Bacillus subtilis 168
Gram-positive, spore-forming model bacterium with QPS (EFSA) status and a long history of safe industrial use. Spores make it robust for field-deployable and environmental biosensors.
Identity
- Species
- Bacillus subtilis
- Strain
- 168 (trpC2)
- NCBI taxid
- 224308
- Genome
- NC_000964.3
Safety
- Biosafety level
- BSL-1
- Pathogenic
- No
- GRAS
- Yes — EFSA Qualified Presumption of Safety (QPS); long history of use in food enzymes and fermentation.
- Biocontainment
- Spore-based and auxotrophic containment; widely used in contained industrial fermentation.
- BSL-1 basis
- ABSA Risk Group 1; EFSA QPS list.
Naturally competent for DNA uptake; excellent protein secretion.
Traits
- Gram
- positive
- Oxygen
- facultative
- Optimal temp
- 37 °C
- Doubling time
- ~25 min
- Spore-forming
- Yes
- Transformable
- Yes
Engineering
- CRISPR tooling
- dCas9/CRISPRi adapted for B. subtilis (e.g. Peters et al.).
- Common promoters
- Pveg, Phyperspank (IPTG), PgsiB (stress)
- Selection markers
- SpcR, ErmR, KanR
- Toolkits
- Bacillus SEVA-Brick, BioBrick Bacillus collection
Biosensors using this chassis
Cadmium sensor (CadC + CRISPRi)
Detects toxic cadmium Cd(II) in water and soil. The CadC metal-responsive repressor gates a CRISPRi circuit driving sfGFP, in spore-forming Bacillus subtilis 168 for field-storable testing.
Formaldehyde sensor (HxlR + CRISPRa)
Detects toxic formaldehyde in water, air, and materials. The native B. subtilis HxlR formaldehyde regulator gates a CRISPRa circuit driving a fluorescent reporter, in spore-forming Bacillus subtilis 168.
Lead water sensor (PbrR + CRISPRi)
Detects lead Pb(II) in water. The PbrR metal-responsive regulator gates a CRISPRi circuit driving sfGFP, in spore-forming Bacillus subtilis 168 for rugged, field-storable testing.
Manganese sensor (MntR + CRISPRi)
Detects manganese in water and soil. The native B. subtilis MntR manganese-responsive regulator gates a CRISPRi circuit driving a fluorescent reporter, in spore-forming Bacillus subtilis 168.
Phosphate sensor (PhoPR + CRISPRa)
Reports phosphate status (relevant to water-quality and eutrophication monitoring). The native B. subtilis PhoP/PhoR phosphate-starvation system gates a CRISPRa circuit driving a fluorescent reporter, in spore-forming Bacillus subtilis 168.
S. aureus sensor (AIP/AgrC + CRISPRa)
Detects Staphylococcus aureus by sensing its autoinducing peptide (AIP). The AgrC/AgrA quorum receptor gates a CRISPRa circuit driving a fluorescent reporter, in safe Gram-positive Bacillus subtilis 168 — no live pathogen handled.