Surface-enhanced Raman spectroscopy monitoring the development of dual-species biofouling on membrane surfaces

Abstract

Surface-enhanced Raman spectroscopy (SERS) was used to monitor the development of a dual-species biofilm formed by two model bacteria (Brevundimonas diminuta, BD and Staphylococcus aureus, SA) on a mixed cellulose ester membrane surface. The highly distinguishable SERS features of BD and SA as well as a semi-quantitative analysis of SERS were used to characterize dynamic changes in dominant species within the biofilm with culture time. SA dominated for the first 8h but detached from the membrane after 24h and were outcompeted by BD. SA also displayed differing behaviors in single and dual cultures, with no detachment in the former case but extensive detachment in the latter after 24h. SERS results were in good agreement with that from scanning electron microscopy. Cell concentrations in solution and competition for limited nutrients accounted for changes in bacterial abundance in dual-species biofilms. Furthermore, bacterial attachment on the membrane as early as 1h was detected by SERS, demonstrating its high sensitivity and capability for early diagnosis of biofouling. The extent of membrane biofouling was also monitored by plotting SERS peak intensity against culture time. This study suggests that SERS will provide insights into interspecies interactions in biofouling development and help the development of antifouling strategies.