# From Dormancy to Eradication: Strategies for Controlling Bacterial Persisters in Food Settings
## 6 Implications of Persister Cells in the Food Industry
### Chemical Treatments  
In addition to the previously discussed physical methods, a range of chemical agents can be utilized against microbial cells in both planktonic and biofilm states [46; 67; 68; 69; 70]. The efficacy of these agents is influenced by factors such as the specific agent employed, its concentration, and the duration of contact with microorganisms. Following application, the microbial load must be reduced to levels deemed safe for human consumption, a process referred to as sanitization [79]. The proper sanitization of food processing equipment is crucial to prevent cross-contamination between food batches [80]. Chemical changes during food production processes, such as variations in pH and osmotic pressure, can significantly influence the development of persister cells. It is well known that lowering pH below 4.6 inhibits the growth of many spoilage and pathogenic microorganisms [81]. Similarly, increasing osmotic pressure by adding salt (curing) or sugar (syrup preservation) creates a hypertonic environment that causes water loss from microbial cells through osmosis, leading to dehydration and the inhibition of microbial activity [82]. These preservation methods are ideal for fermented and pickled foods, fruit preserves, salted meats, and syrups. Acidification is commonly used in dairy products, canned vegetables, and fermented beverages, while osmotic pressure-based preservation works well for dry-cured meats, salted fish, jams, honey, and candied fruits. These techniques are best for foods requiring mild processing and limited refrigeration, but their effectiveness depends on proper formulation and storage to prevent spoilage via acid- or salt-tolerant microorganisms [83]. [PERSON] et al. [84] noted that low pH conditions (pH < 4.5) have varying effects on different bacterial species; for instance, persister _E. coli_ can produce toxins under low pH conditions. Changes in osmotic pressure also impact cell growth rate, turgor pressure, and transport mechanisms between cells and their extracellular environment. One of the main advantages of using pH and osmotic pressure for food preservation is that these methods are natural and do not require high temperatures or synthetic preservatives, aligning with consumer demand for clean-label products. Acidification not only prevents microbial growth but can also enhance flavor, as seen in fermented foods like yogurt, sauerkraut, and vinegar-based pickles. Osmotic pressure methods such as salting and sugaring are simple and cost-effective, and they have been used for centuries to preserve meats, fish, and fruits. However, extreme acidity can affect taste and texture, making foods less desirable. Some microorganisms, like yeasts and molds, can survive in acidic or high-sugar environments, leading to spoilage if storage is not controlled. High salt or sugar concentrations can also impact the nutritional balance, with excessive intake linked to health issues like hypertension and diabetes. Despite these challenges, adjusting pH and osmotic pressure remains a reliable method for preserving food, ensuring safety and quality while supporting traditional processing practices. [PERSON] et al. [85] investigated the effects of sodium nitrite, urea, and acidic pH on the survival of _E. coli_ persisters. These authors found that urea (4%) and sodium nitrite (80 mM) reduced persister levels below the limit of detection while having minimal effects on overall cell viability, as measured using CFU counts. In contrast, lowering the pH below 4.5 significantly compromised _E. coli_ cell viability. Although sodium chloride (NaCl) is commonly used in cell culture media, [PERSON]'s research indicated that concentrations below 8% do not substantially affect the viability or persister levels of _E. coli_. However, elevated NaCl concentrations pose a significant threat to _E. coli_ vitality, as demonstrated by the experimental results. The precise mechanisms through which NaCl concentration influences persister formation remain to be elucidated [84].