Preparation Of Nanosilver By Fermentation Supernatant Of Pseudomonas Aeruginosa L3 And Preparation Of Antibacterial Bacterial Cellulose

Nano silver material is a kind of precious metal nano material,which is widely used.Due to its special physical and chemical properties,silver nanoparticles play an important role in chemistry,biology,optics,electronics and other fields.Because of its strong bactericidal effect and good stability,silver nanoparticles are often used as bactericides,such as in antibacterial dressings and antibacterial fibers.At present,the synthesis of silver nanoparticles by biological method,as a new field of combining nanotechnology and biotechnology,has become a shining point in the interdisciplinary,and has received more and more attention.The preparation of nano silver by microorganism is fast,simple and easy to operate.In our laboratory,a strain of bacteria with strong ability to promote the formation of nano silver was isolated from rare earth samples,which was identified as Pseudomonas aeruginosa by molecular biology assay.It was found that there was a strong correlation between the concentration of pyocyanin and the production of nano silver.The results of single factor and response surface analysis showed that the optimal nutrient composition of the fermentation broth was（g/L）:Na NO₃0.5,Na₃C₆H₅O₇·2H₂O₆,NH₄NO₃0.1,Mg SO₄·7H₂O 0.25,Ca Cl₂0.2,K₂HPO₄0.5,the optimal culture time and culture temperature after optimization were 24 h and 30℃respectively.With a speed of120 rpm and an inoculation volume of 5%,the optimized concentration of pyocyanin has been greatly improved.The concentration of pyocyanin before optimization was 5.14μg/m L,and the concentration of pyocyanin after optimization was 21.57μg/m L,the optimized pyocyanin concentration increased by 4.19 times,and the optimization effect was significant.By optimizing the reaction conditions such as the ratio of fermentation supernatant mixed with Ag NO₃solution,reaction time,light intensity,etc.,the highest yield of nano silver was successfully prepared.When the ratio was 1:2,the reaction was 3 hours,the p H reaction was 7.0,and the temperature was controlled at 35 degrees Celsius,the yield of nano-silver was the highest.At this time,the OD_450nmwas 2.817,which was a 73.8%increase in yield compared to before optimization.In the preparation process,the necessary condition was sufficient light.The light intensity was directly proportional to the output of nano silver.The stronger the light,the higher the output of nano silver,and the wavelength was inversely proportional to the output of nano silver.The longer the wavelength,the higher the output of nano silver.In this paper,by exploring the reaction conditions and necessary conditions,it can provide high-yield guarantee for the subsequent preparation of nano-silver.Antibacterial bacterial cellulose loaded with silver nanoparticles was prepared.Bacterial cellulose was an excellent medical nano material.In this paper,nano silver was loaded on the purified bacterial cellulose to make antibacterial nano bacterial cellulose material.Three different loading methods were used to prepare antibacterial bacterial cellulose,and different air drying methods were used for post-treatment.The results showed that the bacterial cellulose membrane was soaked in Ag NO₃solution for a certain time,then transferred to the microbial fermentation broth for reaction,and the antibacterial effect was the best under the condition of natural air drying.In conclusion,a strain of P.aeruginosa L3 was isolateded,which can be used to prepare sodium silver efficiently.It was found that the main factor promoting the formation of nano silver was the P.aeruginosa L3 in the fermentation liquid.The yield of pyogenic acid was improved by optimizing the conditions.It was found that illumination was the most important condition for the preparation of silver nanoparticles,which directly affected the formation of nano silver.In this paper,antibacterial bacterial cellulose materials loaded with silver nanoparticles were prepared,which laided a foundation for the microbial production of silver nanoparticles.However,the mechanism of the promotion of P.aeruginosa L3on the formation of silver nanoparticles was unclear,and further research was needed.