Community Synergy of Lactic Acid Bacteria and Cleaner Fermentation of Oat Silage Prepared with a Multispecies Microbial Inoculant.

To investigate community synergy of lactic acid bacteria (LAB) and cleaner fermentation of oat silage, oat silages were prepared with or without (control) commercial LAB inoculants LI1 (containing Lactiplantibacillus plantarum, Lentilactobacillus buchneri, Lacticaseibacillus paracasei, and Pediococcus acidilactici) and LI2 (containing Lactiplantibacillus plantarum and Lentilactobacillus buchneri). The microbial community, LAB synergy, and cleaner fermentation were analyzed at 1, 3, 6, 15, 35, and 90 days of ensiling. The LAB inoculant improved fermentation quality, with significantly (P < 0.05) lower pH, ammonia nitrogen content, and gas production and higher lactic acid and acetic acid contents than those of the control. Enterobacteriaceae was the main bacterial community in early stage of fermentation, which utilizes sugar to produce CO2 gas, causing dry matter (DM) and energy loss. As fermentation progressed, the microbial diversity decreased, and the microbial community shifted from Gram-negative to Gram-positive bacteria. The inoculation of multispecies LAB displayed community synergy; Pediococcus acidilactici formed a dominant community in the early stage of fermentation, which produced an acid and anaerobic environment for the subsequent growth of Lentilactobacillus and Lacticaseibacillus species, thus forming a LAB-dominated microbial community. The predicted functional profile indicated that the silage inoculated with LI1 enhanced the carbohydrate metabolism pathway but inhibited the amino acid metabolism pathway, which played a role in promoting faster lactic acid production, reducing the decomposition of protein to ammonia nitrogen, and improving the fermentation quality of silage. Therefore, oat silage can be processed to high-quality and cleaner fermented feed by using an LAB inoculant, and LI1 showed better efficiency than LI2. IMPORTANCE Oat natural silage is rich in Enterobacteriaceae, increasing gas production and fermentation loss. Lactic acid bacteria interact synergistically to form a dominant community during ensiling. Pediococci grow vigorously in the early stage of fermentation and create an anaerobic environment. Lactobacilli inhibit the harmful microorganisms and result in cleaner fermentation of oat silage.

Fermentation quality, bacterial community, and aerobic stability of ensiling Leymus chinensis with lactic acid bacteria or/and water after long-term storage.

Leymus chinensis is a major forage resource for herbivores on typical steppe and meadow steppes in Northern China. This study aimed to reveal the fermentation quality, bacterial community, and aerobic stability of L. chinensis silage treated with lactic acid bacteria or/and water after long-term storage. Leymus chinensis was harvested at the heading stage and ensiled with lactic acid bacteria [LAB, 2.00 ml/kg fresh weight (FW) of LAB, L], water (100 ml/kg FW of distilled water, W), or a combination of both [2.00 ml/kg fresh weight (FW) of LAB and 100 ml/kg FW of distilled water, LW] in polyethylene laboratory-scale silos (diameter, 20 cm; height, 30 cm) at a density of 650 kg/m3. As a control silage (CK), untreated L. chinensis silage was also assessed. The samples were taken at 0 day of opening after 300 days of ensiling (CK_0d, L_0d, W_0d, and LW_0d) and at 10 days of opening (CK_10d, L_10d, W_10d, and LW_10d). The fermentation quality, microbial counts, bacterial community, and aerobic stability of the silage were assessed. The CK_0d contained higher pH and aerobic bacteria count, and lower LA and BC concentrations than L_0d, W_0d, and LW_0d (p < 0.05), and the LAB and yeasts were only detected in CK at 0 day of opening. Lactobacillus had the most abundance among bacterial genera in all silages at 0 day of opening. Just CK had 2°C above the ambient temperature during aerobic exposure (at 224 h). During aerobic exposure, the pH and microbial counts in CK increased (p < 0.05), and Lactobacillus in L and LW had decreasing abundance (p < 0.05). The CK_10d had higher pH and microbial counts, and lower lactic acid and buffering capacity than L_10d, W_10d, and LW_10d (p < 0.05). At 10 days of opening, the coliforms and yeasts were just detected in CK, and Lactobacillus also had the most abundance among bacterial genera in all silages at 10 days of opening. Overall, inoculating LAB and adding water improved the fermentation quality and the aerobic exposure of L. chinensis silage after long-term storage. The activities of coliforms and yeasts during aerobic exposure contributed to the aerobic deterioration of L. chinensis silage without any treating. Lactobacillus dominated the bacterial communities of all silage at 0 and 10 days of opening. During aerobic exposure, the abundance of Lactobacillus reduced in L. chinensis silage treated with LAB or water.

Bacterial Community and Fermentation Quality of Ensiling Alfalfa With Commercial Lactic Acid Bacterial Additives.

The aim of this study was to determine the effects of six common commercial lactic acid bacteria (LAB) additives [A1, Lactobacillus plantarum, L. buchneri, and Enterococcus faecalis; A2, L. plantarum and L. casei; A3, L. plantarum and L. buchneri; A4, L. plantarum, L. buchneri, L. casei, and Pediococcus acidilactici; A5, L. plantarum (producing feruloyl esterase); and A6, L. buchneri, P. acidilactici, ß-glucanase, and xylanase] on the bacterial community and fermentation quality of alfalfa silage. Alfalfa was harvested at the squaring stage, wilted in the field for 24 h, and ensiled without any additives (Control) or with A1, A2, A3, A4, A5, or A6. Microbial counts, bacterial community, fermentation parameters, and nutritional composition were determined after ensiling for 90 days. The total abundance of LAB genera on alfalfa pre-ensiling was 0.38% in bacterial community. The abundances of Lactobacillus, Enterococcus, and Pediococcus in the Control silage were 42.18, 40.18, and 8.09% of abundance, respectively. The abundances of Lactobacillus in A1-, A2-, A3-, A4-, and A5-treatments were 89.32, 92.93, 92.87, 81.12, and 80.44%, respectively. The abundances of Pediococcus and Lactobacillus in A6-treatment were 70.14 and 24.86%, respectively. Compared with Control silage, LAB-treated silage had lower pH and less ammonia nitrogen and water-soluble carbohydrates concentrations (p < 0.05). Further, the A5- and A6-treatments contained lower neutral detergent fiber, acid detergent fiber, and hemicellulose than other treatments (p < 0.05). Overall, LAB genera were presented as minor taxa in alfalfa pre-ensiling and as dominant taxa in alfalfa silage. Adding LAB additives improved the fermentation quality and altered the bacterial community of alfalfa silage. The main bacterial genera in Control silage were Lactobacillus, Enterococcus, and Pediococcus. Lactobacillus dominated the bacterial communities of A1-, A2-, A3-, A4-, and A5-treatments, while Pediococcus and Lactobacillus were dominant bacterial genera in A6-treatment. Inoculating A5 and A6 degraded the fiber in alfalfa silage. It is necessary to ensile alfalfa with LAB inoculants.