Fig. 1

A Mechanism of surface display using Sortase A-mediated system in the vegetative form of B. subtilis. This figure illustrates the use of Sortase A (SrtA) to anchor recombinant antigens or enzymes onto the cell wall of B. subtilis. The recombinant protein is engineered to contain a C-terminal LPDTS sorting motif recognized by SrtA. Upon cleavage of the LPDTS motif, the protein is covalently linked to the pentaglycine cross-bridge in the peptidoglycan layer. This system enables stable surface display of functional biomolecules on the vegetative cells of B. subtilis. Key components of the system, including SrtA, the LPDTS motif, and the peptidoglycan layer, are highlighted. B Mechanism of spore surface display using spore coat proteins CotB, CotC, and CotG in B. subtilis. The figure depicts the use of spore coat proteins as anchoring platforms for the display of antigens or enzymes on B. subtilis spores. Recombinant proteins are genetically fused to CotB, CotC, CotG, or CotX, which are localized on the outer layers of spore coat. CotB and CotC are primarily located in the outermost layer of spore coat, while CotG and CotX serve as scaffold proteins for stable attachment