Resource recovery from lignocellulosic wastes via biological technologies: Advancements and prospects

Lignocellulosic wastes were recently considered as biomass resources, however, its conversion to valuable products is still immature although researchers have put lots of effort into this issue. This article reviews the key challenges of the biorefinery utilizing lignocellulosic materials and recent developments to conquer those obstacles. Available biological techniques and processes, from the pretreatments of cellulosic materials to the valorization processes, were emphasized. Biological pretreatments, including hydrolysis using microbial consortia, fungi, enzymes, engineered bacterial/fungal strains, and co-culture systems, could enhance the release of reducing sugar. Resources recovery, including biogases, ethanol, butanol, PHA, etc., from lignocellulosic materials were also discussed, while the influences of composition of lignocellulosic materials and pretreatment options, applications of co-culture system, and integrated treatments with other wastes, were described. In the review, co-culture system and metabolic engineering are emphasized as the promising biological technologies, while perspectives are provided for their future developments.