Feathers account for 5–7% of the total weight of chicken have become one of the major pollutants due to their recalcitrant nature. Feather which is constituted of 90% keratin can be a good source of peptides, amino acids, and minerals for use as organic fertilizer. Traditional feather degradation methods consume large amount of energy and reduces the overall quality of the proteins. However, degradation of keratin by keratinolytic bacteria may represent as an alternative for the development of cheap, cost effective, eco‐friendly, and easily available nitrogen (N) and minerals rich source as potential organic fertilizers. Keratinase enzymes from bacteria are serine‐type proteases showing optimal activity at pH 6 to 9 and 30 to 50 °C. Mechanism of degradation includes, sulfitolysis, proteolysis, followed by deamination. Keratinolytic bacteria showing antagonism against important plant pathogens may act as biocontrol agent. Feather hydrolyzate can also be employed as nitrogenous fertilizers for plant growth. Tryptophan release from the feather degradation can act as precursor for plant phytohormone, indole‐3‐acetic acid (IAA). Solubilization of inorganic phosphate (P) by keratinolytic bacteria may further elevate the growth of plant. Application of hydrolyzate increases the water holding capacity, N, carbon (C) and mineral content of the soil. It elevates protein, amino acids, and chlorophyll content of plant. Feather hydrolyzate enhances seed germination and growth of plant. Soil application further increases the population of beneficial bacteria. The use of keratinolytic bacteria having antagonistic and plant growth promoting activities, and feather hydrolyzate can emerge as sustainable and alternative tools to promote and improve organic farming, agro‐ecosystem, environment, human health, and soil biological activities.

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Introduction Amyloid fibrils are misfolded, protease-resistant forms of normal proteins. They are infectious such as prions or noninfectious such as β-amyloid (Aβ) fibrils causing Alzheimer's disease (AD). Prions and amyloids are structurally similar, possessing cross β-pleated sheet-like structures. As microbial keratinase could degrade prions, we tested keratinase activity on Aβ fibrils. Methods Lysozyme treated with urea generates Aβ fibrils demonstrated by immunoblotting with anti-Aβ antibody, high-performance liquid chromatography, and Congo red absorption spectroscopy. Two keratinases, Ker1 and Ker2, were purified from an actinomycete Amycolatopsis sp. MBRL 40 and incubated with Aβ fibrils. Results Soluble Ker1 and Ker1 reconstituted on neutral/cationic liposomes degraded Aβ fibrils efficiently. Ker 2 was less potent. Discussion Drugs that target AD inhibit acetylcholinesterase or formation of Aβ fibrils and downstream effects. These drugs have side effects and do not benefit globally in cognition. Keratinases are novel molecules for drug development against AD.

Keratin is a fibrous protein mainly found in higher vertebrates such as mammals, birds, and reptiles. It is also a major constituent of human epithelial tissues. Major keratinaceous wastes include skin, hair, wool, feather, horns, hooves, and nails. Large amounts of such wastes are generated from meat industry, poultry houses, and wool industry etc. Though keratinous wastes contain about 90% protein, keratin is usually recalcitrant to normal proteases. Such wastes have been traditionally digested using physico-chemical methods. But such techniques are energy-intensive and technologically demanding. Also, such approaches lead to degradation of certain amino acids such as lysine. In nature, keratinaceous wastes don't accumulate indicating that keratinolytic microorganisms exist in nature. Keratinase producing strains are distributed among bacteria, fungi, and actinobacteria etc. Hence, potent keratinolytic microbes and their enzymes may be used for valorization of keratinous wastes. Efficient degradation of such wastes may generate value-added products such as feed additives, agricultural biofertilizers, and cosmetics. This chapter will give a comprehensive overview of types of keratinaceous wastes, kinds of keratinolytic microbes and keratinases, and valorization of such wastes using keratinase producing strains and/or keratinases.

Rice (Oryza sativa L.) is a member of Gramineae family which belongs to the genus Oryza, which includes 23 wild species and two cultivated species. Rice is the most important cereal crop of the world. The primary material for rice breeding is the