nanoparticles increased with the increase of light intensity.Under the experimental condition,with the increase of light source wavelength,the yield of nano-silver presents a trend of increasing and then slowly decreasing.The production of nanometer silver is highest under the condition of blue light.It was found that only in the fermentation supernatant,silver nitrate solution and light at the same time it can be prepared nano silver.It was found that the preparation of silver nanoparticles had a red line wavelength and it was instantaneous,and the light intensity had no significant effect on the experimental results under the same wavelength of light source,speculated that the reaction process is mainly rely on the electron transfer under the photoelectric effect.