Institute of Ensiling and Processing of Grass, College of Agro-grassland Science, Nanjing Agricultural University, Nanjing 210095, P.R. China.
Lett Appl Microbiol. 2023 Jan 23;76(1). doi: 10.1093/lambio/ovac036.
The present study aimed to evaluate the effects of delayed harvest and storage length on fermentation products, bacterial community, and metabolic shifts of elephant grass silage. The late-harvested elephant grass (LG) was naturally fermented (NLG) for 1, 3, 7, 15, 30, and 60 days, respectively. After 60-day ensiling, NLG displayed homolactic fermentation with low pH value, butyric acid, and ammonia nitrogen concentrations, and high lactic acid concentration, and ratio of lactic acid to acetic acid. Pseudomonas, Sphingomonas, and Pantoea dominated the bacterial community in LG, but Lactobacillus, Lactococcus, and Pediococcus were the advantageous genera in a 3-day and 60-day NLG. The correlation heatmap revealed that Acetobacter was positively related to acetic acid, ethanol, ammonia nitrogen, and butyric acid concentrations. There were distinct differences in the KEGG (Kyoto Encyclopedia of Genes and Genomes) metabolic profiles of fresh and ensiled LG. Ensiling suppressed the metabolism of amino acid, vitamins, and energy, while promoted the metabolism of carbohydrate. The LG can be well-fermented without additives, but its low crude protein content should not be ignored when applied in agricultural practice. The ensiling process remarkably affected the fermentation quality, bacterial community, and metabolic profiles of NLG.
本研究旨在评估延迟收获和贮藏时间对象草青贮发酵产物、细菌群落和代谢变化的影响。将晚收象草（LG）分别自然发酵（NLG）1、3、7、15、30 和 60 天。60 天青贮后，NLG 表现出同型乳酸发酵，具有低 pH 值、丁酸和氨氮浓度，以及高乳酸浓度和乳酸与乙酸的比例。假单胞菌、鞘氨醇单胞菌和泛菌是 LG 中主要的细菌群落，但在 3 天和 60 天的 NLG 中，乳杆菌、乳球菌和肠球菌是优势属。相关热图显示，醋杆菌与乙酸、乙醇、氨氮和丁酸浓度呈正相关。新鲜和青贮象草的 KEGG（京都基因与基因组百科全书）代谢图谱存在明显差异。青贮抑制了氨基酸、维生素和能量的代谢，同时促进了碳水化合物的代谢。LG 可以不加添加剂就能很好地发酵，但在农业实践中不应忽视其粗蛋白含量低的问题。青贮过程显著影响了 NLG 的发酵质量、细菌群落和代谢谱。
