Composition analysis and application of degradation products of whole feathers through a large scale of fermentation

Effects of various substances on the binding of keratin monomers to S. maltophilia DHHJ cells for the induction of keratinase production

Biodegradation effectiveness of S. maltophilia DHHJ is determined by its ability to attach to the hydrolyzed feather keratin monomers. This binding capacity can be influenced by many components in the culture medium. Keratin monomers from feathers or those produced by gene overexpression can induce keratinase production in S. maltophilia DHHJ, and several proteases lack the ability to degrade keratin fragments and cysteines. In this study, we co-incubated FITC-labelled keratin monomers with S. maltophilia DHHJ cells in the presence of BSA, DNA, ATP, and several metal ions, and measured fluorescence values and keratinase activity. BSA was found to compete with keratins for cell binding sites, resulting in less keratinase production. DNA did not interfere with cellular binding to keratins revealing unchanged keratinase level. ATP, along with metal ions, enhanced the cellular binding capacity to keratins and increased the production of keratinase by S. maltophilia DHHJ. Fragments of keratin monomers degraded by proteases reduced the ability of cells to bind to keratin and affected enzyme production. Cysteine, a characteristic amino acid of feather keratin, did not have an effect on cellular binding to keratin monomer or on keratinase production. This study will facilitate the tweaking of catalytic parameters to improve feather biodegradation by S. maltophilia DHHJ.

Genome-wide analysis of Keratinibaculum paraultunense strain KD-1 T and its key genes and metabolic pathways involved in the anaerobic degradation of feather keratin

Keratinibaculum paraultunense strain KD-1 ^T (= JCM 18769 ^T = DSM 26752 ^T) is a strictly anaerobic rod-shaped bacterium. Under optimal conditions, feather keratin can be completely degraded by strain KD-1 within 24 h. Genomic sequencing showed that the genome was a single circular chromosome consisting of 2,307,997 base pairs (bp), with an average G + C content of 29.8% and no plasmids. A total of 2308 genes were annotated, accounting for 88.87% of the genomic sequence, and 1495 genes were functionally annotated. Among these, genes Kpa0144, Kpa0540, and Kpa0541 encoding the thioredoxin family members were identified, and may encode the potential disulfide reductases, with redox activity for protein disulfide bonds. Two potential keratinase-encoding genes, Kpa1675 and Kpa2139, were also identified, and corresponded to the ability of strain KD-1 to hydrolyze keratin. Strain KD-1 encoded genes involved in the heterotrophic metabolic pathways of 14 amino acids and various carbohydrates. The metabolic pathways for amino acid and carbohydrate metabolism were mapped in strain KD-1 based on KEGG annotations. The complete genome of strain KD-1 provided fundamental data for the further investigation of its physiology and genetics.

Microbial degradation of poultry feather biomass in a constructed bioreactor and application of hydrolysate as bioenhancer to vegetable crops

Bioconversion of recalcitrant keratinous biomass is one of the greatest ways to utilize products of feather hydrolysis and recycle them into bionetwork. Present study revealed 87% degradation of poultry feathers within 48 h in a constructed bioreactor using Chryseobacterium sp. RBT. The resulting feather hydrolysate (FH) was rich in soluble protein (3.56 ± 0.18 mg/ml), amino acids (3.83 ± 0.20 mg/ml), and macro and micro nutrients like N (8.0302%), P (0.3876%), K (0.5532%), Cu (0.0684%), Mg (0.8078%), Mn (0.2001%), Ca (0.4832%), Zn (0.0442%), and Fe (0.0330%). HPTLC analysis of FH revealed presence of tryptophan, cysteine, methionine, phenylalanine, glycine, valine, tyrosine, lysine, leucine, and serine as the primary amino acids. Field studies were conducted to apply FH as the bioenhancer to commercially important crops like brinjal and chilli through root drenching (20%, v/v). FH showed positive impact on the growth and development of plants along with early flowering and improved crop yield. In addition, nutritional quality of brinjal and chilli in terms of protein, amino acids, reducing sugars, phenolics, flavonoids, and antioxidant was elevated. Therefore, promotion and utility of by-products generated in feather degradation would be an effective strategy focusing on sustainable agricultural practices and problems associated with the waste management.

Beyond plucking: Feathers bioprocessing into valuable protein hydrolysates

The livestock production and subsequent processing of meat results in huge quantities of solid waste such as viscera, bones, skin and keratin-rich materials, including feathers, hair, wool, claws and hooves. In particular, the continuous growth of poultry industry generates massive amounts of feathers as major waste material. The conversion of such by-products into materials with increased value has been studied. Hydrothermal, chemical or biological approaches have been investigated to achive effective conversion of highly recalcitrant proteins that are abundant in animal waste, but increasing interest is devoted to the development of biotechnological methods. The processing of feathers and other by-products into protein hydrolysates may have industrial and commercial significance. Therefore, this review comprehensively addresses the postulated applications of hydrolysates obtained from keratinous biomasses. Examples on the utilization of feather hydrolysates as organic soil fertilizers, feed ingredients, cosmetic formulations and biofuel production are described in the literature. Microbial feather hydrolysis can generate bioactive peptides as well. The use of protein-rich waste from meat industry to produce hydrolysates with biological activities constitutes a point of utmost interest for development of functional ingredients with elevated value.

Protein engineering to enhance keratinolytic protease activity and excretion in Escherichia coli and its scale-up fermentation for high extracellular yield

Escherichia coli is one kind of the simple and excellent biosystem to overexpress heterologous enzymes, such as keratinolytic protease, an excellent enzyme to hydrolyze keratin substrate for broad industrial application. However, protein expression in E. coli frequently faces some problems such as inactive and inclusion body formation. This work described a series of protein engineering strategies of N-terminal propeptide replacement and site-directed mutagenesis to modify this enzyme activity and production. Site-directed mutagenesis (S180G/Y215S) on N-terminal propeptide altered mutant contributed to the highest specific activity (4725 ± 65 U/mg, more than 1300 U/mg improvement than wild-type enzyme). This comprehensive mutation also achieved 2.5-fold improvement of extracellular enzyme yield in shake-flask level. The fermentation strategies about optimizing glycerol feeding and inducing point in scale-up bioreactor resulted in tremendous leakage of keratinolytic protease (954 mg/L extracellular yield within 48 h, about 9.26-fold higher than the original shake-flask level) as well as cell lysis. Although this proposed strategy faces a major challenge to maintain cell integrity or viability, it still exists the opportunity to realize other enzymes extracellular expression in E. coli system and simplify downstream processing to meet the industrial application.

Secretory expression and purification of Bacillus licheniformis keratinase in insect cells

The keratinase (kerA) gene from Bacillus licheniformis PWD-1 was expressed and purified in insect cells. First, the sequence encoding Ker-His-Flag was designed based on the amino acid sequence of the protein and peptide and codon optimization in order to ensure the high expression in insect cells. In the next step, the synthetic DNA was inserted into the pUC57 vector and then sub-cloned in the pFastBac™-1 donor vector by BamHI/HindIII restriction sites. The constructed vector was transformed to E. coli DH10Bac™ cell to generate recombinant bacmid carrying Ker-His-Flag. Recombinant viruses were produced by infecting insect Spodoptera frugiperda (Sf9) cells with bacmid DNA and used for proteins production. Target proteins were purified from the cell supernatants by Ni²⁺-NTA affinity chromatography and evaluated by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) and western blot. The purified product contained two peptides with molecular weights of 38 kDa and 30 kDa and had an optimal pH and temperature at 8.0 and 45°C for keratinolytic activity, respectively. The final product had a specific activity of about 635 U/mg. In summary, we have demonstrated that the open reading frame containing recombinant Ker-His-Flag was expressed and secreted by leader peptide of mellittin from Apis mellitera in insect cells and affinity purification through 8His-Flag tag. It presents an alternative technology for producing keratinases. To our knowledge, it was the first report on the expression of functional keratinase from Bacillus licheniformis in insect cells system.

Synergistic effect of Chryseobacterium gleum sp. SUK with ACC deaminase activity in alleviation of salt stress and plant growth promotion in Triticum aestivum L

Soil salinity is major abiotic stresses affecting morphological, biochemical and physiological processes of plant growth. Chryseobacterium gleum sp. SUK isolated from salt-stressed soil exhibited ACC (1-aminocyclopropane-1-carboxylate) deaminase activity with IAA (indole acetic acid), siderophore, ammonia, hydrogen cyanide production, 2% salt tolerance and fungal cell wall degrading enzyme production (cellulase, protease). The isolate also showed a poultry feather degrading activity which is the main waste material of poultry industry and opulent source of proteins, amino acids, nitrogen, phosphorous, calcium, potassium, manganese, zinc and copper. Application of feather-degraded lysate with the degrading isolate, C. gleum sp. SUK denotes triple role of bioformulation to surmount salinity stress, management of poultry waste disposal and utilization of feathers degraded products as a biostimulant for better growth of plants as well as strain SUK having multifarious plant growth promoting traits. Wheat crops exposed to salt stressor were inoculated with studied bioformulation. Results of plant analysis showed improvement in root and shoot length, fresh and dry weight, chlorophyll, proteins, amino acids, phenolics, flavonoids content and decreased level of proline. In addition, Na⁺ uptake was decreased and K⁺ uptake was increased. Therefore, application of novel bioformulation could increase the yield of crops by ameliorating growth of plants and alleviating the salinity stress.

Surface display of a bifunctional glutathione synthetase on Saccharomyces cerevisiae for converting chicken feather hydrolysate into glutathione

The low economic profits of feather recycling lead that the large amount of feathers is currently discarded in China. To convert feather hydrolysates into GSH with high values, surface display of the bifunctional glutathione synthetase encoded by gcsgs from Streptococcus thermophilus on Saccharomyces cerevisiae and the potential in glutathione (GSH) production from feather hydrolysates were studied. The surface-displayed GCSGS could be used to convert feather hydrolysates into GSH. Results showed that 10 g/l of feather was converted into 321.8 mg/l GSH by the Trichoderma atroviride F6 and surface-displayed GCSGS in the study. Compared with production of intracellular GSH by S. cerevisiae from amino acids or feather hydrolysate, the concentration of GSH in the study was higher, and purification of GSH was more feasible. Due to the glycolytic pathway, the S. cerevisiae was used to generate ATP and cheap feather hydrolysate as precursors, the process for GSH production based on surface-displayed GCSGS is cheap and feasible. The process showed the potential to convert feather hydrolysates into GSH on an industrial scale.

A novel source of biofertilizer from feather biomass for banana cultivation

Feather waste is a promising protein biomass available as by-product from poultry processing was found to be rich in peptides, amino acids, and minerals like nitrogen, phosphorus, potassium, calcium, magnesium, iron, manganese, zinc, and copper. Soil and foliar application of these products, besides representing a sustainable solution to the problem of feather disposal, may also represent an effective strategy to tackle the environmental effluence. As a consequence, they were also found to be very attractive in elevating the protein, amino acids, reducing sugar, total chlorophyll, and proline content of plants. On the other side, fertilizing effect enhanced the antioxidant potential of banana fruit which was assessed using 2, 2-diphenyl-1-picrylhydrazyl, ferric reducing/antioxidant power, and N, N-dimethyl-p-phenylendiamine. This was associated with considerably higher antioxidant contents like total phenolics and flavonoids. Therefore, the application of this organic amendment could promote and improve the agro-ecosystem, human health; soil biological activities, and at the same time enhance the production of plant or products rich in bioactive substances.

Feather keratin hydrolysates obtained from microbial keratinases: effect on hair fiber

Background

Hair is composed mainly of keratin protein and a small amount of lipid. Protein hydrolysates, in particular those with low molecular weight distribution have been known to protect hair against chemical and environmental damage. Many types of protein hydrolysates from plants and animals have been used in hair and personal care such as keratin hydrolysates obtained from nails, horns and wool. Most of these hydrolysates are obtained by chemical hydrolysis and hydrothermal methods, but recently hydrolyzed hair keratin, feather keratin peptides, and feather meal peptides have been obtained by enzymatic hydrolysis using Bacillus spp in submerged fermentation.

Results

Keratin peptides were obtained by enzymatic hydrolysis of keratinases using Bacillus subtilis AMR. The microorganism was grown on a feather medium, pH 8.0 (1% feathers) and supplemented with 0.01% of yeast extract, for 5 days, at 28°C with agitation. The supernatant containing the hydrolysates was colleted by centrifugation and ultra filtered in an AMICON system using nano–membranes (Millipore – YC05). The Proteins and peptides were analyzed using HPTLC and MALDI-TOF-MS. Commercial preparations of keratin hydrolysates were used as a comparative standard. After five days the feather had been degraded (90-95%) by the peptidases and keratinases of the microorganism. MALDI-TOF mass spectrometry showed multiple peaks that correspond to peptides in the range of 800 to 1079 Daltons and the commercial hydrolysate was in the range of 900 to 1400 Da. HPTLC showed lower molecular mass peptides and amino acids in the enzymatic hydrolysate when compared with the commercial hydrolysate . A mild shampoo and a rinse off conditioner were formulated with the enzymatic hydrolysate and applied to hair fibers to evaluate the hydration, with and without heat, using a Corneometer® CM 825. The hydration was more efficient with heat, suggesting a more complete incorporation of hydrolysates into the fibers. Scanning Electron Microscopy showed deposits of organic matter in the junction of the cuticles that probably collaborates to the sealing of the cuticles, increasing the brightness and softness.

Conclusions

These results show that the enzymatic method to produce keratin peptides for hair care products is an attractive and eco- friendly method with a great potential in the cosmetic industry.