Effect of endogenous sodium and potassium ions in plants on the quality of alfalfa silage and bacterial community stability during fermentation

Jinhong Shi; Guijie Zhang; Wencan Ke; Yongxiang Pan; Meiling Hou; Chun Chang; Duowen Sa; Mingju Lv; Yinghao Liu; Qiang Lu

doi:10.3389/fpls.2023.1295114

Effect of endogenous sodium and potassium ions in plants on the quality of alfalfa silage and bacterial community stability during fermentation

Front Plant Sci. 2023 Dec 27:14:1295114. doi: 10.3389/fpls.2023.1295114. eCollection 2023.

Authors

Jinhong Shi¹, Guijie Zhang¹, Wencan Ke¹, Yongxiang Pan¹, Meiling Hou², Chun Chang³, Duowen Sa³, Mingju Lv⁴, Yinghao Liu^#³, Qiang Lu^#¹

Affiliations

¹ College of Forestry and Prataculture, Ningxia University, Yinchuan, China.
² College of Life Science, Baicheng Normal University, Baicheng, China.
³ Institute of Grassland Research, Chinese Academy of Agricultural Sciences, Hohhot, China.
⁴ Inner Mongolia Agriculture and Animal Husbandry Extension Center, Hohhot, China.

^# Contributed equally.

Abstract

This study investigated the impact of endogenous sodium and potassium ions in plants on the quality of alfalfa silage, as well as the stability of bacterial communities during fermentation. Silage was produced from the fermented alfalfa, and the chemical composition, fermentation characteristics, and microbiome were analyzed to understand their interplay and impact on silage fermentation quality. The alfalfa was cultivated under salt stress with the following: (a) soil content of <1‰ (CK); (b) 1‰-2‰ (LP); (c) 2‰-3‰ (MP); (d) 3‰-4‰ (HP). The results revealed that the pH of silage was negatively correlated with the lactic acid content. With the increase of lactic acid (LA) content increased (26.3-51.0 g/kg DM), the pH value decreased (4.9-5.3). With the increase of salt stress, the content of Na⁺ in silage increased (2.2-5.4 g/kg DM). The presence of endogenous Na⁺ and K⁺ ions in plants significantly affected the quality of alfalfa silage and the dynamics of bacterial communities during fermentation. Increased salt stress led to changes in microbial composition, with Lactococcus and Pantoea showing a gradual increase in abundance, especially under high salt stress. Low pH inhibited the growth of certain bacterial genera, such as Pantoea and Pediococcus. The abundance of Escherichia-Shigella and Comamonas negatively correlated with crude protein (CP) content, while Enterococcus and Lactococcus exhibited a positive correlation. Furthermore, the accumulation of endogenous Na⁺ in alfalfa under salt stress suppressed bacterial proliferation, thereby reducing protein degradation during fermentation. The pH of the silage was high, and the LA content was also high. Silages from alfalfa under higher salt stress had higher Na⁺ content. The alpha diversity of bacterial communities in alfalfa silages showed distinct patterns. Desirable genera like Lactococcus and Lactobacillus predominated in silages produced from alfalfa under salt stress, resulting in better fermentation quality.

Keywords: anaerobic fermentation; endogenous ions; fermentation quality; microbial community; salt stress.

Grants and funding

The author(s) declare financial support was received for the research, authorship, and/or publication of this article. This work was supported by the Ningxia Higher Education Institutions First-Class Discipline Construction Project (NXYLXK2017A01), the Inner Mongolia Autonomous Region Science and Technology Project (2023YFHH0078), and the 14th Five-Year Plan (JJKH20230024KJ) of Jilin Provincial Department of Education.