Microorganisms have two main lifestyles: planktonic or sessile. In the planktonic mode, bacteria live in a bulk phase with erratic movements according to hydrodynamics. Advantages of this way of life are the ability to reach new ecological niches and easy access to dissolved substrates. When a planktonic cell attaches to a surface, it becomes sessile. If the bacterial cell multiplies and secretes a polysaccharide matrix on the surface, it forms a structure called a biofilm. Biofilms have many advantages including increase of resistance to antimicrobial agents and the ability of microbes to cooperate for nutrients and/or substrates (Simões et al. 2010). According to the type of interactions existing between microbial biofilms and the surface, the support can be classified as inert (silica), nutritious (hydrocarbons) or artificial (electrode). Biofilms that develop on conductive materials and exchange electrons with them are called “electroactive biofilms”. In the case of anode respiring biofilms, i.e. biofilms transferring electrons to the conductive material, the terminal electron acceptor is not chemical (O2, NO3−, Fe(III), Mn(III)) but physical and the bacteria are called electroactive bacteria (EABs).