Effects of microbial inoculants on the fermentation characteristics and microbial communities of sweet sorghum bagasse silage

From waste to value: Multi-omics reveal pomegranate peel addition improves corn silage antioxidant activity and reduces methane and nitrogen losses

Fermentation technology presents promising opportunities for food waste valorization. Pomegranate peel (PP), a food by-product, has potential applications in fermented feed. This study examined the effects of a 6% dry PP additive on the ensiling characteristics, antioxidant activity, metabolites, bacterial community, and in vitro ruminal fermentation, methane (CH4) emission of corn silage ensiled for 7 days and 60 days using microbiome and metabolome analyses. PP-treated silage inhibited (P < 0.05) protein degradation by reducing ammonia nitrogen and non-protein nitrogen concentrations during ensiling. The PP additive increased (P < 0.05) water-soluble carbohydrate content and reduced ethanol production in corn silage. Lactiplantibacillus dominated PP-treated silage at the initial ensiling stage, while Levilactobacillus prevailed at the final stage. Notably, the PP additive exhibited strong antioxidant activity by modulating antioxidant enzymes and flavonoid biosynthesis mediated by key metabolites (epigallocatechin and catechin). Correlation analysis identified Lactiplantibacillus, Citrobacter, Phytobacter and Burkholderia as key microbes in the production of antioxidant metabolites and enzymes in PP-treated silage. Additionally, PP supplementation reduced (P < 0.05) in vitro ruminal CH4 and nitrogen losses, while decreasing dry matter (DM) digestibility in corn silage. In summary, PP-treated corn silage enhanced antioxidant properties and reduced the nitrogen losses and in vitro ruminal CH4 emissions, but lowered DM digestibility. Thus, PP can be recommended as a silage additive, though the dry PP level should be lower than that used in this study.

Effects of Substituting Sweet Sorghum for Corn Silage in the Diet on the Growth Performance, Meat Quality, and Rumen Microorganisms of Boer Goats in China

Due to its superior drought tolerance, high biomass yield, and stress resistance, sweet sorghum (Sorghum bicolor L.) has emerged as an ideal candidate for sustainable forage production in arid, semi-arid, and mildly saline-alkaline regions. This study aimed to evaluate the effects of replacing corn silage (CS) with either forage sorghum silage (FSS) or sugar sweet sorghum silage (SSS) on goat meat quality, the rumen microbial community, and meat composition. Thirty 3-month-old Boer goats (average body weight: 13.44 ± 1.67 kg) were randomly assigned to five dietary treatments; the control group contained 50% corn silage (CON), while the experimental groups contained 50% FSS (group I), 70% FSS (group II), 50% SSS (group III), or 70% SSS (group V), with each group receiving the same concentrate diet but different roughage sources. The results showed that compared to the CON group (50% CS), the experimental groups had a significantly increased average daily weight gain (ADG) (p < 0.05) and slaughter rate (SR). It is noteworthy that group III (50% SSS) showed a significant increase of 12.4% in SR (p < 0.01). Analysis of the silage characteristics and changes in the rumen microbial community revealed that feeding SSS and FSS increased the relative abundance of Ruminococcus in the rumen, further enhanced the degradation and conversion of silage neutral detergent fiber (NDF), and promoted the synthesis of fatty acids and amino acids. Specifically, FSS significantly increased the amino acid content in the meat, while SSS effectively improved the crude protein (CP) and crude fat (CF) contents. In conclusion, replacing 50% CS with FSS or SSS can effectively improve the meat quality and growth performance of Boer goats.

Effects of cellulase or Lactobacillus plantarum on ensiling performance and bacterial community of sorghum straw

This study aimed to evaluate the effects of cellulase or Lactobacillus plantarum (L. plantarum) on the fermentation characteristics and microbial community structure of the sorghum straw silage. Sorghum straw was treated with the following four experimental conditions: distilled water (control, CK), cellulase (CEL), Lactobacillus plantarum (LP), and a combined treatment of Lactobacillus plantarum with cellulase (LPCEL). These results indicated that the LP treatment could markedly (p < 0.05) preserve the crude protein content compared to that in other treatments, whereas the CEL significantly (p < 0.05) reduced the acid detergent fiber content, while the LPCEL had the highest lactic acid content and lowest pH value. Proteobacteria and Pantoea were identified as the dominant phylum and genus in fresh materials, respectively. This phylum level dominance transitioned to Firmicutes post-treatment, while at the genus level, the community shifted from Pantoea to co-dominance of Lactobacillus and Prevotella, with Lactobacillus being the most abundant in both the CEL and LPCEL treatments. In conclusion, adding L. plantarum and cellulase to sorghum straw can significantly improve the fermentation quality of sorghum straw silage, and improve the nutritional value of silage by affecting the microbial community structure and metabolic pathways.

Effects of different additives on fermentation characteristics, nutrient composition and microbial communities of Leymus chinensis silage

BACKGROUND

Leymus chinensis (Trin.) Tzvel is a perennial high-quality indigenous grass in China; characterized by high yield, elevated crude protein content, excellent palatability, substantial leaf volume, adaptability, and longevity. This study aimed to examine the impact of Lactiplantibacillus plantarum (LP), Lactobacillus buhneri (LB), their combination (LPLB), and complex enzyme preparation (CE) on the quality and microbial community of Leymus chinensis silage.

RESULTS

Throughout silage fermentation, pH levels decreased in all treatment groups relative to the control group. The LPLB group exhibited elevated levels of lactic acid (LA) and water-soluble carbohydrates (WSC) content, alongside reduced concentrations of acidic detergent fibre (ADF), and neutral detergent fibre (NDF) content. It exhibited superior silage outcomes compared to the other groups. Lactobacillus predominated in the treatment groups, but Enterobacter was predominant in the control group. The microbial diversity was decreased in LP and LPLB within the treatment groups due to the suppression of unwanted bacteria. Functional predictions indicated that glyoxylate and dicarboxylate metabolism, starch and sucrose metabolism, glycolysis/gluconeogenesis, amino sugar metabolism, and nucleotide sugar metabolism were the most significant metabolic pathways, with LP being particularly important in each.

CONCLUSION

The experimental results demonstrated that the incorporation of various additives influenced the bacterial community structure, fermentation quality, and nutrient composition of Leymus chinensis silage differently. The LP and LPLB groups decreased pH and ADF levels and amassed a significant quantity of LA during fermentation, while preserving CP and WSC content. The microbial composition exhibited greater stability, which markedly enhanced the quality of Leymus chinensis silage, hence preserving its nutrient composition.

CLINICAL TRIAL NUMBER

Not applicable.

Effects of preservatives and drying methods on the nutrient composition and mould counts of hay and pellet processing of Oats

The aim of this study was to investigate the effects of different preservatives and drying methods on the nutrient composition and mould counts of oat hay and oat pellets. Oat hay and oat pellets were divided into 5 groups: CON (without additives, control), CAP (with 5% calcium propionate), CUR (with 5% curcumin), SKU (with 5% Scutellaria baicalensis) and KC (with 2% potassium carbonate). The nutrients and mould counts of each group were determined after air drying, drying at 50 °C and drying at 50 °C with forced air for 48 h and 96 h, respectively. Compared with air drying, drying at 50 °C and drying at 50 °C with forced air significantly increased the dry matter content of oat. Under different drying times and methods, the addition of preservatives at air-drying for 96 h was more effective at improving the crude protein content of oat hay but was not positive for oat pellets. In addition, under different drying times and methods, the addition of preservatives to oat hay dried at 50 °C for 48 h was more effective at reducing the contents of neutral detergent fibres and acidic detergent fibres. The addition of CUR to oat pellets dried at 50 °C was the most effective at reducing the neutral and acidic detergent fibres of oat pellets. Under different drying times and methods, the addition of preservatives during air drying and drying at 50 °C for 48 h was more effective in reducing mould counts in oat hay and oat pellets. In addition, CUR resulted in higher CP contents and lower mould counts not only in oat hay dried at 50 °C for 48 h but also in oat pellets air dried for 48 h, which indicates its potential use in oat hay production.

Metataxonomic characterization of the microbial present in the anaerobic digestion of turkey litter waste with the addition of two inocula: allochthonous and commercial

Turkey litter waste is lignocellulosic waste that can be sustainably used as an energy source through anaerobic digestion (AD). The 16S ribosomal RNA technique helps to unravel microbial diversity and predominant metabolic pathways. The assays were performed in 600-mL-glass bottles with 400 mL volume, for 60 days at 37 °C. The study evaluated the physicochemical parameters, the composition of the microbiota, and the functional inference in AD of different concentrations of turkey litter (T) using two inocula: granular inoculum (S) and commercial inoculum (B). The highest accumulated methane production (633 mL CH4·L-1) was observed in the test containing 25.5 g VS·L-1 of turkey litter with the addition of the two inocula (T3BS). In tests without inoculum (T3) and with commercial inoculum (T3B), there was an accumulation of acids and consequent inhibition of methane production 239 mL CH4·L-1 and 389 mL CH4·L-1, respectively. Bacteroidota, Firmicutes, and Actinobacteria were the main phyla identified. The presence of archaea Methanobacterium, Methanocorpusculum, and Methanolinea highlighted the hydrogenotrophic metabolic pathway in T3BS. Functional prediction showed enzymes involved in three metabolic pathways in turkey litter biodigestion: acetotrophic, hydrogenotrophic, and methylotrophic methanogenesis. The predominant hydrogenotrophic pathway can be observed by analyzing the microbiota, archaea involved in this specific pathway, genes involved, and relative acid consumption for T3S and T3BS samples with higher methane production. Molecular tools help to understand the main groups of microorganisms and metabolic pathways involved in turkey litter AD, such as the use of different inocula, allowing the development of strategies for the sustainable disposal of turkey litter.

Enhancing biomass conservation and enzymatic hydrolysis of sweet sorghum bagasse by combining pretreatment with ensiling and NaOH

Lignocellulosic pretreatment is an important stage in biomass utilization, which usually requires high input. In this study, a low-cost method using combined ensiling and NaOH was developed for lignocellulosic pretreatment. Sweet sorghum bagasse (SSB) was ensiled for 21 days and then treated with diluted NaOH (0%, 1%, and 2%) for fermentation. The results showed that the application of Lactobacillus plantarum (L) reduced fermentation losses of the silages, mainly low water-soluble carbohydrate (WSC) and ammonia nitrogen loss. Meanwhile, the application of Lactobacillus plantarum and ensiling enzyme (LE) promoted lignocellulosic degradation, as evidenced by low neutral detergent fiber (NDF), acid detergent fiber (ADF), lignin (ADL), and hemicellulosic (HC) contents. The dominant bacterial genera were Lactobacillus, uncultured_bacterium_f_Enterobacteriaceae, and Pantoea after silage, which corresponded to the higher lactic acid and acetic contents and lower pH. The reducing sugar yields of SSB increased after combined pretreatment of silage and NaOH and were further enhanced by the 2% NaOH application, as evidenced by the high reducing sugar yield and microstructure damage, especially in the L-2% NaOH group and the LE-2% NaOH group, in which the reducing sugar yields were 87.99 and 94.45%, respectively, compared with those of the no additive control (CK)-0 NaOH group. Therefore, this study provides an effective method for SSB pretreatment to enhance biomass conservation.

Microbial community assembly and chemical dynamics of raw brewers' spent grain during inoculated and spontaneous solid-state fermentation

Solid-state fermentation (SSF) carried out by microbial bioinoculants is an environmentally friendly technology for the sustainable recovery and valorization of agri-food wastes. Particularly, mesophilic SSF processes allows the production of bio-organic fertilizers enriched with beneficial soil microorganisms. However, the establishment of microbial consortia and the interaction with native waste microbiota still require thoughtful investigations. Here, raw brewers' spent grain (BSG), the main waste from the brewing industry, was subjected to two mesophilic SSF processes (maximum temperature of 35 °C) carried out by a multi-kingdom microbial bioinoculant and the BSG spontaneous microbiota. After 90 days, both SSF processes led to stable organic soil amendments, as indicated by the C:N ratio (10.00 ± 1.4), pH (6.66 ± 0.09), and DOC (8.45 ± 1.2 mg/g) values. Additionally, the fermented BSG showed a high nitrogen content (42.2 ± 3.4 mg/Kg) and biostimulating activities towardLepidium sativumseeds. The monitoring of microbial communities by high-throughput sequencing of 16S and ITS rRNA indicated that BSG samples were enriched in microbial genera with interesting agronomic applications (i.e.,Devosia, Paenibacillum, Trichoderma, Mucor, etc.). Microbial cross-kingdom network analyses suggested that the microbial assembly of BSG was significantly influenced by the bioinoculant, despite the inoculated microbial genera being able to persist in BSG samples only the first week of SSF. This suggests that the study of microbial interactions between exogenous microbial inoculants and waste resident microbiota is required to optimize SSF processes aimed at the recovery and valorization of unprocessed wastes.

Ruminal degradation characteristics of bagasse with different fermentation treatments in the rumen of beef cattle

This experiment aimed to study the degradation characteristics of bagasse after three fermentation treatments in beef cattle. Bagasse 1 was treated with 0.3% lactic acid bacteria (w/w). Bagasse 2 was treated with 0.3% mixed strains (Saccharomyces cerevisiae, Aspergillus niger, Aspergillus oryzae, and lactic acid bacteria at 2:1:1:1). Bagasse 3 was treated with 0.1% cellulase and 0.1% xylanase in addition to 0.3% mixed strains of bagasse 2. The dry matter (DM), crude ash (ASH), crude protein (CP), neutral detergent fiber (NDF), and acid detergent fiber (ADF) in the bagasses were determined. Compared to the control bagasse (without the strain and enzyme treatments), three fermented bagasses showed higher DM after 4 h fermentation. The CP and ASH contents in fermented bagasse 3 were the highest, while the contents of NDF and ADF in fermented bagasse 3 were the lowest among all the groups. The effective degradability of DM, CP, NDF, and ADF was highest in fermented bagasse 3 among the evaluated bagasse feed, followed by fermented bagasse 2 > fermented bagasse 1 > bagasse. Overall, fermented bagasse 3 was better than the control and other treated bagasses, thus fermented bagasse 3 is a hopeful source for ruminant diet of beef cattle.

Effect of endogenous sodium and potassium ions in plants on the quality of alfalfa silage and bacterial community stability during fermentation

This study investigated the impact of endogenous sodium and potassium ions in plants on the quality of alfalfa silage, as well as the stability of bacterial communities during fermentation. Silage was produced from the fermented alfalfa, and the chemical composition, fermentation characteristics, and microbiome were analyzed to understand their interplay and impact on silage fermentation quality. The alfalfa was cultivated under salt stress with the following: (a) soil content of <1‰ (CK); (b) 1‰-2‰ (LP); (c) 2‰-3‰ (MP); (d) 3‰-4‰ (HP). The results revealed that the pH of silage was negatively correlated with the lactic acid content. With the increase of lactic acid (LA) content increased (26.3-51.0 g/kg DM), the pH value decreased (4.9-5.3). With the increase of salt stress, the content of Na+ in silage increased (2.2-5.4 g/kg DM). The presence of endogenous Na+ and K+ ions in plants significantly affected the quality of alfalfa silage and the dynamics of bacterial communities during fermentation. Increased salt stress led to changes in microbial composition, with Lactococcus and Pantoea showing a gradual increase in abundance, especially under high salt stress. Low pH inhibited the growth of certain bacterial genera, such as Pantoea and Pediococcus. The abundance of Escherichia-Shigella and Comamonas negatively correlated with crude protein (CP) content, while Enterococcus and Lactococcus exhibited a positive correlation. Furthermore, the accumulation of endogenous Na+ in alfalfa under salt stress suppressed bacterial proliferation, thereby reducing protein degradation during fermentation. The pH of the silage was high, and the LA content was also high. Silages from alfalfa under higher salt stress had higher Na+ content. The alpha diversity of bacterial communities in alfalfa silages showed distinct patterns. Desirable genera like Lactococcus and Lactobacillus predominated in silages produced from alfalfa under salt stress, resulting in better fermentation quality.

The Weissella and Periweissella genera: up-to-date taxonomy, ecology, safety, biotechnological, and probiotic potential

Bacteria belonging to the genera Weissella and Periweissella are lactic acid bacteria, which emerged in the last decades for their probiotic and biotechnological potential. In 2015, an article reviewing the scientific literature till that date on the taxonomy, ecology, and biotechnological potential of the Weissella genus was published. Since then, the number of studies on this genus has increased enormously, several novel species have been discovered, the taxonomy of the genus underwent changes and new insights into the safety, and biotechnological and probiotic potential of weissellas and periweissellas could be gained. Here, we provide an updated overview (from 2015 until today) of the taxonomy, ecology, safety, biotechnological, and probiotic potential of these lactic acid bacteria.

The Effect of Lactiplantibacillus plantarum ZZU203, Cellulase-Producing Bacillus methylotrophicus, and Their Combinations on Alfalfa Silage Quality and Bacterial Community

This study assessed the effects of Lactiplantibacillus plantarum (ZZU203), cellulase-producing Bacillus methylotrophicus (CB), or their combination (ZZU203_CB) on the fermentation parameters of alfalfa after 10 and 60 days of ensiling. Additionally, the bacterial community compositions were analyzed using absolute quantification 16S-seq (AQS). The results showed that CB silage displayed a higher lactic acid (LA) concentration at 10 d, a higher abundance of Lactobacillus, and lower abundance of Pediococcus, Enterococcus, and Weissella than those in the control (CK) silage. Compared with CK silage, the ZZU203 silage increased LA concentration, fructose and rhamnose concentrations, and the abundance of Lactobacillus, and decreased pH value, ammoniacal nitrogen, acetic acid, neutral detergent fiber and acid detergent fiber concentrations, and the abundance of Pediococcus, Enterococcus, Weissella, Hafnia, and Garciella after 60 days of ensiling. In addition, ZZU203 and ZZU203_CB silage had a similar silage quality and bacterial community, while the inoculation of ZZU203_CB significantly promoted LA accumulation and the numbers of Lactobacillus at 10 d compared with ZZU203 silage. Therefore, ZZU203 or a combination of ZZU203 and CB can be used as potential silage additives to improve the silage quality of alfalfa.

Fermentation Properties and Bacterial Community Composition of Mixed Silage of Mulberry Leaves and Smooth Bromegrass with and without Lactobacillus plantarum Inoculation

To evaluate the fermentation properties and bacterial community composition of mulberry leaves when ensiled with smooth bromegrass, and the effects of Lactobacillus plantarum inoculation on the mixed silage of mulberry leaves and smooth bromegrass, mulberry leaves were mixed with smooth bromegrass at ratios of 100:0, 90:10, 80:20, 70:30 and 60:40, and ensiled for 60 d with and without L. plantarum inoculant. The results showed that the sole fermentation of mulberry leaves failed to achieve optimum fermentation quality. Silage with a mulberry leaf ratio of 80% performed better fermentation quality compared with other non-inoculated groups, indicated by lower pH value, adequate lactic acid accumulation, and enriched proportion of Lactobacillus in the bacterial community. L. plantarum inoculation dramatically improved fermentation quality of mulberry leaf silage compared with the non-inoculated control. However, the fermentation quality of the inoculated silage decreased along with the reduction in the ratio of mulberry leaves. In conclusion, L. plantarum inoculation has the capability to improve the silage quality of mulberry leaves. Combined ensiling with smooth bromegrass could also aid in improving silage quality of mulberry leaves, with the optimum ratio of mulberry leaves being 80%.

Can Alhaji maurorum as a halophyte plant be ensiled with molasses and Saccharomyces cerevisiae well?

Alhagi maurorum (Caspian Manna, AM) is a species of legume found commonly in the semi-arid region of the world. Nutritional aspects of silage prepared from AM have not been scientifically investigated so far, therefore, in this study, chemical-mineral composition, gas production parameters, ruminal fermentation parameters, buffering capacity, and silage characteristics of AM were investigated by standard laboratory methods. Fresh AM was ensiled in the mini-silos (3.5 kg) and treated with (1) no additive (control), (2) 5% molasses, (3) 10% molasses, (4) 1 × 10⁴ CFU of Saccharomyces cerevisiae [SC]/g of fresh silage, (5) 1 × 10⁴ CFU of SC/g of fresh silage + 5% molasses, (6) 1 × 10⁴ CFU of SC/g of fresh silage + 10% molasses, (7) 1 × 10⁸ CFU of SC/g of fresh silage, (8) 1 × 10⁸ CFU of SC/g of fresh silage + 5% molasses, and (9) 1 × 10⁸ CFU of SC/g of fresh silage + 10% molasses for 60 days. The lowest concentrations of NDF and ADF were related to treatments no. 6 and 5, respectively (p < 0.0001). The ash content as well as sodium, calcium, potassium, phosphorus and magnesium were highest in treatment no 2. Silages containing 10% molasses (no. 3) had the highest and lowest lactic (p < 0.0001) and butyric (p < 0.0001) acids, respectively. The highest amount of potential gas production was observed in treatments no. 5 and 6, respectively (p < 0.0001). Total yeast was decreased with increasing molasses in the silages (p < 0.0001). Acid-base buffering capacity was also highest in treatments no. 6 and 5, respectively (p = 0.0003). In general, due to the fibrous nature of AM, it is recommended to add molasses at levels of 5 or 10% when ensiling. The silages containing SC at a lower level (1 × 10⁴ CFU) along with higher levels of molasses (10% of DM) had better ruminal digestion-fermentation characteristics compared to other silages. Also, the addition of molasses improved the internal fermentation characteristics of AM in the silo.

Effects of Bacillus coagulans and Lactobacillus plantarum on the Fermentation Characteristics, Microbial Community, and Functional Shifts during Alfalfa Silage Fermentation

This study aimed to investigate the potential of Bacillus coagulans (BC) as an inoculant in alfalfa silage fermentation. Fresh alfalfa was harvested at a dry matter (DM) content of 329.60 g/kg fresh weight (FW), and inoculated without (CON) or with BC (1 × 106 CFU/g FW), Lactobacillus plantarum (LP, 1 × 106 CFU/g FW), and their combinations (LP+BC, 1 × 106 CFU/g FW, respectively). Samples were taken at 3, 7, 14, 30, and 60 d, with three replicates for each. The prolonged ensiling period resulted in a decrease in pH values and an increase in lactic acid (LA) concentrations in alfalfa silages. After 60 d of fermentation, the application of BC and LP decreased the pH values and increased LA concentrations in treated silages, especially when their combination was applied. Application of BC preserved more water-soluble carbohydrates (WSC), and further application of BC increased WSC in LP+BC-treated silage compared to LP-treated silage. There was no significant difference in the crude protein (CP) content between the CON and treated silages, however, the BC and LP treatments reduced the ammonia nitrogen (NH3-N) concentration, especially when their combination was applied. Additionally, the BC and LP-treated silages had lower neutral detergent fiber (NDF) and acid detergent fiber (ADF) when compared to the CON silage (p < 0.001). Inoculants also increased Lactobacillus abundance and decreased Enterococcus abundance after 60 d of fermentation. Spearman's rank correlation analysis revealed a positive correlation between LA concentration and Lactobacillus abundance. It was noteworthy that LP, BC, and their combination increased the relative abundances of carbohydrate metabolism, energy metabolism, cofactors, and vitamin metabolism, decreasing the relative abundances of amino acid metabolism and drug resistance: antimicrobial. Therefore, the inclusion of BC increased the fermentation quality of alfalfa silage, with the optimal combination being LP+BC. According to the findings, BC could be considered a viable bioresource for improving fermentation quality.

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 quality, bacterial community, and predicted functional profiles in silage prepared with alfalfa, perennial ryegrass and their mixture in the karst region

There is little information regarding the dynamics of fermentation products and the bacterial community in silage prepared with alfalfa (MS), perennial ryegrass (LP), and their mixture in the karst region. In this study, we explored the effects of combining MS with LP in different ratios (100% MS, 70% MS + 30% LP, 50% MS + 50% LP, 30% MS + 70% LP and 100% LP; fresh matter basis) on silage chemical composition, fermentation quality, bacterial communities and predicted functions during the ensiling process. Each treatment was prepared in triplicate and stored at room temperature (22–25°C) for 7, 15, and 45 days. The dry matter (DM) and water-soluble carbohydrate content of the silages increased as the LP proportion in the mixed silage increased; at 45 days, the 70% MS + 30% LP, 50% MS + 50% LP and 30% MS + 70% LP silages contained higher (p &lt; 0.05) CP content than the 100% MS and 100% LP silages. The 30% MS + 70% LP and 100% LP silages exhibited lower (p &lt; 0.05) pH and higher (p &lt; 0.05) LA content than the other silages; at 45 days, none of the silages contained PA or BA. As fermentation proceeded, the abundance of harmful (Enterobacteriaceae and Sphingomonas) and beneficial (Lentilactobacillus, Lactiplantibacillus, Secundilactobacillus, and Levilactobacillus) microorganisms decreased and increased, respectively, as the LP proportion in the mixed silage increased. The predicted functional distribution of microbial communities and metabolic pathways revealed that the 30% MS + 70% LP and 100% LP silages had a stronger capacity for fermentation and a weaker capacity for nitrate reduction than the other silages. Moreover, as the fermentation proceeded, the 30% MS + 70% LP and 100% LP treatments enhanced the functions of “Metabolism,” “Genetic information processing” and “Organismal systems” at level 1, the functions of “Amino acid metabolism” and “Nucleotide metabolism” at level 2, and the functions of “Metabolic pathways,” “Biosynthesis of secondary metabolites,” “Biosynthesis of antibiotics” and “Purine metabolism” at level 3. Thus, adding LP could improve the fermentation quality of MS silage by changing the composition and metabolic function of microbes; furthermore, ensiling 30% alfalfa with 70% ryegrass can produce high-quality silage in the karst region.

Effect of cellulase and lactic acid bacteria on the fermentation quality, carbohydrate conversion, and microbial community of ensiling oat with different moisture contents

Oat (Avena sativa L.) is one of the most widely cultivated crops used as forage. The aim of this study was to evaluate the effects of cellulase and Lactobacillus plantarum interactions with different moisture contents on oat ensiling. Oats with three moisture contents were treated with nothing (C), cellulase (CE), lactic acid bacteria (LP), or CE+LP and ensiled for 30 and 60 days. Compared with the control, LP and CE treatments increased crude protein and lactic acid concentrations and reduced the pH and ammonia nitrogen/total nitrogen (NH₃-N/TN) ratios of silages. The addition of CE improved lignocellulosic degradation, compared with approximately 67% (LD) and 81% moisture content (HD) ensiling, CE (CE, CE+LP) ensiling in the approximately 75% moisture content (MD) group retained higher water-soluble carbohydrate, glucose, sucrose and fructose concents. The LP and CE inoculations significantly reduced the microbial community diversity, and lower values for the observed species, ACE, Chao1, and Shannon indices compared with CK-treated samples. Additives inhibited the growth of unfavorable bacteria (such as Clostridium) and increased the abundances of lactic acid bacteria (LAB); the maximum increases in the Lactiplantibacillus abundance were obtained in the LP- and CE+LP-treated samples, improving the microbial community structure in silage. In summary, adding LP and CE effectively improved the oat fermentation quality, and better performances in ensiling oat and lignocellulose degradation were obtained with LP and CE combinations, especially for the MD group of silages that were ensiled for 60 days. The addition of CE and LP at the appropriate moisture content might be helpful for producing high-quality oat silage, and also provide a simple and feasible method to enhance the effects of bacteria and enzymes.

Effects of Lactic Acid Bacteria Additives on the Quality, Volatile Chemicals and Microbial Community of Leymus chinensis Silage During Aerobic Exposure

Silage exposed to air is prone to deterioration and production of unpleasant volatile chemicals that can seriously affect livestock intake and health. The aim of this study was to investigate the effects of Lactobacillus plantarum (LP), Lactobacillus buchneri (LB), and a combination of LP and LB (PB) on the quality, microbial community and volatile chemicals of Leymus chinensis silage at 0, 4, and 8 days after aerobic exposure. During aerobic exposure, LP had higher WSC and LA contents but had the least aerobic stability, with more harmful microorganisms such as Penicillium and Monascus and produced more volatile chemicals such as Isospathulenol and 2-Furancarbinol. LB slowed down the rise in pH, produced more acetic acid and effectively improved aerobic stability, while the effect of these two additives combined was intermediate between that of each additive alone. Correlation analysis showed that Actinomyces, Sphingomonas, Penicillium, and Monascus were associated with aerobic deterioration, and Weissella, Pediococcus, Botryosphaeria, and Monascus were associated with volatile chemicals. In conclusion, LB preserved the quality of L. chinensis silage during aerobic exposure, while LP accelerated aerobic deterioration.

Succession of Bacterial and Fungal Communities during Fermentation of Medicinal Plants

The fermentation of medicinal plants has been studied very little, as compared to the fermentation of food and beverages. One approach applies fermentation by single bacterial or fungal strains and targets the production of specific compounds or preservation of the fermented material. Spontaneous fermentation by an autochthonous starter community may lead to a more diverse blend of fermentation products because co-occurring microbes may activate the biosynthetic potentials and formation of compounds not produced in single strain approaches. We applied the community approach and studied the fermentation of four medicinal plants (Achillea millefolium, Taraxacum officinale, Mercurialis perennis, and Euphrasia officinalis), according to a standardized pharmaceutical fermentation method. It is based on the spontaneous fermentation by plant-specific bacterial and fungal communities under a distinct temperature regime, with a recurrent cooling during the first week and further fermentation for at least six months. The results revealed both general and plant-specific patterns in the composition and succession of microbial communities during fermentation. Lactic acid bacteria increasingly dominated in all preparations, whereas the fungal communities retained more plant-specific features. Three distinct fermentation phases with characteristic bacterial communities were identified, i.e., early, middle, and late phases. Co-occurrence network analyses revealed the plant-specific features of the microbial communities.

Dynamics of the Fermentation Products, Residual Non-structural Carbohydrates, and Bacterial Communities of Wilted and Non-wilted Alfalfa Silage With and Without Lactobacillus plantarum Inoculation

The aim of this study was to investigate effects of wilting and Lactobacillus plantarum inoculation on the dynamics of the fermentation products, residual non-structural carbohydrates, and bacterial communities in alfalfa silage. Fresh and wilted alfalfa were ensiled with and without L. plantarum for 10, 30, 60, and 90 days. A high-throughput sequencing method for absolute quantification of 16S rRNA was adopted to determine the bacterial community composition at different ensiling periods. For the wilted silage, the bacterial community, pH value, and ammonia nitrogen concentration remained stable in the silage at 30 days. L. plantarum inoculation accelerated lactic acid fermentation and altered the predominant genus in the wilted silage as compared with the non-inoculated group. For the non-wilted group, fast consumption of water-soluble carbohydrates (WSCs) was observed at 10 days in the non-inoculated silage along with rapid growth of undesirable Hafnia. L. plantarum inoculation inhibited growth of Hafnia at 10 days in the non-wilted silage. Clostridia fermentation occurred in the non-wilted silage at 90 days, as indicated by an increased pH, formation of butyric acid (BA), and apparent abundance of genera belonging to Clostridia. L. plantarum inoculation inhibited BA accumulation and growth of Garciella in the non-wilted silage at 90 days as compared with the non-wilted silage without inoculation, but had little effect on the growth of Clostridium sensu stricto. Overall, the high moisture content of the non-wilted alfalfa silage led to rapid consumption of WSCs and growth of harmful microorganisms at the early stage of ensiling, resulting in poor fermentation quality. Wilting and L. plantarum inoculation both improved fermentation quality and inhibited the growth of spoilage microorganisms in alfalfa silage, while L. plantarum inoculation alone failed to achieve optimum fermentation quality of non-wilted alfalfa silage.

Effects of applying cellulase and starch on the fermentation characteristics and microbial communities of Napier grass (Pennisetum purpureum Schum.) silage

This study investigated the effects of applying cellulase and starch on the fermentation characteristics and microbial communities of Napier grass silage after ensiling for 30 d. Three groups were studied: No additives (control); added cellulase (Group 1); and added cellulase and starch (Group 2). The results showed that the addition of cellulase and starch decreased the crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF) and pH significantly (p < 0.05) and increased water-soluble carbohydrate (WSC) content (p < 0.05). The addition of additives in two treated groups exerted a positive effect on the lactic acid (LA) content, lactic acid bacteria (LAB) population, and lactic acid / acetic acid (LA/AA) ratio, even the changes were not significant (p > 0.05). Calculation of Flieg’s scores indicated that cellulase application increased silage quality to some extent, while the application of cellulase and starch together significantly improved fermentation (p < 0.05). Compared with the control, both additive groups showed increased microbial diversity after ensiling with an abundance of favorable bacteria including Firmicutes and Weissella, and the bacteria including Proteobacteria, Bacteroidetes, Acinetobacter increased as well. For alpha diversity analysis, the combined application of cellulase and starch in Group 2 gave significant increases in all indices (p < 0.05). The study demonstrated that the application of cellulase and starch can increase the quality of Napier grass preserved as silage.

Dark Fermentation of Sweet Sorghum Stalks, Cheese Whey and Cow Manure Mixture: Effect of pH, Pretreatment and Organic Load

The aim of this study was to determine the optimal conditions for dark fermentation using agro-industrial liquid wastewaters mixed with sweet sorghum stalks (i.e., 55% sorghum, 40% cheese whey, and 5% liquid cow manure). Batch experiments were performed to investigate the effect of controlled pH (5.0, 5.5, 6.0, 6.5) on the production of bio-hydrogen and volatile fatty acids. According to the obtained results, the maximum hydrogen yield of 0.52 mol H2/mol eq. glucose was measured at pH 5.5 accompanied by the highest volatile fatty acids production, whereas similar hydrogen productivity was also observed at pH 6.0 and 6.5. The use of heat-treated anaerobic sludge as inoculum had a positive impact on bio-hydrogen production, exhibiting an increased yield of 1.09 mol H2/mol eq. glucose. On the other hand, the pretreated (ensiled) sorghum, instead of a fresh one, led to a lower hydrogen production, while the organic load decrease did not affect the process performance. In all experiments, the main fermentation end-products were volatile fatty acids (i.e., acetic, propionic, butyric), ethanol and lactic acid.

Assessment of Bacterial Community Composition and Dynamics in Alfalfa Silages With and Without Lactobacillus plantarum Inoculation Using Absolute Quantification 16S rRNA Sequencing

Relative quantification 16S-seq (RQS) has drawn deeper insights into bacterial community compositions in silage. However, it provides no information on dynamics of the total amount of bacterial DNA through the ensiling process and across different treatments. In this study, bacterial compositions in alfalfa silage with and without Lactobacillus plantarum inoculation after 10 and 60days of ensiling were investigated using absolute quantification 16S-seq (AQS), and bacterial composition and its interaction with fermentation properties of silage indicated by AQS and RQS were compared. Variation in total bacterial DNA amounts across different treatments and ensiling periods was illustrated by AQS. AQS indicated higher bacterial richness indices and closer correlations of these indices with fermentation properties than RQS via spearman's correlation analyses, as well as more taxa with significance on bacterial abundance via lefse analyses. In conclusion, AQS effectively illustrated the dynamics of bacterial communities during the ensiling process.

Microbial community dynamics during alfalfa silage with or without clostridial fermentation

This study was conducted to examine the effects of Lactobacillus plantarum (LP) and sucrose (S) on clostridial community dynamics and correlation between clostridia and other bacteria in alfalfa silage during ensiling. Fresh alfalfa was directly ensiled without (CK) or with additives (LP, S, LP + S) for 7, 14, 28 and 56 days. Clostridial and bacterial communities were evaluated by next-generation sequencing. Severe clostridial fermentation occurred in CK, as evidenced by the high contents of butyric acid, ammonia nitrogen, and clostridia counts, whereas all additives, particularly LP + S, decreased silage pH and restrained clostridial fermentation. Clostridium perfringens and Clostridium butyricum might act as the main initiators of clostridial fermentation, with Clostridium tyrobutyricum functioning as the promoters of fermentation until the end of ensiling. Clostridium tyrobutyricum (33.5 to 98.0%) dominated the clostridial community in CK from 14 to 56 days, whereas it was below 17.7% in LP + S. Clostridium was negatively correlated with the genus Lactobacillus, but positively correlated with the genera Enterococcus, Lactococcus and Leuconostoc. Insufficient acidification promoted the vigorous growth of C. tyrobutyricum of silage in later stages, which was mainly responsible for the clostridial fermentation of alfalfa silage.

Dynamic profiles of fermentation characteristics and bacterial community composition of Broussonetia papyrifera ensiled with perennial ryegrass

Broussonetia papyrifera (B. papyrifera) has been proposed to improve silage fermentation due to its high content of protein and abundant active plant extracts. Thus, dynamic profiles of fermentation quality and bacterial community of B. papyrifera mixing with perennial ryegrass in different ratios: 100:0, 90:10, 80:20, 70:30, 60:40, and 50:50 were examined during 60-d fermentation. Results showed that adding perennial ryegrass increased soluble carbohydrate content and lactic acid production in silage and decreased pH and population of epiphytic microorganisms. Adding ryegrass exerted a remarkable effect on the silage bacterial community with a dramatic decrease in the abundance of Enterobacter. Spearman's rank correlation showed that silage lactic acid concentration was positively correlated with Lactobacillus and Stenotrophomonas abundance, while ammonia nitrogen concentration was positively correlated with the abundance of Enterobacter. In conclusion, B. papyrifera ensiled with perennial ryegrass could improve B. papyrifera silage quality and provide high-quality forage resources for sustainable ruminant livestock production.