Purpose: The objective of this study is to characterize the changes of Salmonella cell outer membrane after heating, ethanol and sodium hypochlorite treatments using SERS.
Methods: In this study, Salmonella Enteritidis 710 and 1045 were cultured and inactivated by heating, ethanol and sodium hypochlorite. After inactivation, cells were washed in the saline water and then mixed with 50 nm gold nanoparticles for SERS characterization. Data were analyzed by principle component analysis.
Results: The results show the SERS spectra changed significantly after treatments and the variations in the SERS spectra between treatments demonstrated different mode of actions of these treatments. Among all these treatments, the SERS spectra after sodium hypochlorite treatment showed the largest discrimination from the control. Significant alternations of the lipid peaks were observed, demonstrating the destruction of the phospholipid and lipopolysaccharides in the outer membrane after the treatment. The heating and ethanol treatments altered the protein peaks.
Significance: These results demonstrated the capacity of SERS to characterize the outer membrane of Salmonella cells responding to different treatments, which can help us to further understand the behaviors and mechanisms of bacterial outer membrane responding to different treatments, from a biochemical perspective. The spectral discrimination can be also set as a base for prediction of the sensitivity and viability of cells responding to different treatments using SERS.