such as microalgae, cyanobacteria, Archeabacteria and some methanogens are good
sources of bioenergy (Fu et al. 2016). These organisms produce several types of
bioenergy such as bioelectricity, biohydrogen, biomethanol, bioethanol, and methane gas. Microbial fuel cell (MFC) is the better example of bioelectricity production
(Singh and Mishra 2020; Jin et al. 2014; Ni and Sun 2009). Microalgae are
considered as a good source of bioethanol and biomethanol, and these products
are used as additives in the diesel in present days and also considered as an
alternative option of fossil fuel in the future (Xue et al. 2017; Lutke-Eversloh
2014; Hou et al. 2013). Biohydrogen is considered as a clean and eco-friendly fuel
because it produces zero waste after burning. Various types of microorganisms
(microalgae and bacteria) produce biohydrogen during their growth (Azwar et al.
2014; Saifuddin and Priatharsini 2016). Microorganisms such as algae produce
bio-oil. Bio-oils also produce various types of plant and agriculture biomass. Microorganisms such as bacteria and fungi produce extracellular enzymes involved in the
conversion of biomasses into bio-oils. Biogas is considered as an eco-friendly fuel
and has applications in various fields. Biogas is produced during the bioconversion
of biomass by methanogenic bacteria (Senger 2010; Gowen and Fong 2010; Himmel
et al. 2007). The best alternative for that is microorganism like cyanobacteria and
microalgae which are capable to perform the specific function. Some of them have
the unique capability to take the sugar and convert it into biofuel, whereas many
microalgae contain natural oil content greater than 50% (Zhu et al. 2008). There are
several examples of microbial species used in the conversion of biomass.
Echinodontium taxodii can reduce 30% lignin materials of bamboo tree in
30 days. This fungal species can grow at temperature range from 25 to 35
C
(Philbrook et al. 2013). Ceriporiopsis subvermispora has very good biomass degradation properties. It can degrade 45% lignin materials of corn stover in 30 days
(Philbrook et al. 2013). Some bacterial species are also used in the biofuel production. There are some examples of ethanol-producing bacterial species such as
Escherichia coli (Romero-Garcia et al. 2016), T. reesei (Huang et al. 2014), and
Caldicellulosiruptor bescii (Singh et al. 2020d; Chung et al. 2014). There are some
examples of biobutanol-producing microorganisms like Clostridium acetobutylicum
(Lutke-Eversloh and Bahl 2011) and Pseudomonas putida (Nielsen et al. 2009). In
brief, we can say that engineered microorganisms are the factory for the biofuel
production and at the same time it fits to our sustainable energy source (Clomburg
and Gonzalez 2010; Fatma et al. 2018). There are several methods to get biofuel
from microorganisms, and more research and attention of scientist are required for
them to become ready for future use. We also discussed in this chapter about major
microbial groups (cyanobacteria and microalgae) and their importance in bioenergy
production.
2.3.1 Cyanobacteria
Cyanobacteria belong to the kingdom Monera. The member of cyanobacteria contains a photosynthetic pigment which is a different feature of cyanobacteria from
36
V. Singh et al.
sources of bioenergy (Fu et al. 2016). These organisms produce several types of
bioenergy such as bioelectricity, biohydrogen, biomethanol, bioethanol, and methane gas. Microbial fuel cell (MFC) is the better example of bioelectricity production
(Singh and Mishra 2020; Jin et al. 2014; Ni and Sun 2009). Microalgae are
considered as a good source of bioethanol and biomethanol, and these products
are used as additives in the diesel in present days and also considered as an
alternative option of fossil fuel in the future (Xue et al. 2017; Lutke-Eversloh
2014; Hou et al. 2013). Biohydrogen is considered as a clean and eco-friendly fuel
because it produces zero waste after burning. Various types of microorganisms
(microalgae and bacteria) produce biohydrogen during their growth (Azwar et al.
2014; Saifuddin and Priatharsini 2016). Microorganisms such as algae produce
bio-oil. Bio-oils also produce various types of plant and agriculture biomass. Microorganisms such as bacteria and fungi produce extracellular enzymes involved in the
conversion of biomasses into bio-oils. Biogas is considered as an eco-friendly fuel
and has applications in various fields. Biogas is produced during the bioconversion
of biomass by methanogenic bacteria (Senger 2010; Gowen and Fong 2010; Himmel
et al. 2007). The best alternative for that is microorganism like cyanobacteria and
microalgae which are capable to perform the specific function. Some of them have
the unique capability to take the sugar and convert it into biofuel, whereas many
microalgae contain natural oil content greater than 50% (Zhu et al. 2008). There are
several examples of microbial species used in the conversion of biomass.
Echinodontium taxodii can reduce 30% lignin materials of bamboo tree in
30 days. This fungal species can grow at temperature range from 25 to 35
C
(Philbrook et al. 2013). Ceriporiopsis subvermispora has very good biomass degradation properties. It can degrade 45% lignin materials of corn stover in 30 days
(Philbrook et al. 2013). Some bacterial species are also used in the biofuel production. There are some examples of ethanol-producing bacterial species such as
Escherichia coli (Romero-Garcia et al. 2016), T. reesei (Huang et al. 2014), and
Caldicellulosiruptor bescii (Singh et al. 2020d; Chung et al. 2014). There are some
examples of biobutanol-producing microorganisms like Clostridium acetobutylicum
(Lutke-Eversloh and Bahl 2011) and Pseudomonas putida (Nielsen et al. 2009). In
brief, we can say that engineered microorganisms are the factory for the biofuel
production and at the same time it fits to our sustainable energy source (Clomburg
and Gonzalez 2010; Fatma et al. 2018). There are several methods to get biofuel
from microorganisms, and more research and attention of scientist are required for
them to become ready for future use. We also discussed in this chapter about major
microbial groups (cyanobacteria and microalgae) and their importance in bioenergy
production.
2.3.1 Cyanobacteria
Cyanobacteria belong to the kingdom Monera. The member of cyanobacteria contains a photosynthetic pigment which is a different feature of cyanobacteria from
36
V. Singh et al.