Biophysical Studies of Single Bacterial Spores using Laser Raman Optical tweezers
Biophysical and Physicochemical Fingerprinting of Single Bacterial Spores
Spore-forming bacteria that cause diseases, food spoilage and poisoning, pose a particularly hazardous danger in our society. When in spore form, they can survive harsh conditions. For example, strains of genus Bacillus, which cause anthrax and food poisoning, can stay dormant for several decades in the soil. They can sustain over 100 °C for hours, and resist gamma radiation as well as a plethora of disinfection chemicals. Thus, spores´ possibility to stay dormant and their robustness is a challenge for healthcare, the food, and dairy industry. In this project we investigate means to kill spores. Images to the left are from the Public Health Image Library.
Raman spectrum from a single trapped Bacillus thuringiensis spore
The right figure shows the Raman signal of a single trapped Bacillus thuringiensis spore (exposure time 30 seconds). The vertical axis shows the intensity for each wave number (horizontal axis). These Raman bands specifically represent chemical content that depends on the chemical composition. One can thus identify proteins, lipids, DNA none-invasive. For example, we see here the bands representing: phenylalanine (Phe), tyrosine (Tyr), alanine (A) and dipicolinic acid (CaDPA).
Time Resolved Raman Spectra
The left images shows how the chemical composition of a B. thuringiensis spore changes when exposed to a chemical solution. The left graph shows examples of collected Raman spectra over time, where the uppermost represents the first measurement t = 0 minutes and the last one represents the last measurement t = 60 minutes. The right graph shows the change of each component vs time, i.e., how corresponding bands in the left graph is changing with time.
