Modulation of Fermentation Quality and Metabolome in Co-ensiling of Sesbania cannabina and Sweet Sorghum by Lactic Acid Bacterial Inoculants

Fermentation quality, amino acids profile, and microbial communities of whole-plant soybean silage in response to Lactiplantibacillus plantarum B90 alone or in combination with functional microbes

Promoting the availability of silage with a high protein content on farms can lead to profitable and sustainable ruminant production systems. Whole plant soybean (Glycine max L. Merrill, WPS) is a promising high-protein forage material for silage production. In this study, we investigated the fermentation quality, amino acids profile and microbial communities of WPS silage in response to inoculation of lactic acid bacteria (LAB) alone or in combination with non-LAB agents. Before preparing the treatments, the chopped WPS was homogenized thoroughly with 0.3% molasses (0.3 g molasses per 100 g fresh matter). The treatments included CK (sterilized water), LP (Lactiplantibacillus plantarum B90), LPBS (LP combined with Bacillus subtilis C5B1), and LPSC (LP combined with Saccharomyces cerevisiae LO-1), followed by 60 days of fermentation. The inoculants significantly decreased the bacterial diversity and increased the fungal diversity of WPS silage after ensiling. As a result, the contents of lactic acid and acetic acid increased, while the pH value and propionic acid content decreased in the inoculated silages. The amino acids profile was not influenced by inoculants except phenylalanine amino acid, but LP and LPSC silages had substantial greater (p < 0.05) relative feed values of 177.89 and 172.77, respectively, compared with other silages. Taken together, the inoculation of LP alone or in combination with BS was more effective in preserving the nutrients of WPS silage and improve fermentation quality.

Dynamics of fermentation quality, bacterial communities, and fermentation weight loss during fermentation of sweet sorghum silage

BACKGROUND

Sweet sorghum is used mainly as an energy crop and feed crop in arid and semiarid regions, and ensiling is a satisfactory method for preserving high-quality sweet sorghum. The aim of this study was to reveal the dynamics of the fermentation quality, bacterial communities, and fermentation weight loss (FWL) of sweet sorghum silage during fermentation.

METHODS

Sweet sorghum was harvested at the first inflorescence spikelet stage and ensiled without (CK) or with lactic acid bacterial (LAB) additives (L). After ensiling, samples were collected on days 0, 1, 3, 5, 15, 40, and 100 to assess the fermentation quality, bacterial communities, and FWL.

RESULTS

For CK and L, on day 1, the pH was 5.77 and 5.57, respectively, and the lactic acid (LA) was 1.30 and 2.81 g/kg dry matter (DM), respectively. Compared with CK, L had a lower pH and higher LA from days 1 to 5 (P < 0.05), a lower FWL from days 5 to 100 (P < 0.05), and a greater abundance of Lactiplantibacillus from days 1 to 15 (P < 0.05). The main bacterial genera were Leuconostoc and Weissella in CK and Lactiplantibacillus, Leuconostoc, and Weissella in L on day 1; Lactiplantibacillus in all silages from days 3 to 40; and Lactiplantibacillus and Lentilactobacillus in all silages on day 100.

CONCLUSIONS

Sweet sorghum silage fermented relatively slowly during the first day. Moreover, inoculation with LAB accelerated fermentation and optimized bacterial communities during the initial fermentation phase. Inoculation with LAB also reduced the silage FWL, and the LAB succession relay occurred in the silage throughout the fermentation process.

Impact of Additives and Packing Density on Fermentation Weight Loss, Microbial Diversity, and Fermentation Quality of Rape Straw Silage

To investigate the effects of the combined addition of Lactiplantibacillus plantarum and sucrose on the fermentation weight loss (FWL), fermentation quality, and microbial community structure of ensiled rape straw under varying packing density conditions. After harvesting, the rapeseed straw was collected, cut into 1-2 cm pieces, and sprayed with sterile water to adjust the moisture content to 60%. The straw was then divided into two groups: one treated with additives (1 × 105 CFU/g fresh material of Lactiplantibacillus plantarum and 10 kg/t fresh material of sucrose), and the other sprayed with an equivalent amount of sterile water as the control (CK). The treated materials were thoroughly mixed and packed into silos at densities of 450, 500, and 550 kg/m3. FWL was recorded on days 1, 3, 6, 15, 20, and 45 of fermentation. On day 45, the samples were analyzed for fermentation quality, microbial counts, and microbial diversity. FWL increased significantly (p < 0.05) in both the treated (LS) and control groups during fermentation. The LS group showed higher lactic acid (LA) levels (p < 0.05) and lower ammonia nitrogen levels (p < 0.05) compared to CK. The CK group had significantly higher (p < 0.05) counts of Coliforms and lower bacterial counts (p < 0.05) than LS. The dominant genera in the silage were Xanthomonas, Lactiplantibacillus plantarum, and Lentilactobacillus. In the LS group, the relative abundances of Lactiplantibacillus plantarum and Lentilactobacillus ranged from 16.93% to 20.43% and 15.63% to 27.46%, respectively, with their combined abundance being higher than in CK. At a packing density of 500 kg/m3, the relative abundances of Lactiplantibacillus plantarum and Lentilactobacillus in the LS group were significantly higher (p < 0.05) than in CK. Increasing packing density and applying additives to rape straw silage effectively reduced FWL, improved fermentation quality, boosted the relative abundance of beneficial lactic acid bacteria, and decreased the presence of undesirable bacteria such as Enterobacter and Bacillus.

Antioxidant and anti-inflammatory properties of water kefir microbiota and its bioactive metabolites for health promoting bio-functional products and applications

Inflammation and oxidative stress are implicated in several chronic disorders, while healthy foods and especially fermented beverages and those containing probiotics can provide anti-inflammatory and antioxidant protection against such manifestations and the associated disorders. Water kefir is such a beverage that is rich in both probiotic microbiota and anti-inflammatory bioactives, with an increasing demand as an alternative to a fermented product based on non-dairy matrix with potential health properties. Within this study, the health-promoting properties of the most representative species and strains of microorganisms present in water kefir grains, as well as the health benefits attributed to the bioactive metabolites produced by each individual strain in a series of their cultures, were thoroughly reviewed. Emphasis was given to the antioxidant, antithrombotic, and anti-inflammatory bio-functionalities of both the cultured microorganisms and the bioactive metabolites produced in each case. Moreover, an extensive presentation of the antioxidant and anti-inflammatory health benefits observed from the overall water kefir cultures and classic water kefir beverages obtained were also conducted. Finally, the use of water kefir for the production of several other bio-functional products, including fermented functional foods, supplements, nutraceuticals, nutricosmetics, cosmeceuticals, and cosmetic applications with anti-inflammatory and antioxidant health promoting potential was also thoroughly discussed. Limitations and future perspectives on the use of water kefir, its microorganisms, and their bioactive metabolites are also outlined.

Integrated Metabolomics and Metagenomics Unveiled Biomarkers of Antioxidant Potential in Fermented Brewer's Grains

About one-third of the global food supply is wasted. Brewers' spent grain (BSG), being produced in enormous amounts by the brewery industry, possesses an eminence nutritional profile, yet its recycling is often neglected for multiple reasons. We employed integrated metagenomics and metabolomics techniques to assess the effects of enzyme treatments and Lactobacillus fermentation on the antioxidant capacity of BSG. The biotreated BSG revealed improved antioxidant capability, as evidenced by significantly increased (p < 0.05) radical scavenging activity and flavonoid and polyphenol content. Untargeted metabolomics revealed that Lactobacillus fermentation led to the prominent synthesis (p < 0.05) of 15 novel antioxidant peptides, as well as significantly higher (p < 0.05) enrichment of isoflavonoid and phenylpropanoid biosynthesis pathways. The correlation analysis demonstrated that Lactiplantibacillus plantarum exhibited strong correlation (p < 0.05) with aucubin and carbohydrate-active enzymes, namely, glycoside hydrolases 25, glycosyl transferases 5, and carbohydrate esterases 9. The fermented BSG has potential applications in the food industry as a culture medium, a functional food component for human consumption, and a bioactive feed ingredient for animals.

Chemical characteristics, antioxidant capacity, bacterial community, and metabolite composition of mulberry silage ensiling with lactic acid bacteria

Mulberry has high crude protein and biologically active compounds but is difficult to be ensiled due to the lack of adequate epiphytic LAB. This study aimed to investigate the effects of inoculation with Lactiplantibacillus plantarum and Pediococcus pentosaceus isolated from mulberry with higher antioxidant capacity alone or in combination with Streptococcus bovis on chemical characteristics, antioxidant capacity, bacterial community, and metabolite composition of mulberry silage. The results showed that all inoculation groups had higher dry matter and lower pH than the control group, particularly in LP (dry matter, DM, 32.03% and pH = 4.44) and LP_PP_SB (DM, 31.68% and pH = 4.26) after 60 days of ensiling. Ammonia nitrogen (AN) content was the lowest in both LP_SB and LP_PP_SB groups, which were 1.86 g/kg FM and 1.05 g/kg FM, respectively, (P < 0.05). Only the LP_PP_SB group showed increased polyunsaturated fatty acids (PUFA, 1.2851 g/kg DM, P < 0.05) than the control group. Ferric-reducing antioxidant power (FRAP) values were increased in all inoculation-treated groups compared with the control group (P < 0.05). 2,2-Diphenyl-1-picrylhydrazyl (DDPH), 3-ethylbenzothiazoline-6-sulfonic acid (ABTS), and FRAP exhibited the highest levels in the LP_PP- and LP_PP_SB-treated groups. Enterobacter was dominant in both the control and SB-treated groups, and the relative abundance was 41.18% and 32.35%, respectively (P < 0.05). The relative abundance of Lactiplantibacillus was higher in the LP-, LP_PP-, and LP_SB-treated groups (81.84%-82.69%). Relative abundance of Pediococcus was higher in the PP-, PP_SB-, and LP_PP_SB-treated groups (74.27%-85.27%). Untargeted metabolomics analysis results showed that five flavonoids (apigenin, eriodictyol, quercetin-3-glucoside, rutin, and kaempferol-3-O-rutinoside)were upregulated in all inoculation groups (except for the SB-treated groups). Among them, eriodictyol was both positively correlated with ABTS and FRAP and also showed the highest relative abundance in the LP_PP- and LP_PP_SB-treated groups. To the best of our knowledge, this study was the first to investigate the relationship between inoculants of epiphytic lactic acid bacteria and antioxidant capacity by 16s rRNA Illumina sequencing technology and untargeted metabolomics analysis, respectively. Consequently, inoculated L. plantarum, P. pentosaceus alone, respectively, or in combination with S. bovis increased the relative abundance of Lactiplantibacillus and Pediococcus and decreased the relative abundance of Enterobacter, particularly in the LP_PP_SB-treated group. In addition, inoculants could increase the relative abundance of five flavonoids (apigenin, eriodictyol, quercetin-3-glucoside, rutin, and kaempferol-3-O-rutinoside), especially eriodictyol to improve the antioxidant capacity of mulberry silage.

The influence of low-temperature resistant lactic acid bacteria on the enhancement of quality and the microbial community in winter Jerusalem Artichoke (Helianthus tuberosus L.) silage on the Qinghai-Tibet Plateau

Jerusalem Artichoke (Helianthus tuberosus L.), an emerging "food and fodder" economic crop on the Qinghai-Tibet Plateau. To tackle problems such as incomplete fermentation and nutrient loss occurring during the low-temperature ensilage of Jerusalem Artichokes in the plateau's winter, this study inoculated two strains of low-temperature resistant lactic acid bacteria, Lactobacillus plantarum (GN02) and Lactobacillus brevis (XN25), along with their mixed components, into Jerusalem Artichoke silage material. We investigated how low-temperature resistant lactic acid bacteria enhance the quality of low-temperature silage fermentation for Jerusalem Artichokes and clarify its mutual feedback effect with microorganisms. Results indicated that inoculating low-temperature resistant lactic acid bacteria significantly reduces the potential of hydrogen and water-soluble carbohydrates content of silage, while increasing lactic acid and acetic acid levels, reducing propionic acid, and preserving additional dry matter. Inoculating the L. plantarum group during fermentation lowers pH and propionic acid levels, increases lactic acid content, and maintains a dry matter content similar to the original material. Bacterial community diversity exhibited more pronounced changes than fungal diversity, with inoculation having a minor effect on fungal community diversity. Within the bacteria, Lactobacillus remains consistently abundant (>85%) in the inoculated L. plantarum group. At the fungal phylum and genus levels, no significant changes were observed following fermentation, and dominant fungal genera in all groups did not differ significantly from those in the raw material. L. plantarum exhibited a positive correlation with lactic acid and negative correlations with pH and propionic acid. In summary, the inoculation of L. plantarum GN02 facilitated the fermentation process, preserved an acidic silage environment, and ensured high fermentation quality; it is a suitable inoculant for low-temperature silage in the Qinghai-Tibet Plateau.

Intercropping efficiency of Pteris vittata with two legume plants: Impacts of soil arsenic concentrations

Intercropping of hyperaccumulators with crops has emerged as a promising method for remediating arsenic (As)-contaminated soil in agroecosystems. However, the response of intercropping hyperaccumulators with different types of legume plants to diverse gradients of As-contaminated soil remains poorly understood. In this study, we assessed the response of plant growth and accumulation of an As hyperaccumulator (Pteris vittata L.) intercropped with two legume plants to three gradients of As-contaminated soil. Results indicated that soil As concentration had a substantial effect on the As uptake by plants. P. vittata growing in slightly As-contaminated soil (80 mg kg^-1) exhibited higher As accumulation (1.52-5.49 folds) than those in higher As-contaminated soil (117 and 148 mg kg^-1), owing to the lower soil pH in high As-contaminated soil. Intercropping with Sesbania cannabina L. increased As accumulation in P. vittata by 19.3%- 53.9% but decreased in intercropping with Cassia tora L. This finding was attributed to S. cannabina providing more NO₃^--N to P. vittata to support its growth, and higher resistance to As. The decreased rhizosphere pH in the intercropping treatment also resulted in the increased As accumulation in P. vittata. Meanwhile, the As concentrations in the seeds of the two legume plants met the national food standards(<0.5 mg kg^-1). Therefore, the intercropping P. vittata with S. cannabina is a highly effective intercropping system in slightly As-contaminated soil and provides a potent method for As phytoremediation.

Dry matter content and inoculant alter the metabolome and bacterial community of alfalfa ensiled at high temperature

Alfalfa silage fermentation quality, metabolome, bacterial interactions, and successions as well as their predicted metabolic pathways were explored under different dry matter contents (DM) and lactic acid bacteria (LAB) inoculations. Silages were prepared from alfalfa with DM contents of 304 (LDM) and 433 (HDM) g/kg fresh weight and inoculated with Lactiplantibacillus plantarum (L. plantarum, LP), Pediococcus pentosaceus (P. pentosaceus, PP), or sterile water (control). The silages were stored at a simulated hot climate condition (35°C) and sampled at 0, 7, 14, 30, and 60 days of fermentation. The results revealed that HDM significantly improved the alfalfa silage quality and altered microbial community composition. The GC-TOF-MS analysis discovered 200 metabolites in both LDM and HDM alfalfa silage, mainly consisting of amino acids, carbohydrates, fatty acids, and alcohols. Compared with LP and control, PP-inoculated silages had increased concentrations of lactic acid (P < 0.05) and essential amino acids (threonine and tryptophan) as well as decreased pH, putrescine content, and amino acid metabolism. However, alfalfa silage inoculated with LP had higher proteolytic activities than control and PP-inoculated silage, as revealed by a higher concentration of ammonia nitrogen (NH₃-N), and also upregulated amino acid and energy metabolism. HDM content and P. pentosaceus inoculation significantly altered the composition of alfalfa silage microbiota from 7 to 60 days of ensiling. Conclusively, these results indicated that inoculation with PP exhibited great potential in enhancing the fermentation of silage with LDM and HDM via altering the microbiome and metabolome of the ensiled alfalfa, which could help in understanding and improving the ensiling practices under hot climate conditions. KEY POINTS: • HDM improved fermentation quality and declined putrescine content of alfalfa silage • P. pentosaceus inoculation enhanced the fermentation quality of alfalfa silage • P. pentosaceus is an ideal inoculant for alfalfa silage under high temperature.

Response of fermentation quality and microbial community of oat silage to homofermentative lactic acid bacteria inoculation

Oat (Avena sativa L.) is one of the important forage crops in the world. However, oat grown in Southwest China has higher moisture content and their preservation face significant challenges. In addition, existing commercial lactic acid bacteria (LAB) have poor fermentation effects in hot and humid regions. Consequently, the current study investigated the response of oat fermentation quality and microbial community to self-selected LAB inoculation. The treatments were: CK, sterilized water; LP694, Lactobacillus plantarum 694; LR753, Lactobacillus rhamnosus 753; and LPLR, LP694 combined with LR753, followed by 1, 3, 7, 14, and 60 days (d) of fermentation. The results showed that LAB inoculation significantly raised the lactic acid content, and decreased the level of pH value, acetic acid, and ammonia-N in oat silage. The LR753 group had a significantly higher (p < 0.05) lactic acid content (60.95 g kg-1 DM), and lower pH value (3.95) and ammonia-N content (10.1 g kg-1 DM) followed by the LPLR group. The LR753 showed lower NDF (54.60% DM) and ADF (39.73% DM) contents than other groups. The Lactobacillus was a prevalent genus in LAB-treated groups, and its relative abundance reached maximum in LP694 (69%) on day 3, while in the LR753 group (72%) on 60 days. The Lactobacillus rhamnosus, Lactobacillus plantarum, and Lactobacillus fermentum became the dominant species in LAB-treated groups with fermentation time. The Lactobacillus genus was positively correlated with WSC (R = 0.6, p < 0.05), while negatively correlated with pH (R = -0.5, p < 0.05), and BA (R = -0.5, p < 0.01). Overall, the LR753 group had better fermentation quality and preservation of nutritional components providing theoretical support and guidance for future oat silage production in Southwest China.

Exploring the bacterial community succession and metabolic profiles of Lonicera japonica Thunb. residues during anaerobic fermentation

Discarding Lonicera japonica Thunb. (LJT) residues containing many active metabolites create tremendous waste. This study aimed to effectively use LJT residues by anaerobic fermentation. Fermentation significantly decreased the pH values and reduced the abundance of undesirable bacteria (potential pathogenic and biofilm-forming) while increasing Lactobacillus abundance. Compound additive use further improved fermentation quality (significantly increased the lactic acid (LA) content and decreased the pH values and ammonia nitrogen (a-N) content) and nutrient quality (significantly decreased the acid detergent fiber (ADF) content and increased the water-soluble carbohydrate (WSC) content) and optimized the microbial community (increased the Lactobacillus abundance). Fermentation also altered the flavonoids, alkaloids and phenols contents in the residues with minor effects on the functional metabolites amounts. The LJT residues metabolic profile was mainly attributed to its epiphytic bacteria, with a small contribution from the compound additive. Thus, compound additives may improve anaerobic LJT residue fermentation without functionally impairing the metabolites.

Influence of Lactobacillus plantarum inoculation on the silage quality of intercropped Lablab purpureus and sweet sorghum grown in saline-alkaline region

Ensiling legume with cereal is an effective method to ensure the energy rich-feed, but no information is available on the microbial fermentation mechanism of intercropped Lablab purpureus (Lablab) and sweet sorghum in the saline-alkaline region. Therefore, the present study investigated the silage quality and microbial community of intercropped Lablab and sweet sorghum silages grown in the saline-alkaline region with or without inoculation of Lactobacillus plantarum (LP). The experimental treatments were prepared according to the Lablab and sweet sorghum planting patterns: Lablab and sweet sorghum sowing seed ratios were 1:1 (L), 5:1 (M), and 9:1 (H). After harvesting, each mixture was treated with LP or sterilized water (CK), followed by 60 days of fermentation. Results showed that both LP inoculation and intercropping significantly raised the lactic acid (LA) content and decreased the pH value, acetic acid (AA), and ammonia-N in intercropped silages. The LP addition and intercropping also improved the relative feed value by reducing structural carbohydrates. Moreover, LP silages had a greater relative abundance of Lactobacillus than CK silages, and its relative abundance increased with an increased seed-sowing ratio of Lablab in intercropping. LP was the prevalent species in LP silages compared to CK silages, and its relative abundance also increased with an increased seed-sowing ratio of Lablab in intercropping. The genus Lactobacillus was negatively correlated with ammonia-N (R = -0.6, p = 0.02) and AA (R = -0.7, p < 0.01) and positively correlated with LA (R = 0.7, p < 0.01) and crude protein (R = 0.6, p = 0.04). Overall, the intercropped seeding ratios of Lablab and sweet sorghum of ≥ 5:1 with LP inoculation resulted in better fermentation quality and preservation of nutritional components providing theoretical support and guidance for future intercropped protein-rich silage production in the saline-alkaline region.

Fermentation weight loss, fermentation quality, and bacterial community of ensiling of sweet sorghum with lactic acid bacteria at different silo densities

Sweet sorghum is an important forage in arid and semi-arid climatic regions. This study aimed to reveal the fermentation weight loss (FWL), fermentation quality, and bacterial community of ensiling of sweet sorghum with lactic acid bacteria LAB; (Lactiplantibacillus plantarum and Lentilactobacillus buchneri) at different silo densities. For this study, sweet sorghum was harvested at the first spikelet of inflorescence stage and ensiled without or with LAB (CK or L) in polyethylene laboratory-scale silos (diameter, 20 cm; height, 30 cm) at densities of 650 (CK_650 and L_650), 700 (CK_700 and L_700), and 750 kg/m3 (CK_750 and L_750), respectively. The FWL, fermentation quality, microbial counts, and bacterial community of the silage were assessed after 100 days of ensiling. L_750 had a lower FWL than CK_650, _700, and _750 after 100 days of ensiling (P &lt; 0.005), and the FWL was affected by silo density and inoculating LAB (P &lt; 0.005). All silages had low pH (&lt;4.0) and ammonia nitrogen content (&lt;50 g/kg total nitrogen) and did not contain propionic and butyric acids; moreover, inoculating LAB increased lactic and acetic acids (P &lt; 0.005). Bacterial communities in inoculated and uninoculated silages were clustered together, respectively, and clearly separated from each other. The total abundance of Lactiplantibacillus and Lentilactobacillus in fresh forage was &lt;1%. Lactiplantibacillus had the highest abundance in all silages (from 71.39 to 93.27%), followed by Lentilactobacillus (from 3.59 to 27.63%). Inoculating LAB increased the abundance of Lentilactobacillus in each silo density (P &lt; 0.005) and decreased Lactiplantibacillus in the silage in densities of 700 and 750 kg/m3 (P &lt; 0.005); moreover, increasing silo density decreased Lactiplantibacillus abundance and increased Lentilactobacillus abundance in inoculated silages (P &lt; 0.005). Overall, sweet sorghum silage showed satisfactory fermentation quality, with a density of no &lt;650 kg/m3, and inoculating LAB improved fermentation quality and reduced FWL. Lactiplantibacillus and Lentilactobacillus presented as minor taxa in fresh sweet sorghum and dominated the bacterial community of all silages. Inoculating LAB was the main factor affecting the bacterial community of sweet sorghum silage. Moreover, inoculating LAB and increasing silo density can contribute to the decreasing Lactiplantibacillus abundance and increasing Lentilactobacillus abundance.

Dynamic Changes in Fermentation Quality and Structure and Function of the Microbiome during Mixed Silage of Sesbania cannabina and Sweet Sorghum Grown on Saline-Alkaline Land

Protein-rich Sesbania cannabina and sugar-rich sweet sorghum [Sorghum dochna (Forssk.) Snowden] are characterized by their higher tolerance to saline-alkaline stresses and simultaneous harvests. They could be utilized for coensiling because of their nutritional advantages, which are crucial to compensate protein-rich forage in saline-alkaline regions. The current study investigated the fermentation quality, microbial community succession, and predicted microbial functions of Sesbania cannabina and sweet sorghum in mixed silage during the fermentation process. Before ensiling, the mixtures were treated with compound lactic acid bacteria (LAB) inoculants followed by 3, 7, 14, 30, and 60 days of fermentation. The results revealed that the inoculated homofermentative species Lactobacillus plantarum and Lactobacillus farciminis dominated the early phase of fermentation, and these shifted to the heterofermentative species Lactobacillus buchneri and Lactobacillus hilgardii in the later phase of fermentation. As a result, the pH of the mixed silages decreased significantly, accompanied by the growth of acid-producing microorganisms, especially L. buchneri and L. hilgardii, which actively influenced the bacterial community structure and metabolic pathways. Moreover, the contents of lactic acid, acetic acid, 1,2-propanediol, and water-soluble carbohydrates increased, while the contents of ammonia-N and fiber were decreased, with increasing ratios of sweet sorghum in the mixed silage. Overall, coensiling Sesbania cannabina with >30% sweet sorghum is feasible to attain high-quality silage, and the relay action between homofermentative and heterofermentative LAB species could enhance fermentation quality and conserve the nutrients of the mixed silage. IMPORTANCE The coensiling of Sesbania cannabina and sweet sorghum is of great practical importance in order to alleviate the protein-rich forage deficiency in saline-alkaline regions. Furthermore, understanding the microbial community's dynamic changes, interactions, and metabolic pathways during ensiling will provide the theoretical basis to effectively regulate silage fermentation. Here, we established that coensiling Sesbania cannabina with >30% sweet sorghum was effective at ensuring better fermentation quality and preservation of nutrients. Moreover, the different fermentation types of LAB strains played a relay role during the fermentation process. The homofermentative species L. plantarum and L. farciminis dominated in the early phase of fermentation, while the heterofermentative species L. buchneri and L. hilgardii dominated in the later phase of fermentation. Their relay action in Sesbania cannabina-sweet sorghum mixed silage may help to improve fermentation quality and nutrient preservation.