Meihua Zhou

Characterization of a novel Stenotrophomonas isolate with high keratinase activity and purification of the enzyme.

A feather-degrading bacterium was isolated from poultry decomposition feathers in China. The strain, named L1, showed significant feather-degrading activity because it grew and reproduced quickly on basal medium containing 10xa0g/L of native feather as the source of energy, carbon, and nitrogen. According to the phenotypic characteristics and 16S rRNA profile, the isolate belongs to Stenotrophomonasxa0maltophilia. Keratinase activity of the isolate was determined during cultivation on raw feathers at different temperatures and initial pH. Maximum growth and feather-degrading activity of the bacterium were observed at 40°C and initial pH ranging from 7.5 to 8.0. The crude enzyme was purified by ammonium sulphate precipitation, Sephadex G-100 chromatographic and ceramic hydroxyapatite (CHT) chromatographic. Its molecular mass estimated as 35.2xa0kDa in SDS-PAGE. The enzyme had an optimum activity at the pH was 7.8 and the temperature was 40°C. The keratinase was wholly inhibited by a serine protease inhibitor, PMSF. Its activity was activated or inhibited by different metal ions. The keratinase activity of enzyme from strain L1 functioned on different keratins, such as feather, hair, wool, horn, and so on.

Preparation of regenerated keratin sponge from waste feathers by a simple method and its potential use for oil adsorption

In this work, pigeon feathers, a kind of totally waste by-product from the poultry industry, were utilized to fabricate a highly porous keratin sponge in a very simple way by freeze-drying treatment of the dissolved keratin solution, and applied for the first time as an oil adsorbent. An improved method was proposed to dissolve the feather keratin using the inexpensive sodium disulfite as the reducing reagent for sulfitolysis reaction, with a much lower concentration of all involving reaction regents. Moreover, the regenerated keratin sponges obtained a high oil adsorption capacity of above 30xa0g/g for both liquid paraffin and soybean oil, as well as a good oil holding ability, suggesting that this keratin sponge might be a potential for use as oil adsorbent.

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

PurposeFeathers are one of the most abundant bioresources. They are discarded as waste in most cases and could cause environmental pollution. On the other hand, keratin constituted by amino acids is the main component of feathers. In this article, we reported on biorefined feathers and integrants and application of degraded products.Materials and methodsThe fermentation of whole chicken feathers with Stenotrophomonas maltophilia DHHJ in a scale-up of a 5-L bioreactor was investigated in this article. The fermentation process was controlled at 0.08xa0MPa pressure, 2.5xa0L/min airflow, and 300xa0rpm as 100% oxygen saturation level, 40°C, and pHxa07.8.ResultsFeathers were almost completely degraded in the tested fermentation reaction with the following conditions: 80xa0g of whole feathers in 3xa0L fermentation broth for 72xa0h, seed age of 16xa0h, 100xa0mL inoculation amount, and 50% oxygen saturation level. The degraded products contain 397.1xa0mg/L soluble protein that has mass weight ranging from 10 to 160xa0kD, 336.9xa0mg/L amino acids, and many kinds of metal ions. The fermentation broth was evaluated as leaf fertilizer and found to increase plant growth to 82% or 66% for two- or fourfold dilutions, respectively. In addition, in a hair care assay, the broth showed a hair protective function by increasing weight, flexibility, and strength of the treated hair.ConclusionsThe whole feathers were degraded completely by S. maltophilia DHHJ. The degraded product includes many factors to life, such as peptides, amino acids, and mineral elements. It could be applied as leaf fertilizer and hair care product.

Identification of a Keratinase-Producing Bacterial Strain and Enzymatic Study for Its Improvement on Shrink Resistance and Tensile Strength of Wool- and Polyester-Blended Fabric

A wool-degrading bacterium was isolated from decomposition wool fabrics in China. The strain, named 3096-4, showed excellent capability of removing cuticle layer of wool fibers, as demonstrated by removing cuticle layer completely within 48xa0h. According to the phenotypic characteristics and 16S rRNA profile, the isolate was classified as Pseudomonas. Bacteria growth and keratinase activity of the isolate were determined during cultivation on raw wool at different temperatures, initial pH, and rotation speed using orthogonal matrix method. Maximum growth and keratinase activity of the bacterium were observed under the condition including 30xa0°C, initial pHxa07.6, and rotational speeds 160xa0rpm. The keratinase-containing crude enzyme prepared from 3096-4 was evaluated in the treatment of wool fabrics. The optimal condition of our enzymatic improvement of shrink resistance was the combination of 30xa0°C, initial pHxa07.6, and rotation speeds 160xa0rpm. After the optimized treatment, the wool fabrics felting shrink was 4.1% at 6xa0h, and textile strength was not lost.

Preparation and characterization of sponge film made from feathers.

Feather wastes generated from poultry farms will pose a problem for disposal, but they are sustainable resources of keratin. Reduction is one of the commonly used methods to obtain soluble keratin from feather. However, the residues generated during feather reduction reaction were rarely investigated. In this study, the residues were transformed into a porous and flexible sponge film by freeze-drying without pretreatment or addition of cross-linking agents. Glycerol was used to alter the physical and chemical characteristics of the sponge film. The film was characterized with a fiber strong stretch instrument, a Fourier transform infrared spectrophotometer, scanning electron microscopy, an elemental analyzer, a differential scanning calorimeter and an automatic air permeability apparatus. Tensile strength and melting point of the sponge film with the optimum glycerol content were 6.2 MPa and 170°C respectively. Due to air permeability of 368 mm/s, the film can potentially be used in medicine, biology, textile, environmental technology, and so on. It is ecologically friendly and will produce additional benefits from the renewable materials. The film was utilized as adsorbents to remove Cr(VI) from aqueous solutions and as a filtering material for air pollution. Its maximum Cr(VI) uptake capacity was about 148.8 mg/g and the removal rate of PM10 was 98.3%.

Cr(VI) adsorption on a thermoplastic feather keratin film

AbstractFeather is a kind of waste and hardly to be degraded in the environment. Thermoplastic film was made from feather by mechanical method with enhancing the temperature and pressure to 160°C, 5u2009MPa, respectively. Glycerol was added as plasticizer in various amounts in mass ratio of 10, 20, 40, 60, and 80%, respectively. During film preparation, influence glycerol content on film’s mechanical property was studied, and 40% was chosen as the best ratio. Film with the best mechanical property was used to adsorb Cr(VI) in aqueous solution. Effects of temperature, adsorbent dosage, initial concentration, and pH on adsorption were studied. The adsorption was endothermic and fitted to both Langmuir and Freundlich models, and the process contained both physical and chemical adsorptions. The biggest removal rate was 99.1%, and the best absorption capacity was 75.45u2009mg/g at 60°C. After adsorption, there appeared many particles on the surface of the film that can be seen in SEM. FT-IR was used to study the chemi...