We report the isolation of a keratinolytic-producing Bacillus subtilis strain and the characterization of the exceptional dehairing properties of its subtilisin-like keratinase. This enzyme can be an alternative to sodium sulfide, the major pollutant from tanneries, and may completely replace it. Its unique nonactivity upon collagen enhances its industrial potential.Enzymatic dehairing in tanneries has been envisaged as an alternative to sulfides (4,6,9,22,23). Tanneries are constantly concerned about the obnoxious odor and pollution caused by the extremely toxic sodium sulfide used in the dehairing process step (24). Deaths due to this toxic chemical process have even been reported (2,8). Worldwide, it is estimated that 315 million bovine leathers are produced per year. Considering a waste treatment cost of $0.30 per m 2 of leather produced (A. Klein, personal communication), more than $1 million is spent per day to treat the waste from tanneries around the world. We report here a novel keratinase from Bacillus subtilis that has the potential to replace sodium sulfide in the dehairing process.Microorganism isolation. Bovine hair, skins wastes, and soil samples were suspended and cultivated in a feather-broth medium (composition in grams per liter: delipidated feather meal [the sole carbon and nitrogen source], 10.0; NaCl, 0.5; K 2 HPO 4 , 0.3; and KH 2 PO 4 , 0.4 [pH 7.5]).The best keratinase-producing organism was identified as a B. subtilis strain (named strain S14) after classification based on homology (99%) of its 16S fragment with sequences from the NCBI databank by use of BLASTN 2.2.6 (1) (accession number AY345856).Keratinase production. The microorganism was cultivated in a 14-liter bioreactor in a culture medium composed of whey milk (a dairy byproduct containing 94.0% water, 5% lactose, 0.9% protein, and 0.1% fat), pH 8.5, and bovine hair (40 g/liter). A crude extract (supernatant) was obtained after centrifugation of the culture. Keratinolytic, subtilisin, and collagenase activities were assayed by using azokeratin, as described elsewhere (15). One unit of enzyme activity was defined as the amount of enzyme that increases absorbance by 0.1 per hour in the conditions described above (15).Dehairing assay. A fresh fleshed bovine hide was washed with a commercial detergent solution and cut into 15-by 5-cm pieces. Two hundred grams of skin (usually two pieces) was processed in a drum flask at 4 rpm with crude extract or water (control) in a proportion of 1.0 ml of liquid per g of skin. When necessary, pH was adjusted with lime. At the end of the process, the skin pieces were gently scraped with fingers to remove loose hairs. This procedure was necessary because rubbing in this laboratory-scale process was not as vigorous as in industrial drums. Total skin depilation was observed in the pH range from 7 to 10, with 4.8 U/g of skin. A complete depilation was reached in 9 h at pH 9.0, 24°C, with 4.8 U/g of skin.Samples of bovine skin were kept in contact with the crude extract, and the skin fragments were fi...