## 4 Biofilm
### Biofilm Matrix  
The production of the extracellular matrix (ECM) by bacteria in biofilms provides protection against hostile environments such as antimicrobial agents and the host immune system. Figure 2 shows a scanning electron micrograph of an Escherichia coli biofilm enclosed in an extracellular matrix [36]. ECM contributes to pathogenicity by increasing antibiotic tolerance and promoting immune evasion. The production of the extracellular matrix is central to the development of bacterial biofilm architecture [157; 158]. The matrix is highly hydrated, with up to 97% water content, and is rich in polysaccharides, proteins, and extracellular microbial DNA. It can be composed of one or more microbial species (bacterial or fungal). The matrix is a hydrated mucilaginous layer that prevents bacteria from drying out [159]. The ECM is made up of extracellular polymeric substances (EPS) that have been identified, highlighting its versatility, with various functions (Table 3) [160; 161]. Figure 2: Effect of the biofilm’s extracellular matrix on pathogenicity. EPS promote microbe adhesion to biotic and abiotic surfaces, The stability and functionality of the EPS matrix are critical in the development of a robust and resilient microbiome community, in addition to aiding in the tolerance of these multicellular communities to various antimicrobial agents (Figure 2). Biofilm bacteria are more resistant to external aggressions such as pH, temperature, and antimicrobial agents than planktonic bacteria [162; 163]. Biofilms can withstand antibiotics at concentrations 10 to 1000 times higher than planktonic bacteria, and it has been reported that the matrix acts as a diffusion barrier for toxic molecules [164]. The presence of zones of low or no oxygenation in the biofilm's deep layers may also contribute to resistance to some biocides, which may be inactivated under such conditions or are ineffective against metabolically inactive bacteria. An increasing body of experimental evidence suggests that resistance is linked to the expression of specific genetic mechanisms. All of these characteristics suggest that biofilm is a favorable way of life for bacteria, to the point of constituting a default mode of life for certain bacterial species [165; 166]. Terpenes and Their Derivatives as Good Candidates to Fight against Adherent Bacterial Cells and Biofilm (Antimicrobial and Antibioticfilm Effect)  
Chemical substances or compounds are used as disinfectants to inactivate or to destroy pathogenic microorganisms on inert surfaces used in healthcare sectors or in food industries. They are used as antimicrobials in hospitals, dental offices, kitchens, bathrooms, and food premises, as well as on equipment. The current challenge is to set up new products and avoid toxic by attempting to use biobased antibacterial agents [167]. Green chemistry is a branch of chemistry and chemical engineering that focuses on the development of products and processes that reduce or eliminate the use of hazardous substances [168; 169]. Essential oil, which is derived primarily from herbs and citrus fruits, is a commercially important product with health-promoting properties due to the presence of terpenes and limonoids, as well as other bioactive components such as flavonoids, carotenoids, and coumarins [170]. Essential oils reveals are composed primarily of complex mixtures of two groups of organic compounds: terpenes and phenylpropane derivatives (terpenoids and phenylpropanoids) [171]. Terpenes are naturally occurring hydrocarbons with cyclic or acyclic structures that are made up of a multiple of five carbon atoms and with the general formula (C\({}_{5}\)H\({}_{8}\))\({}_{n}\). The basic molecule is isoprene (2-methyl-1,3-butadiene: C\({}_{5}\)H\({}_{8}\)). This family includes monoterpenes (10 carbon atoms), sesquiterpenes (15 carbon atoms), diterpenes (20 carbon atoms), esterpenes (25 carbon atoms), triterpenes (30 carbon atoms), and polyterpenes (5n carbon atoms).