6533b839fe1ef96bd12a60e6

RESEARCH PRODUCT

UV resistance of Bacillus subtilis spores - Involvement of DPA and characterization by photonic microscopy

subject

description

The aim of this project was to study the UVc resistance of Bacillus subtilis spores. The first part of this project focused on the dipicolinic acid molecule (DPA) which is known to be involved in the UV resistance of spores. However, some points remain unresolved. In particular, it is known that this molecule forms fluorescent photoproducts (DPAp), which were not identified at the beginning of this project. No information concerning the role of these DPAp in UVC resistance was available at that time. During this project, a protocol was established to follow the appearance of these photoproducts directly inside the spore core. A method was also set up to artificially introduce DPAp into the spores. Some of these DPAp seem to have beneficial effects for the spores, by increasing their germination rate, their growth and their resistance to UVc. Finally, it seems that the hydration of DPA at the time of UVc exposure influences the formation of DPAp. The second part of this project was devoted to setting up a UVc equivalent exposure directly under the microscope and directly observing the damage caused on the spores. Using a pulsed infrared laser to provide UV equivalent energy, however, revealed that the damage caused is different from that found in UV. Surprisingly, the spores were only twice as resistant as the vegetative cells to this exposure. The first results show that DPA does not seem to have a significant role here. Finally, the last part of this project was devoted to the development of a labeling of spore structures compatible with PALM/STORM super-resolved imaging methods.