The utilization of feathers as a material has been identified
in various fields, but several quantity of feathers are still
liberated into the environment without the application of
necessary treatment. Feathers have been recognized as one
of the main sources of contaminant which might be linked to
their recalcitrant attributes (Shanmugasundaram et al. 2018).
Moreover, most of the feathers on which treatment has not
been applied could harbor numerous pathogenic microorganisms and liberate numerous contaminants such as
ammonia, hydrogen sulfide, nitrous oxide which have been
identified as a potential hazard to people’s health and environment (Tamreihao et al. 2019). Hence, the transfiguration
of these poultry feathers into value-added products using
economics techniques has drawn the attention of numerous
researchers (Kang et al. 2018). The application of beneficial
microorganism has been identified as one of the environmental and sustainable approaches that could be used for
effective alteration of these feathers into value-added products such as animal feeds and biofertilizers. Hence, this
chapter intends to provide a detailed information on the
recent advances in technology involved in the biological
transformation of poultry waste into useful products.
2 Microbial Degradation of Feathers
It has been observed that the nature of keratin-rich wastes,
which include feathers, has several resistance, especially
through the action of some enzymes such as proteases,
which showed that keratin is not build up in nature. This
indicated that microorganisms are responsible for the process of biodegradation of keratin-containing substances
(Williams and Shih 1989). It has been validated that
numerous microorganisms possess the capability to degrade
numerous wastes that secrete proteolytic enzymes and keratinolytic, which all constitute keratinases enzymes (Tamreihao et al. 2019; Williams and Shih 1989). Typical
examples of these microorganisms include fungi, bacteria,
and actinomycetes (Bohacz and Korniłłowicz-Kowalska
2019). Several microorganisms have been identified to be
domicile from many environs that are rich in keratin which
have been utilized for biodegradation of wastes that possess
keratin especially from various sources (Chaturvedi et al.
2014).
3 Modes of Action Involved in the Biological
Degradation of Microorganisms
Structural investigations which have utilized keratinases for
the biological degradation of feathers when carried out indicated that keratinases might not have sufficient action to
disintegrate the disulfide bonds. Numerous modes of action
have been proposed and identified to entail two major steps
which include keratinolytic procedure, such as proteolysis,
and sulfitolysis (Bohacz and Korniłłowicz-Kowalska 2019).
Sulfitolysis is the stage where the disulfide bonds are separated and the process of proteolysis is required to split the
protein (Lange et al. 2016). The reduction of the disulfide
bonds majorly by the enzymes includes reducing agents and
sulfide reductases that entail sulfites are required for conformational alteration of keratinase and ensures that the sites are
presented for the breaking down of keratinase (Yamamura
et al. 2002). It has been established that the application of
crude enzymes shows a greater keratin degradation when
compared to the purified enzymes. Moreover, it has been
affirmed that the presence of two enzymes is required for the
breaking down of keratin (Lange et al. 2016).
One of them is required for the generation of keratin,
especially that are found in the decreased form so as to break
the sites that are shown to the protease. The following steps
are involved during the keratin degradation: proteolysis,
deamination and sulfitolysis (Yu et al. 1968). Moreover, it
has been observed that fungi and bacteria possess different
modes of action for the breaking down of keratin while the
presence of their keratinase could break the polyproteins.
Furthermore, proteolysis, mechanical destruction and sulfitolysis perform significant function during keratinase
biodegradation especially by the fungi (Bohacz and
Korniłłowicz-Kowalska 2019).
4 Bioconversion of Poultry into Useful
Products
There are several products produced through the application
of biological degradation of waste into biostimulants,
biofertilizer, bioherbicides, biopesticides, animal feeds,
enzymes and biocatalyst. The list of these useful products
was provided in Fig. 1.
5 Bioconversion of Poultry Waste
into Biostimulants and Biofertilizer
Ertani et al. (2013) revealed that utilization of biostimulants
in different industrial sectors has recently gained significant
attention among players of the industries across the globe.
The authors further described biostimulants as a bioactive
material or microorganisms with immense potential when
used in minute quantity with the ability to stimulate nutrients
uptake, protect against internal and external oxidative damage plus promoting plant growth and development. Biostimulants have the capacity to activate enzymes activity,
stimulate hormone production, and regulate various diverse
physiological processes in plant.
338
C. O. Adetunji et al.
in various fields, but several quantity of feathers are still
liberated into the environment without the application of
necessary treatment. Feathers have been recognized as one
of the main sources of contaminant which might be linked to
their recalcitrant attributes (Shanmugasundaram et al. 2018).
Moreover, most of the feathers on which treatment has not
been applied could harbor numerous pathogenic microorganisms and liberate numerous contaminants such as
ammonia, hydrogen sulfide, nitrous oxide which have been
identified as a potential hazard to people’s health and environment (Tamreihao et al. 2019). Hence, the transfiguration
of these poultry feathers into value-added products using
economics techniques has drawn the attention of numerous
researchers (Kang et al. 2018). The application of beneficial
microorganism has been identified as one of the environmental and sustainable approaches that could be used for
effective alteration of these feathers into value-added products such as animal feeds and biofertilizers. Hence, this
chapter intends to provide a detailed information on the
recent advances in technology involved in the biological
transformation of poultry waste into useful products.
2 Microbial Degradation of Feathers
It has been observed that the nature of keratin-rich wastes,
which include feathers, has several resistance, especially
through the action of some enzymes such as proteases,
which showed that keratin is not build up in nature. This
indicated that microorganisms are responsible for the process of biodegradation of keratin-containing substances
(Williams and Shih 1989). It has been validated that
numerous microorganisms possess the capability to degrade
numerous wastes that secrete proteolytic enzymes and keratinolytic, which all constitute keratinases enzymes (Tamreihao et al. 2019; Williams and Shih 1989). Typical
examples of these microorganisms include fungi, bacteria,
and actinomycetes (Bohacz and Korniłłowicz-Kowalska
2019). Several microorganisms have been identified to be
domicile from many environs that are rich in keratin which
have been utilized for biodegradation of wastes that possess
keratin especially from various sources (Chaturvedi et al.
2014).
3 Modes of Action Involved in the Biological
Degradation of Microorganisms
Structural investigations which have utilized keratinases for
the biological degradation of feathers when carried out indicated that keratinases might not have sufficient action to
disintegrate the disulfide bonds. Numerous modes of action
have been proposed and identified to entail two major steps
which include keratinolytic procedure, such as proteolysis,
and sulfitolysis (Bohacz and Korniłłowicz-Kowalska 2019).
Sulfitolysis is the stage where the disulfide bonds are separated and the process of proteolysis is required to split the
protein (Lange et al. 2016). The reduction of the disulfide
bonds majorly by the enzymes includes reducing agents and
sulfide reductases that entail sulfites are required for conformational alteration of keratinase and ensures that the sites are
presented for the breaking down of keratinase (Yamamura
et al. 2002). It has been established that the application of
crude enzymes shows a greater keratin degradation when
compared to the purified enzymes. Moreover, it has been
affirmed that the presence of two enzymes is required for the
breaking down of keratin (Lange et al. 2016).
One of them is required for the generation of keratin,
especially that are found in the decreased form so as to break
the sites that are shown to the protease. The following steps
are involved during the keratin degradation: proteolysis,
deamination and sulfitolysis (Yu et al. 1968). Moreover, it
has been observed that fungi and bacteria possess different
modes of action for the breaking down of keratin while the
presence of their keratinase could break the polyproteins.
Furthermore, proteolysis, mechanical destruction and sulfitolysis perform significant function during keratinase
biodegradation especially by the fungi (Bohacz and
Korniłłowicz-Kowalska 2019).
4 Bioconversion of Poultry into Useful
Products
There are several products produced through the application
of biological degradation of waste into biostimulants,
biofertilizer, bioherbicides, biopesticides, animal feeds,
enzymes and biocatalyst. The list of these useful products
was provided in Fig. 1.
5 Bioconversion of Poultry Waste
into Biostimulants and Biofertilizer
Ertani et al. (2013) revealed that utilization of biostimulants
in different industrial sectors has recently gained significant
attention among players of the industries across the globe.
The authors further described biostimulants as a bioactive
material or microorganisms with immense potential when
used in minute quantity with the ability to stimulate nutrients
uptake, protect against internal and external oxidative damage plus promoting plant growth and development. Biostimulants have the capacity to activate enzymes activity,
stimulate hormone production, and regulate various diverse
physiological processes in plant.
338
C. O. Adetunji et al.