Characterization of biofilms developed on the electrodes of microbial fuel cells and electrolysis cells

Abstract

Biofilms are established microbial communities attached to any surface. These biofilms contain sessile cells (microorganisms and/or fungi) implanted in a self-made extracellular matrix of different polysaccharides, DNA, and components [1]. Biofilms might develop on different surfaces and may be natural and normal in clinical settings. The cells of the microorganism in a biofilm are characteristically remarkable from planktonic cells of a similar organism. It is in contrast to the single-cells that could flow or move freely in a liquid medium. Most of the biofilms are widely seen in wastewater treatment. Recent developments in science and technology have improved the use of biofilms for biodegradation and bioremediation in reactors, but they do have their advantages and disadvantages. Biofilms, flows, and mats are reliable options for greater use and conversions in natural environments that have several microorganisms [2].

Biofilms due to their unique nature are used in natural/artificial environments and investigated in many disciplines of scientific research. The examination of biofilms is an interdisciplinary technique that relates to microbiology and engineering. Initially, an engineering technique was used to observe biofilm’s overall performance at the macroscale (i.e., for the optimization of wastewater treatment plants) [3]. Nowadays, the engineering concepts are applied even at microscale similar to that of the microbiological techniques. Microbiologists concentrate on identifying the forms of microorganisms present, their characteristics, and functions that characterizing the biofilms. The study of immobilized cell systems is gaining momentum in interdisciplinary research over the past decade. The structure, function, and characteristics of the microbial population are determined using immobilized cell systems. A scanning electron micrograph of a biofilm is shown in figure 1. Biofilms find their applications in the removal of pollutants and heavy metals in the wastewater, as bio-barrier for immobilization of groundwater contaminants, in microbe powered oil recovery (MER), in the recovery of metals from the waste ores at the mining fields, and many more. The focus of the researchers in the domain of biofilm research are the studies on the pathogenic activities and metabolism of microbes developing in biofilms, detailed classification, mechanism of resistance to antimicrobial agents, studies on host immune responses, and so on.

The focus of this short review is on the brief description of the formation of the biofilm, its working principle, parameters that affect the performance of a biofilm, characterization of a biofilm, and a few applications.