Study On Microbial Green Synthesis And Antibacterial Activity Of Silver Nanoparticles

As a kind of special nanomaterials,silver nanoparticles have become a research hotspot for researchers due to their unique properties of heat,light,electromagnetism,catalysis and sensitivity.In practice,silver nanoparticles have applications in cancer treatment,antimicrobial,biosensors,magnetic resonance imaging and medical imaging.As an antibacterial material,it has antibacterial and bactericidal effects,stable chemical properties,light resistance and heat resistance,and has been applied in food,textiles and medicine.Silver nanoparticles on food can be added into packaging materials to ensure the freshness of fruit and vegetable food and make it widely used in food packaging.Silver nanoparticles can be embedded in textiles to prevent bacterial infections and effectively heal wounds.In medicine,silver nanoparticles have also been studied in various types of cancer cells,such as hepatocellular carcinoma,lung cancer,breast cancer and cervical cancer.Many preparation methods of silver nanoparticles,the more uses a chemical reduction method,the method was simple,the operation while but need to add the reducing agent and stabilizer in the process of preparation,easy to damage to the environment,potential harm to human body,and increased the cost of production,thus use green,environmental protection method of synthesis of silver nanoparticles has become a new trend in the field of research,compared to traditional physical and chemical synthesis method,using microbial green synthesis of silver nanoparticles has become a green safe alternatives.In recent years,the use of various organisms instead of toxic chemicals to reduce and stabilize silver nanoparticles has attracted wide attention.At present,it has been proved that silver nanoparticles can be synthesized simply and effectively by fungi,however,there are few reports on the preparation of silver nanoparticles from red yeast fermentation broth.Rhodotorula belongs to the fungus world,and it exists widely in nature,and its metabolites are rich..Its distinctive feature is the ability to biosynthesis of natural red or yellow pigments.Due to its own properties and biochemical characteristics,it is easy to grow and can be grown in a mild environment with suitable carbon and nitrogen sources.Because of its high yield of carotenoids and oils,it has been used in medicine,food,chemical industry and agriculture.In this study,silver nanoparticles were successfully synthesized by reaction of red yeast with silver nitrate solution,and the synthesis process was optimized by changing reaction conditions.The antibacterial activities of staphylococcus aureus and escherichia coli were studied with the silver nanoparticles.Staphylococcus aureus and escherichia coli are pathogenic bacteria,is common in our life environment,and when invades the body,can cause some inflammation,such as vomiting,diarrhea,serious can be deadly,the use of silver nanoparticles on staphylococcus aureus and escherichia coli antibacterial activities of research,have very important sense to explore good antibacterial,biosynthesis of silver nanoparticles for red yeast provide theoretical basis for further research.The main results are as follows:?1?Silver nanoparticles with good stability and dispersion were successfully synthesized by biosynthesis with ferment broth of red yeast as reducing agent and protective agent and AgNO₃ solution as precursor,with the size of 17.23±4.99 nm.In the research process,the effects of AgNO₃ solution and age of red yeast on the synthesis of silver nanoparticles were discussed,and the optimal reaction conditions were selected.The results showed that more silver nanoparticles could be produced by adding 1.5 mM final concentration of silver nitrate into the fermentation broth obtained by cultivating red yeast for 48h.?2?Studied using the biosynthesis of silver nanoparticles on staphylococcus aureus,escherichia coli antibacterial activities of research,the quantitative determination of silver nanoparticles on staphylococcus aureus,escherichia coli,the minimum bacteriostasis concentration?MBC?and minimum bactericidal concentration?MIC?,it is concluded that the staphylococcus aureus,the minimum inhibition concentration?MIC?of 1.375?g/mL,minimum bactericidal concentration?MBC?of5.5?g/mL,for e.coli,the minimum inhibition concentration?MIC?of 0.6875?g/mL,minimum bactericidal concentration?MBC?is 1.375?g/mL,It is proved that silver nanoparticles have good antibacterial effect and can be used as antibacterial agent.In summary,this study found that red yeast has the ability to synthesize silver nanoparticles,and optimized a reaction condition suitable for the biosynthesis of silver nanoparticles by red yeast through experiments,and found that the synthesized silver nanoparticles have certain antibacterial and bactericidal activities.New biological functions and functions of red yeast were found in this study,which also accumulated more basis for the study of biosynthesis of silver nanoparticles.