Effects of silver nanoparticles on staphylococcus aureus ATCC 25923 and escherichia coli ATCC 25922 protein profiles

AgNPs were synthesized by the reductive sodium borohydride (NaBH4) method. Three capping agents (4-styrenesulfonic acid – co – maleic acid (PSSMA), alginate, carrageenan) were used and compared with non-capping agent for characterization of particle properties and antibacterial testing. PSSMA capped AgNPs presented a better antibacterial susceptibility than AgNPs capped with others. The antibacterial activity and mechanism of PSSMA capped AgNPs on Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) were then investigated using proteomics technique. Sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used for protein pattern observation and protein identification. From the result, the action of AgNPs against S. aureus and E. coli were determined to be bactericidal. SDS-PAGE gels after staining showed different bacterial protein profiles and protein expression between bacteria exposed and unexposed to AgNPs, which was further confirmed by protein identification and gene ontology based on NCBI and UniProt databases. In addition, data analysis and bioinformatics pathways analysis (String software) concluded that the antibacterial mechanism of AgNPs were based on 6 main functions i.e., signal transduction, molecular transport, metabolic process, DNA replication, transcription, and translation.