Poultry is one of the fast-growing agricultural sub-sector, specially in developing countries. Subsequent growth of poultry meat processing generates a massive amount of feathers as major waste material. If these feathers ended up in dumping sites, it demands increased land area as well as uncontrollable toxic gas production. However, as a by-product that contains a significant amount of keratine, it can be utilized as an abundant and renewable raw material to obtain protein hydrolysates which have industrial and commercial significance.

1. Feather
bioprocessing
and
novel applications
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2. Poultry feather: waste or raw material ?
• Chicken meat processing – fast growing industry
• Worldwide around 5 million tons of feathers are
generated annually
• 90% of the feather mass represent keratin
• Feathers; abundant and renewable resource to obtain
protein hydrolysates
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3. Keratin structure in feather
• High cysteine content in the primary sequence of keratin
• Predominant at the protein N- and C-terminal regions
• ∝- Keratins – 41 – 67 %
• 𝛽- Keratin – 33 – 38 %
• ∝- Keratins are superior in rigidity and resistant compared to
𝛽- Keratins
• It has compact conformation and highly stable nature –
disulfide bridges among cysteine residues
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4. Hydrolysis of feathers
Chemical hydrolysis Hydrothermal hydrolysis Microbial / enzymatic
hydrolysis
• Feathers are treated with
strong acids/ alkali
• Simple and fast
• High hydrolysate yield
• Destroy some useful amino
acids
• High energy demand
• Steam explosion
• Microwave treatment
• Superheated water treatment
• Do not use toxic chemicals
• Extraction yield, composition
of a.a. are highly depend on
the process parameters
• Bac. cultures /crude enzymes/
partially purified enzyme
preparations are used
• Preservation of amino acids
• Easiness of controlling the degree
of hydrolysis
• Easiness of inactivating enzymes
after the process
• Low demand of energy
• Eco-friendly
• Slow
• Expensive
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5. Feather bioprocessing
• Specific process that use complete living cells or their components like enzymes
to obtain desire products.
• This process takes place in the bioreactor which provide optimum environment
for reaction to take place
• Hydrolysis of feathers can be done with
• Solid State Fermentation (SSF)
• Submerge Fermentation (SmF)
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6. Novel applications
of keratin
hydrolysates
Raw material for
animal feed
Organic fertilizer
production
Ingredient in microbial
culture media
Production of
bioactive peptides
Bio fuel production
Raw material for cosmetics
and
pharmaceutical industry
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7. Organic fertilizer production
Keratinous
material
Hydrolysate production
Application as fertilizers
Method Agent (conditions)
Whole
feathers
Microbial
(SmF)
Amycolatopsis sp. MBRL 40
(5 g/L feathers, 30 C, 120 h)
Rice root and shoot growth similar to
urea
Thermoactinomyces sp. RM4
(20 g/L feathers, 60 C, pH 10.0, 96 h)
↑ germination and roots mass of
gram
Bacillus polymyxa B20
(10 g/L feathers, 30 C, pH 7.2, 144 h)
↑ fresh mass and leaf chlorophyll
content of tomato, cucumber, white
cabbage plants
Milled
feathers
Microbial
(SmF)
Bacillus amyloliquefaciens 6B
(5 g/L milled feathers, 37 C, pH 7.2, 12 h)
↑ mung bean germination and
growth in similar to reference
fertilization
Bacillus licheniformis ASU (10 g/L milled
feathers, 30 C, pH 7.2, 120 h)
↑ growth, roots and shoot, number
and weight of root nodules in bean
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8. • Feather hydrolysates contain
Low C /N ratio caused rapid mineralization of organic Nitrogen (N) by microorganisms and
releasing mineral N which is easily uptake by plants.
• Feather hydrolysate contains tryptophan – essential to the synthesis IAA
hormone
• Several keratinolytic bacterial used for bioprocessing have the ability to produce IAA using
feather substrate
• Improve the beneficial microbial population
• Ammonifying bacteria
• Nitrifying bacteria
• Nitrogen-fixing bacteria
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9. • Traditional method to prepare feather meal - hydrothermal processing
• ↓ Digestibility
• ↓ Bioavailability
• Lack of important amino acids due to high processing temperatures and
pressure
• Formation of lanthionine, lysinoalabine like anti nutritional factors
• Bioprocessing methods - effectively convert keratinous materials into animal
feed
• ↑ Digestibility and biological value
• Enhanced amino acid profile
Raw material for animal feed
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10. Hydrolysis of keratinous materials and potential applications of hydrolysates as
animal feed
Keratinous
material
Hydrolysate production
Application as animal feed
Method Agent (conditions)
Whole
feathers
Microbial
(SmF)
Vibrio sp. kr2
(60 g/L feathers, 30 C, pH 6.0, 168 h)
↑ digestibility and BV than feather meal
Replacement of 20% soybean protein in
Wistar rat’s diets supplemented with
methionine
Chryseobacterium sp. kr6
(50 g/L feathers, 30 C, 120 h)
Amino acids enrichment, ↑ digestibility and
BV than feather meal (in vitro)
Bacillus sp. MPTK6
(30 g/L feathers; 30 C, pH 10, 48 h)
↑ digestibility than whole feathers (in vitro)
Milled
feathers
Microbial
(SmF)
Bacillus pumilus A1
(50 g/L milled feathers, 45 C, pH 10.0, 48 h)
↑ growth (weight) of Wistar rats by addition
of 2.5% - 5.0% of feather hydrolysate
Bacillus licheniformis PWD-1
(milled feathers : liquid bacterial culture =
1:4, 50 C, 120 h)
Replacement of up to 5% soybean protein in
broiler diets; supplementation with amino
acids resulted in growth curves identical to
soybean protein 10

11. Ingredient in microbial culture media
• In microbiology, peptones is used as a substrate to culture microorganisms.
• Peptones are expensive
• Protein hydrolysates of feather waste - alternative organic nitrogen for culturing MO
• Chemical hydrolysis gives superior protein hydrolysates which are suitable as an
ingredient in culture media.
• Because ↑ [soluble peptides] available in hydrolysates obtained by alkaline hydrolysis than
bioprocessing.
• There is new trend to apply thermo-chemical approaches with microbial/enzymatic
methods to obtain peptones from keratinous materials.
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12. Hydrolysis of keratinous materials and potential applications of hydrolysates as
ingredients in microbial culture media
Keratinous
material
Hydrolysate production
Ingredient as culture media
Method Agent (conditions)
Whole
feathers
Microbial
(SmF)
Streptomyces sp. IF 5
(5 g/L feathers, 28 C, 72 h)
Organic substrate for growth of
Bacillus, Staphylococus aureus,
Streptomyces, Pseudomonas aeruginosa,
Proteus vulgaris, Aspergillus flavu
Enzymatic Partially purified keratinase from
Pseudomonas sp.P5 (24.9–31.9 g/L feathers,
1–2 U keratinase/mg feather, 50 C, pH 7.5,
24–48 h)
Organic substrate for Escherichia coli
growth
Thermo-
chemical
+
Enzymatic
Autoclaving with Na2SO3 (10 g/L feathers,
121 C, 20 min, 10 mM Na2SO3) +
lyophilized S. pactum DSM 40,530 crude
keratinase (8,000 U keratinase/g
feather/L/day, 50 C, pH 8.0, 24 h)
Cyanophycean biopolymer production
by
recombinant Escherichia coli
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13. Application in bio fuel production
• Methene is the energetic substance of biogas
which is originated from microbial degradation
of organic matters under anaerobic conditions CH4 is produced from Co2 and
H2 by hydrogenotrophic
methanogens
4
Methanogenesis
Homoacetogenic bacteria produce
acetic acid from CO2 and H2
3
Acetogenesis
Resulted monomers from hydrolysis are
converted into organic acids, alcohol and CO2
& H2O
2
Acidogenesis
Resulting amino acids, fatty
acids and simple sugars
1
Hydrolysis
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14. Hydrolysis of keratinous materials and potential applications of hydrolysates
for biofuel production
Keratinous
material
Hydrolysate production
Application for biofuel
Method Agent (conditions)
Whole
feathers
Microbial
(SmF)
B. licheniformis KK1
(feather: water = 1:2, 42 C, pH 7.2, 120 h)
↑ methane yield (12%) when added to
mesophilic anaerobic digesters
(38 C; 30 days)
Milled
feathers
Microbial
(SmF)
Bacillus sp. C4
(50–200 g/L milled feathers, 37 C, pH 7.0,
24–192 h)
↑ methane yield (55%) in comparison
to milled feathers at Mesophilic
anaerobic digesters
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15. Raw material for cosmetics
Feather hydrolysis by:
• Stenotrophomonas maltophilia DHHJ
• Has ability to enter the hair cortex and form transparent film on the hair surface
• Improving flexibility and strength of normal/ damaged hair.
• Bacillus subtilis AMR
• Has ability to improve hydration, softness and brightness of normal/
colored/ bleached hair
• Add to mild shampoos and rinse-conditioners
• Fervidobacterium islandicum AW-1
• Skin whitening agents
• Anti-melanogenic activity in murine melanoma cell line
• These proteins have ability to inhibit tyrosinase and terminate over production
of skin pigments. 15

16. Bioactive peptides derived from
keratinous materials
• Have specific amino acid sequences that contribute to
regulation & modulation of physiological functions
Antioxidant
Anti-hypertensive
Antidiabetic
Antimicrobial
• Keratins are rich in hydrophobic amino acid residues
- represent 50-60% of the polypeptide chain
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17. Bioactivities of protein hydrolysates produced from keratin-rich materials
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Keratinous
material
Hydrolysate production
Function
Method Agent (conditions)
Whole
feathers
Microbial
(SmF)
Kocuria rhizophila p3-3
(50 g/L feathers, 25 C, 96 h)
Radical scavenging
Fervidobacterium islandicum AW-1
(8 g/L feathers, 70 C, pH 7.0, 48 h)
radical scavenging
Chryseobacterium sediminis RCM-SSR-7
(50 g/L feathers, 30 C, pH 7.5, 84 h)
Radical scavenging
Milled
feathers
Microbial
(SmF)
Bacillus pumilus A1
(50 g/L feathers, 45 C, pH 10.0, 48 h)
Radical scavenging
Bacillus subtilis S1-4
(50 g/L milled feathers, 37 C, 72 h)
Radical scavenging

18. Summery
• Management of keratinous waste - problematic
• Bioprocessing of feathers - promising method
Eco-friendly
Less utilization of energy
• Use of different mo. cultures and enzymes in hydrolysis - end product with diverse
characteristics and applications
• There is huge potential to sustainably utilize these keratinous by-products
• New research and development works are needed to identify properties of bio-active
peptides in feather hydrolysates and effectively utilize them
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19. Reference
• Callegaro, K., Brandelli, A., & Daroit, D. J. (2019). Beyond plucking:
Feathers bioprocessing into valuable protein hydrolysates. Waste
Management, 95, 399–415.
https://doi.org/10.1016/j.wasman.2019.06.040
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20. Thank you !
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