Optimizing Laccase Production from Delonix regia Pods by Aspergillus carbonarius F5 Using Response Surface Methodology and it’s Dye Decolorization Potential

Abstract

Introduction: Laccase is a muilti-copper enzyme that directs oxidation of compounds by reducing oxygen to water molecules. It has been identified as a significant enzyme which possesses diverse interest in industrial sector due to its ability to degrade toxicants from dye-utilizing related industries. Aim: The current research focuses on the optimization of laccase from Aspergillus carbonarius F5 on Delonix regia pods, for application in dye degradation. Methodology: Potential laccase producing fungi were screened and characterized using 18s rRNA. Laccase production was further conducted on untreated and acid pretreated Delonix regia pods. Plackett-Burman design and Central Composite Design (CCD) of the Response Surface Methodology (RSM) was used to screen for various nutritional and environmental factors to improve the yield of the enzyme and then applied for dye decolorization studies. Results: The fungal strain with the highest laccase activity was identified as Aspergillus carbonarius F5. The acid pretreated Delonix regia pods showed considerably high enzyme activity when compared with untreated. Moreover, variation of notable nutritional and environmental factors were detected to improve laccase yield. The effect of input parameters such as incubation period, pH, temperature and MgSO4 were documented as the major factors influencing high laccase yield using Plackett-Burman design. Results obtained from the modelling of experiment using CCD-RSM shows that maximum  laccase  production of 8.04 U/ml was recorded  at temperature 36°C, pH 6, MgSO4.7H2O at 0.2 (g/L), and 7 days which reveals a 8.28 –fold increase. The outcome of the investigation performed on dye decolorization suggests an 87.6 % and 62.6 % degradation on congo red and malachite green dyes respectively. Conclusion:  Delonix regia pods could be an added substrate, suitable for optimization of laccase by Aspergillus carbonarius F5 and the enzyme was capable of decolorizing industrial dyes.