Effects of ferulic acid esterase-producingLactobacillus fermentumand cellulase additives on the fermentation quality and microbial community of alfalfa silage

Abstract

Background Alfalfa (Medicago sativa) is an important forage material widely used for animal feed production. Ensiling is an effective method for preserving alfalfa, but it has shown some limitations in the production of high-quality alfalfa silage due to its low water soluble carbohydrates (WSC) content and high buffering capacity. Lactic acid bacteria (LAB) and cellulase are often used as silage additives to promote the ensiling process and enhance fermentation quality. Methods Experiments were conducted to investigate the effects of ferulic acid esterase (FAE)-producing Lactobacillus fermentum 17SD-2 (LF) and cellulase (CE) on the fermentation quality and microbial community of alfalfa silage. After 60 days of ensiling, analysis of fermentation quality and bacterial diversity in alfalfa silages were conducted using high-performance liquid chromatography and high-throughput sequencing methods. Results Alfalfa was ensiled with additives (LF, CE, and LF+CE) or without additives for 60 days. All additives increased lactic acid and decreased pH values and ammonia-N contents compared to control. Among all treatments, the combined addition of LF and CE showed lowest pH (4.66) and ammonia-N (NH3-N, 0.57% DM) content, highest contents of lactic acid (LA, 10.51% DM), dry matter (DM, 22.54%) and crude protein (CP, 24.60% DM). Combined addition of LF and CE performed better in reducing neutral detergent fiber (NDF, 29.76% DM) and acid detergent fiber (ADF, 22.86% DM) contents than the addition of LF (33.71, 27.39% DM) or CE (32.07, 25.45% DM) alone. Moreover, the microbial analysis indicated that LF+CE treatments increased the abundance of desirable Lactobacillus and inhibited the growth of detrimental Enterobacter and Clostridia in alfalfa silage. Discussion Combined addition of FAE-producing LF and CE is more effective than treatments of LF or CE alone in improving fermentation quality and nutrition values of alfalfa silage. This is likely due to a synergistic effect of CE and FAE produced by LF on plant cell wall degradation, indicating that these additives promote each other to improve fiber degradation and silage fermentation. In conclusion, combined addition of FAE-producing LF and CE could be a feasible way to improve alfalfa silage quality.

Enzyme additives influence bacterial communities of Medicago sativa silage as determined by Illumina sequencing

“…Lactobacillus is the genus that is typically present in the highest abundance in silages treated with LAB, and it contributes the most to the production of lactic acids and the decline in pH during fermentation (Li et al 2019 ; Zheng et al 2017 ; Ni et al 2017 ; Cai et al 2020 ; Keshri et al 2018 ). Furthermore, the correlation between Lactobacillus and lactic acids has been in other studies (Yang et al 2019 ; Su et al 2019 ).…”

Effect of 3-Phenyllactic Acid and 3-Phenyllactic Acid-Producing Lactic Acid Bacteria on the Characteristics of Alfalfa Silage

“…For a long time, the growth rate and the ability to reduce the pH of the medium were two rules for selecting LAB as inoculants [21,22]. However, currently, biofunctional LAB are more favorable [4,23]. The metabolite analysis indicated that some inoculants produced more amino acids, organic acids, and phenolic acids in the silage samples than in the blank control-treated silage [23].…”

“…To obtain high-quality alfalfa silage, a variety of additives are added during the process of making silage, such as lactic acid bacteria, propionic acid, formic acid, cellulase, tannin, and benzoic acid [2][3][4][5]. The addition of these additives not only improves the feeding value but also improves the stability of the alfalfa silage.…”

“…Researchers isolated lactic acid bacteria from fresh rumen fluid and silages to stimulate the ensiling process [4]. Lactic acid bacteria with high growth rates, fibrolytic activities, and ferulic acid activities were suggested to be efficient in improving the quality of alfalfa silage [4]. Currently, changes in the content of functional composition during alfalfa ensiling have attracted much attention [6,7].…”

Effects of lactic acid bacteria on the quality of silage and health of ruminants

“…然而布氏乳 杆菌也有其不足之处, 首先是生长速度慢, 布氏乳杆 菌需要在厌氧条件下生长30~60天才能有效改善青贮 有氧稳定性 [22] ; [30,31] . Liu等人 [32] 研究表明, 类谷糠乳杆菌在较低的 相对丰度高于80%, 有助于青贮品质的长期保存 [14,16] .…”