Wool Hydrolysate Research Articles

Towards zero-waste processes: Waste wool derivatives as phosphate adsorbents and auxiliaries for textiles' natural dyeing.

The textile industry is a pillar of the manufacturing sector worldwide, but it still represents a significantly polluting production sector since it is energy-, water- and natural resource-intensive. Herein, waste wool that did not meet the technical requirements to be used for yarns and fabrics was recovered first to prepare materials for wastewater remediation, specifically for phosphate removal. The wool underwent an alkaline treatment, eventually saturated with FeCl3 and then left at room temperature or thermally treated to induce crosslinking/stabilisation, obtaining adsorbent panels. The main characterisation findings concerned the impact of alkaline treatment on morphology and structure; additionally, the samples with iron displayed a behaviour attributable to a crosslinking effect operated by Fe3+. Batch experiments showed that only samples with iron were efficient in phosphate adsorption, with a high removal percentage obtained in a wide pH range. Adsorption isotherms and kinetics were investigated, suggesting a complex system of interactions. Moreover, during the alkaline treatment necessary to prepare such wool-derived adsorbent panels, a significant amount of wool hydrolysates left in the solution was produced. These substances, in view of zero-waste procedures, were isolated and re-employed as dyeing auxiliaries. Preliminary results demonstrated that the wool hydrolysates enabled the dyeing of cotton with natural dyes, which is generally a tricky process.

Textile waste subjected to acid hydrolysis as raw materials for biogas production

Textile waste is a high-volume group of municipal waste that is difficult to dispose of due to synthetic additives and chemicals that give natural fibers the properties preferred by consumers. The paper presents a method of treating textile waste based on natural fibers (cotton and wool) with mineral acids and further biological conversion of obtained hydrolysates into biogas. It was found that the hydrolysates of cotton contain a pool of sugars (≥8 g/L of glucose), which are necessary for the growth of microorganism's consortium. The hydrolysates of the mixture of natural and synthetic fibers do not contain fermentation inhibitors (even when cotton was dotted with polyesters and polyamides), and the addition of an appropriate number of wool hydrolysates (up to 5 % v/v) favours the production of biogas. The results indicate that a moderate methane production from waste textiles composed of both cotton and synthetic materials can be achieved with no need of separation, which would significantly increase the cost of their processing.

Alkali hydrolysis of wool fibres using microwave irradiation as a recycling approach for handling wool-waste

The aim of the present work is to investigate the influence of microwave irradiation on alkali hydrolysis, under various thermochemical conditions, of wool fibres. This perspective seems to be a promising alternative for the valorization of wool waste. The reaction yield is calculated in every case in order to determine the optimum hydrolysis conditions. The solid residue, as well as the filtrate, are subjected to instrumental chemical analysis in order to identify and isolate useful products. The optimal conditions for the hydrolysis of wool resulted to be the use of 5% w/v NaOH, microwave treatment for 10 min in absence of phase-transfer catalyst. In addition, the analysis in the Pyrolysis-Gas Chromatography/Mass Spectrometry (Py-GC/MS) allowed the identification of certain small molecules like N2, H2S, NH3, C6H5OH, C4H9NO and larger ones like amino acids, such as alanine, cystine, proline, valine and leucine. Additionally, the content of wool hydrolysate was specified upon identifying several substituted products of tyrosine, proline and alanine amino acids. Liquid Chromatography–Orbitrap High-Resolution Mass Spectrometry (LC–Orbitrap HRMS) was also employed to identify the components present in the wool hydrolysate, detecting mainly various dipeptides as well as leucylproline and cysteic acid. In this light, the amino acids produced by wool alkali hydrolysis degradation could valorise the wool waste once inserted in industrial chemistry, as a prominent alternative for “greener” adhesives of two components, outlining by these means the feasibility of a practically sustainable circular economy.

Enzymatic dehairing of sheep skin: Recovery and characterization of commercially important wool hydrolysate and fats

Conventional dehairing methods in the traditional leather-making processes, consume large amounts of toxic chemicals and produce a toxic sludge/effluent, posing disposal challenges and consequently environmental pollution. The by-products of leather processing such as hair and fat, contain toxic chemicals. In this study, crude alkaline protease from <i>bacillus cereus strain 1-p, </i>was used to dehair sheepskin with up to 99.00% recovery of valuable wool and fat. The optimum temperature and pH for wool removal were found to be 30 <sup>°</sup>C and 11, respectively. The recovered wool was enzymatically hydrolyzed to obtain wool hydrolysate powder (48.1% yield). FTIR spectra of the wool hydrolysate showed the presence of amide A, I, and II absorption bands. Further, the amino acid analysis, revealed the presence of 15 amino acids, with glutamic acid (19.65 mole %), glycine (12.72 mole %), and leucine (9.42 mole %) being the most abundant. Fat was trans-esterified using methanol, in the presence of tert-butanol, and the resultant fatty acid methyl esters characterization was done using gas chromatography/mass spectrometry (GC/MS) analysis. GC/MS analysis showed the presence of 60 methyl esters corresponding to 60 fatty acids. The most abundant fatty acid was 9-octadecenoic (oleic) acid (41.64%), followed by hexa-decanoic (palmitic) acid (22.50%), and tetra-decanoic (myristic) acid (4.21%). Thermo-gravimetric analysis of the wool hydrolysate showed that it had good thermal stability. It is shown that crude alkaline protease extracted from <i>bacillus cereus strain 1-p</i> can completely eliminate the use of toxic sodium sulfide and lime in dehairing of skins/hide in tanneries, eliminating environmental pollution. Furthermore, the recovery of fat and wool using an eco-friendly enzymatic dehairing process can significantly reduce the pollution load in the effluent. The recovered wool and fats can be applied in the production of wool hydrolysate, which is high in protein content, amino acids and biodiesel.

The effect of wool hydrolysates on squamous cell carcinoma cells in vitro. Possible implications for cancer treatment.

Squamous cell carcinoma of the skin is the second most common cutaneous malignancy. Despite various available treatment methods and advances in noninvasive diagnostic techniques, the incidence of metastatic cutaneous squamous cell carcinoma is rising. Deficiency in effective preventive or treatment methods of transformed keratinocytes leads to necessity of searching for new anticancer agents. The present study aims to evaluate the possibility of using wool hydrolysates as such agents. Commercially available compounds such as 5-fluorouracil, ingenol mebutate, diclofenac sodium salt were also used in this study. The process of wool degradation was based on chemical pre-activation and enzymatic digestion of wool. The effect of mentioned compounds on cell viability of squamous carcinoma cell line and healthy keratinocytes was evaluated. The obtained data show a significantly stronger effect of selected wool hydrolysates compared to commercial compounds (p<0.05) on viability of cells. The wool hydrolysates decreased squamous cell carcinoma cells viability by up to 67% comparing to untreated cells. These results indicate bioactive properties of wool hydrolysates, which affect the viability of squamous carcinoma cells and decrease their number. We hypothesize that these agents may be used topically for treatment of transformed keratinocytes in actinic keratosis and invasive squamous skin cancer in humans.

Toxicity study of isolated polypeptide from wool hydrolysate

The cytotoxicity of wool polypeptide has been evaluated by both cell and animal models. Wool was dissolved in sodium hydroxide solution, the pH value of the solution was adjusted to 5.55 and the precipitate was harvested as wool polypeptide. The spray-dried polypeptide was collected as powders and characterized by SEM, FTIR and TG-DSC. The cell culturing results showed that wool polypeptide had no obvious negative effect on cell viability in vitro. Both acute oral toxicity and subacute 30-day oral toxicology studies showed that wool polypeptide had no influence on body weight, feed consumption, blood chemistry, and hematology at any dose levels. There were no treatment related findings on gross or detailed necroscopy, organ weights, organ/body weight ratios and histology. Our study indicated the absence of toxicity in wool polypeptide and supported its safe use as a food ingredient or drug carrier.

Key determinants affecting sheep wool biodegradation directed by a keratinase-producing Bacillus subtilis recombinant strain

OVAT (one variable at a time) approach was applied in this study to screen the most important physicochemical key determinants involved in the process of sheep wool biodegradation. The process was directed by a keratinase-producing Bacillus subtilis DB 100 (p5.2) recombinant strain. Data indicate that, sheep wool could be degraded efficiently in cultures incubated at 30°C, with initial pH of 7 with agitation at 150 rpm. Two times autoclaved alkali treated and undefatted chopped sheep wool is more accessible to biodegradation. B. subtilis recombinant cells could utilize sheep wool as a sole source of carbon and nitrogen. Sheep wool-based modified basal medium II, lacking NH₄Cl and yeast extract, could greatly support the growth of these bacterial cells. Sheep wool biodegradation was conducted efficiently in the absence of kanamycin consequently; high stability of the recombinant plasmid (p5.2) represents a great challenge upon scaling up this process. Three key determinants (sheep wool concentration, incubation time and inoculum size) imposing considerable constraints on the process are highlighted. Sheep wool-based tap water medium and sheep wool-based distilled water medium were formulated in this study. High levels of released end products, produced from sheep wool biodegradation are achieved upon using these two sheep wool-based water media. Data indicate that, sheep wool hydrolysate is rich in some amino acids, such as tyrosine, phenylalanine, lysine, proline, isoleucine, leucine, valine, aspartic acid and glutamic acid. Moreover, the resulting sheep wool hydrolysate contains soluble proteins of high and intermediate molecular weights. The present study demonstrates a feasible, cheap, reproducible, efficient and rapid biotechnological approach towards utilization of raw sheep wool waste through a recombinant bacterium.

Tyrosinase-Catalysed Coating of Wool Fibres With Different Protein-Based Biomaterials

The potential of tyrosinases to activate tyrosine residues of wool protein fibres for cross-linking with different materials like collagen, elastin and gelatine was assessed. Natural fibres like wool offer an excellent environment for the growth of micro-organisms when the conditions like moisture, oxygen and temperature are appropriate. Coating with collagen, a very useful biomaterial with bactericidal and fungicidal properties, could be used to improve the properties of wool-based materials, especially when applied in hygienically sensitive applications like in hospitals. Tyrosinases were shown to catalyse the oxidation of tyrosine residues in wool and wool hydrolysates as model substrates, as determined by UV-Vis spectroscopy. Structural differences of the surface were evident from the increase of the intensity in the NH bending and stretching regions in the spectra of NIR FT Raman analysis of the enzyme treated and grafted wool fibres. The durability of the coating was also shown by using FITC-labelled collagen that was bound to the wool fibres, even after severe washing. Additionally, antimicrobial properties were successfully imparted due to the collagen grafted on the wool fibres. The functional and mechanical properties of the treated wool fibres showed no significant changes.

Hydrolysed wool: A novel chelating agent for metal chelant-assisted phytoextraction from soil

Phytoextraction has revealed great potential, however it is limited by the fact that plants need time and nutrient supply and have a limited metal uptake capacity. Although the use of synthetic chelators, such as EDTA, enhances heavy metal extraction, it also produces the negative side effects of high phytotoxicity, as well as leaching of essential metals. The aim of this research was to investigate the application of wool, in mobilising metals and in improving the phytoextraction of metals-contaminated soil. We performed column experiments with 14 d and 7 d partially hydrolysed wool as chelating agent on a silty-loamy sand agricultural soil. In the column experiment the 14 d wool hydrolysate mobilised 68% of Cu in soil, whereas in the case of Cd it mobilised 5.5%. The model plant selected for the phytoextraction experiments was tobacco ( Nicotiana tabacum). The plant uptake of Cd and Cu, assisted by the application of 6.6 g kg −1 wool hydrolysate was increased by 30% in comparison to the control plants. The application of 13.3 g kg −1 wool hydrolysate enhanced the Cu uptake by up to 850%. Moreover, high leaching probability frequently observed when applying chelating agents, such as EDTA or ethylene diamine disuccinate (EDDS), were not detected. The use of hydrolysed wool therefore merits further investigation.

Chemical, microbiological and plant analysis of soil fertilized with alkaline hydrolysate of sheep’s wool waste

The effect of adding alkaline hydrolysate of sheep’s wool waste on the chemical and microbiological properties of a park soil (Sofia, Bulgaria) has been assessed in a 9 month laboratory experiment. The waste product contained 75–80% water-soluble materials: peptides, amino acids, salts, dyes, lipids, some carbohydrates, potassium ions, and it seemed likely that the hydrolysate obtained could be used as a harmless and valuable fertilizer in agriculture. It was demonstrated that the organic material positively influenced microbial soil populations and ryegrass growth. As the remaining partially degraded keratin is highly dispersed it should act as a slow release fertilizer thus feeding plants additionally. The results suggest that the wool hydrolysate is beneficial for improving soil characteristics and could successfully be used as alternative biofertilizer. The authors hope that by utilization of the keratin wastes, the environment around leather and fur plants could be influenced positively and that the expense of removing the wastes to controlled landfill sites and part of the expenses for sustaining the latter will be saved.

Chemical preparation of NaOH—Keratin hydrolysate for improving the nutritive value of wheat straw

Wool and chicken feathers were used as sources of keratin hydrolysates for enriching wheat straw in ruminant diets. The optimal conditions for the preparation of keratin hydrolysates from keratin concentrations of 2–12% were attained by hydrolysis of wool and feathers for 6–9 min at boil. The amino-acid profile of the white and black wool hydrolysates were similar, having 1.5–4 times greater amounts of glutamic acid, methionine, tyrosine, histidine and lysine than feather hydrolysates. Keratin hydrolysates of 8.5, 11.5 and 13.9% were sprayed on wheat straw at the rate of 100 ml 100 g −1. In-vitro dry-matter digestibilities were significantly ( P < 0.05) increased with 8.5% keratin-hydrolysate supplement, but no further improvement was noted with higher levels of supplement. The average in-vitro dry-matter digestibility of untreated wheat straw was 44.72%. However, this increased by 21.1–23.7% after treatment. Nitrogen loss from the hydrolysates during treatment ranged from 12 to 15%.

The Formation of Carbonyl Groups during Irradiation of Wool and Its Relevance to Photoyellowing

The carbonyl contents of wool fabrics have been determined by colorimetric analysis after partial acid hydrolysis. Irradiation of dry wool fabrics with simulated sunlight causes an increase in carbonyl content. The rate of production is approximately the same for unbleached, bleached, and fluorescently whitened fabrics, even though these fabrics yellow at markedly different rates. In contrast, irradiation of the same fabrics in water results in few additional carbonyl groups, although extensive yellowing occurs. Thus it seems unlikely that carbonyl groups are directly responsible for yellowing. However, the observation that hydrothermal yellowing of dry-irradiated wool is accompanied by a loss in carbonyl content leads us to suggest that carbonyl groups could be involved indirectly in yellowing. The keto acids present in partial acid hydrolysates of irradiated wool have been identified by reductive amination with sodium 3H-borohydride in ammonia solution, a reaction which converts keto acids to the corresponding 3H-amino acids. The formation of radiolabeled alanine, glycine, proline, serine, threonine, glutamic acid, and tyrosine provides evidence for the photo-oxidation of a number of amino acid residues during irradiation of wool.

Incorporation of [Me-3H]methionine into wool follicle proteins: a biochemical and ultrastructural study.

ABSTRACT The formation of the ‘low-sulphur’ group of proteins which constitutes more than half the cortical cell content of wool was investigated. Of the amino acids present in the low- and high-sulphur proteins isolated from wool, methionine is the only one which is exclusive to the low-S group. The incorporation of [Me-3H]methionine, administered intradermally to a sheep, was examined using both biochemical and autoradiographic procedures. During the first hour after injection, most of the [3H]methionine appeared in the blood, but some was incorporated into the wool follicle proteins at the injection sites. Most of the radio-activity incorporated by the fibre during this period was subsequently retained. Initially, more than 90 % of the activity was present in the prekeratin (8 M urea-soluble) portion of the fibre; 50 h elapsed before half of the radioactive material appeared in the keratinized (8 M urea-insoluble) part of the fibre. Methionine and its oxidation products accounted for more than 80 % of the radioactivity present in hydrolysates of wool removed from injection sites after 4 h or 22 days. Analysis of labelled wool showed that the specific radioactivities of those fractions low in sulphur (α- and β-keratose) were 7 and 14 times greater than that of the high-S (γ-keratose) fraction. Autoradiographic studies showed that the main site of formation of the low-S proteins was in the bulb region of the follicle. Here there was no specific intracellular site of low-S protein synthesis, the [3H]methionine being incorporated into the nucleus, cytoplasm, the various cell organelles and intercellular membranes. The amount of radioactivity incorporated by the cortical cells diminished at progressively higher levels in the fibre. In the keratinization zone, the various cell components showed limited protein synthesis, but 1–8 h after injection there was a localization of tritium over the keratin fibrils. It is suggested that a large proportion of the low-S proteins formed within the developing cortical cell ultimately contribute to the keratin microfibrils. The results provide further evidence for the formation of the low-S and high-S proteins at different sites in the follicle.

The determination of metals in wool by atomic-absorption spectroscopy

Atomic absorption has been shown to provide a simple and precise method for the determination of chromium, copper, mercury, tin, zinc, calcium, strontium and barium in wool. The method of standard additions is used for calcium and a calibration-graph method for the other metals. Both methods have an accuracy and reproducibility of about ±3 per cent. The wool sample is hydrolysed in constant-boiling hydrochloric acid, and the calibration graphs are prepared by using wool hydrolysates containing standard amounts of metal to compensate for physical and chemical interferences caused by hydrochloric acid, amino-acids and ions present in the wool.

The determination of aluminium in wool by atomic-absorption spectroscopy

Atomic-absorption spectroscopy at 3092·7 A in a nitrous oxide-acetylene flame provides a simple and precise method for determining aluminium in wool. The sample is dissolved in constant-boiling hydrochloric acid, and the solution sprayed directly into the flame. The presence of hydrochloric acid partially suppresses the aluminium absorbance, whereas the amino-acids present in the wool hydrolysate enhance the absorbance. A linear calibration graph over the range 0 to 130 µg per ml is obtained from solutions of aluminium in constant-boiling hydrochloric acid containing the hydrolysed protein. Although the calibration graph has an accuracy of ±2 per cent., the heterogeneous nature of wool limits the accuracy of the analysis to ±3 per cent. The method, which has been applied successfully down to 0·02 per cent. of aluminium on wool, is equally suitable for other insoluble protein materials, such as hair and hide.

Studies on Reduced Wool II. The Identification of Terminal N -Acetylalanine in Wool and Extracted Wool Proteins

N-Acetylalanine has been isolated and identified in partial acid hydrolysates of wool and extracted wool proteins. Quantitatively it only accounts for a f{'action of the acetyl groups present in these proteins. Isolation of N-acetylated paptides from enzymic digests of extracted wool proteins is complicated by the large amounts of pyroglutamio acid and pyroglutamyl paptides produced either during the hydrolysis or on subsequent passage through a column of Dowex 50 resin. No N -acetylated peptide could be isolated from either a pronase digest of reduced wool or a partial acid hydrolysate of wool.

The occurrence of bis-(2-amino-2-carboxyethyl) trisulphide in hydrolysates of wool and other proteins

The occurrence of bis-(2-amino-2-carboxyethyl) trisulphide in hydrolysates of wool and other proteins

Biosynthesis of seleno-compounds from inorganic selenium by sheep.

SummaryThe biosynthesis of seleno-analogues of sulfur amino acids has been studied in the ruminant (sheep) by repeated per os administration of H2Se75O3. In the biosynthetic processes of the rumen selenium can replace sulfur to form seleno-analogues of the sulfur compounds. Se75-selenocystine with cystine was chemically separated from wool hydrolysate. Chromatographic separation of the amino acids in wool is reported. Se75-selenocystine and Se75-selenomethionine in the wool hydrolysate was demonstrated. Neither selenocystine nor selenomethionine can be separated by present methods from their sulfur analogues.

Occurrence of bis (beta-amino-beta-carboxyethyl) trisulphide in the hydrolysates of wool and other proteins.

INVESTIGATIONS of acid hydrolysates of wool labelled with sulphur-35, and of non-radioactive wool hydrolysed with 35S-cystine, have shown the presence of unidentified sulphur compounds derived from cystine1,2. The most abundant of these (I) increased in amount with increasing time of hydrolysis up to 100 hr., when about one-tenth of the original sulphur in wool was present as (I). Somewhat smaller amounts of (I), representing about one-fiftieth of the protein sulphur, were found in acid hydrolysates of insulin, ribonuclease and bovine serum albumin, but none could be detected in hydrolysates of lysozyme and β-lactoglobulin.

46—AN INVESTIGATION OF THE SULPHUR COMPOUNDS IN ACID HYDROLYSATES OF WOOL

Seven 35S-labelled compounds, in addition to 35S-methionine and 35S-cystine, have been found in hydrolysates of 35S-labelled wool by starch chromatography, and four of these, tentatively named SI, S2, S3 and S4, gave the characteristic blue colour by the Shinohara disulphide reaction. The S-compound S2 has been shown to be identical with cysteine, and to be produced mainly by reaction between tryptophan and cystine during hydrolysis. The seventeen other amino acids present in wool hydrolysates do not decompose cystine in boiling HCI. The S-compounds SI, S3 and S4 have not so far been identified, but accounted for about 4·5% of the colour developed when the Shinohara disulphide reaction was carried out on 24-hour acid hydrolysates of wool. The 35S-cystine contained 80% of the total 35S activity. Starch chromatography of hydrolysates of 35S-labelled wool oxidized wool revealed the presence of four 35S-compounds in addition to 35S-methionine sulphone. 35S-cysteic acid and 35S-cystine. 73% of the 35S activity...