Biodegradation mechanism of cellulose, hemicellulose, and lignin in bacteria-dominant aerobic composting from agricultural biomass waste:A review

The conversion of abundantly produced agricultural waste has been the bottleneck and research hotspot in the development of the agricultural economy. Composting has been a sustainable treatment method for agricultural-sourced waste, in which aerobic fermentation promotes the decomposition of organic matter into stable humus and provides nutrients for plants. Due to the complex interactions among cellulose, hemicellulose, and lignin, the degradation of biomass during composting remains challenging. The aerobic fermentation relies on the interaction of various enzymes, which gradually cleavaged macromolecules into micromolecules or oligomers through a series of oxidation and hydrolysis processes, concurrently providing the nutrients needed for microbial growth, ultimately degrading lignocellulose. Generally speaking, the degradation efficiency of lignocellulose by fungi is higher than that by bacteria. However, fungi are sensitive to temperature, have poor adaptability to extreme environments, and have a long composting cycle. Therefore, this review mainly summarizes aerobic composting dominated by bacteria and clarifies the biodegradation mechanism of lignocellulose, viz., the multi-scale understanding of the degradation mechanism of lignocellulose. The dominant bacteria (e.g., Bacillus, Pseudomonas, Rhodococcus, Enterobacter, Paenibacillus, Acinetobacter, Xantomonas, Aeromonas, and Pseudomonas) and actinomycetes (e.g., Micromonospora, Thermomonospora, Nocardia, and Streptomyces) can be employed to develop efficient bacterial agents that consequently increase the degradation rate of lignocellulose and promote the harmless, resource utilization, and high-value utilization of agricultural waste.