Keratinolytic bacteria Bacillus polymyxa B20 and B. cereus B5esz during cultures in medium with chicken feathers as a sole nutrient source, accumulated various amounts of sulfur compounds at different oxidation level, including thiols, thiosulfate, sulfite and sulfate. The main difference observed between the two tested strains was higher release of sulfate by the former and elevated concentration of thiols by the latter. Additionally, the activity of glutathione reductase, that could potentially play a role in keratinolysis was confirmed, mainly in the cell homogenate fraction, rather than extracellular. Keratinases in crude culture fluids exhibited activity towards soluble keratin preparation, as well as native feather keratin. Application of 2-mercaptoethanol and sulfite, agents that potentially could take part in keratin sulfitolysis, led to a conclusion that they could play a role in keratin degradation, other than activation of extracellular enzymes.

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