Analyzing and visualizing molecular events in bacterial spore germination

Bacterial spores are one of the most resilient life forms on Earth, and they can remain viable for a long time under extreme conditions. However, once a spore detects an environment conducive for growth, it will quickly trigger reversion to metabolically active cell growth by spore germination. A limited number of germination proteins are involved in the B. subtilis spore germination. However, microscopic analyses of these germination apparatuses are hampered by the relatively low abundance or/and the movement of these proteins, as well as the heavy autofluorescence from the spore coat. In the current thesis, the localization and dynamics of germinant receptors (GRs) and SpoVA proteins were measured by different advanced microscopies, including the structured illumination microscopy (SIM), a new approach by combining annular illumination with rescan confocal microscopy, as well as the rescan confocal microscopy (RCM). The thesis give the evidence for the existence of GRs spots in the inner membrane (IM) of wild-type spores and coat defective spores, and the GRs’ spots remain in one location during germination. In addition, the SpoVAEa proteins were also present in a single spot in spores, however, the spot moved randomly with high frequency in the IM. Meanwhile, an immobile germination related lipids microdomain were observed in the spore IM, and it potentially related to the organization of germinated proteins in spores. The thesis also described the heat activation and heat damage profile of B. subtilis spores for further promoting the decontamination efficacy in the food processing procedures.