Pretreatment of wheat straw with ligninolytic fungi for increased biogas productivity

Biogas production from the agriculture waste biomass is a sustainable approach to managing the energy demand in the future. To do so, pretreatment is needed to remove lignin from the agribiomass to make it easily digestible substrate for the fermentative organisms. The current study was carried out to screen the most effective lignin-degrading fungal culture from their natural habitat. Pretreatment with robust ligninolytic fungi could be an efficient and economical method to degrade lignin. The presence of lignin in lignocellulosic biomass is the rate-limiting factor which reduces the biogas production. So, the best fungal strains were selected based on maximal Azure B dye decolorization. The strains were actively producing lignin peroxidases and laccases and decreased 48.2% of lignin from the wheat straw (WS) within 7 days of batch incubation. The scanning electron micrograph demonstrated visible degradation only in the fungi-treated wheat straw. The ligninolytic fungal culture pretreatment of WS enhanced the biogas yield five times compared with the untreated WS sample. Notably, these fast-acting lignin-degrading fungi gave a biogas yield with a short pretreatment time and additionally reduced the lag phase during the anaerobic digestion process. These findings showed that pretreatment with natural ligninolytic fungi could be considered as a less expensive method. The treatment is also effective in increasing the digestibility of lignocellulosic biomass and suitable for biogas production.