The rumen of ruminants is a natural anaerobic fermentation system that efficiently degrades lignocellulosic biomass and mainly depends on synergistic interactions between multiple microbes and their secreted enzymes. Ruminal microbes have been employed as biomass waste converters and are receiving increasing attention because of their degradation performance. To explore the application of ruminal microbes and their secreted enzymes in biomass waste, a comprehensive understanding of these processes is required. Based on the degradation capacity and mechanism of ruminal microbes and their secreted lignocellulose enzymes, this review concentrates on elucidating the main enzymatic strategies that ruminal microbes use for lignocellulose degradation, focusing mainly on polysaccharide metabolism-related gene loci and cellulosomes. Hydrolysis, acidification, methanogenesis, interspecific H₂ transfer, and urea cycling in ruminal metabolism are also discussed. Finally, we review the research progress on the conversion of biomass waste into biofuels (bioethanol, biohydrogen, and biomethane) and value-added chemicals (organic acids) by ruminal microbes. This review aims to provide new ideas and methods for ruminal microbe and enzyme applications, biomass waste conversion, and global energy shortage alleviation.

反刍动物的瘤胃是一个天然的厌氧发酵系统，可有效降解木质纤维素生物质，主要依赖于多种微生物及其分泌的酶之间的协同相互作用。瘤胃微生物已被用作生物质废物转换器，并因其降解性能而受到越来越多的关注。为了探索瘤胃微生物及其分泌酶在生物质废物中的应用，需要对这些过程有全面的了解。本文以瘤胃微生物及其分泌的木质纤维素酶的降解能力和机制为基础，阐明瘤胃微生物降解木质纤维素的主要酶策略，重点关注多糖代谢相关基因位点和纤维素体。还讨论了瘤胃代谢中的水解、酸化、产甲烷、种间H ₂转移和尿素循环。最后，我们回顾了瘤胃微生物将生物质废物转化为生物燃料（生物乙醇、生物氢和生物甲烷）和增值化学品（有机酸）的研究进展。该综述旨在为瘤胃微生物和酶的应用、生物质废物转化以及缓解全球能源短缺提供新的思路和方法。