As the fossil fuel reserves are depleting rapidly, there is a need for alternate fuels to meet the day to day mounting energy demands. As fossil fuel started depleting, a quest for alternate forms of fuel was initiated and biofuel is one of its promising outcomes. First-generation biofuels are made from edible sources like vegetable oils, starch, and sugars. Second-generation biofuels (SGB) are derived from lignocellulosic crops and the third-generation involves algae for biofuel production. Technical challenges in the production of SGB are hampering its commercialization. Advanced molecular technologies like metagenomics can help in the discovery of novel lignocellulosic biomass-degrading enzymes for commercialization and industrial production of SGB. This review discusses the metagenomic outcomes to enlighten the importance of unexplored habitats for novel cellulolytic gene mining. It also emphasizes the potential of different metagenomic approaches to explore the uncultivable cellulose-degrading microbiome as well as cellulolytic enzymes associated with them. This review also includes effective pre-treatment technology and consolidated bioprocessing for efficient biofuel production.

由于化石燃料储量正在迅速耗尽，因此需要替代燃料来满足日益增长的能源需求。随着化石燃料开始耗尽，人们开始寻求替代形式的燃料，而生物燃料是其有希望的成果之一。第一代生物燃料由植物油、淀粉和糖等可食用来源制成。第二代生物燃料（SGB）源自木质纤维素作物，第三代生物燃料涉及藻类生产。 SGB 生产中的技术挑战阻碍了其商业化。宏基因组学等先进分子技术可以帮助发现新型木质纤维素生物质降解酶，用于 SGB 的商业化和工业生产。本综述讨论了宏基因组结果，以阐明未开发的栖息地对于新型纤维素分解基因挖掘的重要性。它还强调了不同宏基因组方法探索不可培养的纤维素降解微生物组以及与之相关的纤维素分解酶的潜力。本次审查还包括有效的预处理技术和用于高效生物燃料生产的综合生物加工。