Effects of antibacterial peptide-producing Bacillus subtilis and Lactobacillus buchneri on fermentation, aerobic stability, and microbial community of alfalfa silage

Improving fermentation quality, aerobic stability, and microbial community stabilization of triticale by Amomum villosum essential oil

This study aimed to examine the impacts of Lentilactobacillus buchneri (LB), Amomum villosum essential oil (AVEO), and vanillic acid (VA) on the fermentation traits, aerobic stability, and microbial community composition of ensiled triticale samples throughout the duration of air exposure. The chopped triticale was thoroughly blended, and the mixture was subjected to the following experimental treatments: CK, purified water at 1 mL kg-1 fresh weight (FW); AVEO, application at 1 mL kg-1 FW; LB, application at 1 × 106 CFU/g FW; and VA, application at 1 mL kg-1 FW. During the aerobic exposure phase, the dry matter and starch contents of the additive groups were greater, and the neutral detergent fiber content was lower than that of the control group (P < 0.05), particularly in the AVEO treatment group. The pH value, lactic acid concentration, and aerobic stability were also greater (P < 0.05) in the AVEO treatment group than in the other treatment groups. Compared with the control silage, the additive groups presented greater Bacillus and Lactiplantibacillus abundances, whereas the additive groups presented lower Sphingomonas and Stenotrophomonas abundances. The AVEO-treated silage had greater Lactiplantibacillus and Bacillus abundances and lower Sphingomonas and Stenotrophomonas abundances. Compared with the control silage, the additive groups presented greater Rhizopus abundances, while the additive groups presented lower Monascus and Cladosporium abundances. The AVEO-treated silage had more Rhizopus and fewer Monascus and Cladosporium abundances. The use of AVEO in triticale silages resulted in increased aerobic stability, while also reducing the presence of harmful microbial communities.IMPORTANCEThe utilization of ensiling for the preservation of forage has been demonstrated to be an effective and environmentally sustainable approach. Nevertheless, ensiled samples will inevitably come into contact with air during use or under unfavorable circumstances, leading to aerobic deterioration. AVEO helped maintain a high relative abundance of Lactiplantibacillus and Bacillus after aerobic exposure, suggesting that AVEO acts as an enrichment agent for Lactiplantibacillus and Bacillus in triticale silage. The AVEO treatment group also had a greater relative abundance of Rhizopus, resulting in the continuous generation of LA under aerobic conditions. This led to the maintenance of an acidic environment, inhibition of fungal proliferation, and delay in aerobic deterioration. These findings demonstrate that AVEO has the ability to positively impact the microbial community of triticale silage and thus improve fermentation quality and aerobic stability. This study provides a scientific foundation for producing triticale silages of superior quality.

Response Characteristics of Biological Soil Crusts Under Different Afforestation Measures in Alpine Sandy Land

Desertification, which may lead to land degradation, is a significant global ecological issue. Biological soil crusts (BSCs) can play a role in sand fixation, carbon sequestration, and the improvement in soil functions in the ecological restoration of sandy soil. Therefore, elucidating the responses of BSCs to afforestation measures in alpine sandy areas is necessary to guide vegetation configuration in sandy ecosystems and enhance the effectiveness of sand fixation measures to prevent desertification. Herein, we determined the physicochemical properties and enzyme activities of bare sand (no crust) and algal and moss crusts collected from four sites subjected to different afforestation measures, including Salix cheilophila + Populus simonii (WLYY), Salix psammophila + S. cheilophila (SLWL), Artemisia ordosica + Caragana korshinskii (SHNT), and C. korshinskii (NT80) plantations. High-throughput sequencing was also employed to analyze bacterial community structure in BSCs. The results revealed that fine particle contents in algal and moss crusts were higher than in bare sand. During the succession from bare sand to algae to moss crust, their enzymatic activities and water and nutrient contents tended to increase. And the diversity of bacterial communities changed little in the SLWL sample points, while the richness showed a trend of first decreasing and then increasing, but bacterial community richness and diversity first decreased and then increased at the other sites. Among the four measures, SLWL enhanced nutrient contents, enzyme activities, and bacterial community richness and diversity in BSCs relatively more effectively. Alkaline-hydrolyzable nitrogen and soil organic matter were the key factors impacting bacterial community structures in BSCs under the four afforestation measures. From the perspective of BSCs, the results can provide a reference for the prevention and control strategies of other alpine sandy soils.

Effects of compound lactic acid bacteria on the quality and microbial diversity of alfalfa silage in saline-alkali soils

With the rapid development of animal husbandry, forage resources are increasingly scarce. Improving the utilization rate of forage products and silage efficiency of planting is an urgent problem to be solved. This experiment used high moisture alfalfa at the budding stage with a water content of 71.4% from saline-alkali and non-saline-alkali soils as raw materials, setting up four experimental groups: non-saline-alkali alfalfa without additives (HNS-CK), non-saline-alkali alfalfa with compound lactic acid bacteria (Lactobacillus plantarum + Lactobacillus buchneri + Pediococcus pentosaceus + Lactobacillus kimchi, HNS-L4), saline-alkali alfalfa without additives (HS-CK), and saline-alkali alfalfa with compound lactic acid bacteria (HS-L4). After 60 days of silage, the quality and microbial diversity of the silage were tested. The results showed that the dry matter (DM) and lactic acid (LA) of the HNS-L4 group were significantly higher than those of the HS-L4 (P < 0.05), while there was no significant difference in crude protein (CP) between the HNS-L4 group and the HS-L4 (P < 0.05). The neutral detergent fiber (NDF), acid detergent fiber (ADF), pH of the HNS-L4 group were all lower than those of the HS-L4. The results of the microbial community showed that compared with the non-additives group, the Shannon index decreased and the Simpson index increased in the compound lactic acid bacteria group, indicating a significant reduction in microbial diversity in the silage environment (P < 0.05). The dominant bacteria in the HNS-CK and HS-CK groups were Enterobacteriaceae, while the dominant bacteria in the HNS-L4 and HS-L4 groups were Lactobacillus. At the phylum level, the dominant bacteria in alfalfa after lactic acid bacteria treatment were Firmicutes, which were significantly higher than the control group (P < 0.05). Therefore, compound lactic acid bacteria can improve the quality of alfalfa silage in both saline alkali and non-saline-alkali soils, with saline-alkali soils being better than non-saline-alkali soils, and both can reduce microbial diversity.

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.

Effects of mixed biocrusts on soil nutrients and bacterial community structure: a case study from Hilly Loess Plateau, China

The ecological function of biological crusts in arid and semi-arid areas is of great importance. Bacteria, as a crucial microbial group in biological crusts, play a key role in the formation, nutrient cycling, and regulation of these crusts. However, the succession of biological crusts and the diversity of bacterial communities, along with key environmental factors in the Loess Plateau's hilly and gully areas, remain unclear. This study investigated soil bacterial abundance and diversity in bare soil (BS), alga-lichen mixed crust (MC), and alga-lichen mixed crust subsoil (MCS) using high-throughput sequencing methods. It explored the relationship between the bacterial community in biological crusts and key environmental factors. The results indicated that the Chao1, Shannon index, and phylogenetic diversity of bacteria significantly increased with the succession of biological crusts. There were notable differences in the community composition and structure of bacteria at different stages of crust development, with Rubrobacteria and Cyanobacteriia dominating in MCS. Effective phosphorus, available potassium, nitrogen, pH, and total organic carbon were identified as key environmental factors affecting soil bacterial communities. In summary, the succession of biological crusts alters soil physicochemical characteristics and creates different ecological niches for bacterial communities. Soil nutrients and pH play a crucial role in the selection of bacterial species and the shaping of bacterial communities in the Loess Plateau's hilly and gully areas.

Effects of bacteriocin-producing Lactiplantibacillus plantarum on bacterial community and fermentation profile of whole-plant corn silage and its in vitro ruminal fermentation, microbiota, and CH4 emissions

BACKGROUND

Silage is widely used to formulate dairy cattle rations, and the utilization of antibiotics and methane emissions are 2 major problems for a sustainable and environmentally beneficial ruminant production systems. Bacteriocin has received considerable attention because of its potential as an alternative to antibiotics in animal husbandry. However, the impact of bacteriocin-producing lactic acid bacteria on the microbiological conversion process of whole-plant corn silage and rumen fermentation remains limited. The purpose of this study was to assess the effect of 2 class IIa bacteriocin-producing strains Lactiplantibacillus plantarum ATCC14917 and CICC24194 on bacterial community composition and ensiling profiles of whole-plant corn silage and its in vitro rumen fermentation, microbiota, and CH4 emissions.

RESULTS

Both bacteriocin-producing strains increased the lactic acid concentration in silage fermented for 7 d, whereas the lowest lactic acid was observed in the ATCC14917 inoculated silage fermented for 90 d (P < 0.05). The highest DM content was observed in the CICC24194 treatment (P < 0.05), and the silages treated with both strains had the lowest DM loss (P < 0.05). Bacteriocin-producing strains promoted the growth of Levilactobacillus brevis on d 60 of ensiling. In addition, treatment with bacteriocin-producing strains increased the in vitro DM digestibility (P < 0.05) and decreased the CH4 production (P < 0.05). The results of random forest and clustering analyses at the genus level showed that ATCC14917 increased the relative abundance of the influential variable Bacillus compared to that in the control group, whereas CICC24194 decreased the relative abundance of the influential variable Ruminococcaceae UCG-005. The CICC24194 treatment had the lowest total bacterial, fungal, protozoan, and methanogen populations (P < 0.05).

CONCLUSIONS

Both class IIa bacteriocin-producing L. plantarum strains improved the fermentation quality of whole-plant corn silage by regulating the bacterial community composition during ensiling, with CICC24194 being the most effective. Both bacteriocin-producing strains mitigated CH4 production and improved digestibility by modulating the interactions among rumen bacteria, protozoa, methanogens, and the composition of fibrolytic bacteria.

A Novel Sustainable and Self-Sufficient Biotechnological Strategy for Directly Transforming Sewage Sludge into High-Value Liquid Biochemicals

Sewage sludge, as a carbon-rich byproduct of wastewater treatment, holds significant untapped potential as a renewable resource. Upcycling this troublesome waste stream represents great promise in addressing global escalating energy demands through its wide practice of biochemical recovery concurrently. Here, we propose a biotechnological concept to gain value-added liquid bioproducts from sewage sludge in a self-sufficient manner by directly transforming sludge into medium-chain fatty acids (MCFAs). Our findings suggest that yeast, a cheap and readily available commercial powder, would involve ethanol-type fermentation in chain elongation to achieve abundant MCFA production from sewage sludge using electron donors (i.e., ethanol) and acceptors (i.e., short-chain fatty acids) produced in situ. The enhanced abundance and transcriptional activity of genes related to key enzymes, such as butyryl-CoA dehydrogenase and alcohol dehydrogenase, affirm the robust capacity for the self-sustained production of MCFAs. This is indicative of an effective metabolic network established between yeast and anaerobic microorganisms within this innovative sludge fermentation framework. Furthermore, life cycle assessment and techno-economic analysis evidence the sustainability and economic competitiveness of this biotechnological strategy. Overall, this work provides insights into sewage sludge upgrading independent of additional carbon input, which can be applied in existing anaerobic sludge fermentation infrastructure as well as to develop new applications in a diverse range of industries.

The response pattern of the microbial community structure and metabolic profile of jiupei to Bacillus subtilis JP1 addition during baijiu fermentation

BACKGROUND

Baijiu brewing is a complex and multifaceted multimicrobial co-fermentation process, in which various microorganisms interact to form an interdependent micro-ecosystem, subsequently influencing metabolic activities and compound production. Among these microorganisms, Bacillus, an important bacterial genus in the liquor brewing process, remains unclear in its role in shaping the brewing microbial community and its functional metabolism.

RESULTS

A baijiu fermentation system was constructed using B. subtilis JP1 isolated from native jiupei (grain mixture) combined with daqu (a saccharifying agent) and huangshui (a fermentation byproduct). Based on high-throughput amplicon sequencing analysis, it was evident that B. subtilis JP1 significantly influences bacterial microbial diversity and fungal community structure in baijiu fermentation. Of these, Aspergillus and Monascus emerge as the most markedly altered microbial genera in the jiupei community. Based on co-occurrence networks and bidirectional orthogonal partial least squares discriminant analysis models, it was demonstrated that the addition of B. subtilis JP1 intensified microbial interactions in jiupei fermentation, consequently enhancing the production of volatile flavor compounds such as heptanoic acid, butyl hexanoate and 3-methylthiopropanol in jiupei.

CONCLUSION

B. subtilis JP1 significantly alters the microbial community structure of jiupei, enhancing aroma formation during fermentation. These findings will contribute to a broader application in solid-state fermentation. © 2024 Society of Chemical Industry.

An evaluation of the effectiveness of sumac and molasses as additives for alfalfa silage: Influence on nutrient composition, in vitro degradability and fermentation quality

This study investigated the effects of sumac and molasses on nutrient composition, in vitro degradability and fermentation quality of alfalfa silage. Alfalfa was ensiled in quadruplicate in vacuum jars untreated group (A) or after the following treatments: sumac group at 10% (AS), molasses group at 5% (AM), and sumac (10%) and molasses (5%) group (ASM). Silos (n = 64) were stored for 0, 21, 45 or 60 days. The results showed that dry matter (DM) contents of the AS, AM and ASM groups were statistically higher than the control group (p < 0.001). Only on the 21st day of fermentation the crude ash content of the AS group was found to be significantly higher than the other groups (p < 0.05). In vitro, DM and organic matter degradation values of the AMS group increased significantly (p < 0.001). A significant decrease in alfalfa silage's pH values was determined with sumac and molasses additives (p < 0.001). The ammonia nitrogen (NH3-N) values of the control, AS, AM and ASM groups at Day 60 were determined as 9.08%, 7.22%, 7.00% and 6.81% respectively (p < 0.05). The water-soluble carbohydrate (WSC) values of all groups on the 60th day were significantly decreased compared to the 0th day (p < 0.001). When the groups were evaluated within themselves, there was a statistically significant difference between the 0th and 60th day lactic acid values. The acetic acid content of the A group on the 60th day was found to be significantly higher than the other groups (p < 0.01). There was a significant decrease in propionic acid levels on Days 21, 45 and 60 compared to Day 0 of fermentation (p < 0.001). The highest butyric acid (BA) level was determined in the A group on the 21st, 45th and 60th days of fermentation (p < 0.05). In conclusion, sumac prevents proteolysis depending on its tannin content. It improves silage fermentation positively thanks to its organic acid content, while the molasses additive is effective in silage fermentation, mainly depending on the WSC level. However, it was determined that neither additive could reduce the silage pH to the appropriate value ranges due to the low doses, and they could not mainly prevent the formation of BA.

Optimized production and characterization of endo-β-mannanase by Aspergillus niger for generation of prebiotic mannooligosaccharides from guar gum

Optimized production of Aspergillus niger ATCC 26011 endo-β-mannanase (ManAn) on copra meal resulted in 2.46-fold increase (10,028 U/gds). Purified ManAn (47 kDa) showed high affinity towards guar gum (GG) as compared to konjac gum and locust bean gum with Km 2.67, 3.25 and 4.07 mg/mL, respectively. ManAn efficiently hydrolyzed GG and liberated mannooligosaccharides (MOS). Changes occurring in the rheological and compositional aspects of GG studied using Differential scanning calorimetry (DSC), Thermal gravimetric analysis (TGA) and X-ray diffraction (XRD) revealed increased thermal stability and crystallinity of the partially hydrolyzed guar gum (PHGG). Parametric optimization of the time and temperature dependent hydrolysis of GG (1% w/v) with 100 U/mL of ManAn at 60 °C and pH: 5.0 resulted in 12.126 mg/mL of mannotetraose (M4) in 5 min. Enhanced growth of probiotics Lactobacilli and production of short chain fatty acids (SCFA) that inhibited enteropathogens, confirmed the prebiotic potential of PHGG and M4.

Formic acid enhances whole-plant mulberry silage fermentation by boosting lactic acid production and inhibiting harmful bacteria

Mulberry has also been regarded as a valuable source of forage for ruminants. This study was developed to investigate the impact of four additives and combinations thereof on fermentation quality and bacterial communities associated with whole-plant mulberry silage. Control fresh material (FM) was left untreated, while other groups were treated with glucose (G, 20 g/kg FM), a mixture of Lactobacillus plantarum and L. buchneri (L, 106 CFU/g FM), formic acid (A, 5 mL/kg FM), salts including sodium benzoate and potassium sorbate (S, 1.5 g/kg FM), a combination of G and L (GL), a combination of G and A (GA), or a combination of G and S (GS), followed by ensiling for 90 days. Dry matter content in the A, S, GA, and GS groups was elevated relative to the other groups (p < 0.01). Relative to the C group, all additives and combinations thereof were associated with reductions in pH and NH3-N content (p < 0.01). The A groups exhibited the lowest pH and NH3-N content at 4.23 and 3.27 g/kg DM, respectively (p < 0.01), whereas the C groups demonstrated the highest values at 4.43 and 4.44 g/kg DM, respectively (p < 0.01). The highest levels of lactic acid were observed in the GA and A groups (70.99 and 69.14 g/kg DM, respectively; p < 0.01), followed by the GL, L, and GS groups (66.88, 64.17 and 63.68 g/kg DM, respectively), with all of these values being higher than those for the C group (53.27 g/kg DM; p < 0.01). Lactobacillus were the predominant bacteria associated with each of these samples, but the overall composition of the bacterial community was significantly impacted by different additives. For example, Lactobacillus levels were higher in the G, A, and GA groups (p < 0.01), while those of Weissella levels were raised in the L, GL, and GS groups (p < 0.01), Pediococcus levels were higher in the A and GA groups (p < 0.01), Enterococcus levels were higher in the G and S groups (p < 0.01), and Lactococcus levels were raised in the S group (p < 0.01). Relative to the C group, a reduction in the levels of undesirable Enterobacter was evident in all groups treated with additives (p < 0.01), with the greatest reductions being evident in the A, S, GA, and GS groups. The additives utilized in this study can thus improve the quality of whole-plant mulberry silage to varying extents through the modification of the associated bacterial community, with A and GA addition achieving the most efficient reductions in pH together with increases in lactic acid content and the suppression of undesirable bacterial growth.

Effect of Regulation of Whole-Plant Corn Silage Inoculated with Lactobacillus buchneri or Bacillus licheniformis Regarding the Dynamics of Bacterial and Fungal Communities on Aerobic Stability

Enhancing the aerobic stability of whole-plant corn silage is essential for producing high-quality silage. Our research assessed the effect of inoculation with Lactobacillus buchneri or Bacillus licheniformis and its modulation of the bacterial and fungal microbial community structure in an aerobic stage of whole-plant corn silage. Following treatment with a distilled sterile water control, Lactobacillus buchneri, and Bacillus licheniformis (2 × 105 cfu/g), whole-plant corn was ensiled for 60 days. Samples were taken on days 0, 3, and 7 of aerobic exposure, and the results showed that inoculation with Lactobacillus buchneri or Bacillus licheniformis improved the aerobic stability of silage when compared to the effect of the control (p < 0.05). Inoculation with Bacillus licheniformis attenuated the increase in pH value and the decrease in lactic acid in the aerobic stage (p < 0.05), reducing the filamentous fungal counts. On the other hand, inoculation with Lactobacillus buchneri or Bacillus licheniformis increased the diversity of the fungal communities (p < 0.05), complicating the correlation between bacteria or fungi, reducing the relative abundance of Acetobacter and Paenibacillus in bacterial communities, and inhibiting the tendency of Monascus to replace Issatchenkia in fungal communities, thus delaying the aerobic spoilage process. Due to the prevention of the development of aerobic spoilage microorganisms, the silage injected with Lactobacillus buchneri or Bacillus licheniformis exhibited improved aerobic stability.

Effect of soil contamination and additives on fermentative profile, microbial community and iron bioaccessibility of alfalfa silage

Background

During alfalfa harvesting and preservation, it is important to minimize losses and preserve dry matter and nutrients. Soil contamination of alfalfa forage is a common issue that occurs during the ensiling process. Soil contamination can adversely influence the quality of silage, potentially altering the fermentation process, microbial composition, and iron content.

Results

In this study, different levels of soil (0, 1.5% or 7.5% contamination on a wet basis; silt loam soil) and two types of additives (LP, Lactobacillus plantarum inoculant alone; MLP, combination addition of molasses and Lactobacillus plantarum) were added to alfalfa and subjected to anaerobic fermentation for 45 days to evaluate the iron content as well as the alpha diversity and relative abundance of bacterial and fungal communities. Soil-contaminated alfalfa contained lower levels of LA (14.2–41.8 g kg−1 DM) and higher levels of AN (50.0–156.4 g kg−1 DM) compared to uncontaminated alfalfa. Soil contamination of alfalfa forage increased the abundance of Clostridia, Actinobacteria, and Alphaproteobacteria in silage. The application of LP or MLP in soil-contaminated silage increased the abundance of Lactobacillus and inhibited the growth of Enterococcus faecium, Pediococcus pentosaceus, unclassified_f_Enterobacteriaceae, and Weissella cibaria. In addition, as the level of soil contamination increased, both the total and bioaccessible iron contents in alfalfa silage increased. The dominant bacteria Lactobacillus plantarum exhibited a positive relationship with LA and bioaccessible iron contents and a negative relationship with pH, AN and BA. The dominant fungi Neocosmospora rubicola showed a positive relationship with total iron, BA, AN and pH.

Conclusions

Soil contamination of alfalfa increased the abundance of Clostridia, Actinobacteria, and Alphaproteobacteria and it also increased the total and bioaccessible iron content in silage. The addition of LP and MLP improved the fermentation quality of soil-contaminated silage by increasing LA production and reducing the relative abundance of Enterococcus faecium, Pediococcus pentosaceus, unclassified_f_Enterobacteriaceae, and Weissella cibaria.

Graphical Abstract

Effects of lactic acid bacteria inoculants on the nutrient composition, fermentation quality, and microbial diversity of whole-plant soybean-corn mixed silage

The mixture of whole-plant soybean and whole-plant corn silage (WPSCS) is nutrient balanced and is also a promising roughage for ruminants. However, few studies have investigated the changes in bacterial community succession in WPSCS inoculated with homofermentative and heterofermentative lactic acid bacteria (LAB) and whether WPSCS inoculated with LAB can improve fermentation quality by reducing nutrient losses. This study investigated the effect of Lactobacillus plantarum (L. plantarum) or Lactobacillus buchneri (L. buchneri) on the fermentation quality, aerobic stability, and bacterial community of WPSCS. A 40:60 ratio of whole-plant soybean corn was inoculated without (CK) or with L. plantarum (LP), L. buchneri (LB), and a mixture of LP and LB (LPB), and fermented for 14, 28, and 56 days, followed by 7 days of aerobic exposure. The 56-day silage results indicated that the dry matter content of the LP and LB groups reached 37.36 and 36.67%, respectively, which was much greater than that of the CK group (36.05%). The pH values of the LP, LB, and LPB groups were significantly lower than those of the CK group (p < 0.05). The ammoniacal nitrogen content of LB was significantly lower than that of the other three groups (p < 0.05), and the ammoniacal nitrogen content of LP and LPB was significantly lower than that of CK (p < 0.05). The acetic acid content and aerobic stability of the LB group were significantly greater than those of the CK, LP, and LPB groups (p < 0.05). High-throughput sequencing revealed a dominant bacteria shift from Proteobacteria in fresh forage to Firmicutes in silage at the phylum level. Lactobacillus remained the dominant genus in all silage. Linear discriminant analysis effect size (LEFSe) analysis identified Lactobacillus as relatively abundant in LP-treated silage and Weissella in LB-treated groups. The results of KEGG pathway analysis of the 16S rRNA gene of the silage microbial flora showed that the abundance of genes related to amino acid metabolism in the LP, LB, and LPB groups was lower than that in the CK group (p < 0.05). In conclusion, LAB application can improve the fermentation quality and nutritional value of WPSCS by regulating the succession of microbial communities and metabolic pathways during ensiling. Concurrently, the LB inoculant showed the potential to improve the aerobic stability of WPSCS.

Effects of non-pelleted or pelleted low-native grass and pelleted high-native grass diets on meat quality by regulating the rumen microbiota in lambs

Diet modulates the rumen microbiota, which in turn can impact the animal performance. The rumen microbiota is increasingly recognized for its crucial role in regulating the growth and meat quality of the host. Nevertheless, the mechanism by which the rumen microbiome influences the fatty acid and amino acid profiles of lambs in the grass feeding system remains unclear. This study aimed to evaluate the effects of different native grass-based diets on animal performance, meat quality, fatty acid compositions, amino acid profiles, and rumen microbiota of lamb. Seventy-two Ujumqin lambs were randomly assigned into three treatments according to the initial body weight (27.39 ± 0.51 kg) and age (6 months ± 6 days). The lambs received three diets: (i) non-pelleted native grass hay with 40% concentrate diet; the native grass and concentrate were fed individually; (ii) pelleted native grass hay with 40% concentrate diet (PHLC); (iii) pelleted native grass hay with 60% concentrate diet (PHHC). The results showed that among the three groups, the PHHC and PHLC diets had markedly (P < 0.05) higher average daily gain and pH45 min, respectively. All amino acid levels were significantly (P < 0.05) decreased in the PHHC diet than in the PHLC diet. The principal coordinate analysis of the ruminal microbiota indicated the markedly distinct separation (P = 0.001) among the three groups. In addition, the correlation analysis showed that the Rikenellaceae_RC9_gut_group, Prevotellaceae_UCG-003, Succinivibrio, and Succiniclasticum were significantly (P < 0.05) associated with most of the fatty acid and amino acid profiles. The correlation analysis of the association of microbiome with the meat quality provides us with a comprehensive understanding of the composition and function of the rumen microbial community, and these findings will contribute to the direction of future research in lamb.

IMPORTANCE

Diet modulates the gut microbiome, which in turn impact the meat quality, yet few studies investigate the correlation between the rumen microbiome and the fatty acid profile of meat. Here, the current study develops an experiment to investigate the correlation of the rumen microbiome and fatty acid profile of meat: rumen microbiome responses to feed type and meat quality. The results indicated a unique microbiota in the rumen of lamb in response to diets and meat quality. Associations between utilization and production were widely identified among the affected microbiome and meat quality, and these findings will contribute to the direction of future research in lamb.

The process of solid-state fermentation of soybean meal: antimicrobial activity, fermentation heat generation and nitrogen solubility index

BACKGROUND

Bacillus amyloliquefaciens has excellent protease production ability and holds great prospects for application in the solid-state fermentation of soybean meal (SBM).

RESULTS

Among eight strains of bacteria, Bacillus amyloliquefaciens subsp. plantarum CICC 10265, which exhibited higher protease production, was selected as the fermentation strain. The protease activity secreted by this strain reached 106.41 U mL-1 . The microbial community structure differed significantly between natural fermentation and inoculation-enhanced fermented soybean meal (FSBM), with the latter showing greater stability and inhibition of miscellaneous bacterial growth. During fermentation, the temperature inside the soybean meal increased, and the optimal environmental temperature for FSBM was found to be between 35 and 40 °C. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis analysis and nitrogen solubility index (NSI) results demonstrated that solid-state fermentation had a degrading effect on highly denatured proteins in SBM, resulting in an NSI of 67.1%.

CONCLUSION

Bacillus amyloliquefaciens subsp. plantarum CICC 10265 can enhance the NSI of SBM in solid-state fermentation and inhibit the growth of miscellaneous bacteria. © 2023 Society of Chemical Industry.

Investigating the efficacy of an exopolysaccharide (EPS)-producing strain Lactiplantibacillus plantarum L75 on oat silage fermentation at different temperatures

This study investigates the effectiveness of an exopolysaccharide (EPS)-producing strain (Lactiplantibacillus plantarum L75) alone or in combination with Saccharomyces cerevisiae on the fermentation characteristics, antioxidant capacities and microbial community successions of oat silage stored at various temperatures. A rapid decrease in pH and lactic acid accumulation was observed in silages treated with L. plantarum and S. cerevisiae (LS) as early as 3 days of ensiling (p < 0.05). Over the ensiling period of 7-60 days, L. plantarum (L)-inoculated groups showed the lowest pH, lowest ammonia nitrogen and the highest amount of lactic acid regardless of the storage temperatures. When the oat silage was stored at 15°C, LS-inoculated group exhibited a higher superoxide dismutase (SOD) activity than control and L-inoculated group. Furthermore, the proportion of Lactiplantibacillus in the combined inoculation group increased by 65.42% compared to the L-inoculated group (33.26%). Fungal community data revealed abundant Penicillium carneum in the control and L-inoculated groups stored at 15°C. Conclusively, these results showed that combined inoculation of L. plantarum L75 and S. cerevisiae improved the fermentation quality of oat silage at 15°C, thus proposing a technique for enhancing the fermentation quality of silage in regions with low temperatures during harvest season.

Bacillus velezensis promotes the proliferation of lactic acid bacteria and influences the fermentation quality of whole-plant corn silage

Objective

This study aimed to investigate the promoting effect of a Bacillus velezensis (BV) strain on lactic acid bacteria (LAB) and determine its influence on the fermentation quality and aerobic stability of silage.

Methods

Flat colony counting method was used to evaluate the effect of BV on the growth of LAB. Freshly harvested whole-plant corn was inoculated separately with BV and L. plantarum (LP), along with an uninoculated control group (CK), and assessed at 1, 3, 5, 7, 15, and 30 days of ensiling.

Results

The results indicated that BV exhibited a proliferative effect on Weissella confusa, Lactobacillus plantarum L-2, and Pediococcus pentosaceus. And exhibited a more rapid pH reduction in BV-inoculated silage compared with that in CK and LP-inoculated silage during the initial stage of ensiling. Throughout ensiling, the BV and LP experimental groups showed enhanced silage fermentation quality over CK. Additionally, relative to LP-inoculated silage, BV-inoculated silage displayed reduced pH and propionic acid. BV also prolonged aerobic stability under aerobic conditions. The microbial community in BV-inoculated silage showed greater stability than that in LP-inoculated silage. Additionally, Firmicutes and Lactobacillus exhibited more rapid elevation initially in BV versus LP-inoculated silage, but reached comparable levels between the two inoculation groups in the later stage.

Conclusion

In summary, BV enhanced the efficacy and aerobic stability of whole-plant corn silage fermentation by stimulating LAB proliferation.

Characterization of phyllosphere endophytic lactic acid bacteria reveals a potential novel route to enhance silage fermentation quality

The naturally attached phyllosphere microbiota play a crucial role in plant-derived fermentation, but the structure and function of phyllosphere endophytes remain largely unidentified. Here, we reveal the diversity, specificity, and functionality of phyllosphere endophytes in alfalfa (Medicago sativa L.) through combining typical microbial culture, high-throughput sequencing, and genomic comparative analysis. In comparison to phyllosphere bacteria (PB), the fermentation of alfalfa solely with endophytes (EN) enhances the fermentation characteristics, primarily due to the dominance of specific lactic acid bacteria (LAB) such as Lactiplantibacillus, Weissella, and Pediococcus. The inoculant with selected endophytic LAB strains also enhances the fermentation quality compared to epiphytic LAB treatment. Especially, one key endophytic LAB named Pediococcus pentosaceus EN5 shows enrichment of genes related to the mannose phosphotransferase system (Man-PTS) and carbohydrate-metabolizing enzymes and higher utilization of carbohydrates. Representing phyllosphere, endophytic LAB shows great potential of promoting ensiling and provides a novel direction for developing microbial inoculant.

Effect of additive cellulase on fermentation quality of whole-plant corn silage ensiling by a Bacillus inoculant and dynamic microbial community analysis

Whole-plant corn silage (WPCS) has been widely used as the main roughage for ruminant, which promoted the utilization of corn stover for animal feed production. However, rigid cell wall structure of corn stover limits the fiber digestion and nutrients adsorption of WPCS. This study investigated the effect of adding cellulase on improving the fermentation quality of WPCS ensiling with a Bacillus complex inoculant. With the Bacillus (BA), the lactic acid accumulation in the WPCS was significantly higher than that in control (CK). The additive cellulase (BC) increased the lactic acid content to the highest of 8.2% DW at 60 days, which was significantly higher than that in the CK and BA groups, and it reduced the neutral detergent fiber (NDF) and acid detergent fiber (ADF) contents from 42.5 to 31.7% DW and 28.4 to 20.3% DW, respectively, which were significantly lower than that in the CK and BA groups. The crude protein and starch were not obviously lost. Dynamic microbial community analysis showed that the Bacillus inoculant promoted the lactic acid bacteria (LAB) fermentation, because higher abundance of Lactobacillus as the dominant bacteria was observed in BA group. Although the addition of cellulase slowed the Lactobacillus fermentation, it increased the bacterial community, where potential lignocellulolytic microorganisms and more functional enzymes were observed, thus leading to the significant degradation of NDF and ADF. The results revealed the mechanism behind the degradation of NDF and ADF in corn stover, and also suggested the potential of cellulase for improving the nutritional quality of WPCS.

Effect of sodium diacetate on fermentation, aerobic stability, and microbial diversity of alfalfa silage

Alfalfa (Medicago sativa L.) is a vital source of forage protein for ruminants, yet its ensiling poses challenges due to high buffering capacity and low water-soluble carbohydrates (WSC). This study investigated the impact of sodium diacetate (SDA) on alfalfa silage quality and aerobic stability. SDA was applied at four different rates to wilted alfalfa on a fresh basis: 0 g/kg, 3 g/kg, 5 g/kg, and 7 g/kg, and silages were ensiled in laboratory-scale silos for 45 days, followed by 7 days of aerobic exposure. A 16S rRNA gene sequencing assay using GenomeLab™ GeXP was performed to determine the relationship between dominant isolated lactic acid bacteria species and fermentation characteristics and aerobic stability on silage. The results showed that Lentilolactobacillus brevis, Pediococcus pentosaceus and Enterococcus faecium were the most prevalent bacteria when silos were opened, whereas Weissella paramesenteroides, Bacillus cereus, B. megaterium and Bacillus spp. were most prevalent bacteria after 7 days of aerobic exposure. Dry matter, pH, and WSC content were not affected by SDA, but doses above 5 g/kg induced a homofermentative process, which increased lactic acid concentration and lactic acid to acetic acid ratio, decreased yeast count during aerobic exposure, and improved aerobic stability. These findings offer useful information for optimizing SDA usage in silage, assuring improved quality and longer storage, and thereby improving animal husbandry and sustainable feed practices.

Identification, characterization and optimization of culture medium conditions for organic acid-producing lactic acid bacteria strains from Chinese fermented vegetables

Lactic acid bacteria (LAB) are widely exploited in fermented foods and are gaining attention for novel uses due to their safety as biopreservatives. In this study, several organic acid-producing LAB strains were isolated from fermented vegetables for their potential application in fermentation. We identified nine novel strains belonging to four genera and five species, Lactobacillus plantarum PC1-1, YCI-2 (8), YC1-1-4B, YC1-4 (4), and YC2-9, Lactobacillus buchneri PC-C1, Pediococcus pentosaceus PC2-1 (F2), Weissella hellenica PC1A, and Enterococcus sp. YC2-6. Based on the results of organic acids, acidification, growth rate, antibiotic activity and antimicrobial inhibition, PC1-1, YC1-1-4B, PC2-1(F2), and PC-C1 showed exceptional biopreservative potential. Additionally, PC-C1, YC1-1-4B, and PC2-1(F2) recorded higher (p < 0.05) growth by utilizing lower concentrations of glucose (20 g/L) and soy peptone (10 g/L) as carbon and nitrogen sources in optimized culture conditions (pH 6, temperature 32 °C, and agitation speed 180 rpm) at 24hr and acidification until 72hr in batch fermentation, which suggests their application as starter cultures in industrial fermentation.

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.

Integrated microbiology and metabolomic analysis reveal the improvement of rice straw silage quality by inoculation of Lactobacillus brevis

BACKGROUND

Ensiling technology holds promise for preserving and providing high-quality forage. However, the preservation of rice straw poses challenges due to its high lignocellulosic content and low water-soluble carbohydrate levels. Developing highly effective lactic acid bacteria (LAB) for rice straw silage remains a priority.

RESULTS

This study evaluated the impact of three LAB strains, Lactobacillus brevis R33 (Lac33), L. buchneri R17 (Lac17), and Leuconostoc pseudomesenteroides (Leu), on the fermentation quality of rice straw silage. Rice straw silage inoculated with Lac33 alone or in combination with other strains exhibited significantly lower neutral detergent fiber (NDF) (66.5% vs. 72.3%) and acid detergent fiber (ADF) (42.1% vs. 47%) contents, along with higher lactic acid (19.4 g/kg vs. not detected) and propionic acid (2.09 g/kg vs. 1.54 g/kg) contents compared to control silage. Bacterial community analysis revealed Lactobacillus dominance (> 80%) and suppression of unwanted Enterobacter and Clostridium. Metabolomic analysis highlighted increased carbohydrates and essential amino acids, indicating improved nutrient values in Lac33-inoculated rice straw silage and a potential explanation for Lac33 dominance.

CONCLUSIONS

This research identified a highly efficient LAB candidate for rice straw silage, advancing our comprehension of fermentation from integrated microbiology and metabolomic perspectives.

Whole-Genome Analysis of Termite-Derived Bacillus velezensis BV-10 and Its Application in King Grass Silage

Bacillus velezensis (B. velezensis) is a cellulose-degrading strain that has the potential as an additive in fermented feed. B. velezensis BV-10 was isolated and screened from the termite gut. We sequenced the whole genome of this new source of B. velezensis to reveal its potential for use in cellulose degradation. Whole-genome sequencing of B. velezensis BV-10 showed that it has a circular chromosome of 3929792 bp containing 3873 coding genes with a GC content of 45.51% and many genes related to cellulose, hemicellulose, and lignin degradation. King grass silage was inoculated with B. velezensis BV-10 and mixed with other feed additives to assess the effect of B. velezensis BV-10 on the fermentation quality of silage. Six treatment groups were established: the control, B. velezensis BV-10, molasses, cellulase, B. velezensis BV-10 plus molasses, and B. velezensis BV-10 plus cellulase groups. After 30 days of silage-fermentation testing, B. velezensis BV-10 was found to rapidly reduce the silage pH value and significantly reduce the acid-detergent fiber (ADF) content (p < 0.05). The addition of B. velezensis BV-10 plus molasses and cellulase in fermented feed significantly reduced the silage neutral-detergent fiber and ADF content and promoted organic-acid accumulation (p < 0.05). The above results demonstrate that B. velezensis BV-10 promotes the fermentation quality of silage and that this effect is greater when other silage-fermentation additives are included. In conclusion, genes involved in cellulose degradation in B. velezensis BV-10 were identified by whole-genome sequencing and further experiments explored the effects of B. velezensis BV-10 and different feed additives on the fermentation quality of king grass silage, revealing the potential of Bacillus velezensis as a new silage additive.

Effects of nisin on bacterial community and fermentation profiles, in vitro rumen fermentation, microbiota, and methane emission of alfalfa silage

BACKGROUND

Alfalfa (Medicago sativa L.) has been used widely in preparing silage. However, forage legumes are prone to contamination by spoilage bacteria during fermentation. Nisin has broad-spectrum antibacterial properties and has been applied as an inhibitor of rumen methane emissions. However, little research has been carried out on the application of nisin in silage. This study therefore aimed to investigate the impacts of different nisin concentrations on the bacterial community and fermentation dynamics, in vitro ruminal fermentation characteristics, microbiota, and methane emissions of alfalfa silage.

RESULTS

The detection limits of organic acid in nisin-treated silages were not reached in 0.09 g kg-1 nisin (0.09 level) from days 1 to 7 of ensiling. With increasing nisin concentrations, the silage dry matter increased linearly (P < 0.05), and dry matter loss decreased linearly (P < 0.05). Moreover, both the 0.06 g kg-1 nisin (0.06 level) and 0.09 level treatments increased the relative abundance of Pediococcus acidilactici during ensiling. Concurrently, as the nisin concentrations increased, ruminal methane production decreased linearly (P < 0.05), while the relative abundances of ruminal Succinivibrio, Fibrobacter succinogenes and Ruminobacter amylophilus increased linearly (P < 0.05). The populations of ruminal total bacteria, methanogens, protozoa, and fungi decreased linearly with increasing nisin concentrations (P < 0.05).

CONCLUSION

The addition of nisin delayed the fermentation process, preserved more nutrients in alfalfa silage, and promoted fermentation dominated by P. acidilactici in the late phase of ensiling. Moreover, nisin reduced in vitro rumen methane emissions without adverse effects on dry matter digestibility. © 2023 Society of Chemical Industry.

Infrared Thermography Assessment of Aerobic Stability of a Total Mixed Ration: An Innovative Approach to Evaluating Dairy Cow Feed

A major objective of this study is to identify factors influencing the quality of high-moisture total mixed rations (TMRs) for livestock feed and explore possible manipulations that can enhance their fermentation characteristics and stability in order to address the problem of poor aerobic stability. Therefore, the current study utilized infrared thermography (IRT) to assess the aerobic stability of water-added TMRs in the feed bunker. By manipulating the moisture content of freshly prepared TMRs at four different levels through water addition and subjecting it to storage at two consistent temperatures, significant correlations between IRT values (center temperature (CT) and maximum temperature difference (MTD)) and key parameters such as lactic acid bacteria, water-soluble carbohydrates, and TMR pH were established. The first and second principal components together accounted for 44.3% of the variation, with the first component's load influenced by IRT parameters, fermentation characteristics, and air exposure times, while the second component's load was influenced by dry matter content and lactic acid concentration. The results of these studies indicate the possibility that feeding methods can be optimized by identifying portions with higher CT or MTD data using IRT measurements just before feeding dairy cows in the field. As a result, increasing the use of IRT in feed management and preservation processes is projected to have a positive impact on animal productivity in the future.

Fermentation profile, aerobic stability, and microbial community dynamics of corn straw ensiled with Lactobacillus buchneri PC-C1 and Lactobacillus plantarum PC1-1

Corn straw is suitable for preservation as silage despite being neglected due to its varying chemical composition, yield, and pathogenic influence during ensiling. This study examined the effects of beneficial organic acid-producing lactic acid bacteria (LAB), including Lactobacillus buchneri (Lb), L. plantarum (Lp), or their combination (LpLb), on fermentation profile, aerobic stability, and microbial community dynamics of corn straw harvested at late maturity stage after 7d, 14d, 30d, and 60d of ensiling. Higher levels of beneficial organic acids, LAB counts, and crude protein (CP), and lower levels of pH and ammonia nitrogen were detected in LpLb-treated silages after 60d. Lactobacillus, Candida, and Issatchenkia abundances were higher (P < 0.05) in Lb and LpLb-treated corn straw silages after 30d and 60d ensiling. Additionally, the positive correlation between Lactobacillus, Lactococcus and Pediococcus, and the negative correlation with Acinetobacter in LpLb-treated silages after 60d emphasizes a potent interaction mechanism initiated by organic acid and composite metabolite production to reduce pathogenic microorganisms' growth. Also, a significant correlation between Lb and LpLb-treated silages with CP and neutral detergent fiber after 60d further highlights the synergistic effect of incorporating L. buchneri and L. plantarum for improved nutritional components of mature silages. The combination of L. buchneri and L. plantarum improved aerobic stability, fermentation quality, and bacterial community and reduced fungal population after 60d of ensiling, which are properties of well-preserved corn straw.

Metal coordinating-induced self-assembly of cyclic lipopeptides into high-performance antimicrobial supramolecules

This study designed a green hydrothermally-chelating approach to generate robust antimicrobial complexes via metal-coordinated supramolecular self-assembly of cyclic lipopeptides (CLs). The metal ion (Ca²⁺ and Zn²⁺)-coordinated CL (Ca/CL or Zn/CL complex; 1 mg/mL) demonstrated potent antibacterial activity against fungi (A. niger) and bacteria (E. coli and S. aureus) respectively, and in particular, completely suppressed the microbial resistance. Further physicochemical and spectal analysis showed that this coordination approach led to CL with enhanced hydrophobic and intermolecular electrostatic interactions, forming β-sheet-rich secondary structures allowing the complexes easily contact with and destroy the membrane of microorganisms. Practical application experiments validated that the Ca/CL and Zn/CL complexes strongly avoided table grape and fresh tomato from the contamination of pathogen. The findings of this study laid foundation for the utilization of metal ions to improve the biological activity of natural antimicrobial peptides.

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.

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 Cellulase or Lactiplantibacillus plantarum on the Ensiling Performance and Bacterial Community in Mixed Silage of Alfalfa and Leymus chinensis

The objective of this study was to evaluate the effects of Lactiplantibacillus plantarum or cellulase on the fermentation characteristics and bacterial community of mixed alfalfa (Medicago sativa L., AF) and Leymus chinensis (LC) silage. The harvested alfalfa and Leymus chinensis were cut into 1-2 cm lengths by a crop chopper and they were thoroughly mixed at a ratio of 3/2 (wet weight). The mixtures were treated with no addition (CON), Lactiplantibacillus plantarum (LP, 1 × 10⁶ cfu/g fresh material), cellulase (CE, 7.5 × 10² U/kg fresh material) and their combination (LPCE). The forages were packed into triplicate vacuum-sealed, polyethylene bags per treatment and ensiled for 1, 3, 5, 7 and 30 d at room temperature (17-25 °C). Compared to the CON groups, all the additives increased the lactic acid content and decreased the pH and ammonia nitrogen content over the ensiling period. In comparison to the other groups, higher water-soluble carbohydrate contents were discovered in the CE-inoculated silages. Compared to the CON groups, the treatment with LPCE retained the crude protein content and reduced the acid detergent fiber content. The principal coordinate analysis based on the unweighted UniFrac distance showed that individuals in the AF, LC, CON and LPCE treatment could be significantly separated from each other. At the genus level, the bacterial community in the mixed silage involves a shift from Cyanobacteria_unclassified to Lactobacillus. Lactobacillus dominated in all the treatments until the end of the silage, but when added with Lactiplantibacillus plantarum, it was more effective in inhibiting undesirable microorganisms, such as Enterobacter, while reducing microbial diversity. By changing the bacterial community structure after applying Lactiplantibacillus plantarum and cellulase, the mixed silages quality could be further improved. During ensiling, the metabolism of the nucleotide and carbohydrate were enhanced whereas the metabolism of the amino acid, energy, cofactors and vitamins were hindered. In conclusion, the relative abundance of Lactobacillus in the mixed silage increased with the addition of Lactiplantibacillus plantarum and cellulase, which also improved the fermentation quality.

Effects of growth stage on the fermentation quality, microbial community, and metabolomic properties of Italian ryegrass (Lolium multiflorum Lam.) silage

Introduction

This study aimed to investigate the effects of different growth stages (booting period-SYK; initial flowering-SCK; full flowering-SSK) on the fermentation quality, microbial community, metabolic pathways and metabolomic characteristics of Italian ryegrass silage.

Methods

Single molecule real-time (SMRT) sequencing and ultra-high performance liquid chromatography-mass spectrometry (UHPLC-MS/MS) were used to analyze bacterial communities and metabolites, respectively.

Results

After 60 d of fermentation, SYK had the lowest pH and the highest lactic acid content, which were significantly different from the other groups. The bacteria with the highest abundance in SYK, SCK and SSK groups were Lactiplantibacillus plantarum (63.98%), Weissella minor (28.82%) and Levilactobacillus brevis (64.81%), respectively. In addition, among the main differential metabolites in different growth stages, the number of amino acids was the most, and the corresponding metabolic pathways were mainly amino acid metabolic pathways. The biosynthesis of phenylalanine, tyrosine and tryptophan was significantly enriched (p<0.01) at booting stage and full flowering stage. Purine metabolism and ABC transporter pathway were significantly enriched at the initial flowering (p<0.001). Lactiplantibacillus plantarum had a negative correlation with xanthine and ganoderic acid F. Weissella minor had a positive correlation with D-Mannose and ganoderic acid F. Levilactobacillus brevis had a positive correlation with xanthine, and Latilactobacillus sakei had a positive correlation with cinnamic acid, D-Mannose, 2-Hydroxycinnamic acid and uridine.

Discussion

In conclusion, this study reveals the interaction mechanisms between ryegrass raw materials at different growth stages and epiphytic microorganisms during ensiling fermentation, providing new ideas for screening functional lactic acid bacteria, and laying a theoretical foundation for the production of safe and high-quality silage.

Varieties and ensiling: Impact on chemical composition, fermentation quality and bacterial community of alfalfa

Introduction

Six species of alfalfa commonly found in northern China were collected in the present study.

Methods

The chemical composition and epiphytic microbial communities during the ensiling were analyzed; and their effects on fermentation quality and silage bacterial communities were assessed. The effects of physicochemical characteristics of alfalfa on the bacterial community were also investigated in terms of nutritional sources of microbial growth and reproduction.

Results and discussion

The results showed that the chemical composition was significantly different in various alfalfa varieties, yet, the dominant genera attached to each variety of alfalfa was similar, except for pantoea (p<0.05). After ensiling, both the fermentation quality and microbial community changed obviously (p<0.05). Specifically, ZM2 had lower pH and ammonia nitrogen (NH₃-N) content but higher LA content than other varieties of alfalfa silage. Beneficial bacteria such as Lentilactobacillus and Lactiplantibacillus were predominant in ZM2, which accounted for the higher fermentation quality. Significant correlations between the chemical composition of silage, fermentation quality and bacterial communities composition were observed. Moreover, variations in bacteria community structure during the fermentation of alfalfa were mainly influenced by water-soluble carbohydrates (36.79%) and dry matter (21.77%).

Conclusion

In conclusion, this study revealed the influence of chemical composition on microbial community and fermentation quality, laying the groundwork for future studies on high-quality silage.

Metagenomics analysis reveals the performance of homo- and heterofermentative lactic acid bacteria in alfalfa silage fermentation, bacterial community, and functional profiles

Alfalfa (Medicago sativa L.) is a kind of roughage frequently utilized as an animal feed but challenging to be ensiled due to its low water-soluble carbohydrate (WSC), high water content, and elevated buffering capacity, thus requiring the application of lactic acid bacteria (LAB) to improve its fermentation. This study employed high-throughput metagenomic sequence technology to reveal the effects of homofermentative LAB, Lactobacillus plantarum (Lp), or Pediococcus pentosaceus (Pp), and heterofermentative LAB, L. buchneri (Lb), or their combinations (LbLp or LbPp) (applied at 1.0 × 109 colony forming units (cfu) per kilogram of alfalfa biomass fresh material) on the fermentation, microbial community, and functional profiles of alfalfa silage after 7, 14, 30, and 60 ensiling days. The results indicated a reduction (P < 0.05) in glucose and pH and higher (P < 0.05) beneficial organic acid contents, xylose, crude protein, ammonia nitrogen, and aerobic stability in Lb-, LbPp-, and LbLp-inoculated alfalfa silages after 30 and 60 d. Also, higher (P < 0.05) WSC contents were recorded in LbLp-inoculated alfalfa silages after 30 d (10.84 g/kg dry matter [DM]) and 60 d (10.92 g/kg DM). Besides, LbLp-inoculated alfalfa silages recorded higher (P < 0.05) LAB count (9.92 log10 cfu/g) after 60 d. Furthermore, a positive correlation was found between the combined LAB inoculants in LbLp-inoculated alfalfa silages and dominant LAB genera, Lactobacillus and Pediococcus, with fermentation properties after 30 and 60 d. In addition, the 16S rRNA gene-predicted functional analyses further showed that the L. buchneri PC-C1 and L. plantarum YC1-1-4B combination improved carbohydrate metabolism and facilitated further degradation of polysaccharides in alfalfa after 60 d of ensiling. These findings reveal the significant performance of L. buchneri and L. plantarum in combination with dominant LAB species in suppressing the growth of Clostridia, molds, and yeasts and improving the fermentation characteristics and functional carbohydrate metabolism of alfalfa after 60 d ensiling, thus suggesting the need for further studies to uncover the diverse performance of the LAB combination and their consortium with other natural and artificial inoculants in various kinds of silages.

Effects of Bacillus subtilis or Lentilactobacillus buchneri on aerobic stability, and the microbial community in aerobic exposure of whole plant corn silage

This study aimed to evaluate the effects of Bacillus subtilis or Lentilactobacillus buchneri on the fermentation quality, aerobic stability, and bacterial and fungal communities of whole plant corn silage during aerobic exposure. Whole plant corn was harvested at the wax maturity stage, which chopped to a length of approximately 1 cm, and treated with the following: distilled sterile water control, 2.0 × 10⁵ CFU/g of Lentilactobacillus buchneri (LB) or 2.0 × 10⁵ CFU/g of Bacillus subtilis (BS) for 42 days silage. Then, the samples were exposed to air (23-28^°C) after opening and sampled at 0, 18 and 60 h, to investigate fermentation quality, bacterial and fungal communities, and aerobic stability. Inoculation with LB or BS increased the pH value, acetic acid, and ammonia nitrogen content of silage (P < 0.05), but it was still far below the threshold of inferior silage, the yield of ethanol was reduced (P < 0.05), and satisfactory fermentation quality was achieved. With the extension of the aerobic exposure time, inoculation with LB or BS prolonged the aerobic stabilization time of silage, attenuated the trend of pH increase during aerobic exposure, and increased the residues of lactic acid and acetic acid. The bacterial and fungal alpha diversity indices gradually declined, and the relative abundance of Basidiomycota and Kazachstania gradually increased. The relative abundance of Weissella and unclassified_f_Enterobacteria was higher and the relative abundance of Kazachstania was lower after inoculation with BS compared to the CK group. According to the correlation analysis, Bacillus and Kazachstania are bacteria and fungi that are more closely related to aerobic spoilage and inoculation with LB or BS could inhibit spoilage. The FUNGuild predictive analysis indicated that the higher relative abundance of fungal parasite-undefined saprotroph in the LB or BS groups at AS2, may account for its good aerobic stability. In conclusion, silage inoculated with LB or BS had better fermentation quality and improved aerobic stability by effectively inhibiting the microorganisms that induce aerobic spoilage.

Preservation characteristics and bacterial communities of crimped ensiled barley grains modulated by moisture content and additive application

Information about the relationships between preservation characteristics and main bacterial communities of fermented feeds can guide decision making during feed preservation and silage additive development. The objective was to evaluate fermentation quality, aerobic stability, microbial quality and bacterial profile of crimped barley grains ensiled under three moisture contents (MC): 228 (low MC), 287 (medium MC) and 345 (high MC) g/kg fresh matter; and using four additive treatments: 1. Control (CONT), 2. Formic and propionic acid-based additive (FPA), 3. Inoculation with homofermentative and heterofermentative strains of lactic acid bacteria (LAB), and 4. Salt-based additive (SALT). There was a quadratic effect (p < 0.05) of incremental MC on pH where greater decline happened from low (5.81) to medium (4.83) MC than from medium to high (4.28) MC, while lactic acid concentration and aerobic stability increased in a linear manner (p < 0.05). Ammonia-N and acetic acid concentrations increased quadratically (p < 0.05) with increasing levels of MC. The effects of additives depended on MC so that improvements in preservation characteristics in response to LAB and SALT were observed at medium and high MC, while FPA was effective at all MC levels. A minor shift was observed in bacterial ecology from raw material towards low MC samples, with Erwiniaceae sp., Enterobacterales spp. and Pseudomonas dominating the fermentation. A major change occurred in medium and high MC materials, where Fructilactobacillus dominated the fermentation in CONT, FPA and SALT silages. LAB-treated silages at medium and high MC resulted in a distinguished pattern with dominance of Lentilactobacillus followed by Lactiplantibacillus. Most abundant communities in the samples, such as Fructilactobacillus, Erwiniaceae sp., Enterobacterales spp. and Pseudomonas, were correlated with several fermentation characteristics. Our results showed that crimped barley grains could be successfully ensiled under various MC and additive treatments. Low MC feeds had higher risk to be aerobically unstable while high MC resulted in more extensive fermentation, with potentially poor fermentation quality. The suitable additive depends on the raw material characteristics as LAB and SALT require relatively high MC to be effective, while FPA showed consistent improvements over all MC levels used in the current study. Awareness of the MC of grain prior to ensiling allows to identify the risks to preservation quality and provides information for choosing an effective additive.

Lentilactobacillus buchneri Preactivation Affects the Mitigation of Methane Emission in Corn Silage Treated with or without Urea

The aim of this study was to investigate the effect of different forms of Lentilactobacillus buchneri on the in vitro methane production, fermentation characteristics, nutritional quality, and aerobic stability of corn silage treated with or without urea. The following treatments were applied prior to ensiling: (1) no urea treatment and LB; (2) no urea treatment+freeze dried LB; (3) no urea treatment+preactivated LB; (4) with urea treatment+no LB; (5) with urea treatment+freeze dried LB; (6) with urea treatment+preactivated. LB was applied at a rate of 3 × 108 cfu/kg on a fresh basis, while urea was applied at a rate of 1% on the basis of dry matter. Data measured at different time points were analyzed according to a completely randomized design, with a 2 × 3 × 5 factorial arrangement of treatments, while the others were analyzed with a 2 × 3 factorial arrangement. Preactivated LB was more effective than freeze-dried LB in reducing silage pH, ammonia nitrogen, cell-wall components, yeast count, and carbon dioxide production, as well as increasing lactic acid and residual water-soluble carbohydrate and aerobic stability (p < 0.0001). A significant reduction in the methane ratio was observed after 24 h and 48 h incubation with preactivated forms of LB (p < 0.001). The results indicated that preactivated LB combined with urea improved fermentation characteristics, nutritional quality, and aerobic stability and reduced the methane ratio of corn silages.

Fermentation quality and bacterial ecology of red clover dominated silage modulated by different management factors

Identification of bacterial communities in both the raw material and the subsequent silages provides new insights into understanding the silage fermentation process. The objective was to evaluate how different silage management factors affect silage preservation characteristics, the microbiome, and their correlations. A red clover dominated sward was used as the raw material and ensiled in pilot scale using a 3 × 4 design, with three management conditions including the level of compaction (loose and tight), and further, for the tightly compacted silages contamination with soil and faeces was conducted; and four different additive treatments with different modes of action: Control without additive (CONT), formic and propionic acid-based additive (FPA), homofermentative lactic acid bacteria inoculant (LAB) and salt-based additive (SALT). Samples of the raw material and subsequent silages were taken and routinely analysed, including DNA extraction and PCR amplification using universal primers. Tight compaction reduced slightly the extent of silage fermentation, but contamination with soil and faeces stimulated a non-desired type of fermentation with higher concentrations of ethanol, acetic acid and propionic acid and a higher pH. Use of LAB and SALT had only minimal effects on silage fermentation, but FPA clearly restricted fermentation and resulted in a better fermentation quality (lower pH, ammonia N and acetic acid concentration) of the silages compared to CONT. The FPA silages presented greater diversity of bacterial communities compared to the other silages. Proteobacteria were the most abundant in raw material, followed by Firmicutes, and major shifts happened in these communities during the silage fermentation process. Weissella was found in small amounts in the raw material but it dominated in the silages. The most abundant communities in the silages, such as Weissella, Lactobacillus and Pseudomonas, were correlated with several silage fermentation characteristics. Use of FPA improved fermentation quality of silages, but SALT and LAB differed from CONT to a smaller extent. All additives modified the bacterial profiles of grasses ensiled under different management conditions. The combination of parameters related to silage quality and bacterial communities provided a deeper understanding of the silage fermentation process and how they can be manipulated to obtain better feed quality.

Diversity of growth performance and rumen microbiota vary with feed types

Diet is a major factor in influencing the growth performance and the microbial community of lambs. This study aimed to investigate how diverse diets influence their growth performance and rumen microbiota. Ninety male lambs were randomly allocated into three groups in a completely randomized design with equal lambs: non-pelleted native grass hay (HA) as the control diet and pelleted native grass hay (GP) and pelleted native grass hay with concentrate (GPC) as experimental diets. The rumen fluid samples of the lambs in the HA, GP, and GPC groups were used to study rumen microbiota diversity through 16S rDNA high-throughput sequencing. In the present study, the final body weight, dry matter intake, and average daily gain differed significantly (p &lt; 0.05) among the HA, GP, and GPC groups. Compared to the HA group, higher final body weight, dry matter intake, and average daily gain were found in the GP group. Similarly, better animal performance was observed in the GPC group than in the GP group. The principal coordinates analysis displayed that the composition of the rumen microbiota in the three groups was distinctly separated from each other. Bacteroidetes and Firmicutes were the dominant members of the community in the HA and GP groups, while Bacteroidetes, Firmicutes, and Proteobacteria became the predominant members in the GPC group. The comparison among these groups showed significant (p &lt; 0.05) differences in Rikenellaceae_RC9_gut_group, Prevotella_1, Ruminococcaceae_NK4A214_group, and Succiniclasticum. These results suggest that the GP and GPC diets are more beneficial for growth performance than the HA diet and also indicate that the rumen microbiota varied in response to different feed types. In conclusion, these results could provide strategies to influence rumen microbiota for better growth and a healthier ecosystem on the Mongolian Plateau and lay the theoretical groundwork for feeding the pelleted native grass diet.

Effects of Lactiplantibacillus plantarum and Lactiplantibacillus brevis on fermentation, aerobic stability, and the bacterial community of paper mulberry silage

The present study investigated the dynamic profiles of fermentation quality, aerobic stability, and the bacterial community of paper mulberry silage inoculants without (Control) or with Lactiplantibacillus plantarum (LP), Lactiplantibacillus brevis (LB), or their combination (LPLB), which was screened from naturally fermented paper mulberry. The results showed that the inoculated treatments had significantly reduced neutral detergent fiber, water-soluble carbohydrates, and ammoniacal nitrogen contents compared with the control after 60 days of ensiling (the decreased proportion of LP, LB, and LPLB treatments ranged from 7.33%-11.23%, 9.60%-21.44%, and 21.53%-29.23%, respectively, p < 0.05). The pH value of the LP and LB treatments was significantly lower than that of the control after 60 days of ensiling (4.42 and 4.56 vs. 4.71, p < 0.05). The LP treatment promoted lactic acid accumulation and LAB number compared with the control (66.59% vs. 54.12% and 8.71 log10 CFU/g vs. 8.52 log10 CFU/g, respectively, p < 0.05), and the LB and LPLB treatments inhibited the growth of yeast and mold after 14 days of fermentation. After 5 days of aerobic exposure, both the LB and LPLB treatments increased the aerobic stability time and acetic acid content (from 29 to 75 h and 16.14%-48.72%, respectively, p < 0.05), inhibited the growth of yeast and mold, and did not detect butyric acid. Additionally, the bacteria community of each treatment was dominated by Aerococcus on day 3 of ensilage (accounting for 54.36%-69.31%), while the inoculated treatments reduced the abundance of Aerococcus on day 60 (from 59.73% to 85.16%, p < 0.05), and Lactobacillus became the dominant genus (accounting for 54.57%-70.89%). Inoculation of L. plantarum effectively maintained the acidic environment at the end of the fermentation system by maintaining the abundance of Lactobacillus, maximizing the preservation of dry matter and protein, and reducing protein corruption. Inoculation of L. brevis alone or in combination with L. plantarum significantly inhibited the growth of mold and improved the aerobic stability of paper mulberry silage.

Effects of Acremonium cellulase and heat-resistant lactic acid bacteria on lignocellulose degradation, fermentation quality, and microbial community structure of hybrid elephant grass silage in humid and hot areas

To better evaluate the effects of Acremonium cellulase (AC) and previously screened heat-resistant Lactobacillus plantarum 149 (LP149) on lignocellulose degradation, fermentation quality, and microbial community during ensiling in humid and hot areas, this study used a small-scale fermentation system to prepare hybrid elephant grass silage at 30 and 45°C, respectively. Compared to control and commercial inoculant Lactobacillus plantarum (LP), the addition of AC or strain LP149 decreased the contents of neutral detergent fiber, acid detergent fiber, and cellulose and increased the contents of glucose, fructose, and sucrose during fermentation. Furthermore, AC and LP149 treatments altered the microbial communities' structure during ensiling. AC treatment provided more substrate for microbial fermentation, resulting in an increase in bacterial alpha diversity. LP149 treatment increased the Lactobacillus abundance and optimized the bacterial community compositions. In addition, AC and LP149 treatments had higher (P < 0.05) lactic acid and acetic acid contents and lower (P < 0.05) pH, butyric acid, and NH3-N levels compared to the control. These results indicated that AC and strain LP149 are promising silage additives that can promote lignocellulose degradation and improve the fermentation quality of hybrid elephant grass in humid and hot areas.

Effects of Different Additives on Fermentation Quality, Microbial Communities, and Rumen Degradation of Alfalfa Silage

This study examined the effects of different additives on the fermentation quality, nutrient composition, microbial communities, and rumen degradation of ensiled alfalfa. Six treatments were employed in which additives were applied to alfalfa on a fresh weight basis: CK (no additive), FA (0.6% formic acid), CaO (3% calcium oxide and 3% urea), LB (1 × 106 cfu/g Lentilactobacillus buchneri), GLB (2% glucose and 1 × 106 cfu/g L. buchneri), and FLB (2% fucoidan and 1 × 106 cfu/g L. buchneri). After 60 days of ensiling, all treatments altered the bacterial communities, improved the fermentation quality, reduced dry matter (DM) and crude protein (CP) losses, and enhanced the rumen degradation of nutrients. The addition of LB increased the relative abundance of Lactobacillus spp. (p < 0.05), whereas GLB reduced (p < 0.05) the NH3-N:TN ratio and elevated (p < 0.05) the concentrations of Lactobacillus and lactic acid content. The FA treatment reduced (p < 0.05) the pH, as well as the DM and CP degradations, while the CaO treatment increased the degradations of DM, acid detergent fiber, and neutral detergent fiber. We concluded that FA, LB, GLB, and FLB had beneficial effects on alfalfa fermentation, and that CaO increased alfalfa silage rumen degradation.

Improving the quality of Napier grass silage with pyroligneous acid: Fermentation, aerobic stability, and microbial communities

The presence of undesirable microorganisms in silage always leads to poor fermentation quality and low aerobic stability. Pyroligneous acid (PA), a by-product of biochar production, is known to have strong antimicrobial and antioxidant activities. To investigate the effects of PA on fermentation characteristics, aerobic stability, and microbial communities, Napier grass was ensiled with or without 1 and 2% PA for 30 days and then aerobically stored for 5 days. The results showed that PA application decreased (P < 0.01) the pH value, ammonia nitrogen content, and number of undesirable microorganisms (coliform bacteria, yeasts, and molds) after 30 days of ensiling and 5 days of exposure to air. The temperature of the PA-treated group was stable during the 5-day aerobic test, which did not exceed room temperature more than 2°C. The addition of PA also enhanced the relative abundance of Lactobacillus and reduced that of Klebsiella and Kosakonia. The relative abundance of Candida was higher in PA-treated silage than in untreated silage. The addition of PA decreased the relative abundance of Kodamaea and increased that of Monascus after 5 days of exposure to air. The abundances of Cladosporium and Neurospora were relatively high in 2% PA-treated NG, while these genera were note observed in the control group. These results suggested that the addition of PA could improve fermentation characteristics and aerobic stability, and alter microbial communities of silage.

Role of Lactiplantibacillus paraplantarum during anaerobic storage of ear-removed corn on biogas production

To optimize the volatile fatty acid production for anaerobic fermentation, the ear-removed corn was ensiled without (control) or with Lactiplantibacillus plantarum (LP), Lacticaseibacillus paracasei (LC) and L. paraplantarum (LpP). Inoculation of LpP increased acetic acid content by 40%, and decreased butyric acid content by 38% in relative to control. Moreover, inoculation of LpP decreased the bacterial alpha diversity indices, while inherent species of Lentilactobacillus buchneri and L. hilgardii dominated the anaerobic fermentation. In particular, inoculation of LpP restricted the growth of yeasts and production of propionic acid at the early stage of storage, but continuously stimulated anaerobic fermentation, resulting in a higher maximal cumulative gas emissions of methane (by about 20 %) than that of LP and LC. Therefore, inoculation of LpP during anaerobic storage was favorable to produce intermediate metabolites (acetic acid) for subsequent biogas production of ear-removed corn.

Effect of exogenous microorganisms on the fermentation quality, nitrate degradation and bacterial community of sorghum-sudangrass silage

This study aims to investigate the effects of adding Lactobacillus buchneri (LB), Lactobacillus brevis (LBR) and Bacillus subtilis (BS) on the fermentation quality, nitrate degradation and bacterial community of sorghum-sudangrass silage. The results showed that the addition of LB significantly increased the pH and acetic acid content (p < 0.05), but high-quality silage was obtained. The addition of LBR and BS improved the fermentation quality of sorghum-sudangrass silage. The use of additives reduced the nitrate content in sorghum-sudangrass silage. The LB group increased the release of N₂O at 3–7 days of ensiling (p < 0.05), and LBR and BS increased the release of N₂O at 1–40 days of ensiling (p < 0.05). On the first day of ensiling, all silages were dominated by Weisslla, over 3 days of ensiling all silages were dominated by Lactobacillus. Acinetobacter, Serratia, Aquabacterium, and unclassified_f_enterobacteriaceae showed significant negative correlations with nitrate degradation during sorghum-sudangrass ensiling (p < 0.05). The BS and LBR groups increased the metabolic abundance of denitrification, dissimilatory nitrate reduction, and assimilatory nitrate reduction (p < 0.05). Overall, the additive ensures the fermentation quality of sorghum-sudangrass silage and promotes the degradation of nitrate by altering the bacterial community.

Effects of antibacterial peptide-producing Bacillus subtilis, gallic acid, and cellulase on fermentation quality and bacterial community of whole-plant corn silage

In the current study, we assessed the effects of antibacterial peptide-producing Bacillus subtilis (BS), gallic acid (GA) and cellulase (CL) on the fermentation quality and bacterial community of various varieties of whole-plant corn silage. Three different varieties of whole-plant corn (Yuqing386, Enxiai298, and Nonghe35) were treated with 0.02% BS (fresh material basis), 0.2% GA (fresh material basis) and 0.02% CL (fresh material basis), after which 45 days of anaerobic fermentation were conducted. With the exception of its low dry matter content, the results showed that Yuqing386's crude protein, water-soluble carbohydrate, and lactic acid contents were significantly higher than those of the other two corn varieties. However, its acid detergent fiber and cellulose contents were significantly lower than those of the other two corn varieties. Among the three corn variety silages, Yuqing386 had the highest relative abundance of Lactobacillus at the genus level and the biggest relative abundance of Firmicutes at the phylum level. In addition, the three additives markedly enhanced the quantity of dry matter and crude protein as compared to the control group. The application of GA considerably decreased the level of neutral detergent fiber while significantly increasing the content of lactic acid and water-soluble carbohydrates. Even though all additives enhanced the structure of the bacterial community following silage, the GA group experienced the greatest enhancement. On a phylum and genus level, the GA group contains the highest relative abundance of Firmicutes and Lactobacillus, respectively. Overall, of the three corn varieties, Yuqing386 provides the best silage qualities. GA has the biggest impact among the additions employed in this experiment to enhance the nutritional preservation and fermentation quality of whole-plant corn silage.

Microbial Community, Co-Occurrence Network Relationship and Fermentation Lignocellulose Characteristics of Broussonetia papyrifera Ensiled with Wheat Bran

Broussonetia papyrifera has a high lignocellulose content leading to poor palatability and low digestion rate of ruminants. Thus, dynamic profiles of fermentation lignocellulose characteristics, microbial community structure, potential function, and interspecific relationships of B. papyrifera mixing with wheat bran in different ratios: 100:0 (BP100), 90:10 (BP90), 80:20 (BP80), and 65:35 (BP65) were investigated on ensiling days 5, 15, 30, and 50. The results showed that adding bran increased the degradation rate of hemicellulose, neutral detergent fiber, and the activities of filter paper cellulase, endoglucanase, acid protease, and neutral protease, especially in the ratio of 65:35. Lactobacillus, Pediococcus, and Weissella genus bacteria were the dominant genera in silage fermentation, and Pediococcus and Weissella genus bacteria regulated the process of silage fermentation. Compared with monospecific B. papyrifera silage, adding bran significantly increased the abundance of Weissella sp., and improved bacterial fermentation potential in BP65 (p < 0.05). Distance-based redundancy analysis showed that lactic acid bacteria (LAB) were significantly positive correlated with most lignocellulose content and degrading enzymes activities, while Monascus sp. and Syncephalastrum sp. were opposite (p < 0.05). Co-occurrence network analysis indicated that there were significant differences in microbial networks among different mixing ratios of B. papyrifera silage prepared with bran. There was a more complex, highly diverse and less competitive co-occurrence network in BP65, which was helpful to silage fermentation. In conclusion, B. papyrifera ensiled with bran improved the microbial community structure and the interspecific relationship and reduced the content of lignocellulose.