# Electrochemical Control of Biofilm Formation and Approaches to Biofilm Removal
## 2 Biofilms
### Influence of Environment on Biofilm Formation  
Several environmental factors have been reported to strongly influence the potential of an organism to form biofilms on a surface. The pH, incubation temperature, water activity, ingredients composition (glucose, sodium chloride, ethanol, minerals, heavy metals, and dilution rate of media), contact duration, and the type of surface have been shown to be important factors affecting the phenotypic change from planktonic cells to sessile forms such as biofilms [57; 58; 59; 60; 61; 62].  
Highly diverse environmental conditions ideal for biofilm formation are encountered in the food processing environment [57; 61; 63]. The ability of food spoilage and pathogenic bacteria to adhere to food-processing surfaces, such as stainless steel (SS), silicon rubber (SR), plastic (PLA), and food surfaces and form biofilm is a major health hazard because of a constant source of contamination by resistant biofilms [57; 64].  
The type of material used for industrial equipment and piping systems also influences biofilm structure and behavior, and specifically their tolerance to disinfection and cleaning procedures [65]. The general principles for CIP circuits recommend the use of AISI316 or AISI304 stainless steel (SS) with an electropolished surface finish [66]. In addition, biofilms formed on SS are shown to be more susceptible to biocides than those formed on plastic materials, such as high-density polyethene (HDPE) and polystyrene (PS) [67; 68]. However, plastic materials are indispensable in industrial settings due to their flexible application, (bio)corrosion resistance, and low cost. For instance, HDPE is broadly used in water systems, particularly for DWDS and food industries, offering high mechanical performance [69]. Additionally, HDPE has also been used for other purposes related to the food industry, such as the production of larger moldings (transport and storage tanks), modular conveyor belts, sheets, tubes, bearings, and gears [70; 71; 72].  
Effect of Metal Ions on Biofilm Formation  
Since this review article focuses on the electrochemical control of biofilm formation in food processing environments, it is necessary to show the possibility of real-time electrochemical monitoring of concentration levels of the metal ions, which could provide useful information about the current composition of the environment, because it is well known that the presence of different metal ions can increase the abundance of attached bacteria cells onto surfaces or inhibit their growth.  
For example, in 2006, [PERSON] and [PERSON] found that the presence of Mg\({}^{2+}\) cations significantly increases the abundance of attached cells of _Pseudomonas fluorescens_[73]. On the other hand, another study suggests the inhibitory effect of copper and zinc ions on the growth of _Streptococcus pyogenes_ and _Escherichia coli_ biofilms. However, it was also observed that copper and zinc cations had no effect on mature biofilm [74]. Silver cations and silver nanoparticles (AgNP) show good antimicrobial activity and are widely used in many fields, even in food technology as an effective preservative [75]. This phenomenon can be attributed to the non-competitive inhibition of enzyme activity [76]. It has been shown experimentally that silver is able to prevent biofilm formation in modified Robbins [77] with polyvinyl chloride and stainless steel surfaces [78]. It was confirmed that the electrochemically deposited silver on stainless steel container surfaces can effectively inhibit microbial proliferation within potable water supplies [79].