Optimization of environmental and nutritional parameters for enhanced tyrosinase production from Bacillus cereus MUTY-5

Abstract

Tyrosinase, a multicopper enzyme in the oxidoreductase family, plays an essential role in melanin biosynthesis across a wide range of organisms, from bacteria and fungi to invertebrates and plants. This enzyme exhibits dual catalytic activities—monophenolase and diphenolase—enabling it to hydroxylate monophenols to diphenols and further oxidize them to quinones. In this study, we optimized environmental and nutritional conditions to enhance tyrosinase production by a bacterial strain, Bacillus cereus MUTY-5, isolated from industrially contaminated soil. This research evaluates the effects of various environmental (pH, temperature, agitation, and incubation time) and nutritional (carbon and nitrogen sources) parameters on tyrosinase yield. The findings reveal that a neutral to slightly basic pH (optimal at 7.0) and moderate temperature (35±2°C) are conducive to maximizing tyrosinase activity, while extreme conditions reduce enzyme yield. Agitation at 120 rpm yielded the highest enzyme activity due to increased oxygen transfer, which is critical for tyrosinase function. Maximum production was recorded at 48 hours of incubation, with a decline beyond this period due to nutrient depletion and by-product toxicity. Nutritionally, glucose supported the highest enzyme activity, while fructose also encouraged notable production. In contrast, cellulose and glycerol were the least effective carbon sources. Ammonium sulfate emerged as the most favorable nitrogen source, while beef extract fostered substantial enzyme synthesis. This work highlights the importance of optimizing environmental and nutritional parameters for enhanced tyrosinase production, contributing valuable insights for its application in biotechnology and industrial processes.