Wool and poultry feathers are mainly made of keratin. Their waste materials are increasing which due to their difficult degradability, have an indirect negative effect on the environment. Composting is an aerobic process of decomposition of organic materials, the products of which can be used for further use. Various microorganisms (bacteria, actinomycetes, fungi and protozoa) participate in the composting process. They use their enzymes to cleave the bonds in macromolecules and mineralize the organic matter. Keratin waste is broken down by keratinolytic microorganisms with keratinase enzymes. The process takes place in two stages, first the disulfide bonds are split in the sulfitolysis stage. The molecule is then accessible for proteolysis, where it breaks down into smaller peptides and amino acids. Many keratinolytic microorganisms have been isolated and studied so far, which has enabled further research on how to improve the composting process of keratinolytic materials and transfer it to an industrial level. One of the more successful keratinolytic strains is Streptomyces sp. SCUT-3, whose productivity can be improved with more air flow and changes at the genetic level. With these methods we can accelerate the composting process of waste wool and feathers in combination with the addition of mixed cultures of keratinolytic microorganisms and different bulking agents, like rice or wheat straw.
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