The Hidden World Inside Every Smile

Each smile hides a complex microbial ecosystem. Inside every mouth, beneficial and harmful bacteria constantly compete for space and nutrients. Under normal conditions, friendly species form protective biofilms and buffer pH. When sugar intake and acidity rise, S. mutans gains the upper hand, forming plaque, producing lactic acid, and slowly eroding enamel.

LactoLock began with a simple question: Can we re-engineer nature's own microbes to defend the mouth from within?

When Balance Breaks

Current oral-care methods treat symptoms rather than causes. Fluoride strengthens enamel but cannot target the bacteria driving decay. Antiseptics and antibiotics kill indiscriminately, removing beneficial communities that help protect us.

This imbalance, called oral dysbiosis, allows acid-tolerant species to dominate and creates a persistent cycle of decay. To truly prevent cavities, we need a precision approach that distinguishes friend from foe and acts only when harmful microbes appear.

Introducing LactoLock

LactoLock is our solution: an engineered Lactobacillus probiotic that acts as a microbial sentry. It senses cues produced by S. mutans and responds by releasing antimicrobial peptides (AMPs) that selectively inhibit its growth. Once conditions return to normal, AMP production shuts down, preserving the rest of the microbiome.

• Intelligent detection: Genetic circuits activate only when harmful signals are present.
• Targeted defense: AMPs are tuned to specifically weaken S. mutans.
• Microbiome harmony: Beneficial bacteria remain untouched, supporting a balanced and resilient ecosystem.

This responsive design allows LactoLock to act precisely where and when it is needed most.

Built on Safety. Guided by Science.

Every aspect of LactoLock’s design follows iGEM’s principle of Safe-by-Design. We focus on biological safety at the genetic, cellular, and system levels to ensure the probiotic functions predictably and safely.

• GRAS Chassis: built in Lactobacillus, a species recognized as safe for human use.
• Controlled Circuits: regulatory safeguards prevent unnecessary AMP production.
• Containment Strategies: exploring auxotrophy and non-antibiotic selection systems for environmental safety.
• Rigorous Documentation: design reviews, risk assessments, and Human Practices feedback guide development.

Our goal is a probiotic that strengthens oral health without compromising safety or ecological integrity.

From Concept to Culture

Turning design into data, our experiments bring LactoLock to life through rigorous testing and iteration.

• Cloning and Validation: Circuit genes are assembled, sequence-verified, and transformed into E. coli for early testing.
• Induction Testing: Reporter assays measure when and how strongly the sensing module activates under S. mutans-like conditions.
• Co-culture Studies: Mixed cultures reveal selective inhibition patterns between LactoLock and S. mutans.
• Biofilm Quantification: Crystal violet staining and microscopy evaluate reductions in harmful biofilm mass.
• Selectivity Screens: We test compatibility with beneficial oral species such as S. sanguinis and L. casei.

Each experiment refines our circuit toward a living therapy capable of preventing cavities before they begin.

Connecting Innovation Across Continents

LactoLock is a collaboration between Georgia State University (USA) and Southwest Jiaotong University (China). Our international team combines expertise in synthetic biology, microbiology, and human practices to build a safer, smarter approach to oral health for all.