approaches (Azambuja et al. 2019; Lee and Seo 2019). There are several analytical
approaches such as biomass degradation using several enzymatic digestions, selection of bioreactor, as well as biodiesel conversion. Recently, genetic engineering is
also a hot topic for biodiesel research. In genetic engineering approaches, the
modification is done in the genetic level in several genes which are responsible for
the production of biomass-degrading enzymes. Metabolic engineering is also considered as a better option for fourth-generation biodiesel production. It is mainly
focused on increasing the fatty acid accumulation through fatty acid synthesis
pathway as well as decreasing the production of other macromolecules such as
protein and carbohydrates (Jeong et al. 2020; Chen et al. 2020a, b, c; Liang et al.
2020).
There are several methods like those of pyrolysis, micro-emulsification, dilution,
as well as transesterification that have been used for biodiesel production. This
method plays an effective role in the deduction of viscosity of triglycerides and
enhancement of the biodiesel production (Canakci and Sanli 2008). There are mainly
two types of process like biological or chemical involved in the transesterification
reaction. Chemical process is performed through homogeneous and heterogeneous
nanocatalysts and supercritical fluids (SCFs). These processes have a need for high
energy to complete the transesterification reaction or obtain the end products. Hence,
biological catalysts like lipases and laccase are considered as more appropriate for
the reaction called transesterification (Shah et al. 2004; Bajaj et al. 2010; Singh et al.
2020b).
In the environment, more than 99% of microorganisms are difficult to culture.
Metagenomic techniques overcome the disadvantage of cultivation process. It is the
direct extraction of microbial genetic DNA samples from environmental concerns.
Metagenomic libraries were formed for further analysis as well as its application in
the different areas (Asada et al. 2012). Isolation of genetic DNA as well as characterization of the microbial communities from the natural resources to grasp the
knowledge of human-health disease by extracting mouth, skin, gut sample as well
as the plant-microbe interaction by using samples of soil (Attwood et al. 2019).
Next-generation sequencing-based metagenomic study provides a platform to study
about the diversity of the microbial communities (Jünemann et al. 2017; Zhou et al.
2015). It provides the characterization and function of microbes in the environment.
Metagenomic analysis takes place by marker-dependent sequencing and shotgun
sequencing using next-generation sequencing method. Metagenomic approaches
were used in the identification of the microbial enzymes for biodiesel production.
Approaches of the metagenomics are microbial analysis with the application of
industrial enzymes in biodiesel formation like microbial lipase from that of target
screening (Alves et al. 2018). These enzymes show an effective role in the degradation of biomass as well as are applicable in the transesterification reaction. This
chapter mainly compiled the overview of biodiesel production, sources of biodiesel,
methods for production, as well as metagenomic approaches for biodiesel
production.
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N. Singh et al.
approaches such as biomass degradation using several enzymatic digestions, selection of bioreactor, as well as biodiesel conversion. Recently, genetic engineering is
also a hot topic for biodiesel research. In genetic engineering approaches, the
modification is done in the genetic level in several genes which are responsible for
the production of biomass-degrading enzymes. Metabolic engineering is also considered as a better option for fourth-generation biodiesel production. It is mainly
focused on increasing the fatty acid accumulation through fatty acid synthesis
pathway as well as decreasing the production of other macromolecules such as
protein and carbohydrates (Jeong et al. 2020; Chen et al. 2020a, b, c; Liang et al.
2020).
There are several methods like those of pyrolysis, micro-emulsification, dilution,
as well as transesterification that have been used for biodiesel production. This
method plays an effective role in the deduction of viscosity of triglycerides and
enhancement of the biodiesel production (Canakci and Sanli 2008). There are mainly
two types of process like biological or chemical involved in the transesterification
reaction. Chemical process is performed through homogeneous and heterogeneous
nanocatalysts and supercritical fluids (SCFs). These processes have a need for high
energy to complete the transesterification reaction or obtain the end products. Hence,
biological catalysts like lipases and laccase are considered as more appropriate for
the reaction called transesterification (Shah et al. 2004; Bajaj et al. 2010; Singh et al.
2020b).
In the environment, more than 99% of microorganisms are difficult to culture.
Metagenomic techniques overcome the disadvantage of cultivation process. It is the
direct extraction of microbial genetic DNA samples from environmental concerns.
Metagenomic libraries were formed for further analysis as well as its application in
the different areas (Asada et al. 2012). Isolation of genetic DNA as well as characterization of the microbial communities from the natural resources to grasp the
knowledge of human-health disease by extracting mouth, skin, gut sample as well
as the plant-microbe interaction by using samples of soil (Attwood et al. 2019).
Next-generation sequencing-based metagenomic study provides a platform to study
about the diversity of the microbial communities (Jünemann et al. 2017; Zhou et al.
2015). It provides the characterization and function of microbes in the environment.
Metagenomic analysis takes place by marker-dependent sequencing and shotgun
sequencing using next-generation sequencing method. Metagenomic approaches
were used in the identification of the microbial enzymes for biodiesel production.
Approaches of the metagenomics are microbial analysis with the application of
industrial enzymes in biodiesel formation like microbial lipase from that of target
screening (Alves et al. 2018). These enzymes show an effective role in the degradation of biomass as well as are applicable in the transesterification reaction. This
chapter mainly compiled the overview of biodiesel production, sources of biodiesel,
methods for production, as well as metagenomic approaches for biodiesel
production.
108
N. Singh et al.