Vol. 25, No. 1 (2026), Bio26710 https://doi.org/10.24275/rmiq/Bio26710

Crude protease of Bacillus smithii AP67 isolated from the El Chichón volcano crater lake as a potential eco-friendly alternative for enzymatic dehairing in the leather industry

 

Authors

A. Peña-Blassi, J. A. Montes-Molina, N. Ruiz-Lau, L. M. C. Ventura Canseco, P. E. Álvarez-Gutiérrez, V. M. Ruíz-Valdiviezo

Abstract

Microbial proteases from thermophilic organisms are of great biotechnological interest due to their stability and activity under extreme conditions. Among their applications, enzymatic skin depilation is becoming a more environmentally friendly and specific alternative compared to conventional chemical methods. In this study, thermophilic bacteria were isolated from the geothermal water of the crater lake of the El Chichón volcano. Of the 50 strains isolated, 92% showed extracellular protease activity. The strain with the highest protease production showed high phylogenetic similarity to Bacillus smithii, reaching an activity of 102.75 ± 6.39 U/mL. The enzyme showed optimal conditions at pH 8.0 and 60°C. The presence of Ca²⁺ increased its activity and remained stable with Mg²⁺ and Mn²⁺, while Co²⁺, Fe²⁺, and Cu²⁺ partially inhibited it. It also remained stable in ethanol and methanol but decreased in hexane, acetone, and chloroform. The activity remained stable in the presence of nonionic surfactants, although it was reduced with SDS. The application of the protease to goat skin allowed complete hair removal after 8 h at 60 °C without damaging the dermis, demonstrating its potential as an ecological biocatalyst in sustainable leather tanning.

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Keywords

Thermophile; Protease; Bacillus smithii; Volcanic Crater Lake, Enzymatic Dehairing.

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