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ORIGINAL RESEARCH article

Front. Microbiol.

Sec. Microbiotechnology

Volume 16 - 2025 | doi: 10.3389/fmicb.2025.1669207

Surface display of a manganese-binding domain enhances production and stress resistance in Bacillus subtilis spores

Provisionally accepted
Hoang  Duc NguyenHoang Duc Nguyen*Nhi  Ny NguyenNhi Ny NguyenTuom  Tt TruongTuom Tt TruongDong  Van NguyenDong Van NguyenTrang  Tp PhanTrang Tp Phan
  • VNUHCM-University of Science, Ho Chi Minh City, Vietnam, Vietnam, Vietnam

The final, formatted version of the article will be published soon.

Bacillus subtilis spores are widely used as platforms for antigen display due to their stability and safety. However, the potential impact of surface-expressed functional proteins, such as metal-binding antigen proteins, on spore physiology remains largely unexplored. This study investigated the effects of the surface-expressed manganese-binding domain of manganese transport protein C (MntC) from Staphylococcus aureus on spore development and stress resistance. A recombinant B. subtilis strain, BsHT2380, was engineered by double cross-over integration of PcotB-cotB-mntC at the amyE locus, confirmed by PCR. MntC expression on the spore surface was verified via western blot, spore ELISA and confocal fluorescence microscopy. BsHT2380 spores exhibited increased manganese accumulation compared to controls, as measured by flame atomic absorption spectroscopy (F-AAS). EDTA treatment confirmed that the bound Mn²⁺ was surface-associated. Correlation between Schaeffer-Fulton staining and CFU counts indicated that Mn²⁺ accumulation enhanced spore production efficiency. The BsHT2380 strain produced 71% mature spores by 48 hours, with spore levels remaining stable from 48 to 72 hours, suggesting this period represents the peak of sporulation. Importantly, BsHT2380 spores displayed enhanced resilience, with significantly higher survival rates under lysozyme (73%) and wet heat (70%) stress compared to control strains. These findings demonstrated that surface-expressed manganese binding domain could modulate spore physiology, improving both production and resistance, and highlight the potential of surface-displayed proteins in spore-based biotechnological applications, particularly recombinant spore-based vaccines that combine immunogenic antigen presentation with enhanced structural robustness.

Keywords: Bacillus subtilis, spore, sporulation, MntC, manganese binding domain, surfacedisplay, Vaccine delivery, Stress resistance

Received: 19 Jul 2025; Accepted: 22 Sep 2025.

Copyright: © 2025 Nguyen, Nguyen, Truong, Van Nguyen and Phan. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Hoang Duc Nguyen, ndhoang@hcmus.edu.vn

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