State Key Laboratory of Grassland and Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China.
State Key Laboratory of Grassland and Agro-ecosystems, School of Life Sciences, Lanzhou University, Lanzhou 730000, PR China; Probiotics and Biological Feed Research Center, Lanzhou University, Lanzhou 730000, PR China.
Sci Total Environ. 2024 May 20;926:172114. doi: 10.1016/j.scitotenv.2024.172114. Epub 2024 Mar 30.
The microbial hosts of antibiotic resistance genes (ARGs) found epiphytically on plant materials could grow and flourish during silage fermentation. This study employed metagenomic analysis and elucidated the occurrence and transmission mechanisms of ARGs and their microbial hosts in whole-crop corn silage inoculated with homofermentative strain Lactiplantibacillus plantarum or heterofermentative strain Lentilactobacillus buchneri ensiled under different temperature (20 and 30 °C). The results revealed that the corn silage was dominated by Lactobacillus, Leuconostoc, Lentilactobacillus, and Latilactobacillus. Both the ensiling temperature and inoculation had greatly modified the silage microbiota. However, regardless of the ensiling temperature, L. buchneri had significantly higher ARGs, while it only exhibited significantly higher mobile genetic elements (MGEs) in low temperature treatments. The microbial community of the corn silage hosted highly diverse form of ARGs, which were primarily MacB, RanA, bcrA, msbA, TetA (58), and TetT and mainly corresponded to macrolides and tetracyclines drug classes. Plasmids were identified as the most abundant MGEs with significant correlation with some high-risk ARGs (tetM, TolC, mdtH, and NorA), and their abundances have been reduced by ensiling process. Furthermore, higher temperature and L. buchneri reduced abundances of high-risk ARGs by modifying their hosts and reduced their transmission in the silage. Therefore, ensiling, L. buchneri inoculation and higher storage temperature could improve the biosafety of corn silage.
在植物材料表面发现的具有抗生素抗性基因（ARGs）的微生物宿主，在青贮发酵过程中可能会生长和繁殖。本研究采用宏基因组分析，阐明了在接种同型发酵乳杆菌（Lactiplantibacillus plantarum）或异型发酵 Lentilactobacillus buchneri 的全株玉米青贮中，ARGs 及其微生物宿主的发生和传播机制，这些玉米青贮在不同温度（20 和 30°C）下进行青贮。结果表明，玉米青贮主要由乳杆菌、肠球菌、 Lentilactobacillus 和 Latilactobacillus 组成。青贮温度和接种均极大地改变了青贮微生物群落。然而，无论青贮温度如何，L. buchneri 都具有更高的 ARGs，而在低温处理中，它仅表现出更高的移动遗传元件（MGEs）。玉米青贮的微生物群落宿主具有高度多样化的 ARGs 形式，主要为 MacB、RanA、bcrA、msbA、TetA（58）和 TetT，主要对应于大环内酯类和四环素类药物。质粒被鉴定为最丰富的 MGEs，与一些高风险 ARGs（tetM、TolC、mdth 和 NorA）具有显著相关性，其丰度在青贮过程中降低。此外，高温和 L. buchneri 通过改变宿主和减少青贮中 ARGs 的传播，降低了高风险 ARGs 的丰度。因此，青贮、L. buchneri 接种和较高的储存温度可以提高玉米青贮的生物安全性。
