Production of spore laccase from Bacillus pumilus W3 and its application in dye decolorization after immobilization

Given that spore laccase from the Bacillus genus is heat- and alkali-resistant, it is more suitable for industrial applications than fungal laccase. To determine the optimal culture conditions for spore laccase production, the effects of Cu²⁺ concentration, oxygen content, and culture time on spore laccase production from Bacillus pumilus W3 were investigated. The optimal production parameters were 0.2 mM of Cu²⁺, 200 rpm shaking speed, 100 mL liquid loading, and 5 days of cultivation. Spore laccase was efficiently immobilized on amino-functionalized celite. When used in dye decolorization, the immobilized spore laccase removed 84.15% of methyl green and 69.70% of acid red 1 after 48 h of treatment. Moreover, the immobilized spore laccase retained 87.04% of its initial decolorization activity after six cycles in the decolorization of acid red 1. These insights into the culture conditions and immobilization of spore laccases should be useful in the development of spore laccase as a biocatalyst in the treatment of textile wastewater.