The metabolome and bacterial composition of high-moisture Italian ryegrass silage inoculated with lactic acid bacteria during ensiling

Abstract

Background With its high nutritional value and productivity, Italian ryegrass as a biomass feedstock constantly supplies rumen degradable nitrogen and digestible fiber to ruminants. However, biofuel production is easily reduced during ensiling due to the high-moisture content of Italian ryegrass, leading to economic losses. Lactic acid bacteria inoculants could improve lignocellulosic degradation and fermentation quality and decrease dry matter loss during the bioprocessing of silage. Therefore, this study analyzed the effects of Lactobacillus buchneri TSy1-3 (HE), Lactobacillus rhamnosus BDy3-10 (HO), and the combination of HE and HO (M) on fermentation quality, bacterial community and metabolome in high-moisture Italian ryegrass silage during ensiling. Results The results showed that the pH value was significantly lower in the HO groups than in the other treatments at the end of ensiling, and the dry matter and acetic acid contents were significantly higher in the HO group than in the other inoculated groups. All inoculants decreased the diversity of the bacterial community and significantly increased the relative abundance of Lactobacillus. Inoculation with HO significantly improved the concentrations of organic acids, dipeptides, ferulic acid, apigenin, and laricitrin. Compared with Lactobacillus buchneri TSy1-3 (HE), HO significantly upregulated the flavonoid compounds in the flavone and flavonol biosynthesis pathway. Conclusions Overall, these findings suggest that inoculation with HO was beneficial for the development of Italian ryegrass as a biomass feedstock, improving fermentation quality, accelerating changes in bacterial community composition and increasing biofunctional metabolites in high-moisture Italian ryegrass silage.

Effects of inoculation and dry matter content on microbiome dynamics and metabolome profiling of sorghum silage

“…The variation in DM loss resulting from different DM contents during ensiling can be attributed to the presence of a highly active microbial population and a faster rate of fermentation in low-DM silage, as these factors may promote oxidation of organic matter (Wilkinson and Davies 2013 ; Kim et al 2016 ). Ensiling low-DM forages may delay pH reduction, possibly causing a less inhibitory effect on the growth and activity of undesirable microorganisms, which thus may increase nutrient loss during the early stages of ensiling fermentation (Ellis et al 2016 ; Xia et al 2023 ).…”

“…More recently, Xia et al ( 2023 ) investigated the impact of L. rhamnosus inoculation on the metabolome profile of low-DM (17.7%) Italian ryegrass silage. The authors reported that this homofermentative strain resulted in an upregulation of flavonoid compounds in the flavone and flavonol biosynthesis pathway, which thereby increased apigenin concentration after 60 days of ensiling fermentation.…”

The growth promotion in endophyte symbiotic plants does not penalise the resistance to herbivores and bacterial microbiota

“…Libraries for sequencing were prepared by Macrogen Inc. using the primers 799F: AACMGGATTAGATACCCKG and 1193R: ACGTCATCCCCACCTTCC. These primers have been frequently used in metabarcoding studies and are highly specific for amplifying bacterial sequences in grasses (Liu, Tang, et al, 2022; Xia et al, 2023).…”

Mechanistic Insights into Nitrite Degradation by Metabolites of L. plantarum A50: An LC-MS-Based Untargeted Metabolomics Analysis

“…Glucose fermentation carried out by lactic acid bacteria leads to the production of organic acids like lactic acid and acetic acid [61]. These organic acids serve as the primary products of lactic acid bacteria fermentation, contributing to the regulation of the acid-base balance and inhibition of the growth of other detrimental microorganisms [62]. Simultaneously, organic acids also serve as a significant means of nitrite degradation.…”