**Abstract**

*Salmonella* is a major food-borne pathogen around the world. In the European Union (EU), this pathogen is responsible of more than 90,000 human cases of salmonellosis every year. Salmonellosis in normally linked to the consumption of contaminated food, especially poultry products as meat, eggs and the products elaborated with them. Several control measures have been implemented in the EU to reduce the prevalence of *Salmonella* in the food chain. However, the ability of *Salmonella* to form biofilm along the food chain difficult its eradication. Also, ineffective cleaning and disinfection measures favors biofilm formation. The widespread use of biocides along the food chain has led to the emergence of resistant *Salmonella* strains. Therefore, it is necessary to look for alternatives to biocides to eradicate *Salmonella* biofilms. In this chapter we evaluate the use of bacteriocins and bacteriophages and their derivatives as a new alternative to eliminate *Salmonella* biofilms along the food chain.

**Keywords:** *Salmonella*, biofilms, control, bacteriocins, bacteriophages

### **1. Introduction**

*Salmonella* genus is composed only by two species, *S. enterica* and *S. bongori* and more than 2600 different serotypes. *S. bongori* is composed of about 20 different serotypes and strains of this species are rarely isolated. Most of the serotypes belong to *S. enterica.* This species is subdivided in six different subspecies: *S. enterica* subsp. *enterica* (I)*, S. enterica* subsp. *salamae* (II), *S. enterica* subsp. *arizonae* (IIIa), *S. enterica* subsp. *diarizonae* (IIIb)*, S. enterica* subsp. *houtenae* (IV) and *S. enterica* subsp. *indica* (VI) (**Table 1**) [1]. The subspecies *enterica* attracts most of the attention of researchers as it is responsible for more than 99% of *Salmonella* infections in humans*.* Although the other *S. enterica* subspecies can also cause infections in humans, these infections tend to occur mainly in people with a very weakened immune system. The non-*enterica* subspecies of *Salmonella enterica* are usually isolated mainly from cold-blooded animals such as reptiles [2].


#### **Table 1.**

*Number of serotypes present in each* Salmonella *species and subspecies.*

*Salmonella* is important because it is one of the world's leading food-borne pathogens. In the European Union (EU), *Salmonella* is the second food-borne pathogen in number of human infections only behind the genus *Campylobacter*. In the year 2018, *Salmonella* was responsible of 91,857 human cases of salmonellosis and 119 deaths in the EU. Most infections are due to the consumption of food contaminated with *Salmonella* [3]. Thus, this pathogen can be isolated from different type of animals and their food derived products as bovine, porcine, ovine, fish or seafood [4–6]. But the largest number of human infections are related to the consumption of poultry products, especially meat and eggs as well as derived products [3]. As a consequence, the EU has developed legislation for member states to implement national control plans for *salmonella* in poultry production [7, 8]. The objective of this legislation is to reduce annually the prevalence of *Salmonella* in different types of farms including breeder farms, layer farms and broiler farms. Furthermore, this legislation also establishes that those serotypes that are of major epidemiological importance will be subject to special surveillance. For example, in broiler flocks *S.* Typhimurium and *S.* Enteritidis are subjected to this control. The ultimate goal of the European Union is for the combined prevalence of *S.* Typhimurium and *S.* Enteritidis to be less than 1% [9]. This due to these two serotypes are responsible of more than the 70% of human infections in the EU [3]. Cleaning and disinfection processes are of great importance to reduce the prevalence of *Salmonella* in the food chain. The implementation of inadequate control measures may result in *Salmonella* being able to resist in the food chain environment and contaminate different batches of food [10]. One of these bacterial resistance mechanisms is the formation of biofilms. For decades, biocidal substances such as quaternary ammoniums have been used to eliminate the presence of biofilms in the food industry [11]. However, the presence of multidrug-resistant strains is increasing [12]. This is a major concern as it may hinder the removal of biofilms from the food chain. Therefore, the development of alternative substances to combat food pathogen biofilms is necessary [13]. A brief description of *Salmonella* biofilms and the use of natural alternatives such as bacteriocins and bacteriophages to combat biofilms will be given throughout this chapter.
