Laccase mediator system obtained from a marine spore exhibits decolorization potential in harsh environmental conditions

Laccases play a significant role in remedying dye pollutants. Most of these enzymes are originated from terrestrial fungi and bacteria, thus they are not proper to be used in the environments with neutral/alkaline pH, or they may require laborious extraction/purification steps. These limitations can be solved using marine spore laccases through high stability and easy to use application. In the current study, laccase activity of the marine spore -forming Bacillus sp. KC2 was measured according to the guaiacol and syringaldazine oxidation. Abiotic stresses like pH of 6, temperature of 37 °C and 0.3 mM CuSO₄ (in comparison with optimal sporulation conditions: pH of 8, temperature of 20 °C and 0.0 mM CuSO₄) enhanced laccase formation in sporal coat. Maximum activity of enzyme was observed at 50 °C and pH 7, which did not change in the alkaline pH and temperature range of 20-70 °C. Results indicated ions, inhibitors and solvent stability of the enzyme and its activity were stimulated by Co²⁺, Mn²⁺, PMSF, acetone, acetonitrile, ethanol, and methanol. The spore laccase could decolorize synthetic dyes from various chemical groups including azo (acid orange, amaranth, trypan blue, congo red, and amido black), indigo (indigo carmine), thiazine (methylene blue, and toluidine blue), and triarylmethane (malachite green) with ABTS/syringaldazine mediators after 5 h. Degradation products were not toxic against Sorghum vulgare and Artemia salina model organisms. The enzyme mediator system showed high potentials for dye bioremediation over a wide range of harsh conditions.