Institute of Ensiling and Processing of Grass, College of Agro-Grassland Science, Nanjing Agricultural University, Nanjing, China.
J Appl Microbiol. 2022 Jan;132(1):177-188. doi: 10.1111/jam.15234. Epub 2021 Aug 10.
To explore the microbiological factors that cause the difference in silage fermentation characteristics between temperate gramineous (Italian ryegrass and oat) grass and legume forage.
Through γ-ray irradiation sterilization and bacterial transplantation technology, the sterilized red clover was inoculated as follows: (i) aseptic water (STRC); (ii) epiphytic bacteria on red clover (RCRC); (iii) epiphytic bacteria on oat (RCOT); and (iv) epiphytic bacteria on Italian ryegrass (RCIR). Red clover was ensiled in laboratory-scale silos made of vacuum-packed plastic bags for 1, 3, 7, 14, 30 and 60 days. STRC remained unfermented state based on similar chemical components with fresh red clover. Compared with RCRC and RCIR, higher lactic acid content and ratio of lactic acid to acetic acid, and lower pH, acetic acid and ammonia nitrogen contents were observed in RCOT after 60 days of ensiling. Using next-generation sequencing, higher abundances of Methylobacterium and Sphingomonas were observed in the epiphytic bacteria on red clover. Pediococcus was dominant in RCRC after 3 days of ensiling. Lactobacillus was the most predominant in each group after 60 days of fermentation. RCRC and RCIR had a more hetero-fermentative process, while RCOT possessed a more homo-fermentative pathway. According to the 16S rRNA gene-predicted functional profiles, the metabolism of amino acids was accelerated by the epiphytic bacteria from red clover.
Inoculating the epiphytic bacteria from oat could alter the fermentation characteristics and bacterial compositions of red clover silage. The relative abundance and activity of Methylobacterium, Sphingomonas, Enterobacteriaceae and hetero-fermentative Lactobacillus in red clover silage could be changed by the epiphytic bacteria on temperate gramineous grass.
The exogenous micro-organisms inhibiting the metabolism of amino acids can be a good potential source to improve the silage quality of legume forage.
探讨造成温带禾本科（黑麦草和燕麦）牧草与豆科牧草青贮发酵特性差异的微生物因素。
通过γ射线辐照灭菌和细菌移植技术，将灭菌的红三叶草接种如下：（i）无菌水（STRC）；（ii）红三叶草上的附生菌（RCRC）；（iii）燕麦上的附生菌（RCOT）；和（iv）黑麦草上的附生菌（RCIR）。将红三叶草在实验室规模的真空包装塑料袋青贮中进行青贮，时间分别为 1、3、7、14、30 和 60 天。根据与新鲜红三叶草相似的化学成分，STRC 保持未发酵状态。与 RCRC 和 RCIR 相比，RCOT 在青贮 60 天后乳酸含量和乳酸与乙酸的比例较高，pH 值、乙酸和氨氮含量较低。通过下一代测序，在红三叶草上的附生菌中观察到更高丰度的甲基杆菌和鞘氨醇单胞菌。在青贮 3 天后，Pediococcus 在 RCRC 中占优势。在发酵 60 天后，每个组中乳酸菌是最主要的。RCRC 和 RCIR 具有更多的异型发酵过程，而 RCOT 具有更多的同型发酵途径。根据 16S rRNA 基因预测的功能图谱，红三叶草上的附生菌加速了氨基酸的代谢。
接种来自燕麦的附生菌可以改变红三叶草青贮的发酵特性和细菌组成。红三叶草青贮中甲基杆菌、鞘氨醇单胞菌、肠杆菌科和异型发酵乳酸菌的相对丰度和活性可能因温带禾本科草上的附生菌而发生变化。
抑制氨基酸代谢的外生微生物可以成为改善豆科牧草青贮质量的良好潜在来源。
