A study on solid state fermentations of Sugarcane Bagasse using different fungi

This research work focuses on microbial degradation of lignin in lignocellulosic biomass (sugarcane bagasse) by three different fungi and analysis of degradation products obtained in each case. A comparison of growth characteristics, lignin degradation and products formed amongst the different fungi will be presented. The major constituents of sugarcane bagasse are cellulose (45-55% dry weight basis), hemicellulose (20-25%) and lignin (18-24%). Traditional pre-treatment methods for lignin breakdown include physical and chemical methods that require high energy inputs and employ toxic chemicals. In recent years biological pretreatment using white rot fungi has received renewed attention since it causes selective degradation of lignin, has reduced energy demands and offers milder, eco-friendly process conditions. However, considerable efforts are required to optimize the process parameters to increase the final yields of the product and reduce the time.

Another largely unexploited area is the production of value added products from the lignin, which would be an important aspect that could improve the process economics of biorefineries for biofuel production. In our lab, we are therefore attempting to integrate these two aspects of developing an environment friendly pre-treatment process that would also result in value added products such as vanillin, syringaldehyde, phenol derivatives etc. Solid state fermentations of sugarcane bagasse using different strains of fungi were carried out. The different fungi whose growth characteristics in the fermentations were studied were Phanerochaete chrysosporium, Pleurotus ostreatus, a locally isolated fungus from wood (wood fungus) and mixed culture of P. chrysosporium and wood fungus. Depending on the fungi used, solubilization, shrinkage and decoloration of the biomass was observed. Thin layer chromatography and spectrophotometry were employed for analysing the residual lignin as well as various degradation products of lignin, which indicated clear differences in the fermentation by the different fungi studied.