## 4 Biocontrol Methods
### Bacteriophages  
Bacteriophages, also known as phages, are viruses that infect and specifically kill bacteria. Bacteriophages were discovered in the late 19 th century when British bacteriologist [PERSON] observed the bactericidal activity of water from the Ganga and Jamuna rivers against Vibrio cholerae. In 1915, [PERSON], a British microbiologist, first described bacteriophages, and two years later, [PERSON] used them to treat dysentery. Although the use of phages declined with the discovery of antibiotics, bacterial resistance to them has brought the potential of phages back into focus [129]. In recent decades, the use of phages to combat bacterial pathogens in food, an approach called \"phage biocontrol\", has become increasingly common. For example, ListShield(tm) was the first commercial phage product approved by the Food and Drug Administration (FDA) in 2006, followed by Listex(tm) P100, to combat _L. monocytogenes_ in ready-to-eat foods. Since then, other phage preparations have been approved by regulatory agencies in the US and other countries, including Canada and Israel. Phages have been shown to be effective in controlling _L. monocytogenes_, significantly reducing its presence in foods, such as vegetables and fruits, as well as in cheese and smoked fish. Phages are also used to decontaminate meat and cheese during the ripening process. For example, studies have shown that ListShield(tm) can reduce _L. monocytogenes_ contamination by 2.2 log units on prepackaged frozen foods, making it effective in a variety of applications. Other products, such as Listex(tm), have shown similar results in reducing bacterial contamination [130]. Phage biocontrol is considered an effective, environmentally friendly, and natural method of controlling pathogenic bacteria in food. Most commercially available phage products consist of natural lytic phages, which are not genetically modified and are considered safe for consumption. Many of these products are also certified Kosher, Halal, and organic, making them attractive to a wide range of consumers. The low cost of phage application in the food industry makes them competitive compared to other food safety methods such as irradiation or high-pressure pasteurization. However, phage biocontrol has some limitations, such as a more modest reduction of bacterial load in the range of 1-3 log units compared to chemical disinfectants. Also, the specificity of phages makes it necessary to use several products to combat different pathogens in case of multiple food contamination. However, this specificity is an advantage, as it targets only pathogenic bacteria without affecting the beneficial microflora or food quality. Phages have two types of life cycles: lytic and lysogenic [131]. Lytic phages are preferred for biocontrol because they destroy bacterial cells, while lysogenic phages integrate into the DNA of the host bacterium and do not cause its death. Phages do not pose a risk to humans due to their specificity for host bacteria. Studies have demonstrated the effectiveness of phages in combating _Listeria monocytogenes_ biofilms formed on stainless steel surfaces, which are commonly found in food processing environments. For example, ListShield(tm) successfully reduced _L. monocytogenes_ biofilm in 100% of cases, and Listex(tm) P100 had a similar effectiveness against biofilm on stainless steel. Phages are widely used in countries such as the United States and Canada, but their use in the European Union is still limited. Although the EFSA (European Food Safety Authority) has given a positive opinion of Listex(tm) P100, the product has not been approved for use in the food industry in all EU member states. This highlights the need for further research on the safety and efficacy of phages, as well as monitoring the emergence of phage-resistant strains [78]. An alternative method to using phages is to apply their enzymes, called endolysins. These enzymes destroy the bacterial cell wall and can be used to control pathogenic bacteria without involving phages entirely.