Electricity harvesting from organic matter has been a topic in several studies and reviews

as the recent signs of progress in MFC are being described as a promising technology to

generate electricity. Alongside that, a variety of microorganisms seems to produce proteic

nanowires with electrically conductive properties. In that sense, Geobacter pili have pro­

vided one of the most satisfactory results in terms of nanowire conductibility [37]. For EET,

some bacteria have employed different mechanisms including direct or indirect/mediated

EET, as provided in Figure 11.6. Within this line, microorganisms such as G. sulfurreducens

and S. oneidensis have gained attention from the scientific community within the field of

microbiology and bioengineering due to their promising conducting properties. Such an

effect is based on the consumption of several compounds that are converted into electricity,

just like MFCs.

MFC is a type of bioelectrochemical system that converts organic wastes into electricity

through the catalytic action of EAMs associated with an electrode. That process can en­

able novel applications such as the generation of electricity, wastewater treatment, and

biosensor applications. In that sense, an MFC is a bioreactor incorporated with an elec­

trochemical system that employs bacteria to generate electricity from bioconvertible

substrates directly. The concept of MFC as promising environmental biotechnology was

first explored in the 1970s, which proposed power production and wastewater treatment

using microorganisms. To generate current, the MFCs use bacteria as the catalysts to

oxidize organic compounds [3,46]. Several studies have been conducted using UFCs in­

oculated with S. oneidensis MR-1 as a strain with potential electron transfer for generating

bioelectricity along with energy production from biomass or carbon sources as electron

donors [47,48]. Recently, MFC-based systems were employed as biosensors, which were

employed for the identification of toxic substances in water and wastewater and therefore

serving as a tool for environmental monitoring. In that sense, a biosensor is a device that

can identify different analytes which can be employed for monitoring ecosystems, quality

control of food and water, identification of pathogens, and drug delivery systems. It can

be integrated into a bacteria or enzyme with an electronic component. In addition, bio­

sensors can be fabricated in several sizes along with presenting extremely low detection

limits to the other of around 1 × 10⁻¹⁵, which aids in the precise identification of pa­

thogens microorganisms, or toxic substances [49]. Biosensors can be classified on different

FIGURE 11.6

Types of microbial EET mechanisms at the anode of MFCs. Reprinted with permission [ 44]. Copyright © 2017

MDPI. The article is available under the Creative Commons CC-BY license.

Microbial Nanowires

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