Online characterization of bacteria culture using Raman and SERS

Hygiene is becoming a key issue in a world with an increasing global population and an increasing number of antibioticresistant bacteria. In the next few years, a crucial challenge will be finding better methods for disinfection. Currently, these methods are studied with traditional microbiology techniques, where bacteria are grown, exposed to a treatment and further growth is followed for several days. However, this paradigm is slow and does not offer chemical insights in the mechanism of action of disinfecting agents. Without new analytical tools, we risk slowing down the critical research into new disinfecting agents. There is a large body of literature reporting bacterial inhibition mechanisms are diverse and include cell membrane disruption, DNA/RNA damage, ribosome degradation, protein denaturation, etc. Also, it is widely known that bacteria inactivation mechanisms are complex and multiple mechanisms can be involved in a synergetic manner. Current knowledge regarding the mechanism of action for bacteria inhibition is largely based on results from analytical tools that include mass spectrometry, nuclear magnetic resonance spectroscopy and fluorescence spectroscopy in combination with a suite of biochemical assays. All these methods require significant effort and sample preparation/treatment to obtain results. In addition, chemical insights obtained from biochemical assays rely tightly to the initial hypotheses. Herein, we propose to use Raman and surface-enhanced Raman scattering (SERS) to study the mechanism of action for bacteria inhibition. Vibrational spectroscopies have numerous advantages over the current paradigm for this analysis, including low sample preparation requirements and spectra rich in chemical information. These advantages permit to monitor bacteria cultures easily and quickly, while also obtaining chemical insights regarding mechanism of action for bacteria inhibition. In this work, we will show the monitoring of treated bacteria via Raman spectroscopy and how we can use SERS to further streamline this process.