Surface enhanced Raman spectroscopy‐based evaluation of the membrane protein composition of the organohalide‐respiring Sulfurospirillum multivorans

Abstract

Bacteria often employ different respiratory chains that comprise membrane proteins equipped with various cofactors. Monitoring the protein inventory that is present in the cells under a given cultivation condition is often difficult and time‐consuming. One example of a metabolically versatile bacterium is the microaerophilic organohalide‐respiring Sulfurospirillum multivorans. Here, we used surface enhanced Raman spectroscopy (SERS) to quickly identify the cofactors involved in the respiration of S. multivorans. We cultured the organism with either tetrachloroethene (perchloroethylene, PCE), fumarate, nitrate, or oxygen as electron acceptors. Because the corresponding terminal reductases of the four different respiratory chains harbor different cofactors, specific fingerprint signals in SERS were expected. Silver nanostructures fabricated by means of electron beam lithography were coated with the membrane fractions extracted from the four S. multivorans cultivations, and SERS spectra were recorded. In the case of S. multivorans cultivated with PCE, the recorded SERS spectra were dominated by Raman peaks specific for Vitamin B12. This is attributed to the high abundance of the PCE reductive dehalogenase (PceA), the key enzyme in PCE respiration. After cultivation with oxygen, fumarate, or nitrate, no Raman spectral features of B12 were found.

Investigation of the Influence of Stress on Label-Free Bacterial Surface-Enhanced Raman Spectra

“…A major challenge in label-free SERS bacterial detection is the lack of standardized sample handing procedures, which results in the poor reproducibility of the technique. ,, Label-free SERS spectra reflect signals that arise from both bacterial cells and metabolites − and as such the spectra are affected by the bacterial growth state and metabolite production. Common bacterial growth parameters (e.g., nutrient components and availability, temperature, oxygen, pH, and bacterial growth phase) − and external stress stimuli (e.g., antibiotic exposure, phage infection, UV irradiation, and the presence of environmental contaminants) − can greatly affect the label-free SERS/Raman features of bacterial cells or metabolites. To minimize the effect of such parameters and to acquire stable SERS signals, bacterial growth conditions should ideally be maintained as consistently as possible.…”

Preface to the special issue dedicated to Professor Richard P. Van Duyne (1945–2019)

“…The specific detection of the tetrachloroethene reductive dehalogenase is helpful for monitoring the active dehalogenation processes of bacteria in a low oxygen environment. [ 20 ]…”

“…The specific detection of the tetrachloroethene reductive dehalogenase is helpful for monitoring the active dehalogenation processes of bacteria in a low oxygen environment. [20] Ji, Ozaki, et al review the recent advances in SERSbased sensors for the determination of inorganic ions, with emphasis on the sensing mechanism and methods. In addition, the review briefly introduces current challenges and future research opportunities for SERS in inorganic ion sensing.…”