De‐hairing activity of extracellular proteases produced by keratinolytic bacteria

Abstract

The depilatory activity of keratinolytic bacteria was investigated. Three keratinolytic bacteria isolated from feather waste were tested for their ability to grow in mineral medium containing bovine hair as sole carbon, nitrogen and energy source. The strains kr2, kr6 and kr10 grew well on bovine hair, producing proteolytic activity as judged by assay with azokeratin as substrate. The proteolytic enzymes from all three strains showed similar pH and temperature optima. Strain kr2 showed mainly serine-type protease activity, whereas kr6 and kr10 enzymes showed metalloprotease characteristics. The culture supernatants were used as crude enzyme preparations for depilatory studies on bovine pelts. All three strains were efficacious in promoting de-hairing. Microscopic analysis revealed that the epidermis was completely removed and the absence of hair in follicles was observed. Proteases of keratinolytic bacteria were efficient in promoting depilation of bovine pelts. Enzymatic de-hairing represents a suitable alternative to the conventional tannery process, with the benefit of avoiding environmental pollution.

Production of an extracellular keratinase from Chryseobacterium sp. growing on raw feathers

“…kr6 under different growth conditions. This enzyme has been shown to be useful for biotechnological purposes such as hydrolysis of poultry feathers (Riffel et al 2003a) and dehairing of bovine pelts (Riffel et al 2003b). …”

“…One unit of activity was the amount of enzyme that caused a change of absorbance of 0.01 at 440 nm in 15 min at 50ºC. Azokeratin was synthesized as described by Riffel et al (2003b). The protein concentration was measured by the Folin phenol reagent method (Lowry et al 1951).…”

Production and properties of keratinolytic proteases from three novel Gram-negative feather-degrading bacteria isolated from Brazilian soils

“…Keratinolytic activity was also assayed by a similar protocol utilizing azokeratin as substrate. Azokeratin was synthesized as described elsewhere (Riffel et al 2003a). …”

Evaluation of Keratinolytic Activity Succeeds by Keratinophilic Fungi in Jaipur, India

“…After 3-4 days, with the growth of fungal mycelium, there was started the consumption of keratin substrate and release an extracellular enzyme known as keratinase. In the mid of inoculation, on 4, 8, 12 and 16 day, After respective day's incubation, mycelium was removed by filtration and the filtrated was centrifuged at 10000 rpm using cooling centrifuged for 10 min and the supernatant was used as a crude enzyme (Riffel et al, 2003;Kim, 2003). Keratinase activity was evaluated by the modified method of Yu et al (1968).…”