Economic growth and industrial energy demand necessitate sustainable energy resources. The food vs. fuel issue means that first generation biofuels appear unsustainable. Therefore, biofuel production using lignocellulosic biomass clearly needs to be explored and promoted. However, due to technological barriers, the production of biofuel from lignocellulose (second generation biofuel) is currently not cost effective. Although microbial fermentation is an ecofriendly way to convert lignocellulose into biofuel, it will take time to become a commercial reality. Biofuels of different generations can contribute synergistically to fulfill energy demand. More research and government participation is needed to make the biofuel production process more feasible. This review focuses on the pretreatment of biomass, the production of biofuel (biodiesel, bioalcohol, and biogas) using microbial systems, and the various efforts that have been implemented to improve biofuel production. (C) 2017 Elsevier Ltd. All rights reserved.