B. amyloliquefaciens TCCC 11319, a new Cr(iii)-tolerant bacterium for chromium-tanned leather shaving disposal

Abstract

A strain of B. amyloliquefaciens, TCCC11319, was isolated from tannery soil and identified by 16S rRNA gene sequencing. The enzyme produced by this strain was successfully applied to the treatment of chromium-tanned leather shavings (CTLS). Furthermore, the species and characteristics of the enzyme, including collagenase, alkaline protease, neutral protease, and keratinase, were analyzed. Under optimized conditions (5% inoculum, pH 8, 37 °C, 32 h), the collagenase activity of the crude broth reached 900 U mL⁻¹ and exhibited relatively high tolerance toward Cr(III) (≤900 mg L⁻¹). Moreover, the conditions and effects of enzyme-treated CTLS disposal were studied. The results showed that more than 95% CTLS was successfully liquefied at 10% enzyme concentration, pH 8, and 35 °C within 24 h. The enzyme has the potential to be reused in leather production processes at an industrial scale to generate value-added products.