Non-destructive Monitoring of Staphylococcus aureus Biofilm by Surface-Enhanced Raman Scattering Spectroscopy

Biofilms are organized bacterial communities embedded in extracellular polymeric matrices attached to living or abiotic surfaces. Eradicating biofilms completely is challenging and leads to repeated pollution. Thus, development of on-site and rapid biofilm detection methods is necessary. Various approaches for measuring biofilm formation have been implemented over the last decade. These include the crystal violet (CV) assay and confocal laser scanning microscopy (CLSM). However, the existing approaches are associated with issues, such as complexity and length of analysis. Consequently, in this work, a novel and rapid detection technique, specifically surface-enhanced Raman scattering (SERS), was investigated for the measurement of the Staphylococcus aureus biofilm formation. After 5, 7, 9, 11, and 13 days of culture in simulated pipes, the biofilm growth was analyzed by SERS, CV assay, and CLSM. The study revealed that the SERS approach gave optimal results following linear fitting at the relative peak intensities of I1172 cm–1/I722 cm–1 and I1384 cm–1/I722 cm–1, with the R2 values of 0.9576 and 0.9640. It was established that the two characteristic Raman peaks reflected the change of biofilm more adequately. The SERS method was compared with the CV assay and CLSM by Pearson correlation analysis. In addition to a good correlation between SERS and CV assay (P < 0.05), a significant correlation between SERS and CLSM (P < 0.01) was determined. Moreover, the novel SERS method considerably shortened the detection time, eliminating the necessity for an elution step. Overall, the described technique is a reliable on-site and non-destructive biofilm formation detection method.