Microbes are an integral part of any bioelectrochemical system (BES). In pure
culture systems, they are occupied in catalyzing the transfer of electrons to an
anode or from a cathode. In mixed cultures, in addition to these exoelectrogenic
and exoelectrotrophic populations, there may be community members involved in
other metabolisms that indirectly assist electrochemical activity (e.g., by converting
a complex substrate into acetate) or compete with and impair electrochemical
reactions (e.g., diverting acetate to methane). A thorough considerate of these
systems and the accurate understanding of system performance often require the
classification of the microbial communities that institute on either electrode, or
perhaps even in postponement or on other reactor surfaces (Schröder 2007). The
BES research community has used a multiplicity of techniques to study microbial
populations and communities. This chapter focuses on nucleic acid-based methods
for community categorization, primarily 16S rRNA and 16S rRNA gene-targeted
techniques (although they could be adapted to study other genes), which is consistent
with the majority of BES ecology studies. Successful bioelectrochemical systems
(BESs) application and research efforts necessitate a comprehensive understanding
about the microbial behavior associated with the bioelectrocatalytic conversion of
chemical and electrical inputs. BES reactors utilize living microorganisms to drive
catalytic activity, and these microbes will respond to system changes in poles apart
ways than abiotic catalysts. This chapter introduces methods and protocols for
quantifying microbial biomass, extracting DNA from electrode surfaces, 16S
rRNA gene sequencing, and sequence data analysis. Using these methods,
researchers can quantify electron transfer activity per unit biomass and more accurately normalize electricity production results. In addition, 16S rRNA gene sequencing enables researchers to begin taxonomically describing the microbial populations
that are present in anode-associated biofilms (Rabaey et al. 2010). The gene
sequence data analysis is critical for gaining a basic considerate about the types of
microbes that are interacting with electrode surfaces, estimating their function, and
quantifying total biomass. These combined data sets can be used as a basis for more
detailed analyses relative to microbial function and population dynamics in BESs.
5.3
Functions of Microbial Groups in Bioelectrochemical
Systems
The goal of this part is to endow with practical information and fundamental
knowledge to researchers who study biofilms on electrodes. The part particularly
focuses on cyclic voltammetry (CV) of anodic and cathodic biofilms. We put
emphasis on that researchers must obtain cyclic voltammograms during the growth
of a biofilm and under no turnover circumstances and put side by side these to known
electrochemical controls. We also discussed verifying the suitability of a biofilm
reactor setup for electrochemical analysis. We concluded that CV can be more useful
in amalgamation with other tools, such as gyratory disk electrodes, quartz crystal
microbalance, and microsensors (Dominguez-Benetton et al. 2012). The outcome of
any biofilm electrochemical experiment involving a coupled technique relies on the
researcher’s ability to incorporate the CV analysis discussed in this chapter into a
5 Microbiology of Bioelectrochemical System
109
culture systems, they are occupied in catalyzing the transfer of electrons to an
anode or from a cathode. In mixed cultures, in addition to these exoelectrogenic
and exoelectrotrophic populations, there may be community members involved in
other metabolisms that indirectly assist electrochemical activity (e.g., by converting
a complex substrate into acetate) or compete with and impair electrochemical
reactions (e.g., diverting acetate to methane). A thorough considerate of these
systems and the accurate understanding of system performance often require the
classification of the microbial communities that institute on either electrode, or
perhaps even in postponement or on other reactor surfaces (Schröder 2007). The
BES research community has used a multiplicity of techniques to study microbial
populations and communities. This chapter focuses on nucleic acid-based methods
for community categorization, primarily 16S rRNA and 16S rRNA gene-targeted
techniques (although they could be adapted to study other genes), which is consistent
with the majority of BES ecology studies. Successful bioelectrochemical systems
(BESs) application and research efforts necessitate a comprehensive understanding
about the microbial behavior associated with the bioelectrocatalytic conversion of
chemical and electrical inputs. BES reactors utilize living microorganisms to drive
catalytic activity, and these microbes will respond to system changes in poles apart
ways than abiotic catalysts. This chapter introduces methods and protocols for
quantifying microbial biomass, extracting DNA from electrode surfaces, 16S
rRNA gene sequencing, and sequence data analysis. Using these methods,
researchers can quantify electron transfer activity per unit biomass and more accurately normalize electricity production results. In addition, 16S rRNA gene sequencing enables researchers to begin taxonomically describing the microbial populations
that are present in anode-associated biofilms (Rabaey et al. 2010). The gene
sequence data analysis is critical for gaining a basic considerate about the types of
microbes that are interacting with electrode surfaces, estimating their function, and
quantifying total biomass. These combined data sets can be used as a basis for more
detailed analyses relative to microbial function and population dynamics in BESs.
5.3
Functions of Microbial Groups in Bioelectrochemical
Systems
The goal of this part is to endow with practical information and fundamental
knowledge to researchers who study biofilms on electrodes. The part particularly
focuses on cyclic voltammetry (CV) of anodic and cathodic biofilms. We put
emphasis on that researchers must obtain cyclic voltammograms during the growth
of a biofilm and under no turnover circumstances and put side by side these to known
electrochemical controls. We also discussed verifying the suitability of a biofilm
reactor setup for electrochemical analysis. We concluded that CV can be more useful
in amalgamation with other tools, such as gyratory disk electrodes, quartz crystal
microbalance, and microsensors (Dominguez-Benetton et al. 2012). The outcome of
any biofilm electrochemical experiment involving a coupled technique relies on the
researcher’s ability to incorporate the CV analysis discussed in this chapter into a
5 Microbiology of Bioelectrochemical System
109