Microbial decomposition of keratin in nature—a new hypothesis of industrial relevance

Discovery of keratin-degrading enzymes from fungi and bacteria has primarily focused on finding one protease with efficient keratinase activity. Recently, an investigation was conducted of all keratinases secreted from a fungus known to grow on keratinaceous materials, such as feather, horn, and hooves. The study demonstrated that a minimum of three keratinases is needed to break down keratin, an endo-acting, an exo-acting, and an oligopeptide-acting keratinase. Further, several studies have documented that disruption of sulfur bridges of the keratin structure acts synergistically with the keratinases to loosen the molecular structure, thus giving the enzymes access to their substrate, the protein structure. With such complexity, it is relevant to compare microbial keratin decomposition with the microbial decomposition of well-studied polymers such as cellulose and chitin. Interestingly, it was recently shown that the specialized enzymes, lytic polysaccharide monoxygenases (LPMOs), shown to be important for breaking the recalcitrance of cellulose and chitin, are also found in keratin-degrading fungi. A holistic view of the complex molecular self-assembling structure of keratin and knowledge about enzymatic and boosting factors needed for keratin breakdown have been used to formulate a hypothesis for mode of action of the LPMOs in keratin decomposition and for a model for degradation of keratin in nature. Testing such hypotheses and models still needs to be done. Even now, the hypothesis can serve as an inspiration for designing industrial processes for keratin decomposition for conversion of unexploited waste streams, chicken feather, and pig bristles into bioaccessible animal feed

Do Changes in Regulation Affect Temporary Agency Workers' Job Satisfaction?

This paper evaluates the impact on temporary agency workers' job satisfaction of a reform that considerably changed regulations covering the temporary help service sector in Germany. We isolate the causal effect of this reform by combining a difference-in-difference and matching approach and using rich survey data. We find that the change of the law substantially decreased agency workers' job satisfaction while regular workers' job satisfaction remained unchanged. Further analysis reveals that the negative effect on agency workers' job satisfaction can be attributed to a decrease in wages and an increase in perceived job insecurity. These results are also robust to the use of different specifications and placebo tests

Do changes in regulation affect temporary agency workers' job satisfaction?

This paper evaluates the impact on temporary agency workers' job satisfaction of a reform that considerably changed regulations covering the temporary help service sector in Germany. We isolate the causal effect of this reform by combining a difference-in-difference and matching approach and using rich survey data. We find that the change of the law substantially decreased agency workers' job satisfaction while regular workers' job satisfaction remained unchanged. Further analysis reveals that the negative effect on agency workers' job satisfaction can be attributed to a decrease in wages and an increase in perceived job insecurity. These results are also robust to the use of different specifications and placebo tests.Diese Studie untersucht den Einfluss einer Reform des Arbeitnehmerüberlassungsgesetzes, die die Vorschriften im Zeitarbeitssektor deutlich lockerte. Wir isolieren den kausalen Effekt dieser Reform, indem wir umfangreiche Befragungsdaten nutzen und einen Differenz-von-Differenzen-Schätzer mit einem Matching-Ansatz verknüpfen. Es zeigt sich, dass die Gesetzesänderung zu einem Rückgang der Arbeitszufriedenheit von Leiharbeitern führte, während die Arbeitszufriedenheit von regulär Beschäftigten unverändert blieb. Weitere Analysen zeigen, dass der negative Effekt auf die Arbeitszufriedenheit von Leiharbeitern sowohl auf einen Rückgang der Löhne sowie eine erhöhte wahrgenommene Arbeitsplatzunsicherheit zurückgeführt werden kann. Diese Ergebnisse bleiben auch bei alternativen Modellspezifizierungen und Placebotests robust

Use of continuous positive airway pressure reduces airway reactivity in adults with asthma

Asthma is characterised by airway hyperreactivity, which is primarily treated with β-adrenergic bronchodilators and anti-inflammatory agents. However, mechanical strain during breathing is an important modulator of airway responsiveness and we have previously demonstrated in animal models that continuous positive airway pressure (CPAP) resulted in lower in vivo airway reactivity. We now evaluated whether using nocturnal CPAP decreased airway reactivity in clinically-stable adults with asthma. Adults with stable asthma and normal spirometry used nocturnal CPAP (8-10 cmH(2)O) or sham treatment (0-2 cmH(2)O) for 7 days. Spirometry and bronchial challenges were obtained before and after treatment. The primary outcome was the provocative concentration of methacholine causing a 20% fall in forced expiratory volume in 1 s (PC(20)). The CPAP group (n=16) had a significant decrease in airway reactivity (change in (Δ)logPC(20) 0.406, p<0.0017) while the sham group (n=9) had no significant change in airway reactivity (ΔlogPC(20) 0.003, p=0.9850). There was a significant difference in the change in airway reactivity for the CPAP versus the sham group (ΔlogPC(20) 0.41, p<0.043). Our findings indicate that chronic mechanical strain of the lungs produced using nocturnal CPAP for 7 days reduced airway reactivity in clinically stable asthmatics. Future studies of longer duration are required to determine whether CPAP can also decrease asthma symptoms and/or medication usage

Genome and secretome analyses provide insights into keratin decomposition by novel proteases from the non-pathogenic fungus <i>Onygena corvina</i>

Poultry processing plants and slaughterhouses produce huge quantities of feathers and hair/bristle waste annually. These keratinaceous wastes are highly resistant to degradation. Onygena corvina, a non-pathogenic fungus, grows specifically on feathers, hooves, horn, and hair in nature. Hence, the proteases secreted by O. corvina are interesting in view of their potential relevance for industrial decomposition of keratinaceous wastes. We sequenced and assembled the genome of O. corvina and used a method called peptide pattern recognition to identify 73 different proteases. Comparative genome analysis of proteases in keratin-degrading and non-keratin-degrading fungi indicated that 18 putative secreted proteases from four protease families (M36, M35, M43, and S8) may be responsible for keratin decomposition. Twelve of the 18 predicted protease genes could be amplified from O. corvina grown on keratinaceous materials and were transformed into Pichia pastoris. One of the recombinant proteases belonging to the S8 family showed high keratin-degrading activity. Furthermore, 29 different proteases were identified by mass spectrometry in the culture broth of O. corvina grown on feathers and bristle. The culture broth was fractionated by ion exchange chromatography to isolate active fractions with five novel proteases belonging to three protease families (S8, M28, and M3). Enzyme blends composed of three of these five proteases, one from each family, showed high degree of degradation of keratin in vitro. A blend of novel proteases, such as those we discovered, could possibly find a use for degrading keratinaceous wastes and provide proteins, peptides, and amino acids as valuable ingredients for animal feed. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s00253-015-6805-9) contains supplementary material, which is available to authorized users