Multi-omics of Bacillus subtilis spores and cells sheds new light on bacterial survival

B. subtilis, found ubiquitously in diverse environments, is renowned for its ability to form endospores under harsh conditions. In this thesis, omics approaches were applied to gain insights into the complex protein and metabolite compositions that underlie the remarkable resilience of B. subtilis spores. An optimized extraction method, using 60% ethanol, allowed for the identification and comparison of proteins and metabolites in both vegetative cells and spores efficiently. Moreover, this study revealed that sporulation temperature significantly influences various spore characteristics, including heat resistance, germination responses, morphology, protein expression, and metabolite composition. The pivotal role of Calcium Dipicolinic Acid (CaDPA) in B. subtilis spores was meticulously examined. Findings suggested that a deficiency in CaDPA correlates with pronounced alterations in spore membrane proteins and fluidity, underscoring its essential role in spore thermotolerance. Additionally, the efficiency of the Sample Preparation by Easy Extraction and Digestion (SPEED) protocol in the proteomic analysis of B. subtilis samples was assessed. Results highlighted the protocol’s efficiency and determined the minimal sample quantity required for consistent protein identification. These findings also revealed shared metabolic pathways between cells and spores, suggesting a conserved molecular toolkit that bestows spores with their remarkable resilience to environmental stresses. In summary, these insights unveil the intricate adaptive strategies of B. subtilis at the molecular level, providing a foundation for targeted interventions and accentuating the potential of omics technologies in the study of B. subtilis species.