Hydrogen Peroxide-Resistant CotA and YjqC of Bacillus altitudinis Spores Are a Promising Biocatalyst for Catalyzing Reduction of Sinapic Acid and Sinapine in Rapeseed Meal

For the more efficient detoxification of phenolic compounds, a promising avenue would be to develop a multi-enzyme biocatalyst comprising peroxidase, laccase and other oxidases. However, the development of this multi-enzyme biocatalyst is limited by the vulnerability of fungal laccases and peroxidases to hydrogen peroxide (H 2 O 2 )-induced inactivation. Therefore, H 2 O 2 -resistant peroxidase and laccase should be exploited. In this study, H 2 O 2 -stable CotA and YjqC were isolated from the outer coat of Bacillus altitudinis SYBC hb4 spores. In addition to the thermal and alkali stability of catalytic activity, CotA also exhibited a much higher H 2 O 2 tolerance than fungal laccases from Trametes versicolor and Trametes trogii . YjqC is a sporulation-related manganese (Mn) catalase with striking peroxidase activity for sinapic acid (SA) and sinapine (SNP). In contrast to the typical heme-containing peroxidases, the peroxidase activity of YjqC was also highly resistant to inhibition by H 2 O 2 and heat. CotA could also catalyze the oxidation of SA and SNP. CotA had a much higher affinity for SA than B . subtilis CotA. CotA and YjqC rendered from B . altitudinis spores had promising laccase and peroxidase activities for SA and SNP. Specifically, the B . altitudinis spores could be regarded as a multi-enzyme biocatalyst composed of CotA and YjqC. The B . altitudinis spores were efficient for catalyzing the degradation of SA and SNP in rapeseed meal. Moreover, efficiency of the spore-catalyzed degradation of SA and SNP was greatly improved by the presence of 15 mM H 2 O 2 . This effect was largely attributed to synergistic biocatalysis of the H 2 O 2 -resistant CotA and YjqC toward SA and SNP.