The potential and effects of saline-alkali alfalfa microbiota under salt stress on the fermentation quality and microbial

Abstract

Background The objective of this study was to evaluate the chemical compositions and microbial communities of salt-tolerant alfalfa silage. Salt-tolerant alfalfa was ensiled with no additive control, and cellulase for 30 and 60 to 90 days. In this study, the dry matter (DM) content of the raw material was 29.9% DM, and the crude protein (CP) content of the alfalfa was 21.9% CP. Results After 30 days of fermentation, the DM content with the cellulase treatment was reduced by 3.6%, and the CP content was reduced by 12.7%. After 60 days of fermentation, compared with alfalfa raw material, the DM content in the control group (CK) was reduced by 1%, the CP content was reduced by 9.5%, and the WSC (water-soluble carbohydrates) content was reduced by 22.6%. With the cellulase, the lactic acid content of the 30- and 60-day silages was 2.66% DM and 3.48% DM. The content of Firmicutes in salinized alfalfa raw material was less than 0.1% of the total bacterial content. Before and after ensiling, the microbes had similar composition at the phylum level, and were composed of Firmicutes, Actinobacteria, Bacteroidetes, and Proteobacteria. The abundance of Pantoea was dominant in fresh alfalfa. In the absence of additives, after 30 days and 60 days of silage, the dominant lactic acid bacteria species became Lactococcus and Enterococcus. Conclusions The results showed that LAB (Lactobacillus, Lactococcus, Enterococcus, and Pediococcus) played a major role in the fermentation of saline alfalfa silage. It also can better preserve the nutrients of saline alfalfa silage. The use of cellulase enhances the reproduction of Lactobacillus. The fermentation time would also change the microbial community of silage fermentation.

Effects of Malic Acid and Sucrose on the Fermentation Parameters, CNCPS Nitrogen Fractions, and Bacterial Community of Moringa oleifera Leaves Silage

“…Bacteroidetes was positively correlated with PA, LA, and AN and negatively correlated with NDF, ADF, and WSC, probably because Bacteroidetes is mainly involved in the hydrolysis of complex macromolecules [ 52 ]. In addition, Sa et al reported that Chloroflexi is associated with acid production [ 53 ], but our results showed no correlation between Chloroflexi and organic acid (LA and AA). We could speculate that Chloroflexi only accounted for 0.01% of the bacterial community and that the effects of Chloroflexi on fermentation were negligible.…”

Effects of Lactic Acid Bacteria and Molasses Additives on Dynamic Fermentation Quality and Microbial Community of Native Grass Silage

“…Similarly, Bai et al (2021) also discovered that the expression of the carbohydrate metabolism pathway was connected to the relative abundance of total L in the bacterial community. The abundance of amino acid metabolism, nucleotide metabolism, and cofactor and vitamin metabolism gradually increased with fermentation, which contradicted the findings of Sa et al (2021) who observed that amino acid metabolism, nucleotide metabolism, and metabolism of cofactors and vitamins were decreased in the inoculated silages during the fermentation stage. This might be because the raw materials attached to L and WSC content were low, while the exogenous additives contributed to the increase in this metabolism.…”

“…In the present study, Pantoea was found to be the most common facultative aerobic genus in FM. Pantoea has been observed in fresh native grass ( You et al, 2021 ), alfalfa ( Sa et al, 2021 ), and soybean ( Ni et al, 2017 ). Pantoea abundance decreased after 30 days of fermentation, which might be attributable to their great sensitivity to pH decline ( Ogunade et al, 2018 ).…”

Effects of Different Types of LAB on Dynamic Fermentation Quality and Microbial Community of Native Grass Silage during Anaerobic Fermentation and Aerobic Exposure

“…LEfSe analysis was used to further analyze the differences in bacterial communities between treatment groups. Among the YL groups, Proteobacteria, Enterobacter , and Pantoea were the common microorganisms in silage feedstock, and their growth and reproduction were inhibited and abundance decreased significantly after silage fermentation, so they were the differential microorganisms with respect to silage, which is in agreement with the results of Li et al [ 64 ] and Sa et al [ 65 ]. The differential bacteria in the CK group were Enterobacteriaceae and Limosilactobacillus .…”