Exposing a Synthetic Oral Bacterial Community to Simulated Phases of Digestion

Begin with a tube containing a synthetic bacterial community commonly found in the human mouth.

Add simulated salivary fluid containing mucin, a glycoprotein, and the enzyme α-amylase to mimic the oral environment, then incubate with shaking.

The bacteria interact with mucin, which promotes aggregation, while α-amylase replicates the enzymatic conditions of saliva.

Collect a sample.

Next, introduce simulated gastric fluid with mucin at an acidic pH to mimic the stomach environment, and incubate with shaking.

The acidic conditions kill acid-sensitive bacterial species, but acid-tolerant and mucin-coated, mildly acid-tolerant bacterial species survive.

Collect another sample.

Finally, add simulated intestinal fluid containing bicarbonate and physiological salts. Incubate with shaking.

The salt-rich environment induces ionic stress, which disrupts the bacterial membrane and reduces viability.

Collect a final sample.

All three post-simulation samples are now ready for bacterial viability assessment.

To simulate oral digestion, transfer 3 milliliters of the bacterial community in a 50 milliliter sterile tube, and mix with 3 milliliters of simulated saliva fluid or SSF.

Add 75 units per milliliter o