Application of Trametes pubescens for dye removal and biological pretreatment of sugarcane bagasse

Abstract

Sugarcane bagasse (SB) is an abundantly available agrowaste that is used extensively as a substrate for the production of different industrial enzymes. It is a renewable resource, rich in fermentable sugars. However, the presence of lignin makes it difficult for microbes to degrade it and so it is difficult to utilize it. Keeping in mind the role of white rot fungi in lignin degradation, Trametes pubescens MB89 was used in this study for the delignification of SB with the simultaneous production of laccase. The fungus was also used for the degradation of malachite green dye. A Box–Behnken design (BBD) was used to optimize variables affecting solid state fermentation of SB for laccase production. The leftover SB after fermentation was used for cellulase production by the thermophilic bacterium Neobacillus sedimentimangrovi UE25. The BBD depicted optimized conditions as 60% moisture, particle size 100 μ, 10 days’ incubation period, 450 μM CuSO4, and a temperature of 30 °C. The laccase titers of 1271 IU mL−1 were obtained under optimized conditions. Neobacillus sedimentimangrovi UE25 produced 4.574 IU mL−1 of endoglucanase and 1.812 IU mL−1 of β‐glucosidase by utilizing fungal pretreated SB. Scanning electron microscopy and Fourier transform infrared spectroscopy confirmed the impact of fungal cultivation on SB. Pores were observed after microbial pretreatment and there were changes in the morphological characteristics such as the pith and fiber of SB. To test the ability of laccase to break down aromatic dyes, we grew the fungus T. pubescens MB89 in a nutrient‐rich medium supplemented with malachite green dye. The fungus was able to remove 73.68% of the malachite green dye from the medium in 24 h. This shows that T. pubescens MB89 has a range of potential applications for environmental and industrial purposes.